Mars Science Laboratory
|Mars Science Laboratory|
|Phase : E / Status : active|
Self-portrait of the Curiosity rover
|COSPAR designation :||2011-070A|
|NORAD / SCN-ID :||37936|
|Start date:||11/26/2011 3:02 PM UTC|
|Starting place:||Cape Canaveral , LC-41|
|Launcher:||Atlas V (541) (AV-028)|
|Mission duration:||Primary mission: 669 Mars Sols
(687 Earth days)
Current: 2864 Sols
(2943 Earth days)
|Landing place:||" Bradbury Landing " in Gale crater
Mars Science Laboratory ( MSL for short ) is a NASA mission as part of the flagship program that studies Mars with regard to its current and past suitability as a biosphere . For this purpose, a largely autonomous rover with the name Curiosity ( English for 'curiosity'), which is equipped with ten instruments for examining rock, atmosphere and radiation , was placed on the surface . In addition to a large number of different spectrographs , cameras and meteorological instruments are used to analyze them, which send the measurement data to earth for evaluation. With a mass of 900 kg and the size of a compact small car , Curiosity is by far the heaviest man-made object on the surface of Mars to date and has replaced the Viking daughter probes, each weighing almost 600 kg.
The technology was developed on the basis of the experience with the two Mars Exploration Rovers and has significantly more power in all areas. In addition, some innovations have been incorporated, especially in the area of its landing system (gentle, targeted landing instead of imprecise airbag impact landing ). Furthermore, Curiosity received radionuclide batteries instead of weather-dependent solar cells for its energy supply .
On November 26, 2011, the probe launched aboard an Atlas V (541) from Cape Canaveral Air Force Station ; the landing on Mars was confirmed on August 6, 2012. Shortly after landing began Curiosity , the first images to Earth to send and works since 2864 Sol .
The mission was first mentioned in 2003 in a document called "New Frontiers in the Solar System: An Integrated Exploration Strategy," published by the National Academies , with costs ranging from $ 325 million to $ 650 million . In April 2004, NASA issued a call for the scientific community to submit ideas and concepts for the scientific instruments at the Mars Science Laboratory. At the end of the year, Aerojet tested an old reserve engine from the Viking program in order to obtain initial data for the design of an improved version for the descent stage . Shortly afterwards, eight concepts were selected from the responses to the spring call for integration and further development. In May 2006 the first workshop to determine the landing location for the rover took place. The project then passed the Preliminary Design Review , which resulted in the release of $ 1.63 billion for development, and in June 2007 it passed the final Critical Design Review.
By November 2008, most of the systems development and integration were almost complete and testing began. Shortly afterwards, however, it became clear that the original start date in October 2009 could no longer be met, which is why it was postponed to the end of 2011. The reason for this were technical problems that could not be resolved quickly enough to be able to complete all the scheduled tests in time. The actuators , most of which had to be redesigned, were particularly affected . This delay added another $ 400 million to the mission's cost to a total of $ 2.2 billion, with that number growing to $ 2.5 billion by launch.
On May 27, 2009, the mission's rover's official name was finally announced: Curiosity . Previously, a public competition for naming had been announced, which sixth grader Clara Ma won with this suggested name and a short essay on its meaning. On June 22, 2011, after final tests, the Mars Science Laboratory left the JPL factory in California and was flown on a C-17 of the United States Air Force to the Kennedy Space Center , where the final preparations for the launch and integration with the Atlas -V launcher took place.
On July 22, 2011, after more than five years of searching, it was announced that the Gale crater had been chosen as the landing site.
The overarching, general goal of Curiosity is to investigate whether Mars was currently or in the past capable of harboring life.
Eight specific scientific tasks are derived from this:
- Recording of the composition and amount of carbonaceous organic compounds
- Quantitative measurement of the basic building blocks of life ( hydrogen , nitrogen , oxygen , carbon , phosphorus and sulfur )
- Look for structures that indicate biological processes
- Investigation of the surface of Mars with regard to its mineralogical , chemical and isotope composition
- Research into the processes that created and influenced the soil and rocks
- Determination of the current distribution and status of water and carbon dioxide
- Analysis of the evolution of the atmosphere over a period of 4 billion years
- Detection of the radiation level and spectrum on the surface of Mars
From a technological point of view, three further goals are to be achieved:
- Demonstration of long-range locomotion (5–20 km) on Mars
- Precision landing in a target circle of 20 km in diameter
- Validation of the possibility of landing a heavy and large rover on Mars (important for a later Mars sample return mission )
Send your name to Mars
Under the keyword "Send Your Name to Mars" , NASA made it possible for interested participants to register so that their names can be immortalized on a microchip in the Mars Science Laboratory Rover. By November 2010, 958,424 people worldwide had already registered with their names. Ultimately, 1.2 million names were scanned, lasered onto two small, coin-sized microchips and installed on board the rover. A similar campaign under the same name (“Send your Name to Mars”) already took place with the predecessor Spirit , in which around four million names of schoolchildren and students were burned onto a DVD.
Leonardo da Vinci
In addition, the self-portrait of Leonardo da Vinci and some of his texts and drawings (for example his code on bird flight ) were reduced to microscopic dimensions and also housed on board the rover.
Technical overview Mars Science Laboratory
The following drawing illustrates the structure of the Mars Science Laboratory and provides a brief overview of the functions of the individual components.
|This module controlled the Mars Science Laboratory during the flight from Earth to Mars. It also contained parts for communication and temperature control. Before entering the Martian atmosphere, the module was separated from the capsule.|
|capsule||The capsule contained the descent stage. It protected them and the rover from the effects of open space and the stresses caused by entering the Martian atmosphere. On the upper part there was a container for the parachute, which slowed the descent of the capsule. Various antennas for communication were also attached to the parachute mount.|
|Level of relegation||
After the heat shield and capsule had done their job, they were separated and released the descent stage. This ensured that the rover touched down gently and precisely on the surface of Mars, which was achieved through the use of radar and individual control engines. In addition, the stage contained important components for communication during the cruise flight, as well as the SkyCrane. The descent step hovered a few meters above the surface. With the SkyCrane, the rover was then lowered the last few meters on ropes and gently touched the surface of Mars.
|Rover Curiosity||The rover with the name Curiosity is the core of the mission and carries all scientific instruments and important communication systems. To save space, the undercarriage was folded in during transport.|
|Heat shield||The heat shield protected the other components from the extremely high temperatures when entering the Martian atmosphere.|
|Overall system||Put together, the 3.4 tonne, ready-to-fly construction resulted as shown in the picture. The descent stage and rover were inside the capsule, on which the cruise flight module was mounted.|
The following illustration provides an overview of the Mars Science Laboratory communication system.
Technology of the cruise flight and landing systems
The Mars Science Laboratory was controlled by the cruise flight module, which was mounted on the capsule , as it traveled from Earth to Mars . The module was ring-shaped with a diameter of four meters and had a mass of 600 kg including fuel. It was made of aluminum and was stabilized by several struts . Twelve individual solar cells for energy supply were attached to the surface of the ring , which, with an efficiency of 28.5%, were designed to produce at least 1 kW of electrical power at the end of the mission (shortly before the capsule entered the Martian atmosphere) . In order to be able to call up enough power for very energy-intensive operations, several lithium-ion accumulators were also available. In addition, the module was connected to the batteries of the descent stage and the power supply system from Curiosity , so that it was possible to reorganize the power supply in the event of problems in flight.
During the cruise, the MSL was spin-stabilized at a speed of 2 min −1 around the axis of symmetry. A star sensor and one of two sun sensors were used to determine the position in space . The former observed several dynamically selected guide stars , the sun sensor only used the sun as a reference point. The system was designed redundantly so that the security of the mission could be increased. To control the spin stabilization and for performing path maneuvers eight thrusters served with hydrazine were operated -fuel. This was in two spherical tanks made of titanium .
Since the radionuclide of Curiosity resistant large amounts of heat gave (See power supply ), had this to be removed from the interior of the capsule, so that overheating could be avoided. Therefore, the cruise flight module had a total of ten radiators , which radiated the heat into space. These were simple metal surfaces that were clearly visible on the sides of the module. Using a complex pipeline and a pump, they formed a coolant circuit with the rover's radionuclide battery. Some components (e.g. the batteries and accumulators) were also specifically heated in this way so that they could be protected from cold damage. Several temperature sensors ensured the automatic setting of the cooling and heating system.
Although the cruise flight module itself did not contain its own communication systems, it did have the "Medium Gain Antenna" (MGA), which could be connected to the transmitter / receiver complex of the descent stage via switches. A large part of the communication was handled via this horn antenna during the cruise flight and the first landing phase. Since the MGA had a medium-strong directivity , it had to be at least roughly aligned with the earth in order to achieve a good connection quality. In return, this feature offered a higher data rate with the same transmission power compared to simple, omnidirectional antennas such as B. the PLGA . With optimal alignment, the antenna gain was around 18 decibels , and signals polarized either left or right could be transmitted. It was transmitted at 8401 MHz with a data rate of up to 10 kBit / s, reception took place at around 1.1 kBit / s at 7151 MHz.
The 731 kg capsule, manufactured by Lockheed Martin , protected the parachute, the descent stage and the Rover Curiosity from the influences of open space and from the harsh conditions during the entry into the Martian atmosphere. The structure was designed as a honeycomb core , in which two CFRP plates were supported by an aluminum honeycomb core. On the surface was a thin ablative heat shield made of a cork-like , silicon-based compound. This was the last version of a family of materials whose roots go back to the Viking probes and were most recently used in the Stardust and Genesis missions.
In order to be able to carry out control maneuvers in space and during the entry into the Martian atmosphere, the capsule had eight small engines (arranged in pairs) and eight ballast weights made of tungsten each weighing 25 kg . During the cruise flight, the tungsten weights ensured that the axis of rotation and axis of symmetry matched. During entry they were ejected to change the center of gravity, which in turn affected the angle of attack . The engines, which could develop a thrust of up to 267 Newtons, were only used to control rotation and alignment, they were not used for braking.
On the upper part of the capsule was the container for the parachute , with which the capsule was further decelerated in the lower part of the atmosphere. Several antennas for communication were attached to the bracket. The parachute measured approx. 16 m in diameter and reached a length of over 50 m with its 80 fastening ropes. The parachute holder was designed to be flexible and was able to compensate to a certain extent for the movement and vibrations of the parachute. The parachute was designed for use when falling below the Mach 2 limit and a braking force of up to 289 kN.
The lowest part of the capsule was formed by an ablative heat shield that protected all other components from the very high temperatures (up to 2000 ° C) when entering the Martian atmosphere. With a diameter of 4.57 m it was the largest heat shield ever built for a research mission. The tiles on the shield were made from a relatively new material called the Phenolic Impregnated Carbon Ablator (PICA), which until now has only been used on the Stardust mission. It is based on a carbon - phenol compound, which has a particularly good ratio of protective effect to mass. The shield was designed for a thermal load of 216 W / cm², a shear of up to 540 Pa and a dynamic pressure during flight through the atmosphere of about 37 kPa.
The heat shield also contained seven pressure and temperature gauges. These should record the loads on the shield during entry with high accuracy. The data are of great importance for the designers, since the shields are currently being designed according to the results of simulations. However, these are optimized for the Earth's atmosphere and not that of Mars, which is over a hundred times thinner and consists of 95% carbon dioxide. Therefore, large safety margins were added to the simulation results in order to secure the mission, which, however, consumed considerable amounts of payload mass. The new data from the MSL entry should eliminate these surcharges or at least greatly reduce them so that the scientific payload of future Mars missions can be increased.
Like the cruise flight module, the capsule did not contain its own communication system, but it had three antennas in the area of the parachute holder. There were two identical models in the X-band , the "Parachute Low-Gain Antenna" (PLGA) and the "Tilted Low Gain Antenna" (TLGA), which were responsible for part of the communication during the cruise flight. Both differed only in their position on the structure, whereby they were arranged in such a way that they could fill the blind spots of the other antenna. The directivity of the construction was very low, so that no precise alignment was necessary, which, however, required a low data rate. The antenna gain fluctuated between 1 and 5 dB, as the parachute mount caused considerable reflection effects. At the beginning of the mission (near Earth), data could still be received at 1.1 kBit / s and sent at 11 kBit / s, but with increasing distance the data rate continuously decreased to a few dozen bit / s.
During the first landing phase, UHF communication took place via the "Parachute UHF Antenna" (PUHF). This was an arrangement of a total of eight small patch antennas , which were attached all around the outer cladding of the parachute holder. This resulted in a very stable, omnidirectional emission and reception behavior compared to the PLGA and TLGA, so that data could be transmitted at sufficient speed even in extreme flight situations. This construction has already been successfully tested on the Mars lander Phoenix . The antenna gain was between −5 and +5 dB, with a data rate of at least 8 kBit / s.
Level of relegation
The further deceleration after the parachute was separated about 1,800 m above the ground was carried out by the eight engines of the descent stage, each of which was mounted in pairs. The design was based on the brake engines of the Viking Lander, with the materials and control systems used being adapted to the current state of the art. Each engine was able to generate 0.4 to 3.1 kN of thrust and achieved a specific impulse of up to 221 s. Operation with very low power was also possible (1% of the possible fuel flow) in order to warm up the engines and improve their response behavior. The fuel consumption averaged around 4 kg per second, with a reserve of 390 kg. Two Li-FeS 2 thermal batteries were used to supply the stage with energy .
In order to correctly calculate the rate of descent and distance to the ground, the descent stage had its own radar system , which was mounted on a separate boom and was called the "Terminal Descent Sensor" (TDS). It determined these parameters from a height of 4 km and a speed of less than 200 m / s. For this purpose, the 12 W direction finder signal sent in the Ka band (36 GHz) was emitted via six small antennas, each with an opening angle of 3 °. This arrangement enabled the navigation system to precisely calculate the movement in all three axes, which was essential for the use of the SkyCrane. The system weighed 25 kg and required 120 W of electrical power during active operation.
The most notable part of the approximately 2.4-ton descent step was the so-called SkyCrane complex. This was activated about 20 meters above the surface of Mars and lowered Curiosity on several eight-meter-long ropes like a construction crane . Compared to the usual airbag method, this new process enabled the heavy rover to land safely even on unfavorable terrain and significantly reduced the requirements for its shock resistance (sinking speed: 0.75 m / s instead of approx. 12 m / s for the MER rovers or about 29 m / s for Beagle 2 ). The impact energy was so low that the landing gear could completely absorb it, which meant that no additional landing devices were necessary, such as special shock-absorbing legs, such as those used on the Viking landers. The touchdown of the rover was recorded by force sensors , as the tension on the ropes decreases significantly when it touches the ground. These measurements also made it possible to determine whether Curiosity touched down on the ground at an angle or straight. After the rover was safely on the surface of Mars, the ropes were pyrotechnically cut, and the descent step increased the engine power again in order to make a crash landing a little over a hundred meters away from Curiosity . The process of setting down the rover took a total of 13 seconds.
The descent stage, along with the rover itself, was the only part that had its own communication system. Specifically, a transmitter called “Small Deep Space Transponder” (SDST) was available to the stage in the area of the X-band . This was a further development of the version that was already used on the Mars Exploration Rovers . The two main improvements were increased signal stability in the event of temperature fluctuations and a significantly lower leakage effect . The SDST was responsible for communication during the entire cruise flight and the landing phase. There is an identical model in the rover, but it only became active after landing. Signals could be received up to a threshold of −70 dBm, the bandwidth was designed for 20 to 120 Hertz , depending on the signal strength and setting . The data rate could be automatically set between 8 and 4000 bits per second by the electronics, depending on the signal quality. The system weighed 3 kg and required up to 15 W of power.
Since the signals from the SDST were too weak to send data, they were first amplified by the so-called “Traveling Wave Tube Amplifier” (TWTA). The core element was a traveling wave tube , whereby the design was a modification of the MRO amplifier. The TWTA required up to 175 W electrical power and had a transmission power of up to 105 W. The system was protected against undervoltage and overvoltage damage and weighed 2.5 kg.
In the final phase of landing, after separation from the capsule, the “Descent Low Gain Antenna” (DLGA) provided a connection with the ground station on earth. However, this was more of an open waveguide than a special antenna. This was necessary because it was also the signal connector between the descent step and the antennas of the higher steps. The antenna thus behaved as a normal waveguide until it was separated from the capsule and the end was exposed. The antenna gain could fluctuate between −5 and +8 dB because, depending on the flight situation, there were many reflections and interferences with the surrounding structure. The mass of the "antenna" was 0.45 kg.
After separating the capsule, the UHF communication system lost contact with the PUHF antenna, so that the “Descent UHF Antenna” (DUHF) was then used so that the data connection could be maintained in this frequency band. The antenna gain was extremely volatile due to reflections and interference from the surrounding structure , fluctuating between −15 and +15 dB.
Technology of the Rover Curiosity
Compared to previous Mars rovers
|Dimensions (meter, L × W × H)||3.1 x 2.7 x 2.1||1.6 x 2.3 x 1.5||0.7 x 0.5 x 0.3|
|Energy generation ( kWh / Sol )||2.9||0.3-0.9||Max. 0.1|
|Max. Speed (cm / s)||4th||5||1|
|Data (MB / day)||19-31||6-25||Max. 3.5|
|Computing power ( MIPS )||400||20th||0.1|
In contrast to earlier rover missions on Mars, Curiosity is powered by a radionuclide battery , which is known as a "Multi-Mission Radioisotope Thermoelectric Generator" (MMRTG), instead of the usual solar cells . This solution is independent of the weather, offers a stable thermal environment for the systems in the rover and ensures greater mobility. In addition, the construction is lighter than a solar panel with the same performance, so that more space remains for scientific instruments. 43 kg battery contains 4.8 kg plutonium obtained by the α-decay of the contained plutonium - isotope 238 Pu ( half-life of 87.7 years) initially 2000 W releases heat performance. This heat is by means of Te Sb Ge Ag - and Pb Te - thermocouples converted to 110 W electrical power, which corresponds to an efficiency of about 6%. The energy supply is designed for more than seven times the primary mission time. The DC voltage generated is 28 V, which also corresponds to the voltage of the vehicle electrical system. Some of the heat generated is also used to keep the interior of the rover at an optimal operating temperature. Since the thermocouples have been giving off large amounts of heat continuously since their manufacture, the MMRTG was only attached to the carrier system provided for it at the rear of Curiosity a few days before the start . At this point in time, the rover was already inside the capsule and on the Atlas V rocket, so the deployment had to take place in the Vertical Integration Facility (VIF).
Of Boeing -designed construction is based on the outside of the SNAP-19 battery that even at Pioneer 10 / 11 and Viking 1 / 2 successfully was used. Inside, however, eight “General Purpose Heat Source” capsules (GPHS) are used, which contain all the radioactive material and supply the heat required. These are also considered tried and tested, as they have already been used with the Cassini-Huygens , Galileo , Ulysses and New Horizons probes .
Since the plutonium contained is highly radioactive and toxic, a multi-layered safety concept was implemented to prevent its release in the event of a missile launch. When subjected to mechanical stress, the plutonium dioxide ceramic does not disintegrate into fine dust, but into larger fragments that prevent the absorption of radionuclides into the lungs through breathing . In addition, the material can withstand the heat on re-entry without evaporating and hardly reacts chemically with other substances such as air or water. Inside the battery, the plutonium ceramic is housed in eight individual capsules, each of which has its own heat shield and impact-proof housing. Inside these capsules, the ceramic is surrounded by several layers of different materials (including iridium and graphite ) which, thanks to their high melting point and their high resistance to corrosion , are intended to prevent radioactive substances from escaping after an impact.
NASA gave the probability of an accident with the release of radioactivity at 0.4%. In this case, however, the individual exposure to radioactivity in the starting area should only be 0.05–0.10 millisievert (corresponds roughly to an X-ray examination of the jaw). In previous false starts with protected American radionuclide batteries ( ALSEP and Nimbus B1 ), however, the protective measures proved to be so reliable that no radioactivity could be detected at all.
Nevertheless, there was criticism of this energy supply concept, as a distribution of 238 Pu in the event of a false start could not be ruled out.
In order to be able to operate several energy-intensive systems, such as the SAM instrument, in parallel for a short period of time, Curiosity has two additional lithium-ion batteries . These have a capacity of 42 ampere hours each , deliver an output voltage of 28 V and are designed for several charging cycles per Martian day .
The rover's data processing takes place in the so-called “Rover Compute Element” (RCE), of which an identical reserve unit is available. The central part of RCE is a rad750 - processor of BAE Systems , a clock rate having of 200 MHz and about 400 million instructions per second can handle. The processor, which is located in a CCGA housing, is specified for a total radiation dose of one Mrad and can operate within a very wide temperature range (−55 ° C to 125 ° C). In addition, its structure having a width comprising of 150 nm against the latch-up immune. A main memory with a size of 256 MB, a flash memory with 2 GB and an EPROM with 256 kB are available for storing data, whereby all parts are designed to be fault and radiation tolerant. The operating system used is VxWorks , which manages over 130 threads . A total of 2.5 million lines of C code were written for the mission software.
For an illustrated overview, see also the section Communication system overview
For communication with the ground station on earth, Curiosity has two communication complexes. One works in the UHF band (0.4 GHz) and is responsible for receiving control commands and sending status data, the other complex works in the X band (7–8 GHz) and ensures the transmission of scientific data at a high rate Data volume (up to 250 Mbit per day) during the primary mission. In the cruise flight phase, it complemented the X-band system in its role. This is also the case if there is no direct line of sight to earth or if the rover is in safe mode due to a system failure.
The UHF system has two redundant transmitters, called "Electra Lite Transponders" (ELT), which contain all components for processing and generating radio signals (amplifier, oscillator , transponder, etc.). This is a lighter and less powerful variant of the system that was already used in the Mars Reconnaissance Orbiter . The data rate when sending, which is automatically selected by the electronics depending on the signal quality, is up to 2 Mbit / s, when receiving up to 256 kBit / s. Each transmitter weighs 3 kg and requires up to 96 W of electrical power.
The "Rover UHF Antenna" (RUHF) is Curiosity's primary antenna for transmitting scientific data to the ground station on earth. The UHF communication system of the Mars Reconnaissance Orbiter serves as a relay station . This receives the signals from Curiosity , processes them and then transmits them to the antennas of the Deep Space Network on earth via a high-performance transmission system in the X-band . If the Mars Reconnaissance Orbiter had not been functional when the rover arrived, Mars Odyssey could have been used as a relay, whereby the data rate would have been slightly lower. In addition, the UHF system of the ESA Mars Express probe is also able to communicate with Curiosity , but this is only intended for a short time during possible emergency situations. The RUHF is designed as a helical antenna and, due to its weak directional effect, achieves an antenna gain of around 3 to 6 dB over a large angular range. Data is received at 437 MHz and transmitted at 401 MHz.
In the area of the X-band, Curiosity has a transmitter called “Small Deep Space Transponder” (SDST), which is identical to the one in the descent stage . The SDST on board Curiosity is not normally used for communications during cruise, as the signals are significantly weaker than those of the descent stage. However, if the SDST or amplifier of this stage fails, the rover's transceiver system can also be connected to the antennas of the other stages via a switch. However, the weaker signal is already by 85% by this circuit further 6 dB attenuated , so that the data rate by a multiple fails lower.
Since the signals of the SDST are too weak to send data, they are first amplified by the so-called "Solid State Power Amplifier" (SSPA). This is a transistor amplifier ( MESFET / HEMT combination), the design of which is a further development of the corresponding systems of the Mars Exploration Rover . It can amplify the signal up to 15 W, which requires up to 62 W of electrical power. The amplifier weighs 1.4 kg, is specified for radiation doses of up to 100 krad and was manufactured by General Dynamics .
The HGA (“High Gain Antenna”) is responsible for receiving commands and sending status data in the X-band. It is a patch antenna with a very strong directional effect, which is why it must be aimed very precisely at the earth. However, despite the low amplifier power, relatively high data rates can be achieved in this way. It measures 28 cm in diameter and weighs a total of 8 kg. With optimal alignment, the antenna gain is 26 dB in transmission mode and 21 dB in reception. A misalignment of 8 ° leads to a halving of the profit, with a deviation of more than 12 ° communication is no longer possible. The data rate when sending is at least 160 bit / s or 800 bit / s, depending on the size of the receiving antenna on earth. Commands can typically be received at a rate of 190 bit / s. Transmission takes place at a frequency of 8395 MHz, reception takes place at 7183 MHz.
If there is a problem with the HGA (e.g. due to a defect in the alignment mechanism), the so-called "Rover Low Gain Antenna" (RLGA) is available as a reserve. This has practically no directional effect, which enables communication from almost any position. However, this property greatly reduces the data rate (down to a few bits per second under poor conditions) so that this antenna is only used in emergencies. Due to the extremely weak transmission signal, data can only be sent to the ground station under very good conditions (at a few dozen bits per second). The RLGA is essentially an open waveguide with a special attachment so that a wide antenna pattern can be created with it.
To move about on the surface of Mars, a total of six wheels are used, which are symmetrically attached to two tubular frames (" bogies "), which in turn are connected to one another by a single axis in the center of gravity of the rover. Titanium is used as the material for the frame , while the wheels are made of aluminum, the surface of which is so thin that it behaves somewhat like conventional rubber car tires. Each wheel measures 51 cm in diameter and has a tread depth of about 1.3 cm. Rectangular and square recesses result in a Morse code per wheel , which will later be seen as an imprint on the Martian soil and which stands for Jet Propulsion Laboratory . (J. - - - P. - -. L. - ..) There is a dedicated, brushless DC motor per wheel , which is designed for a total of 45 million revolutions during the entire mission. The rover is steered via the two pairs of wheels at the front and rear, which can turn 90 ° to the left or right, which means that Curiosity can turn 360 ° on the spot. The drive system is able to move the rover at up to four centimeters per second and enables it to cope with inclinations of up to 45 ° (in all directions) and obstacles up to 75 cm high. In practice on Mars, however, these specifications are not fully exhausted for safety reasons, which is why an effective speed of 0.15 to 0.45 cm / s is assumed, which corresponds to a travel distance of 100 to 300 meters per day. The control software is also programmed in such a way that it avoids inclinations of over 30 °. In order to reduce the effort for the ground team, Curiosity is equipped with software that can autonomously recognize and avoid obstacles. This effectively makes the rover much faster, since not every movement command has to be sent from the earth ( signal transit time : up to 40 minutes). To record the required environmental data, four so-called "Hazard Avoidance Cameras" (Hazcam) are attached to the lower part of the rover. It is a pair of two black-and-white cameras that together cover a field of view of 120 ° and can take 3D images. This means that the entire area can be searched for obstacles up to four meters away.
Robotic arm and sample collection
Curiosity has an approximately two meter long robotic arm on its front, which is called “Sample Acquisition, Processing, and Handling” (“SA / SPaH” for short). Due to its three joints, its design is similar to the human system of shoulder , elbow and wrist , which makes it very flexible (five degrees of freedom ). This property is required to bring some instruments close to the objects to be examined. In addition, the end of the arm has a drilling system, an excavator shovel , a brush and a sieve with various collecting containers. This equipment can also make deeper soil and rock layers accessible for analyzes. The two scientific instruments, APXS and MAHLI , are decoupled from the housing so that problems caused by the vibrations during drilling can be avoided. All devices are attached to a rotatable head element at the end of the arm. The most important part of the arm is the drill at the top. This can drill holes up to 5 cm deep in rocks, whereby the material of the drill core is pulverized and conveyed to the CHIMRA filter system. In addition to the rotating movement, the drill head is hammered against the target rock up to 30 times per second according to the principle of a percussion drill , so that it can be penetrated and crushed better. The impact energy can be between 0.05 and 0.8 joules . If a bit gets stuck and cannot be pulled out again, it can be separated and replaced with a new bit. For this purpose, there are two reserve bits in corresponding holders on the front of the rover. The entire drilling system is specified for 81 drilling processes and can work in a temperature range of +70 ° C to −70 ° C.
The "Collection and Handling for Interior Martian Rock Analysis" system (CHIMRA), which is located at the front end of the arm, is responsible for the initial preparation of the drill samples. With the help of several sieves, it can remove particles larger than 150 µm or 1000 µm (depending on the setting) from the sample and direct the remaining material into several small collecting containers. In addition, there is a shovel with which loose Martian soil can be picked up directly without drilling. All conveying processes are triggered by rotating and tilting the arm, and vibrating elements are also installed in some places to prevent material from sticking inside the CHIMRA, as this could contaminate subsequent samples.
Since Curiosity's instruments are highly sensitive to the detection of organic substances, it must be ensured that the measurement results are not distorted by earthly contamination or damage. That is why there are five fist-sized containers at the front of the rover, which are filled with an amorphous silicon dioxide ceramic and a small amount of two fluoroaromatic compounds . The latter can be perceived by the instruments, but usually do not occur in nature. If the ceramic block is drilled, contamination and losses within the conveying and analysis system can be recorded on the basis of differences between expected and actual measurement results. In this way, even unusual measurement results can be reliably identified as errors or as facts.
A distinctive feature of Curiosity is the 1.1 meter high mast (also known as the remote sensing mast) on the front left corner of the chassis. To save space, it was folded back during the cruise flight and was only brought into an upright position after landing. The upper part, which contains almost all instruments, resembles the human head in its freedom of movement, although it can rotate through 360 °. The following scientific instruments are attached to the mast:
Two “navigation cameras” (navcams) are added to these instruments for navigation and orientation. This is an arrangement of a total of four identical black and white cameras with an effective resolution of 1024 × 1024 pixels each. These are attached in pairs to the right and left of the MastCam and thus enable the creation of 3D images. Only one camera is active on the right and one on the left, the other two are connected to the backup computer and are therefore intended as a backup. The optics have a focal length of 15 mm, an aperture number of f / 12 and a near limit of 0.5 m. Together with the CCD image sensor, the construction achieves a resolution of 0.82 mrad per pixel and a field of view of 45 °. Each camera weighs 220 g and requires around 2.2 W of electrical power to operate, whereby a picture can be taken every 5.4 seconds with an exposure time of up to 335 seconds.
Mast Camera (MastCam)
In the "Mast Camera" (short "MastCam") is a complex of two high-resolution cameras at the large mast of Curiosity are attached. With them, the topology, fine surface structures and the atmosphere are to be examined optically in the visible and near infrared spectrum. The use of zoom lenses was sometimes discussed, but these could not be made ready for use in time, so the focal length is fixed. Both cameras use the same Bayer sensors , which achieve a resolution of 1200 × 1200 pixels (1.44 megapixels) and are able to record 720p videos at around 10 frames per second.
The electronics for processing and temporarily storing the image data are also identical. It contains 8 GB of flash memory per camera , which offers space for around 5500 unprocessed images. These can then be compressed in real time either losslessly or lossy using the JPEG process. The only difference between the two cameras is the filters available , the field of view and the focal length . The latter is 34 millimeters for the Mastcam-34 and 100 mm for the Mastcam-100. The field of vision is significantly larger with the Mastcam-34 at 15 ° than with the Mastcam-100, which only reaches 5.1 °. Both cameras can focus over a range of 2.1 m to infinity , which means that the Mastcam-100 can resolve structures with an accuracy of up to 0.15 mm at a distance of 2 m. In addition, there is a filter system that enables targeted scientific analyzes. The individual filters are mounted on a wheel in front of the image sensor and are turned in front of it as required. Each camera has eight filters, whereby the Mastcam-34 is more focused on the visible, the Mastcam-100 more on the infrared. The entire MastCam complex was designed and built by Malin Space Science Systems .
Chemistry & Camera (ChemCam)
The “Chemistry & Camera” complex (“ChemCam” for short) consists of a powerful laser , a spectrometer and a special camera. This device combination is able to analyze the Martian soil as well as rocks and rubble at a distance of up to 7 meters with high accuracy. To do this, the laser is focused on a small point in order to strongly heat the matter there. On the one hand, the top layers of the object can be removed and, on the other hand, the resulting gases and plasmas are examined for their composition by the optical spectrometer . Part of the complex is attached to the mast so that a large number of targets can be analyzed in a short time thanks to its good mobility. The quick identification of rock types is therefore also the primary task of the ChemCam, so that interesting targets can be found for more detailed investigations with other instruments. Further tasks are the analysis of erosion and weather effects, the detection of ice and frost traces as well as the rapid detection of hydrogen carbonates . The system is a cooperative development led by Los Alamos National Laboratory and CNES ( Center national d'études spatiales ), the French space agency based in Toulouse .
The complex of laser and spectrometer is called “Laser-Induced Breakdown Spectrometer” ( LIBS ) and is responsible for the essential part of the analysis. The laser is a major innovation in space travel, as such devices previously either only had an extremely short range or were only used for distance measurement. The laser generates infrared pulses (1067 nm) with a length of 4.5 ns and an energy of up to 14 millijoules on the sample surface. It is strongly focused, which results in a heat output of over 10 MW per square millimeter. This energy acts on a point with a diameter of 0.3 to 0.6 mm. Due to the high power density, a small plasma is generated on the target surface, the emitted light of which is captured by a small telescope (diameter: 11 cm) and guided into an optical fiber . This ends in three optical spectrometers, which cover a wavelength range from 240 to 850 nm (far UV to near infrared light) and can differentiate between 6144 spectral channels with a resolution of 0.09 to 0.30 nm. In the wavelength range, the emission lines of the most important main and minor elements are included, such as barium, strontium and hydrogen.
For better recording of the geological context of the sample, the "Remote Micro-Imager" (RMI) is available, which can record exactly where the laser beam hits. This is a CCD image sensor with 1024 × 1024 pixels and a field of view of 1.1 °. The LIBS telescope is also used as the optics.
Rover Environmental Monitoring Station (REMS)
The “Rover Environmental Monitoring Station” is responsible for general meteorological measurements. The entire complex weighs 1.3 kg and was brought into the project by Spain. The most striking part of the system are the two rod-shaped arms on the mast . Everyone has a hot wire anemometer and a thermopile thermometer. All sensors, with the exception of the UV measuring device and the pressure sensor, are located on the mast of the rover, the electronics are housed in the central chassis.
Six parameters are recorded:
- The soil temperature in a range of 150-300 K , with an accuracy of better than 10 K and a resolution of 2 K.
- Air temperature from 150–300 K (−120 to +30 ° C), accuracy better than 5 K, resolution of 0.1 K.
- Air pressure from 1–1150 Pa , accuracy 10 Pa (20 Pa towards the end of the service life), resolution 0.5 Pa. The pressure sensor is located on the chassis near the electronics of the REMS complex.
- Relative humidity , 0–100%, resolution 1%.
- Ultraviolet radiation : The measuring range 210–370 nm should be covered by six photodiodes (Note: Not to be confused with the UV spectrum UV-A to EUV!): 315–370 nm (UVA), 280–320 nm (UVB), 220-280 nm (UVC), 200-370 nm (total dose), 230-290 nm (UVD), and 300-350 nm (UVE). During the calibration it was found that the channels UVC and UVD only deliver a weak signal. However, the mast camera periodically takes pictures of the diodes in order to determine the dust coverage and to correct the measurement results accordingly. The UV meter is located on top of the central chassis.
- The wind speed : The anemometers can measure horizontal winds in the range from 0 to 70 m / s with an accuracy of 1 m / s and a resolution of 0.5 m / s. Vertical winds, however, can only be recorded up to 20 m / s. They consist of three 2D wind transducers to determine the 3D wind direction. Aerodynamic simulations are used to compensate for measurement errors caused by interference from the rover, mast and boom.
Chemistry & Mineralogy (CheMin)
The CheMin instrument is another spectrometer that is supposed to analyze collected soil samples. This is done with the help of an X-ray source, which irradiates the sample, and a CCD sensor, which uses the phenomenon of X-ray diffraction and X-ray fluorescence to determine its composition. This can provide information about water-related influences and possible biological signatures. The instrument was developed and built by the Ames Research Center .
The soil sample delivered is first passed through the CHIMRA filter system so that too large or too fine components that are not suitable for the measurement can be sorted out. For this purpose, the sample inlet funnels of the CheMin (as with the SAM) are vibrated by piezo actuators at the lower end of these funnels in order to sieve and homogenize the soil samples for the subsequent spectrometric analysis. The design of the sample inlet funnels was verified by laser vibrometers . Particles with a size of up to 150 µm are then evenly fed into a cell with a diameter of 8 mm. Each cell is 175 µm thick, with the sample being filled between two 6 µm thick Mylar sheets or Kapton plastic. A total of 27 refillable cells are arranged on a rotary wheel so that the instrument can easily switch back and forth between several samples. There are also five cells with reference material for calibrating the instrument. To analyze a sample, its cell is positioned in front of the X-ray source. This generates the radiation through the effect of bremsstrahlung , which occurs when electrons from a small amount of radioactive cobalt isotopes hit silicon . The resulting X-ray photons are then concentrated in a beam with a diameter of about 50 µm and directed onto the sample.
After the radiation has penetrated the sample, it is measured by a UV-sensitive CCD sensor with 600 × 600 pixels. This analyzes the strength and refraction of the photons in order to produce spectra that provide information about the composition of the sample. The sensor with a pixel size of 40 × 40 µm takes 224 measurements per second and is cooled down to −60 ° C so that the highest possible sensitivity is achieved. A complete measurement usually takes several hours to produce good results.
Sample Analysis at Mars (SAM)
The SAM complex is Curiosity's heaviest and most powerful instrument . With a mass of 38 kg, it takes up about half of the total mass fraction for scientific payload. Using three combined sensor systems, it is supposed to determine to what extent Mars was and is now a suitable habitat. The focus is on the identification and analysis of organic compounds and light elements as well as the determination of isotope ratios in the atmosphere. It was developed and built by the Goddard Space Flight Center , the peak power can be up to 240 W.
The SAM can analyze both soil samples and gas from the atmosphere, although the material must first be processed. For soil samples, this is the “Sample Manipulation System” (SMS), which has several sieves and then directs the filtered material into one of 74 collecting containers. If volatile substances are to be evaporated from the sample, it can then be heated in one of two ovens, where outgassing then takes place. Since temperatures of up to 1100 ° C are reached in the ovens, which each require up to 40 W electrical power, pyrolysis of organic compounds is also possible. The gas from this process, or a sample from the atmosphere, is then sent to the Chemical Separation and Processing Laboratory (CSPL). This is a very extensive system for further preparation of the measurement. It consists of almost 50 valves, 16 valve blocks and several gas absorbers as well as diverse mixing and separation systems.
After the preparation phase, the gas can be fed into one of the three measuring instruments. The gas chromatograph (GC) is particularly suitable for examining organic compounds . It has six separation columns, each specializing in a certain subgroup of organic compounds. With the help of a helium gas flow, the vaporized material is pushed through the separation columns. A chromatography column is also coated with a chiral substance to enable separation of enantiomers. The organic substances are transported through the column at different speeds depending on their interaction with the column material. A thermal conductivity detector enables detection and determination based on the transit time of the substances coming out of the column. For further analysis, the gas can then be forwarded to the “Tunable Laser Spectrometer” (TLS), but above all to the “Quadrupole Mass Spectrometer” (QMS). The latter is a quadrupole mass spectrometer that determines the mass of the components of the gas. Due to the ionization method used, the molecules break down into characteristic fragments, which can be used to precisely identify the organic molecules. The measuring range extends to elements and molecules with an atomic mass of 2 to 535 u . Alternatively, the Tunable Laser Spectrometer can be used to measure the compounds water, methane and carbon dioxide . It is characterized by a very high sensitivity for these substances and can also determine their internal isotope distribution.
Radiation Assessment Detector (RAD)
The "Radiation Assessment Detector" instrument has been developed for measuring cosmic rays on the surface of Mars. The measuring range is very broad, so that for the first time the total radiation dose for a person on Mars can be determined, which is of great importance for later manned Mars missions . Radiation dose data are also an important parameter for hypotheses about life on Mars . In addition, particle showers can also be measured precisely, which makes it easier to check current models for the structure of the Martian atmosphere. The instrument is housed in the central chassis, weighs 1.56 kg and requires 4.2 W of electrical power. It was developed in a joint project of the Southwest Research Institute , the Christian-Albrechts-Universität zu Kiel and the German Aerospace Center .
The opening of the instrument points exactly upwards and has a field of view of 65 ° for trapping particles. Is measured by means of silicon-based sensors with three pin diodes , a cesium iodide - scintillator and a plastic scintillator based specifically for neutrons. These components are located in the cylinder part of the instrument, the electronics for signal processing are located in the lower part of the instrument (gold-colored in the picture on the right). The measuring range of the RAD instrument for light ions ( Z <9 ) and protons extends from 5 to about 1300 MeV per nucleon, heavier ions (up to Z = 26) can only be detected from 10 MeV. Neutrons can be measured in the range from 5 to 100 MeV, gamma radiation between 0.7 and 5 MeV. Electrons and positrons can be detected from 0.2 MeV, the upper limit for electrons is 100, for positrons already 1 MeV. In most cases, the particles can be measured directly, but in the case of ions, protons and electrons, the measurement can also be made indirectly via the Compton effect from an energy of around 120 MeV . Due to the limited power supply of the rover, RAD was only operated for a maximum of 16 minutes per hour at least until 2017.
Mars Descent Imager (MARDI)
The “Mars Descent Imager” is a high-resolution camera that took pictures of the landing zone during the final descent phase (below 4 km). This should determine the exact landing location and measure the immediate surroundings with high accuracy. The instrument is attached to the front left of the central rover chassis and looks exactly downwards. The Bayer image sensor has 1600 × 1200 pixels and achieves - depending on the height - a resolution of 2500 to 0.33 centimeters per pixel, whereby about five images per second can be taken. MARDI was built by Malin Space Science Systems, weighs 0.66 kg and requires up to 10 W of electrical power.
The field of view of the optics is 90 °; however, only a field of 70 ° × 50 ° is shown, with the longer side running parallel to the direction of flight. As the data could not be transferred immediately due to the low communication bandwidth, there is an 8 GB buffer memory that can store up to 4000 raw images. With the help of the high-resolution images of the MARDI instrument, the inertial sensor of the rover should also be checked for accuracy. This was done by comparing the movement measurement of the sensor with the image shift between two recordings of the camera.
Alpha Particle X-ray Spectrometer (APXS)
The "Alpha Particle X-ray Spectrometer" (APXS for short) is an alpha particle X-ray spectrometer that works on the principle of X-ray fluorescence analysis and particle-induced X-ray emission . The sensor is on the arm of Curiosity fixed and requires a very close contact with the ground. Its elements are brought into an excited state by means of the emitted radioactivity of a small amount of curium-244 , which is located on the "head" of the instrument . These then emit X-rays , which are captured by a silicon drift detector (SDD). In this way, a large number of elements can be identified and their proportion in the sample can be recorded. The aim of the APXS is to explore the rover's geological environment and research the processes that have shaped the soil and rock. The spectrometer is particularly sensitive to salt-forming elements such as calcium or bromine . The APXS was funded by the Canadian Space Agency and built by MDA Space Missions . The silicon drift detector was manufactured by the Bavarian company KETEK.
The instrument's spectrometer can take measurements in the X-ray spectrum from 1 to 25 keV, with a resolution of up to 150 eV . This resolution is only achieved at a detector temperature of below −45 ° C, which is why a Peltier element is available for cooling. The analysis time ranges from 10 minutes to 3 hours, depending on the desired sensitivity (the mass fraction of certain elements can be determined with an accuracy of up to 10 ppm ). During the measurement, a circular area with a diameter of 1.7 cm is irradiated, whereby the instrument can register light elements down to a depth of 5 micrometers, heavy elements up to 50 micrometers. Regardless of the duration of the measurement, the instrument delivers 32 kB of data at the end of the analysis.
Mars Hand Lens Imager (MAHLI)
In the "Mars Hand Lens Imager" (Mahli) is a high resolution camera at the front end of the arm of Curiosity . It serves as a kind of microscope and is intended for the optical examination of very small structures. The 1600 × 1200 pixel CCD sensor, which comes from Kodak , can resolve structures with an accuracy of up to 15 micrometers per pixel at maximum approach (25 mm distance from the sample). In addition to the usual color and sample palette, a penny from 1909 is also attached to the front of the rover housing for calibration . There are several LEDs on the camera housing itself so that recordings can also be made at night. As with the MastCam , 720p videos can also be recorded at around seven frames per second. MAHLI was developed and built by Malin Space Science Systems.
The CCD chip is designed as a Bayer sensor and achieves a quantum yield of 30 to 40%, depending on the wavelength. The active area is 105 mm², including the base, the complete photo electronics measure 20 mm in width and 33 mm in length. The exposure time can be selected between 0.005 and 2 seconds. In addition to the two pairs of LEDs that work in the visible light range, there are also two models for UV light (365 nm), which can be used to detect fluorescent substances in the ultraviolet spectrum .
Dynamic Albedo of Neutrons (DAN)
With the help of the “Dynamic Albedo of Neutrons” instrument, the distribution of hydrogen-containing compounds in the Martian soil at a depth of up to one meter will be determined. For this purpose, the ground is first bombarded with neutrons so that the energetic profile of the backscattered particles can be measured. This method of finding hydrogen is already being used many times on earth, but it is being used for the first time on another celestial body on board Curiosity . The instrument is located at the rear of the rover, weighs just under 5 kg and is provided by Russia .
Two separate modules are responsible for the measurements: The DAN-DE contains the control electronics and the sensors, while the DAN-PNG emits free neutrons on command by means of the reaction 3 H + 2 H → 4 He + n. With each 1 µs pulse, around 10 million neutrons with an energy of 14 MeV per particle are emitted into the ground. The backscattered neutrons are then measured by two 3 He -based sensors. These have an identical structure, one only has an additional cadmium shield, with which it blocks neutrons with an energy of less than 0.4 eV. The sensors have the same upper measurement limit of 1 eV. The DAN instrument can take measurements while driving as well as at a standstill, the duration of which in the latter case is between 2 and 30 minutes, depending on the desired accuracy. The vertical hydrogen distribution can be determined with a resolution of decimetres, in the horizontal plane resolutions of 50 cm to 100 m are the rule along the path of the rover.
Mission progression to landing
The Mars Science Laboratory was launched on board an Atlas V (541) with a " Centaur " upper stage on November 26, 2011 at 15:02 UTC . This was the first start of this Atlas variant. The Cape Canaveral AFS Launch Complex 41 served as the launch site . During the flight with the “Centaur” there were unexpectedly many failures in the telemetry, but this did not have a negative effect on the course of the mission: The MSL was disconnected about 44 minutes after take-off, exactly as planned.
Flight to Mars
On December 1, 2011, the JPL announced that a planned orbit maneuver would not be carried out on December 10, but about two weeks later. The reason for this was the unexpectedly precise entry into the Mars transfer orbit by the Centaur upper level. Two days earlier there had been problems in the navigation system so that the probe switched to safe mode. The reason was a bug in the software, which is responsible for identifying stars in the star sensor images . For this reason, the position control was temporarily only carried out using the two sun sensors, while engineers worked on a solution to the problem. With the exception of this system, the probe could be returned to normal operating mode shortly thereafter. A little later, the RAD instrument went into operation to collect data on radiation exposure during the cruise flight . These measurements are to be used primarily when planning future manned missions. On July 13th, the instrument was switched off again and configured for operation on the surface of Mars. First evaluations showed a significantly higher radiation exposure compared to the ISS , mainly from cosmic radiation and less from emissions from the sun .
On February 9, 2012, the JPL announced that the computer problems in the navigation system had been fixed. An error in the software of the memory management led under certain conditions to errors when accessing the instruction cache of the processor. As a result, some commands were lost, whereupon the probe switched to safe mode. With a revised software that was installed in a maintenance mode, this error could finally be fixed permanently.
In order to accelerate the scientific work, NASA reduced the target landing area from 20 × 25 km to 7 × 20 km in June 2012. Thanks to new simulations and estimates of the precision of the landing system, this change enables the rover's travel time to the main research area to be reduced by several months.
A few days before landing
On July 31, 2012, the Rover Opportunity was used to check whether a signal from Curiosity could also be received directly from Earth. After that, Opportunity was programmed for nine days and then "parked" so that the radio network and the orbiters could be kept as free as possible from communication with Opportunity for time-critical communication with Curiosity during its landing. After Curiosity landed on August 6th, Opportunity resumed its journey on August 12th.
Landing August 2012
The signal that the rover had touched the ground was received on August 6, 2012 at 5: 31: 45.4 UTC and the successful landing was confirmed with the arrival of a first image at 5:35 a.m. The landing site is about 2 km from the center of the intended landing ellipse. The signal propagation time was the time of landing 13:48 minutes for at this time good 248 million kilometers from Mars to Earth.
After a five-year assessment phase, the Gale crater was selected as the landing region from more than 100 considered destinations. This crater was chosen because its bottom is very deep. Many layers of different materials have deposited here, including clay minerals and sulphates , which are formed under the influence of water. Among other things, these layers could provide comprehensive information about the history of the climate and the atmosphere.
The following table contains the most important stages of the landing phase. The times (in UTC) refer to the local time on Mars.
|Outside the atmosphere|
|05:00:45||1609 km||Separation of the cruise flight module|
|1440 km||Dropping the control weights for alignment for entry into the atmosphere|
|05:10:45||127 km||Entry into the upper atmosphere|
|29 km||Maximum heating of the heat shield|
|23 km||Maximum braking of the capsule|
|05:15:05||11 km||Parachute deployment|
|05:15:25||9.8 km||Separation of the heat shield|
|7.6 km||Activation of the landing radar|
|1.6 km||Separation of the capsule and the parachute|
|1.3 km||Activation of the brake engines of the descent stage|
|Sky crane phase|
|20 m||Abseiling Curiosity|
|05:17:39||6 m||Unfolding the Rover landing gear|
|05:17:57||0 m||Ground contact of the rover|
|Separation of the ropes and flight of the descent step|
After landing at what will later be known as the “Bradbury Landing” landing site, Curiosity's primary mission started with checking the instruments and the rover. The commissioning of the vehicle and instruments at the landing site, which lasted until August 22, 2012, was successful with the exception of a wind sensor - while the sampler was tested on suitable material for the first time on the way to the destination “ Glenelg ”, 400 meters away .
On the way there, the rover took a closer look at individual points and used various instruments for the first time. On August 19 (Sol 13), still at the landing site, a picture was taken of an object called "Goulburn", which was interpreted as part of a water bed. Gravel was found on recordings on September 2 (Sol 27) . The investigated region, called "Link" (Sol 26–28), is an alluvial cone , but it is crossed by several fixed channels, which suggests a regular flow of water. The area examined is said to have been ankle to waist-deep under water, which was moving at about one meter per second. A few days later, on September 14th (Sol 39), the rover found what was known as the “Hottah” spot, something that was interpreted as a water bed. With these objects, direct evidence of the existence of water-bearing rivers on Mars could be provided for the first time. This follows from the observed shapes of the individual pebbles, which cannot be formed by the wind, but only by flowing water.
The next object was a pyramid-shaped stone about 25 cm high and 40 cm wide, called "Jake Matijevic". 19.-23. September (Sol 43-47). On September 28th (Sol 50) the rover arrived in the “Glenelg” area, where it stayed for several months. Different types of soil formations collide here, which means that many investigations are possible, including the so-called “Bathurst Inlet” stone on September 30th (Sol 54) and later the approximately 1.5 m by 5 m large sand field with several stones, called “Rocknest” . The drill was supposed to be used for the first time at “Point Lake” (Sol 102–111), but a decision was made against it and a long search for a suitable object began and it was not until the end of January 2013 that the first of three drillings in the region named “ Yellowknife Bay ”started. The edge of "Shaler" was discovered on December 7th (Sol 120) and a few days later on December 11th (Sol 125) the rover reached the southwestern edge of the "Yellowknife Bay" region, where detailed scientific investigations were planned. "Yellowknife Bay" is characterized by the fact that the area is about fifty centimeters below the surrounding area.
With the help of the first measurements with the SAM instrument it could be confirmed in November that the loss of light isotopes of certain substances had a considerable influence on the development of the planet. The measurements show a five percent increase in heavy carbon isotopes compared to the point in time when the Martian atmosphere was formed. This is a clear indication of a loss into open space, as the light isotopes migrate to the upper layers of the atmosphere and there were carried away by the solar wind due to the lack of a global magnetic field. In addition, methane was searched, which is only present in very low concentrations in the atmosphere. However, the measurements provided such low readings that, due to the inaccuracy of the instruments, it cannot be ruled out that practically no methane was present in the Gale crater at the time of the measurement.
At the beginning of December all available instruments were used for the first time in a soil sample. The sample essentially showed a composition that was already known from previous rover missions. No organic compounds were found, but the more sensitive instruments from Curiosity enabled the detection of particularly low-concentration substances and the measurement of isotope ratios.
On January 17th (Sol 160) the Rover Curiosity ran over a small stone (3 cm * 4 cm) called "Tintina" and broke it. This made it possible to look inside and examine it. The white color of the fracture surface is noticeable, which indicates the accumulation of water molecules ( hydration ).
In January, the "John Klein" area was designated as the location of the first well. Drilling began on January 31, 2013 (Sol 174), with only the hammer mechanism used until February 2 (Sol 176), with which pulverized rock near the surface was extracted for the CHIMRA system. Subsequently, on February 6th (Sol 180), the first, only 2 cm deep hole was drilled to the end. A second hole was then drilled directly next to it, this time with the maximum depth of about 6.5 cm, in order to be able to examine material from a greater depth. A third hole, this time at the "Cumberland" location (Sol 279), was then drilled a little further away.
The reason for the long dwell time of the rover at the location "John Klein" was that there was a problem with the computer's data storage on February 27, 2013 (Sol 200), which is why the rover was stopped. Normal work could only be resumed on March 23rd (Sol 223). However, since no communication between Mars and Earth was possible between April 8 and 28, 2013 due to a solar conjunction, the rover stood there until May and only then did it drive to the "Cumberland" site, where it drilled the third borehole on the 279th Sol bored.
In mid-July 2013, the rover left the “ Glenelg ” region with the aim of reaching the base of the central mountain “Aeolis Mons” - NASA calls it “Mount Sharp” - next year. To do this, the rover usually drove between 50 m and 100 m per day. The limitation of the rover's daily distance is due to the fact that the drivers on earth give the rover the route and for this they need image material recorded by the rover in the necessary image resolution. The software for an autonomous driving style of the rover was already available at this time, but was not yet used., July 27, 2013. For the first time, the rover was switched to autonomous mode on August 27, in order to be able to work on part of a day's stage due to pictures taken while driving to independently cover the exact path to a destination and avoid larger obstacles.
On the several kilometers long route to “Mount Sharp” (planned arrival in August 2014), five places (“waypoints”) where the rover should carry out scientific investigations lasting several days were determined by satellite images. On September 10th the first target was reached, "Darwin", a small depression where the rover examined several places at 10 sols. At the end of October 2013 the rover reached the second “waypoint”, where it examined the approximately 30-meter-long cliff edge “Cooperstown” in more detail. At the beginning of December 2013, the third position was reached. Much research was not done here, the main topic at the time was maintenance problems on the rover.
On March 12th, the JPL announced that a large number of the so-called “building blocks of life” had been found in the first 6.4 cm deep borehole at the beginning of February. This is a strong indication that Mars was able to host life in its past. In the analysis using SAM and CheMin, significant amounts of the elements hydrogen , oxygen , carbon , nitrogen , phosphorus and sulfur were found in the sample. These were also in different oxidation states , which indicates a dynamic chemical environment, with the sulfur compounds as an energy supplier for microorganisms , such as. B. Green sulfur bacteria , could have served. Since not all elements are oxidized, the rock sample is rather greyish and not rust-colored like the surface of Mars. The sampling location was also on the edge of an old river bed, where the pH was moderate and it was generally humid, which could have made life even easier.
Investigations in the vicinity of the drilling site also revealed an increased proportion of hydrogen both in the ground and on the surface. This suggests that the conditions surrounding the borehole were also friendly to life.
After early image analyzes already indicated a river bed and thus flowing water, this assumption was further reinforced with a study published in May. An exact quantitative measurement of the pebbles found, published in May, not only confirmed this assumption, it also found clear indications of a previously constant water flow for at least several months. Accordingly, in times when Mars still had a sufficiently dense atmosphere, complex and permanent river systems could have formed.
Results on radiation exposure during the cruise flight of the MSL were published on May 30th. These are based on the measurements of the RAD instrument, which is on board Curiosity and carried out measurements during the entire flight to Mars. The rover received a dose of 1.8 millisievert per day , with only 3% of the radiation exposure coming from the sun, as the sun remained calm and the entry capsule provided additional shielding against its rather low-energy radiation. Accordingly, the exposure was mainly due to high-energy cosmic rays . The total dose obtained in this way would not be fatal for astronauts during the flight, but it is significantly above the current limit values, which are considered to be acceptable. Without further shields, a Mars mission would massively increase the risk of cancer for the space travelers involved.
A total of six measurements to find methane in the Martian atmosphere were carried out from October 2012 to June 2013, but all of them were negative. But on June 15, 2013, the rover reported methane levels of up to 6 ppbv . Later on, the data recorded by the Esa orbiter Mars Express measured 15.5 ± 2.5 ppbv in the same region on June 16, 2013. Within a period of 60 sol, further measurements were made by the rover and the methane concentrations were also increased there, after which the value fell again to the average value of 0.69 ± 0.25 ppbv. An ice field east of the Gale crater - that is, very close to Curiosity - was identified as a possible source, which had long been considered a dry lake.
On October 12th, the JPL published a summary of the findings from the Curiosity landing area. For the first time a stone on the surface was dated exactly radiometrically . Previously, it was only possible to make rough estimates of the age of Martian rocks on site using the number of impact craters and the state of weathering. With the help of the rover's capabilities, it was now possible to reliably determine the age by measuring the argon trapped in the stone . This is formed by the slow radioactive decay of potassium and is released as soon as a sample is sufficiently heated. Thus, by measuring the ratio between potassium and argon, the age of the sample could be dated to 3.86 to 4.56 billion years, which is in good agreement with previous estimates. During the investigations, organic substances could also be identified in the drilling sample. At the moment, however, it cannot be ruled out that this is contamination from the earth that entered the measuring system during construction.
Several scientists have now dealt with the living conditions in the landing area. It has been found that most of the materials were washed up late and accumulated in the area. In combination with an advantageous composition of the clay minerals, it can therefore be assumed that the region was suitable for microbial life around four billion years ago. In addition, these conditions were also present for a longer period than previously assumed.
After a longer period of use, the first findings on radiation exposure were also obtained. This averages 0.67 millisieverts per day and around 95% comes from cosmic radiation , as there were no solar storms during the measurement period. In combination with a return flight, a person would be exposed to an exposure of around 1,000 millisieverts during a Mars mission, which would increase the risk of cancer and death by 5%. NASA's current exposure limit would not allow such an increase in risk, as astronauts may not continue to be exposed to increased radiation throughout their careers once a three percent increase in risk is reached. Therefore, a future mission will require additional radiation protection.
Five days later, a hole about two centimeters deep was drilled into the target called "Windjana". The stone is a candidate for the third sampling and has therefore been thoroughly examined.
In the first half of July the rover drove through the "Zabriskie plateau", which is interspersed with dangerously sharp stones. Damage to the aluminum wheels in a comparable terrain made it necessary to change the route to avoid this rocky area as much as possible. A detour of 200 meters to the more distant scientific goals was accepted. This previously unexpected challenge was ultimately overcome with only minor damage to the wheels.
At the end of July there were problems with the backup computer. Curiosity has two identical main computers and was controlled from the B-side at that time, as the A-side failed for a short time in February 2013. After the problems with the A-side could be resolved, it took over the task of the backup system. After the rover stopped operating for two days, it was confirmed that the A-side can still serve as a backup.
Shortly before the second anniversary of the landing on August 6, the rover reached the bedrock of Aeolis Mons. The actual goals were still 3 kilometers to the southwest, but less than 500 meters away were the first isolated rocks, called "Pahrump Hills". The geological formations are now changing from the structures at the bottom of the Gale crater to the hilly structures at the foot of the mountain.
On September 24th, the hammer drill drilled a 6.7 centimeter deep hole in a basalt stone and collected the dust samples obtained in this way. The collected dust was initially stored in a container in the rover arm. The drill sample is from the deepest area of the mountain, later younger rock will be examined in higher areas. The investigation of these environments should enable a better understanding of the origin of the mountain and provide clues for the reason for its growth.
In November, a match between measurements from orbit and those from Curiosity on the ground was announced for the first time. The reddish rock dust from the first borehole at the foot of the mountain agrees well with the results from the orbit in terms of the composition of the minerals. The rover arm had put a small pinch of the dust into the Chemin (Chemistry and Mineralogy) instrument, where it was being examined. The sample from the "Pahrump Hills" contains significantly more hematites than previous analyzes on this mission. Hematites are minerals made from iron oxide and provide information about the early stages of the environment in which they were formed. The measurements from orbit were made in 2010 by NASA's Mars Reconnaissance Orbiter .
In mid-November, Curiosity had completed the first lap around the rock at the foot of the mountain and now began a second run to examine selected targets more closely. An important reason for choosing this region for the mission was the expectation to find more precise clues about the development of the environment on Mars from the rocks at the foot of the mountain. On its first way through the "Pahrump Hills", the rover covered 110 meters with a difference in altitude of 9 meters. The different rocks and their different erosion are of particular interest in the investigations.
In the second round, close-ups and spectroscopic examinations from the rover arm should provide more details about the selected objects. It should also be decided whether further drilling will be undertaken in a third round. The rocks to be examined are sediments that have later hardened into rocks. The causes could be standing or flowing water as well as the wind. The investigations should provide new information on this.
Before these tests, the wheels were tested on a small sand deposit; one would like to understand better why these previous actions were more difficult to overcome than expected. In addition, work was carried out on a solution for the possible failure of a laser to focus the telescope in the ChemCam spectrometer. The small laser lost its power and should be replaced by the main laser with a few short pulses.
In January, drilling took place on the "Mojave 2" sample. There are indications of the influence of water in a long time past and the sample was more acidic than in previous measurements. The hammer drill was used with a new technique in which less pressure was exerted on the object. The first preliminary tests found high levels of jarosite , an oxidized mineral containing iron and sulfur that is formed in acidic environments. It remains to be seen whether the sediments developed in acidic waters or later through flooding.
Another hole was drilled on February 24th to collect and analyze additional dust samples. The position called "Telegraph Peak" is in the higher regions of the "Pahrump Hills" at the foot of Aeolis Mons. The composition of the samples here contained more silicon in relation to elements such as aluminum or magnesium. This was most evident in the last sample compared to the previous, deeper ones. The cause could have been a leaching of the minerals. The drilling was the first that took place without a previous test drilling. The technique was again used in which relatively little pressure was exerted on the object. After the investigations in the "Pahrump Hills", the rover should be driven through a narrow valley, called "Artist's Drive", towards higher basalt regions of the mountain.
A temporary short circuit on February 27 briefly interrupted all operations of the rover. The incident happened when samples from the last hole in the robot arm were being transferred between different devices. The security procedures stopped all activities of the arm. On March 11th, the sample could then be sieved and then given to the CheMin instrument provided . In tests over the past ten days, the short circuit could be reproduced exactly once; it lasted less than a hundredth of a second and didn't cut the engine.
Investigations with the SAM instrument (Sample Analysis at Mars) revealed the first finds of nitrogen by heating Mars sediments. The samples came from the previously explored "Rocknest". The nitrogen was measured in the form of nitrogen oxides and may have resulted from the breakdown of nitrates when heated. Nitrates can be used by life forms and their existence gives another indication that Mars may once have been life-friendly. Nitrogen normally exists as a molecule (N2) and does not react with other molecules. The nitrogen molecule must first be broken down in order to then form other connections. On earth these are mainly biological processes, but to a lesser extent also natural events such as lightning.
In March, NASA reported the results of measurements of the heavy noble gas xenon in the Martian atmosphere. The tests were carried out with the SAM (Sample Analysis at Mars) instrument. Since noble gases react neither with elements in the atmosphere nor with those in the ground, they are particularly good indicators of the state of the former Martian atmosphere. Xenon is only present in very small traces and can therefore only be detected directly on site. Planets lose a certain part of their atmosphere to space, and Mars in particular is believed to have a significantly denser atmosphere in its early phase four to four and a half billion years ago. In such a process, lighter elements are lost faster than heavier ones. This also applies to the various xenon isotopes with an atomic mass of 124 to 136. Changes in the ratio of these isotopes to the natural composition allow conclusions to be drawn about the processes involved in loss. In contrast to other gases, interactions with other elements can be excluded here and very precise data can be obtained. Measurements with the SAM instrument now show that the heavy isotopes must also have been released into space during a violent phase. The lighter isotopes were released just a little more than the heavier ones. This composition had previously been found in Martian meteorites found on Earth .
On April 16, Curiosity had covered a total of ten kilometers since landing. For the past six months he had explored the "Pahrump Hills" and was now on his way to "Logan Pass", a destination about 200 meters to the southwest.
Between May 7th and 13th, the rover had problems with the soft ground. On three out of four trips, the wheels spun more than permitted and were stopped. The computer compares the measurements of the rotation of the wheels with the distance calculated from captured images. If the differences are too great, the system stops automatically. These incidents and further analyzes of the panoramic images from the surrounding area ultimately led to the choice of a new route to the “Logan Pass”.
After the small laser of the ChemCam (Chemistry and Camera) used for autofocusing failed, there were difficulties in taking the images with the necessary accuracy. The main laser sends pulsed laser beams onto a rock in order to measure the blasted out and evaporating rock with a spectrometer. In the past few months, therefore, several measurements with different focussing were ultimately carried out and sent to Earth in order to then look for the best results. A new software update should make it possible to determine the focus point with several different images in order to then only carry out a laser measurement and send it to earth.
In June there was a longer compulsory break because the sun was exactly between Mars and Earth. This constellation is repeated every 26 months and leads to a temporary failure of the radio link. At the beginning of July the rover was at the “Marias Pass” and discovered two different types of rock: on the one hand, the scree known from the “Pahump Hills” and a darker, finely embedded sandstone. On Mars as well as on Earth, the different layers of sedimentary rocks provide information about the environmental conditions during their formation. Curiosity climbed an incline of up to 21 degrees.
In mid-July, Curiosity discovered rock with a high proportion of silica, a material that consists largely of silicon and oxygen and that forms into rock. On earth this is better known as quartz . The region called "Elch" lies a little below the previously examined "Marias Pass". In addition to silicon, the ChemCam (Chemistry and Camera) and DAN (Dynamic Albedo of Neutrons) measuring instruments also found a larger proportion of hydrogen. This rock could have included organic material and is therefore of particular interest for later, more detailed investigations. Since the rover landed on Mars on August 6, 2012, ChemCam had examined 1,000 samples and used its laser more than 260,000 times. Tests on the short circuit in the rover arm gave no further indications of problems, so that further checks would take place during the next scientific investigations.
For the third anniversary of the landing, Curiosity took another “ selfie ” on August 5th . The picture consists of many individual shots and was cut together so that only a small part of the arm with the camera and the shadow on the ground can be seen.
On August 12th, the rover finished its investigations at “Marias Pass” and continued on its way to Aeolis Mons. By August 18, he had covered 132 meters; a total of 11.1 kilometers since 2012. The samples collected beforehand were carried along for later investigations. In particular, the high proportions of hydrogen found by the DAN instrument indicate larger amounts of water below the surface. The DAN instrument initially only detected unexpectedly high levels of hydrogen in a passive mode, so the rover drove over this area again. In active mode, water-containing material was detected under a thin, drier layer by bombarding the ground with neutrons and measuring the reflections.
On September 29, the drill drilled the eighth hole, about 6.5 centimeters deep, in a Martian rock, the fifth since reaching Aeolis Mons. The drilled stone was a normal sandstone and the surroundings gave the impression that water might have flowed here.
In early October, NASA announced that studies had confirmed the existence of lakes billions of years ago. The structure of the sediments at the foot of the Aeolis Mons showed clear evidence of formation within rivers and lakes around 3.3 to 3.8 billion years in the past. There are debris from fast-flowing rivers as well as multilayer deposits from stagnant waters. These sediments from the calm lakes formed the environment at the base of the mountain and further up. Where the mountain is today, there used to be a basin and this was at least temporarily filled with water. According to measurements by the Mars Reconnaissance Orbiter , these deposits extend 150 to 200 meters upwards from the base of the mountain, possibly up to 800 meters. There is no evidence of any layers affected by water. The crucial question is how the flowing water could exist. The atmosphere must have been much denser and the temperature warmer than the current models describe. Some of the water may have been created on the slopes by rain or snow, but that doesn't explain how water could have been liquid over a geologically longer period.
After detailed analyzes of mineral-bearing veins, which were examined in March 2015 in the region known as "Garden City", NASA published the first results in November. Some of these veins are up to two fingers thick and they criss-cross through the rock. The formation goes back to drier periods in which the water washed up substances in different compositions. Cores from different periods also have different compositions. Veins with calcium sulfate and magnesium sulfate were found; others were high in fluorine or iron. These measurements were made possible by upgrading the ChemCam instrument and also with the help of around 350 comparative measurements of rocks in a test instrument for a better understanding of the data. However, the veins also give clues to the naked eye due to their geometry; younger veins continue at the junctions with the older ones and thus give an indication of the relative age.
Next, Curiosity moved towards the “Bagnold Dunes”, a region on the north-western flank of the Aeolis Mons with strikingly dark dunes, some of which are as high as a two-story house and the area of a football field. The "Bagnold dunes" are active and move around one meter per earth year. But not only the movement is of interest, but also the process of how sandstone and later rock can have formed from such dunes.
Over the past two months, Curiosity had explored various dunes to find out how the wind moves and sorts the sand particles. For this purpose, several samples were collected and placed in the CHIMRA device (Collection and Handling for In-situ Martian Rock Analysis). The second sample was passed through two different sieves to obtain a sample of sand grains 0.15 to 1 millimeter in size. This sample was then given to the chemical laboratory. The investigation of these active dunes was the first outside of the earth and provided information about the movement processes in a much thinner atmosphere and with lower gravity than on earth. In addition, the rover wheeled into the dune and took the photo shown on the right.
At the beginning of February, the rover left the "Namib Dune" and headed for further rock formations. On Sol 1249 (February 9, 2016), Curiosity had reached the distance of twelve kilometers since landing.
After the dunes, the rover made its way to the Naukluft Plateau , the highest point the rover has reached since landing in Gale crater in 2012. Once there, investigations were carried out on deposits on the slopes.
The Naukluft Plateau was the most rugged terrain that the rover had to cross so far. Wind erosion over the course of millions of years made the rock there very sharp-edged and the operating team had to bypass it, as damage to the wheels was identified as early as 2013.
Next, the rover drove through terrain that resembled a dry lake and was less stressful on the wheels.
Since arriving on Mars, the Curiosity has covered 12.7 kilometers.
On May 11, 2016, the rover began Sol 1337, on this day began its third Martian year on the planet. In the past two Martian years, temperatures in the Gale crater fluctuated between 15.9 degrees Celsius on an afternoon in summer and minus 100 degrees Celsius in winter. So far, 34 million weather measurements have been taken by the rover.
On July 2, 2016, the rover unexpectedly went into safe mode. All activities that are not essential for survival are stopped and the rover follows a fixed plan in order to be able to communicate with the earth again. Data from the camera software and the data processing software of the main computer probably did not match and triggered the safe mode. Curiosity had already put itself in this state three times in 2013. NASA also extended the mission by two years, starting October 1, 2016.
On July 9, 2016, the rover was returned to normal operating mode.
With the Chemistry and Camera (ChemCam) instrument, Curiosity has so far targeted and examined more than 1,400 objects and fired more than 350,000 shots with the laser. Rock is shot at with the laser of this instrument. A small part of it evaporates and this plasma is then examined with the camera from a distance of up to seven meters. By installing new software, the rover can now select new destinations more independently.
On August 5, 2016, Curiosity took dozens of pictures with the mast camera (MastCam) for a 360-degree panorama and the appearance of "Murray Buttes" on the lower "Mount Sharp". The formation was on the planned route of the rover and is named after the former Caltech planetologist Bruce Murray (1931 - 2013).
The rover has been on the surface of Mars for four Earth years since August 6, 2016 and has since traveled 13.57 kilometers and sent more than 128,000 images to Earth. In the time before the anniversary, Curiosity prepared the investigation of the 17th soil sample on a rock called "Marimba". On September 8, 2016, Curiosity took pictures of layered sandstone at the "Murray Buttes" with its mast camera (MastCam). These table mountains and pointed peaks that rise above the surface in this region are the eroded remnants of ancient sandstone that was formed when sand was deposited by the wind after lower Mount Sharp was formed. These sand dunes have also been chemically altered by groundwater, buried and dug up again, creating the landscape as it is currently seen on Mars. The new images represent Curiosity's last stop in Murray Buttes, where the rover has been traveling for a little over a month. Since this week Curiosity has left this region for the south and drove to the base of the last pointed knoll on the way out. This is where the rover started its last drilling campaign (September 9th). Upon completion of this drilling, Curiosity will travel further south and higher up Mount Sharp.
On September 14, 2016, Curiosity made another attempt to drill, which, however, had to be stopped due to a short circuit. This attempt was repeated and successfully completed on September 18, 2016. Soil samples from this borehole were then taken to the internal laboratory. This drilling site, the 14th total for the rover, is located in an area composed primarily of mudstone formed from mud that had accumulated at the bottom of the ancient lakes. Furthermore, this drilling site is located in a geological layer that is approximately 180 meters thick, the so-called "Murray Formation". The results show that this lake environment was permanent and not volatile. Since the two-year mission extension from October 1, 2016, Curiosity has continued uphill on this ridge of Mount Sharp, which is rich in iron oxide mineral hematite and clay-rich bedrock. This goal on lower Mount Sharp, which is about the size of Mount Rainier , is about two and a half kilometers away and should be reached after about half of the two-year extension. Once there, the rover will investigate evidence of ancient, water-rich environments in the younger layers of Mount Sharp that are in complete contrast to today's rough and dry Martian surface.
On October 27, 2016, the scientists discovered a strange looking chunk in pictures from the MastCam from that day. The rover took these pictures on the lower Mount Sharp in the "Murray Formation". On October 30, 2016, this chunk, which is about the size of a golf ball, was examined more closely with the ChemCam and it was determined that it was an iron-nickel meteorite . These types of meteorites are also very common on Earth. They have also been seen quite often on Mars, but this so-called "Egg-Rock" is the first to be examined. The meteorite was shot at by the ChemCam laser dozens of times and iron, nickel and phosphorus were detected in nine places. Iron-nickel meteorites probably originate from asteroids, during which the heavy elements iron and nickel are deposited inside. These meteorites provide information about various asteroids that have disintegrated and whose nuclei fell on Mars and Earth, and Mars may have received a different population of asteroids than Earth. "Egg-Rock" hit Mars millions of years ago. The scientists are also investigating how the Martian surface affects the meteorites, compared to meteorites on Earth. The rover remains in good shape to continue its investigations, having worked more than twice as long as its originally planned main mission of around 23 months, although two of its ten scientific instruments have recently shown signs of potentially impaired performance. The neutron generating component of the Curiosity DAN instrument provides data indicating a reduced voltage. Even if DAN could no longer generate neutrons, the instrument could continue to search for water molecules in the soil using its passive mode. The performance of the wind measurement function of the REMS also changes, although this instrument continues to return weather data such as temperature, humidity and pressure on a daily basis.
On December 1, 2016, the rover failed to properly execute a previously issued drill order. The rover discovered a bug in an early step where the "drill feed" mechanism did not extend the drill bit to contact the rock target with the drill bit. This 16th drilling attempt should be carried out for the first time only with the rotary movement of the drill and not, as before, with a hammering and rotating drill. Two of the possible causes that are being investigated are that a brake on the drill feed mechanism did not fully release or that an electronic encoder for the mechanism's motor did not work as expected. Short circuits in the impact mechanism have occurred several times, intermittently and unpredictably, since the first occurrence in February 2015. Since landing in August 2012, Curiosity has covered 15.01 km and more than 840 meters since leaving the "Murray Buttes". In addition, the rover has climbed around 165 meters, 44 meters of which since the Murray Buttes in September 2016.
By mid-2020, the rover had covered almost 22.31 km. The two pictures show the kilometers and the location in June 2020:
Selected panorama pictures
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