Schiaparelli (Marslander)

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Full-size model of the lander in the control center (ESOC) in Darmstadt, as planned after the lower and upper protective shields were dropped
Greatly simplified model of the lander at the Paris Air Show 2013, without heat protection shield, back cover cap and thermal insulation film, visible at an angle from above: 3 spherical tanks for hydrazine, 1 for helium, 2 of 3 triple engine nozzles, on the plateau on the left the high Micro-ARES mast, next to it the smaller Met (eorology) mast with 3 instruments, the laser reflector raised several times

Schiaparelli was a Mars - Lander of the European Space Agency (ESA) and Roscosmos , the as demonstration module for the [atmospheric] entry, descent and landing ( English entry, descent and landing demonstrator modules , short EDM ) was designed. It was named after the Italian astronomer Giovanni Schiaparelli .

The landing on October 19, 2016 failed due to technical problems. According to the official investigation report, a fault in a measuring device led to the on-board computer being overloaded. As a result, the Mars probe crashed unchecked from a height of almost 4 km onto the surface of the red planet and hit there at a speed of 540 km / h.

Mission flow

With the help of the device that was transported to its target planet with the ExoMars Trace Gas Orbiter , all technologies for future landings on Mars should be tested. These include special materials for heat protection, the parachutes, the Doppler radar for determining altitude and the brake rockets operated with liquid fuel. After landing, Schiaparelli was supposed to work on the surface for two to four days on Mars . Since Schiaparelli had no solar cells, only batteries for power supply, the functionality was limited to a few days.

The launch took place on March 14, 2016 with a Russian Proton rocket from the Baikonur Cosmodrome . During the journey to Mars, Schiaparelli was firmly connected to the orbiter and was put into a "deep sleep". The planned mission was structured as follows:

  • On October 16, three days before reaching the Martian atmosphere, Schiaparelli separated from the orbiter. With the heat protection shields, it has a flat conical disc shape.
  • During the further journey to Mars, the lander initially remained in a deep sleep in order to save energy.
  • Shortly before reaching the atmosphere, the systems were activated at a height of 122.5 km at a speed of around 21,000 km / h.
  • A heat shield was intended to protect Schiaparelli in the first phase of entry and to slow it down so that the parachute could be deployed at an altitude of around 11 km at a speed of around 1650 km / h.
  • Then the front and then the rear heat protection should be thrown off.
  • A Doppler altimeter and speedometer should then be used to determine the position in relation to the surface of Mars.
  • Finally, the liquid engine should be activated and the speed reduced to 15 km / h up to a height of 2 m. The engine should then be switched off and the lander should fall to the bottom. The impact should be cushioned by the plastically compressible structure.
  • With a data connection to the orbiter, the most important data should be transmitted to the orbiter in real time. In addition, the data should be completely transmitted within 8 Mars days after landing and the Schiaparelli mission should then be terminated.

Meridiani Planum had been designated as the primary landing site . The NASA rover Opportunity also explored this region. The plain is of particular interest to scientists because it contains hematite - an iron oxide that occurs almost exclusively on Earth in environments with liquid water.

Before and after image of the surface of Mars by NASA's Mars Reconnaissance Orbiter: The spots detected on October 20, 2016 represent the crash site of the lander (black, above) and parachute (white, below). On the right side an enlarged representation of the framed area.
High-resolution MRO image: dark rays emanating from the crash site are interpreted as an indication that the lander caused a crater on impact (above). The upper heat shield can be seen close below the parachute (below).

Shortly after the expected time of landing, however, ESA announced that the lander's radio contact with the Giant Metrewave Radio Telescope (GMRT) located in Pune, India had been broken off during the landing phase. At the same time, Schiaparelli's radio contact with the Mars Express space probe was broken. According to ESA, the data recorded by both sources as well as the mother ship and sent to Earth showed “that the phases of entry and descent into the atmosphere went as expected, but the events after the rear heat shield and parachute were dropped on a non-scheduled one Indicate course. The launch seems to have occurred earlier than planned. ”At the same time, ESA announced in an initial analysis on October 20, 2016:“ As far as the engines are concerned, it can be said with certainty that they were ignited for a short time, it but it looks like they stopped operating earlier than expected. ”The misconduct resulted in“ no soft landing ”.

The impact location of the lander and the dropped parachute was verified on October 20, 2016 using photographs of the Martian surface using MRO images; at the same time, the ESA reported on October 21, 2016: "It is estimated that Schiaparelli fell from a height of between 2 and 4 km and thus hit at a speed of more than 300 km / h." It is possible "that that Lander exploded on impact because the fuel tanks were probably still full. ”The final investigation report presented by ESA in May 2017 ultimately attributed the failure of the soft landing to a sequence of malfunctions. The trigger was therefore the malfunction of the Inertial Measurement Unit (IMU) , a measuring device that was supposed to monitor the probe's own movement. Apparently, when entering the Martian atmosphere, Schiaparelli moved back and forth more strongly than expected, so that the IMU was overloaded and - for much longer than intended for such a case - was not operational. During this downtime, incorrect altitude information was calculated, which - although it was completely implausible to indicate a position below the surface of Mars - led to the parachutes being dropped and the brake rockets being briefly detonated. Then Schiaparelli fell to the ground unchecked at a speed of 540 km / h.

However, the failure of the landing had no fundamental consequences for the planned dropping of the European ExoMars rover in 2020 . On December 2, 2016, ESA released the required funds.

construction

Like TGO, Schiaparelli's design was derived from earlier studies as part of the ExoMars project. A number of sensors should record the essential parameters of the key technologies to be tested. These included, in particular, the heat protection, the parachute, the Doppler radar and the brake engines operated with liquid fuel. The data should then be transmitted to Earth and used for future European missions. The structure in detail:

  • Diameter: 2.4 m with heat shield, 1.65 m without
  • Mass: 600 kg
  • Material of the heat shield: carbon fiber sandwich structure with 90 Norcoat lounger insulating tiles ( cork- based insulation )
  • Structure: aluminum sandwich with top layers of carbon fiber reinforced plastic
  • Parachute: Disk-Gap-Band-Cap, 12 m diameter
  • Drive: three times three hydrazine engines (each 400 N), operated in pulse mode
  • Electrical energy: accumulators
  • Communication: UHF link with two antennas to the orbiter

European industry, led by Thales Alenia Space, developed the probe for ESA.

Scientific instruments

The measuring instruments were selected jointly by NASA and ESA in 2011. These were divided into two areas of responsibility: DREAMS comprised all surface-based experiments and AMELIA those that were supposed to provide information about the behavior of the lander during the descent. In addition, the heat flow in the heat shield was to be recorded with COMARS +, the landing site was to be photographed with the DECA ( de scent ca mera) descent camera and the transparency of the atmosphere was to be determined. The camera came from the holdings of the Herschel space telescope program. The top of Schiaparelli contained an array of laser reflectors for orbital location.

DREAMS
The name stands for Dust Characterization, Risk Assessment, and Environment Analyzer on the Martian Surface ( English for dust determination, risk assessment and environmental measuring device on the Martian surface ). The ingredients were: MetWind (wind speed and direction), DREAMS-H (humidity, English humidity ), DREAMS-P (print, English pressure ), MarsTem (temperature near the surface), solar irradiance sensor, SIS (sunlight, transparency of Atmosphere) and Atmospheric Radiation and Electricity Sensor, MicroARES (radiation and electrical charge in the atmosphere). More precise knowledge should be gained about the influence of electrical forces, also depending on the humidity, on the dust. Dust storms are triggered by this mechanism.
AMELIA
This name stands for Atmospheric Mars Entry and Landing Investigation and Analysis (English for Atmospheric Marseintritts- and Mars landing examination and analysis ). Atmospheric conditions such as density and wind from great heights to the surface should be determined.
DECA
The landing camera weighs about 600 g with dimensions of about 9 cm × 9 cm × 9 cm. It should provide high-resolution photos of the landing site and form the basis for a three-dimensional topographic model of the region. After the front heat protection was thrown off, the recordings should begin. 15 pictures should be taken and saved at an interval of 1.5 seconds. To avoid electrostatic discharges during flight through the atmosphere, they should not be sent to the orbiter until after a delay of several minutes.

The laser reflector (INRRI - IN instrument for Landing - R oving laser R etroreflector I nvestigations ) consisted of a dome-shaped arrangement of eight cube corner reflectors (CCR) from quartz glass SUPRASIL 1. He would have been the first measurement reflector, which had been placed on Mars and should function longer as a purely passive element. It should also be used to measure the precipitation of dust and its being blown away again by the wind.

Web link

Individual evidence

  1. ↑ ExoMars Trace Gas Orbiter and Schiaparelli Mission (2016). At: Exploration.ESA.int. October 16, 2016, u. a. with detailed pictures by Schiaparelli.
  2. ↑ Ticker for Mars landing: The last hope is a reset. At: HNA.de. October 20, 2016, with the section Mars landing: where the landing capsule Schiaparelli got its name from.
  3. ↑ Mars probe. Computer was to blame for "Schiaparelli" crash. At: Spiegel.de. May 24, 2017.
  4. ↑ a b ExoMars 2016 - Schiaparelli Anomaly Inquiry. At: Exploration.ESA.int. 18th May 2017.
  5. ↑ Schiaparelli: The ExoMars Entry, Descent and Landing Demonstrator Module. At: Exploration.ESA.int. October 16, 2016.
  6. ↑ ESA Operations: Flight Director Michel Denis: confirmed separation! At: Twitter .com. October 16, 2016.
  7. ↑ Detailed images of Schiaparelli and his hardware after landing on Mars. At: esa.int. October 27, 2016.
  8. ↑ a b Analysis of Schiaparelli's relegation data is in progress. At: ESA.int. 20th October 2016.
  9. ↑ Mars Reconnaissance Orbiter sees Schiaparelli landing site. At: ESA.int. October 21, 2016.
  10. ↑ Esa mission "ExoMars". Software errors caused "Schiaparelli" to crash. At: Spiegel.de. October 26, 2016.
  11. ↑ Computing glitch may have doomed Mars lander. At: Nature .com. October 25, 2016.
  12. ↑ Europe moves ahead with Mars mission, kills asteroid lander. At: sciencemag.org. 2nd December 2016.
  13. ↑ Heat shields for ExoMars are ready. At: Aerosieger.de. July 8, 2014.
  14. ↑ a b Schiaparelli science package and science investigations. At: Exploration.ESA.int. 19th October 2016.