Mars Express

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Mars Express
Mars Express (artist's impression)

Mars Express (artist's impression)

Probe type Orbiter
Start date June 2, 2003 17:45 UTC
Arrival of Mars December 25, 2003
Final orbit reached December 30, 2003
Takeoff mass 1120 kg
Fuel mass 427 kg
Payload mass 116 kg
Mass of beagle 2 71 kg
Size of the probe bus 1.5 m × 1.8 m × 1.4 m
Span of the solar cells 12 m
Size of the solar cells 11.42 m²
Manufacturer Main contractor EADS Astrium and 25 subcontractors from 15 countries
Launcher /
flight number
Soyuz Fregat /
ST 11
lifespan 6089 days in Mars orbit
Stabilization 3-axis
Antennas Parabolic antenna with 1.6 m diameter, omnidirectional antenna and UHF antenna for communication with Beagle 2
Channel 1 S-band
1 X-band
5 watts in the S-band, 65 watts in the X-band.
Data rate probe - earth 10.7-230 kb / s
Data rate earth - probe 7.8-2000 bit / s
Data storage 1.5 GB of RAM
power supply
Electrical power planned 660 W at Mars due to wiring errors only approx. 460 W
Batteries 3 lithium-ion batteries
Engine system
Main engine S 400 with 400 N thrust
Steering thrusters 2x4 S 10 with 10 N thrust
fuel MMH
Oxidizer Nitrogen tetroxide
First orbit 250 - 150,000 km altitude with 25 ° equatorial inclination
Current orbit 258 - 11,560 km altitude with 86.3 ° equatorial inclination, orbit time 6 h 43 min

Mars Express (abbreviated MEX ) is a Mars - probe of ESA . It was launched in June 2003 and reached the planet on December 25, 2003. The main task of the mission was the complete mapping of Mars, the exploration of its atmosphere, its surface and the material that is up to two meters deep. The probe also had the Beagle 2 lander on board. The primary mission of the orbiter was designed for a Mars year (around 23 earth months) beginning in June 2004. It has since been extended several times and currently runs until 2022 , subject to a review at the end of 2020. Template: future / in 2 years

Mission history

Mars Express was launched on June 2, 2003 with a Russian Soyuz FG / Fregat rocket from Baikonur . The launch mass of the probe was 1223 kg.

The Beagle 2 lander was supposed to land on Mars on December 25, 2003 to look for traces of organic life. Since no contact could be established despite repeated attempts, the lander was declared lost on February 11, 2004. After the unsuccessful search for Beagle 2, the other instruments on board were gradually activated.

Mars Express reached the scheduled orbit around Mars in January 2004. The probe orbits it on an elliptical orbit near the pole ( inclination : 86 °) at a minimum distance of almost 300 km and a maximum distance of 11,000 km.

On October 19, 2014, the comet Siding-Spring came within 140,000 km of Mars. Mars Express analyzed the comet's nucleus and the comet's tail.

Extending the MARSIS antennas

The last episode in the instrument activation on board Mars Express was the deployment of two 20 m and one 7 m MARSIS antennas. This instrument was designed to search for liquid or frozen water up to a few kilometers below the surface. However, the activation, which was actually planned for March 2004, was postponed several times because it was only after the start of the probe that it became clear that extending the antennas could have damaged other instruments on board and the probe itself. MARSIS should therefore be activated between May 2 and May 12, 2005, whereby the antennas should be extended in three phases in order to limit possible damage to the probe. After another three weeks of extensive checks of the probe and its instruments, the time had come for MARSIS to start its scientific work. The first antenna was deployed on May 4th, but shortly thereafter it was discovered that one of the antenna's segments was not fully engaged. But already on May 10th, the ESA engineers managed to unfold the antenna completely by warming up the unlatched segment in the sunlight. The extension of the second 20 m antenna was carried out on June 13th, previously the folded antenna was also warmed up in the sunlight. On June 16, the process was declared successful. On June 17th the third and last, 7 m long antenna was deployed. However, this last operation was not classified as dangerous. After a few more tests, MARSIS was able to start its scientific work on July 4th, 2005.


Mars Express has seven measuring devices with it: With MARSIS ( Mars Advanced Radar for Subsurface and Ionospheric Sounding ) the Martian soil is to be examined down to a depth of five kilometers for water and ice, among other things. NASA's 2001 Mars Odyssey probe , on the other hand, can only investigate a depth of a few meters, but not with radar , but with a neutron spectrometer . MARSIS works in the frequency range from 1.3 to 5.5 MHz, can penetrate from 500 meters up to 5 kilometers deep into the Martian crust, has a horizontal resolution of 5 to 9 km along the direction of flight and 15 to 30 km across the direction of flight as well a vertical resolution of 70 meters. MARSIS is supplemented in its research results by Shallow Radar ( SHARAD for short ), which is due to start work on board the Mars Reconnaissance Orbiter from the end of 2006 . Both devices work in different frequency ranges and have different penetration depths.

Image of the Thaumasia Mountains by Mars Express
Ares Vallis
Central Mountain in Nicholson Crater

The high-resolution stereo camera HRSC delivers images with a resolution of up to 10 meters from which a three-dimensional map of the world can be created. For this purpose, it has nine CCD lines that "look" through the same optics at different angles. Moving the probe over the surface creates 9 complete images that show Mars from different angles. A computer-technical processing creates a three-dimensional surface model from this, color filters in front of four CCD lines enable a colored representation. Due to limitations in the data rate and volume, usually only one of the sensors is operated with the maximum resolution, the others generate images with a resolution that is two, four or eight times worse. Because the color filters were chosen on a scientific basis, it is difficult to use them to produce views "how an astronaut would see Mars". The HRSC is currently the only camera on a Mars probe that can take 3D color images of the surface; the HiRISE of the Mars Reconnaissance Orbiter, for example, only allows black and white 3D images.

In addition, the HRSC has a Maksutov-type optics called Super Resolution Channel (SRC) . This has an aperture of 100 mm and a focal length of 1000 mm. This enables a theoretical resolution of almost 2 meters. However, the SRC does not provide satisfactory results, as a temperature profile forms in the tube. The front end cools down, while the inner end has a slightly higher temperature due to the warmth of the satellite. This creates tensions in the optics which impair the sharpness of the image. One tries to reduce this by pointing the camera at Mars before the picture is taken and letting the reflected radiation warm it up. However, this is only possible for a short time, since during this time the solar cells cannot be aligned with the sun and therefore the power supply must be provided by batteries.

The camera was developed in the Berlin Institute for Planetary Research of the DLR under FU professor Gerhard Neukum and built at Astrium in Friedrichshafen.

Other measuring devices such as the Planetary Fourier Spectrometer ( PFS for short ) collect information about the nature of the atmosphere. The Mars radio science experiment MaRS explores the atmosphere, ionosphere and solar corona (see radio occultation ), provides information about the Martian surface and examines gravitational anomalies.

ASPERA-3 had the mission to learn more about the Martian atmosphere and its interaction with the solar wind and to investigate the sources of the so-called ENAs ( Energetic Neutral Atoms ) on Mars. ASPERA-3 also had the task of analyzing and categorizing plasma and neutral gases in the vicinity of Mars.

Scientific knowledge

After arriving on Mars and calibrating the devices, the HRSC stereo camera began to map the surface. An area that is larger than North America has already been recorded. The total area of ​​Mars corresponds roughly to the total land area of ​​the earth.

The OMEGA ( Visible and Infrared Mineralogical Mapping Spectrometer ) measuring device was able to detect large amounts of water ice on the southern polar caps of Mars. The American Mars Odyssey probe provided similar data in lower quality as early as 2001 , but its European confirmation also provides evidence of the reliability of ESA's first mission to Mars.

At the end of March 2004, ESA announced that Mars Express had found traces of methane in the Martian atmosphere with the help of its spectrometer . Although the occurrence is very small, the question arises how this compound got into the Martian air. Methane is produced both in volcanic processes and in the decomposition of organic materials. In this respect, this discovery could also be a small indication of possibly existing or long ago existing life on Mars , which is still speculation at the current time.

In late November 2005, data from OMEGA provided evidence that large amounts of liquid water were present on the surface in the early days of Mars. At the same time, MARSIS provided evidence that water ice may be buried under the surface of a Martian crater. An ice sheet about 1 km thick was probably found under the surface near the North Pole.

In November 2008, the high-resolution stereo camera HRSC, operated by DLR , took pictures in the area of ​​the Eumenides Dorsum (Greek: back of the furies ) west of the Tharsis region , showing numerous pronounced yardang structures that were created by wind erosion. These provide information about the dynamics of the wind on the surface of Mars; the density of the Martian atmosphere is only about 0.75 percent of the density of the atmosphere on earth at sea level. Similar structures have already been proven several times by Mars Express, for example in the area of Olympus Mons and, next to table mountains, in Aeolis Mensae .

In July 2018, it was announced that liquid water was found beneath the surface near the South Pole.

See also

Web links

Commons : Mars Express  - collection of images, videos and audio files

Individual evidence

  1. ^ ESA: Extended Life for ESA's Science Missions. November 14, 2018, accessed December 20, 2018 .
  2. Communication from ESA of August 5, 2005
  3. Communication from ESA dated July 28, 2005
  4. Communication from ESA dated November 30, 2005
  5. Communication from ESA dated November 30, 2005
  6. HRSC images show the force of wind erosion on Mars. DLR, November 28, 2008, accessed April 15, 2013 .
  7. DLR: Yardangs and table mountains in Aeolis Mensae (June 28, 2007)
  8. ^ Esa: Mars Express detects liquid water hidden under planet's south pole . In: European Space Agency . ( [accessed July 26, 2018]).