Mars Express

Mars Express ( artist's impression)

Mars Express ( MEX abbreviated ) is a Mars probe ESA. She reached the planet on 25 December 2003. Primary objective of the mission is the complete mapping of Mars, the exploration of its atmosphere, its surface, and the material is located in up to two meters deep. In addition, the probe had the Beagle 2 lander on board. The primary mission of the orbiter was designed, starting with June 2004, a Martian year ( about 23 Erdmonate ). It has since been extended several times, most recently until 2012 with an option for 2014.

Mission History

Mars Express was launched on 2 June 2003 with a Russian Sojus-FG/Fregat rocket from Baikonur. The take-off mass of the probe was 1223 kg.

The lander Beagle 2 on 25 December 2003 should land on Mars to search for signs of organic life. Because despite repeated attempts, no contact could be established, the lander was declared on 11 February 2004 as lost. After the unsuccessful search for Beagle 2 by and by the other instruments were activated on board.

Mars Express scheduled orbit around Mars in January 2004, the probe encircled him on an elliptical near polar orbit. (Inclination: 86 ° ) in the minimum distance of nearly 300 miles and a maximum distance of 11,000 km.

Deployment of the MARSIS antennas

The last episode in the activation instrument on board Mars Express was the deployment of two 20 m long and 7 m long MARSIS antennas. This instrument was intended to look to a few kilometers below the surface by liquid or frozen water. However, the original planned already for March 2004 activation was postponed several times, as had been found only after the start of the probe that the deployment of the antennas could damage other instruments on board and the probe itself. MARSIS should therefore be activated in a period from 2 May to 12 May 2005, the antennas should be deployed in three phases in order to minimize potential damage to the probe within limits. After another three weeks of extensive checks of the probe and its instruments, the time had come for MARSIS his scientific work should take. The first antenna was extended on May 4, but was shortly found out that one of the segments of the antenna was not fully engaged. But already on 10 May succeeded ESA engineers, the antenna fully to unfold by the unlatched segment was warmed in the sunlight. The extension of the second antenna 20 m was conducted on June 13, before the folded antenna has also been heated in the sun. On June 16, the operation was declared successful. On 17 June, the third and final, 7 m long antenna was extended. This last operation was not classified as hazardous. After a few more tests MARSIS could resume his scientific work on 4 July 2005.

Equipment

Mars Express carries seven instruments with off: With MARSIS (Mars Advanced Radar for Subsurface and Ionospheric Sounding ) of the Martian soil to be examined to a depth of five kilometers, among others, by water or ice. The NASA probe Mars Odyssey 2001, however, can examine only a depth of a few meters, but not with a radar, but with a neutron spectrometer. MARSIS operates in the frequency range of 1.3 to 5.5 MHz, 500 meters can penetrate up to 5 kilometers deep in the crust of Mars, has a horizontal resolution of 5-9 km along the flight direction and 15 to 30 km transverse to the direction of flight and a vertical resolution of 70 meters. MARSIS is in his research results from the Shallow Radar ( SHARAD short ) supplements, which is to start from the end of 2006 on board the Mars Reconnaissance Orbiter his work. Both devices operate in different frequency ranges and have different Durchdringtiefen.

The High Resolution Stereo Camera HRSC provides images with a resolution of up to 10 meters, from which a three-dimensional map of Mars can be created. For this purpose, it has nine CCD line, which " look " at different angles through the same optics. By moving the probe over the surface caused 9 full images representing Mars from different angles. A computer technical processing generated from a three-dimensional surface model, color filters in front of four CCD line allow a colored illustration. Due to limitations in data rate and extent of only one of the sensors is usually operated at the maximum resolution, the others produce images with a two -, four - or eight times poorer resolution. Since the color filters were selected according to scientific criteria, it is difficult for views to produce, " like an astronaut would see Mars ". The HRSC is the only camera of a Mars probe that can record 3D color images of the surface; the HiRISE on Mars Reconnaissance Orbiter about permitted only black and white 3D images.

In addition, the HRSC has a Super Resolution Channel (SRC ) said optics from the Maksutov type. This has an aperture of 100 mm and a focal length of 1000 mm. This allows a theoretical resolution of nearly 2 meters. However, the SRC does not provide satisfactory results, as is a temperature gradient in the tube. The front end of cooling, while the inner end thereof by the heat of the satellite, a slightly higher temperature. This creates tension in optics, which affect the image sharpness. Attempts to reduce this by directing the camera before shooting to Mars and can warm up by the reflected radiation. However, this is only possible for short periods, as during this time the solar cells can not be aligned to the sun and therefore must be supplied with power from the battery.

The camera was developed at the Berlin Institute of Planetary Research, DLR FU Professor Gerhard Neukum and built by Astrium in Friedrichshafen.

Other instruments such as the Planetary Fourier Spectrometer ( PFS short ) collect information on the nature of the atmosphere. The Mars Radio Science Experiment MaRS explores the atmosphere, ionosphere and solar corona ( see Radio Occultation ), provides statements on the Martian surface and examined gravitational anomalies.

Scientific Evidence

Upon arrival at Mars and the calibration of the equipment, the HRSC stereo camera began to map the surface. In this case, an area has already been recorded, that is greater than North America. The total area of ​​Mars corresponds approximately to the total land area of the earth.

By the meter OMEGA ( Visible and Infrared Mineralogical Mapping Spectrometer ) large amounts of water ice could be detected on the southern polar caps of Mars. Similar data delivered in lower quality early as 2001, the American Mars Odyssey, leaving the operational European confirmation also a proof of the reliability of the first Mars mission of ESA dar.

End of March 2004 divided the ESA, Mars Express did with the help of his spectrometer found traces of methane in the Martian atmosphere. Although the incidence is very low, the question arises how this connection could reach the Mars air. Methane is produced in both volcanic processes and in decay processes of organic materials. In this respect, this discovery could also be a slight indication of any existing or long existing life on Mars before, but at the present time is still speculation.

End of November 2005 provided data from OMEGA evidence that large amounts of liquid water were present in the early days of Mars on the surface. At the same time delivered MARSIS findings that under the surface of Mars crater possibly water ice is buried. Near the North Pole was found below the surface probably a 1 km thick ice sheet.

In November 2008, shooting in the area of the Eumenides Dorsum were made (Greek back of the Furies ) west of the Tharsis region of the operated by DLR HRSC high-resolution stereo camera, which show numerous distinct Yardang structures caused by wind erosion. They 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 been proven several times by Mars Express, for example, in the region of Olympus Mons and, in addition mesas, in Aeolis Mensae.