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Mars Express / Beagle 2

Mars Express [Astrium]

Beagle 2 (Mars Express Lander) [ESA]

The Mars Express mission's main objective is to search for sub-surface water from orbit and drop a lander on the Martian surface.

Mars Express Orbiter

Seven scientific instruments onboard the orbiting spacecraft will perform a series of remote sensing experiments designed to shed new light on the Martian atmosphere, the planet's structure and geology.

  • MARSIS (Sub-Surface Sounding Radar/Altimeter) will map the sub-surface structure to a depth of a few kilometers. The instrument's 40 m long antenna will send low frequency radio waves towards the planet, which will be reflected from any surface they encounter. For most, this will be the surface of Mars, but a significant fraction will travel through the crust to be reflected at sub-surface interfaces between layers of different material, including water or ice. MARSIS will also study the ionosphere, as this electrically-charged region of the upper atmosphere will reflect some radio waves.
  • HRSC (High Resolution Stereo Camera) will image the entire planet in full color, 3D and with a resolution of about 10m. Selected areas will be imaged at 2 m resolution. One of the camera's greatest strengths will be the unprecedented pointing accuracy achieved by combining images at the two different resolutions. Another will be the 3D imaging which will reveal the topography of Mars in full color.
  • OMEGA (Visible and Infrared Mineralogical Mapping Spectrometer) will build up a map of surface composition in 100 m squares. It will determine mineral composition from the visible and infrared light reflected from the planet's surface in the wavelength range 0.5-5.2 mm. As light reflected from the surface must pass through the atmosphere before entering the instrument, OMEGA will also measure aspects of atmospheric composition.
  • SPICAM (Ultraviolet and Infrared Atmospheric Spectrometer) will determine the composition of the atmosphere from the wavelengths of light absorbed by the constituent gases. An ultraviolet (UV) sensor will measure ozone, which absorbs 250 nm light, and an infrared (IR) sensor will measure water vapor, which absorbs 1.38 micron light.
  • PFS (Planetary Fourier Spectrometer) will determine the composition of the Martian atmosphere from the wavelengths of sunlight (in the range 1.2-45 mm) absorbed by molecules in the atmosphere and from the infrared radiation they emit. In particular, it will measure the vertical pressure and temperature profile of carbon dioxide which makes up 95% of the Martian atmosphere, and look for minor constituents including water, carbon monoxide, methane and formaldehyde.
  • ASPERA (Energetic Neutral Atoms Analyser) will measure ions, electrons and energetic neutral atoms in the outer atmosphere to reveal the numbers of oxygen and hydrogen atoms (the constituents of water) interacting with the solar wind and the regions of such interaction. Constant bombardment by the stream of charged particles pouring out from the Sun, is thought to be responsible for the loss of Mars's atmosphere. The planet no longer has a global magnetic field to deflect the solar wind, which is consequently free to interact unhindered with atoms of atmospheric gas and sweep them out to space.
  • MaRS (Mars Radio Science Experiment) will use the radio signals that convey data and instructions between the spacecraft and Earth to probe the planet's ionosphere, atmosphere, surface and even interior. Information on the interior will be gleaned from the planet's gravity field, which will be calculated from changes in the velocity of the spacecraft relative to Earth. Surface roughness will be deduced from the way in which the radio waves are reflected from the Martian surface.

Beagle-2 Lander

The lander, called Beagle 2 after the ship in which Charles Darwin set sail to explore unchartered areas of the Earth in 1831, is an exciting opportunity for Europe to contribute to the search for life on Mars. After coming to rest on the surface, Beagle 2 will perform exobiology and geochemistry research.

The instruments on the arm's PAW (Position Adjustable Workbench) include

  • a rock corer-grinder, for burring away the surface eroded layers of rocks and extracting samples.
  • a stereo camera for photographing the landscape and navigating the arm.
  • a microscope has filters for red, green, blue and ultraviolet light
  • a wind sensor on the arm allows Beagle to look for variations in wind speed with height, and
  • a X-ray spectrometer and
  • a gamma-ray Mössbauer spectrometer.

As well as its science objectives, Mars Express will also provide relay communication services between the Earth and landers deployed on the surface by other nations, thus forming a centre piece of the international effort in Mars exploration.


Both Mars Express and Beagle-2 arrived on 25. December 2003 on their destination, but while Mars Express was successfully inserted into a Mars orbit, no signal from the Beagle-2 lander has been received.

Beagle 2 was discovered partially deployed on the martian surface in January 2015 on Mars Reconnaissance Orbiter (MRO) imagery, about 11 years after it has been lost.

The science operations of Mars Express are extended until end of 2026 and the SPC also approved the indicative extension of Mars Express from 1 January 2027 to 31 December 2028, enabling support to the JAXA-led Mars Moons eXploration (MMX) mission. This will be followed by two years of post-operations; the extension to 2028 will be reviewed in 2025/2026, after MMX launch and arrival at Mars.

Nation: Europe
Type / Application: Mars orbiter, Mars lander (Beagle 2)
Operator: ESA
Contractors: Astrium
Propulsion: S400
Power: 2 deployable solar arrays, batteries
Mass: 1042 kg
Orbit: Heliocentric, then Mars orbit
Satellite COSPAR Date LS Launch Vehicle Remarks
Mars Express (MEX) 2003-022A 02.06.2003 Ba LC-31/6 Soyuz-FG Fregat with Beagle 2
Beagle 2 (Mars Express Lander) 2003-022# 02.06.2003 Ba LC-31/6 Soyuz-FG Fregat with Mars Express


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