Phoenix (space probe)
Phoenix was a NASA - spacecraft to explore the planet Mars , which started on 4 August 2007 on 25 May 2008 (UTC) near the northern polar region of Mars ( vastitas borealis landed) and November 2, 2008 for the last time signals Earth sparked. The probe was part of NASA's Mars Scout program , which included smaller and cheaper space probes.
Phoenix was largely based on the Mars Surveyor 2001 lander , which was built for a launch in 2001 but failed to launch after losing the previous Mars Polar Lander in December 1999. Since then, the almost completed probe has been stored in a clean room until the decision was made in 2003 to modernize the probe and send it to Mars in 2007. Hence the name of the probe - in Greek mythology , the phoenix is a bird that rises from its ashes.
The mission was led by the University of Arizona , which also supplied some of the instruments, while Lockheed Martin was responsible for building the probe and testing. It was a mission with international contributions from Denmark , Germany , Finland , Great Britain , Canada, and Switzerland, and the first in NASA history to be directed by a state university. The total budget for the mission, including the launch vehicle and mission implementation through November 2008, was $ 420 million.
Mission objectives
In contrast to the rovers Spirit and Opportunity, which were launched in 2003, Phoenix was a stationary probe. It landed in a region of Mars where, according to the data from Mars Odyssey, close to the surface from about two to five centimeters deep, the soil should consist of up to 80 percent water ice. To study the ice, Phoenix could use a robotic arm to penetrate the ground to a depth of up to half a meter.
The probe's measurements served two purposes: First, to study the geological history of water ice in order to understand the change from what was once warm and humid to today's cold and frozen Mars. The second goal was to look for clues to possible former life on Mars that could be present in the ice sheet. For the investigations, the probe with the TEGA instrument had several small ovens that were filled with samples by the robot arm. After the samples had been heated, the proportion of water and carbon was measured; in addition, they looked for traces of minerals that could have formed in a warm and humid climate. The presence of organic substances was also measured.
Other instruments of the probe examined the smallest soil particles up to 16 micrometers in size. They measured the electrical and thermal conductivity of the particles with the help of sensors attached to the robot arm in order to be able to draw conclusions about their properties.
technology
The Phoenix, which weighed 670 kg at takeoff, consisted of a cruise stage and the actual, 350 kg heavy lander, which was placed in a protective cover consisting of the front heat shield ( aeroshell ) and the rear heat shield ( backshell ). The cruise stage was only required for the flight to Mars to supply the spacecraft with energy and to ensure communication with Earth. It was detached five minutes before entering the Martian atmosphere (fourteen minutes before landing), after which the lander turned in the direction of flight (13.5 minutes before landing), at 125 km altitude at 5.6 km / s into the atmosphere occurred (422 seconds before landing) and was decelerated by the Martian atmosphere with up to ten times the acceleration of gravity.
Shortly afterwards (−203 s) a parachute unfolded at a height of 12.6 km , which reduced the speed to 55 m · s −1 (≈ 200 km · h −1 ). At a height of 11 km (−188 s), the front heat shield was thrown off, the landing legs extended (−178 s) and the radar for recording the surface was activated (−128 s). 880 m above the ground, the parachute and the rear heat shield were cut off (−31 s) and the brake engines ignited (−10 s); these braked the lander further and enabled control for a horizontal landing on the legs. The energy supply of the probe is provided by round solar panels that were unfolded about 25 minutes after landing. The lander only had a small UHF antenna for communication . The radio link to earth was normally established via one of the Mars orbiters using store-and-forward technology . Mars Odyssey only served as a relay station during the landing phase .
Instruments
The probe carried 55 kg scientific payload, an extensive arsenal of instruments:
- Mars Descent Imager (MARDI)
- A camera system that was supposed to take color photographs of the surface as the probe descended. However, the camera was not used because there was a risk (albeit a small one) that the handling of the image data produced during the descent could cause the mission to fail. The original plan was for the instrument to be activated immediately after the Aeroshell was dropped and to take pictures until the probe touched down. The recordings could have helped to study the geological environment of the landing site in order to better integrate the results of other instruments into the overall context. MARDI was already manufactured by Malin Space Science Systems for the Mars Surveyor 2001 Lander and was installed largely unchanged at Phoenix.
- Stereo Imager (SSI)
- A camera that is installed on a two meter high, movable mast. It is a modified version of the camera already used on Mars Polar Lander and Mars Pathfinder . SSI has two lenses offset from one another, with which 3D recordings were possible, and over 12 spectral filters , which allowed geologically interesting recordings of the landing site. In addition, SSI served to support robotic arm activities by using the camera to create 3D maps of the immediate surroundings.
- Thermal Evolved Gas Analyzer (TEGA)
- A combination of eight small melting furnaces (each the size of a printer's ink cartridge) and a mass spectrometer . The samples that were taken from the ground with the robot arm were heated in the ovens at a constant rate up to 1000 degrees Celsius. Phase transitions from solid to liquid and to gaseous state were detected by measuring the required heating power ; this corresponds in its basic function to a " DSC " (Differential Scanning Calorimeter) . From this one can draw conclusions about the chemical composition of the sample. The composition of the escaping gases was analyzed with a mass spectrometer. Each of the eight ovens was only available once for a single sample. The instrument was developed by the University of Arizona.
- Mars Environmental Compatibility Assessment (MECA)
- Formerly called M icroscopy, E lectrochemistry, and C onductivity A nalyzer. MECA consists of a wet chemistry laboratory, two microscopes (an optical and an atomic force microscope ) and a probe attached to the robot arm for measuring the thermal and electrical conductivity (TECP - Thermal and Electrical Conductivity Probe). MECA was used to examine the soil for its chemical components. The wet chemistry laboratory consists of four containers, in whose aqueous solution small soil samples were dissolved. The composition of the samples was then examined with the aid of 26 sensors. The properties of the sample such as the acid content and the proportion of sodium, potassium, chlorides, bromides and other substances were examined. Each of the four containers could only be used once for a single soil sample. In addition, photographs of the samples were taken with the aid of microscopes. The optical microscope was able to resolve particles down to a size of 10 micrometers, the atomic force microscope developed by a Swiss consortium led by the University of Neuchâtel even managed to image structures as small as 10 nm. MECA was already manufactured by the Jet Propulsion Laboratory for the Mars Surveyor 2001 Lander and was used largely unchanged at Phoenix. It was the first atomic force microscope to be used on a planetary mission.
- Robotic Arm (RA)
- The probe's robotic arm, which was primarily used to collect soil samples, which were then examined by the TEGA and MECA instruments. The robot arm is 2.35 m long and has four degrees of freedom : 1) up and down, 2) left and right, 3) forwards and backwards and 4) turning around its own axis. With the robot arm, samples could be retrieved from a depth of at least 50 cm. RA was already manufactured by the Jet Propulsion Laboratory for the Mars Surveyor 2001 Lander and then used in Phoenix.
- Robotic Arm Camera (RAC)
- A camera attached to the robot arm. It was used for close-ups of the bottom of the trench made by the robot arm and was able to resolve even the smallest structures up to 16 micrometers in size. The camera was built by the Jet Propulsion Laboratory and the Max Planck Institute for Solar System Research (Germany) for the Mars Surveyor 2001 lander and then used in Phoenix.
- Meteorology Suite (MET)
- A weather station provided by the Canadian space agency CSA , which consists of a LIDAR and temperature and pressure sensors. The LIDAR was used to study the atmosphere of Mars up to a height of 20 km by measuring the distribution of dust particles and clouds. It was jointly developed and built by Optech and MDA . MET has provided daily weather reports from the Martian surface.
Mission history
On August 4, 2003, NASA chose the Phoenix lander concept from several proposals as part of its Mars Scout program , according to which the almost completed Mars Surveyor Lander was revised and equipped with modernized instruments. This saved costs in the construction of the Phoenix, so that the actually quite demanding probe could be financed as part of the Mars Scout program.
In order to avoid possible dangers, the Mars Reconnaissance Orbiter , which has been available since November 2006, examined the selected landing sites more closely with its high-resolution camera.
Phoenix was sent on its way to Mars on August 4, 2007 at 09:26:34 UTC with a one-day delay by a Delta II 7925 rocket. One month after take-off, the scheduled inspection of the instruments was completed, especially the communication for the landing.
In contrast to the Mars rovers Sojourner , Spirit and Opportunity, the landing did not take place with an airbag landing system , but with the help of brake engines, which, like the Viking probes, worked until they touched down on the planet's surface. The lander's primary mission ended as planned in November 2008.
The perfect landing took place on May 25, 2008 at 23:38 UTC. Because of the distance to earth of 276 million kilometers, the first radio signals from the landing site could only be received on earth 15 minutes later, i.e. at 23:53:44 UTC. In order to be able to safely record the telemetry data during the critical EDL phase (Entry, Descent and Landing), the orbits of the active Mars orbiters were coordinated in such a way that the signals from the probe from all three orbiters ( MRO , Mars Express and Mars Odyssey ) could be received.
The first images from the landing site, transmitted by the Mars Odyssey orbiter, arrived at the JPL control center ( Jet Propulsion Laboratory ) in Pasadena on May 26 at 01:53 UTC .
The commissioning of the probe's robotic arm was delayed by a day because the communication system of the MRO (Mars Reconnaissance Orbiter) , via which the probe was to receive commands from Earth, had gone into stand-by mode for reasons that were not yet clear. The probe then automatically processed a previously defined camera recording sequence. Since May 28, the Mars Odyssey spacecraft has been used as a transmission station as long as the problems with the MRO were not resolved. The robotic arm was put into operation step by step and additional images were taken for a panoramic shot. On June 20, 2008, Mission Chief Scientist Peter Smith of the University of Arizona announced evidence of the discovery of water ice. During the excavation of Phoenix's shovel arm, the ice had come to light a few centimeters below the landing site. On August 1, 2008 the media reported a success in the search for water: a soil sample was taken with a shovel and heated in an oven; this produced water vapor. It is therefore certain that the soil sample contained ice and that water definitely occurs on Mars.
On August 5, 2008, the media reported that the Wet Chemical Laboratory (MECA) found significant amounts of perchlorates in a soil sample. On earth, perchlorates occur in the arid desert areas.
On September 3, the Canadian Lidar was able to detect showers of ice crystals / snow falling from passing clouds at a height of about 3 kilometers. Due to the temperature in the atmosphere, it must have been water ice that sublimated again at a height of about 2.5 kilometers before reaching the ground.
The beginning of winter at the landing site of the probe on the neighboring planet, which began in October 2008, was heralded by the reduced solar radiation with sharply falling temperatures. The heating of the probe required more and more electricity from the energy supply. In order to continue operating the main camera and meteorological instruments, part of the heating module was switched off in October 2008. As a result, the robot arm (RA) and the melting furnace (TEGA) of the probe were shut down. It was hoped that this measure would enable the operating time to be extended again with the energy saved. On November 2, 2008, the probe sent scientific data for the last time before contact was lost. On November 10th, the end of the mission was announced.
Between January and May 2010, NASA tried several times to establish radio contact with Phoenix through the 2001 Mars Odyssey orbiter , but this did not succeed. High-resolution images from the Mars Reconnaissance Orbiter on May 7, 2010, just before the summer solstice, indicated that during the Martian winter, Phoenix's solar panels were bent or broken off under the ice load, ultimately rendering the lander inoperable.
Images from the surface of Mars
A photo that was taken shortly after landing and shows one of the spacecraft's main legs.
One of the first images of the Martian surface from Phoenix
Near Phoenix there are polygon-like structures corresponding to the frost pattern soils on earth
The robot arm exposed ice.
See also
Web links
Wikinews: Phoenix (Mars probe) - in the news
- Phoenix site (English)
- NASA: Phoenix launch press kit (English, PDF; 6.5 MB)
- Phoenix probe Twitter diary
- Video: "A Mars landing is a critical maneuver" . 2008, made available by the Technical Information Library (TIB), doi : 10.5446 / 12855 .
Individual evidence
- ↑ Where is Phoenix? University of Arizona, May 4, 2014, accessed on May 4, 2014 (English): "The University of Arizona is honored to be the first public university to lead a mission to Mars."
- ↑ Stars and Space, May 2008, pp. 24-25, Phoenix - Landing in the Martian Arctic
- ↑ The University of Arizona: Mars Descent Imager (MARDI)
- ↑ The University of Arizona: Stereo Imager (SSI)
- ↑ The University of Arizona: Thermal Evolved Gas Analyzer (TEGA)
- ↑ The University of Arizona: Mars Environmental Compatibility Assessment (MECA)
- ↑ Thorsten Dambeck: Landing in the Arctic of Mars, Neue Zürcher Zeitung of May 21, 2008
- ↑ The University of Arizona: Robotic Arm (RA)
- ↑ The University of Arizona: Robotic Arm Camera (RAC)
- ↑ The University of Arizona: Meteorology Suite (MET)
- ↑ NASA: Phoenix Mars Lander Status Report: Radar and Other Gear Pass Checkouts , September 4, 2007 (English)
- ↑ US Mars probe Phoenix landed on the Red Planet. AFP Agence France-Presse, May 26, 2008.
- ↑ Getting By with a Little Help from Friends . NASA, May 23, 2008.
- ↑ NASA: NASA's Phoenix Spacecraft Commanded to Unstow Arm
- ↑ Thorsten Dambeck: Phoenix discovers ice on Mars, Spiegel Online June 20, 2008
- ↑ NASA: NASA Mars Lander Sees Falling Snow
- ↑ Mars Phoenix Lander Finishes Successful Work On Red Planet. University of Arizona, November 10, 2008, accessed May 4, 2014 .
- ↑ Ralph-Mirko Richter: The last listening campaign to Phoenix was unsuccessful. In: Raumfahrer.net. May 25, 2010. Retrieved May 25, 2010 .
“Mars” space probes (1960–1973) | Mariner 3, 4, 6-9 (1964-1971) | Zond 2 (1964) | Viking 1,2 (1975) | Fobos 1,2 (1988) | Mars Observer (1993) | Mars Global Surveyor (1996) | Mars 96 (1996) | Mars Pathfinder with Sojourner (1996) | Nozomi (1998) | Mars Climate Orbiter (1998) | Mars Polar Lander with Deep Space 2 (1999) | 2001 Mars Odyssey (2001) | Mars Express with Beagle 2 (2003) | Mars Exploration Rover with Spirit (2003) and Opportunity (2003) | Mars Reconnaissance Orbiter (2005) | Phoenix (2007) | Fobos-Grunt (2011) | Yinghuo-1 (2011) | Curiosity Rover (2011) | Mars Orbiter Mission (2013) | MAVEN (2013) | ExoMars Trace Gas Orbiter (2016) | Schiaparelli (2016) | InSight (2018) | al-Amal (2020) | Tianwen-1 (2020) | Mars 2020 (2020)
Planned missions
ExoMars Rover (2022) |
Escapade (2022) |
Martian Moons Exploration (2024)
Missions in italics are active.
Canceled missions: Mars Surveyor 2001 | Mars Telecommunications Orbiter | Mars Science and Telecommunications Orbiter | P5A | Red Dragon
( See also: List of man-made objects on Mars | Chronology of Mars missions )