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Mars Express


 
written by Jeff Harr on July 24, 2001
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Mars Express.
Mars Express.
Credit: ESA
The newly formed European Union has expressed for a long time their desire to explore space with the likes of the United States, Russia, and others. It looks like they may finally do so, in their upcoming launch of the Mars Express scheduled for 2003. And they might even set a precedent this time for NASA.

The important factors of this exciting new mission include low costs (a prevalent concern in every mission), an emphasis on multinational space exploration and the detection of sub-surface water, for which the Mars Express will be equipped with a special array of new scientific instruments.

In June 2003, the Mars Express will take off from remote Kazakhstan aboard a Soyuz Fregat launcher. Soon after entering Earth's orbit, the spacecraft will fire it's own engines, taking it on a direct path towards Mars. A few days after this initial firing, ESA stations will relay minute course corrections and make sure it heads for Mars. Once reaching Mars' orbit, the spacecraft will release its lander, named Beagle 2, to land on the surface. The orbiter will then get into an orbital lock with the Red planet. When the spacecraft is close to Mars, it will point towards the planet so that its instruments can take measurements and its antenna can receive transmissions from the Beagle 2 lander on the surface. Then, when the orbiter is far from the surface in its elliptical orbit, it will relay information back to Earth.

The spacecraft bus is a foray into the reduction of mission cost and production time. It is being kept to a minimum weight and cheap technology is being utilized to the fullest. Another cost effective procedure involves the onboard thrusters' limited use. The craft will only use its own power to make minor corrections and the final deceleration, saving space and fuel while keeping power (400 Newtons of it). Electrical power is provided by the spacecraft's solar panels that fold to its body during flight, and a unique idea using chargeable lithium-ion batteries in case of a solar eclipse. A large dish mounted on the orbiter will provide communications, transmitting at 230Kbps. European Space Operations Control Centre (ESOC) in Darmstadt will communicate with the spacecraft via the ESA ground station in Perth, Australia. Other communications innovations include star trackers, laser gyros, and coarse sun sensors. Temperature regulation is also an important issue. Two instruments, PFS and Omega, have infrared detectors that need to be kept at very low temperatures, and the sensors on the camera (HRSC) need to be kept cool. However, the rest of the instruments and on-board equipment function best at room temperatures. The regulation will be achieve by thermal blankets and selective cooling. By only cooling the instruments that need it, the orbiter will save energy and space yet again.

The scientific objectives of the Mars Express mission represent an attempt to complete in part the lost scientific goals of the ill-fated Russian Mars '96 mission. They also include 10m resolution photogeology, mineral mapping, atmospheric mapping, subsurface structure mapping, and research on the interaction of the atmosphere and the surface. A major goal of the mission is to determine the existence of water, and possibly even life. To find out if water was once present on the surface, the mission hopes to record the escape patterns of planetary substances.

Below is a brief description of each scientific instrument aboard the lander:

Energetic Neutral Atoms Analyzer - ASPERA
The ASPERA module will study how solar wind interacts with the Martian atmosphere and reveal processes by which water vapor and other gases could have escaped from Mars. This instrument uses a energetic neutral atom imaging to visualize the charged and neutral gas environments around Mars.

High/Super Resolution Stereo Color Imager - HRSC
The HRSC is a stereoscopic camera that will reveal details of the Martian surface to 2 m resolution. The images will then be used to make a geological map showing different minerals and rock types.

Radio Science Experiment - MaRS
MaRS will use radio waves to study the surface and atmosphere of Mars, and to measure gravity, temperature, and pressure variations.

Subsurface Sounding Radar/Altimeter - MARSIS
Using reflections of radio waves to map the distribution of water and ice in the upper portions of the Martian crust and to reveal subsurface structure.

IR Mineralogical Mapping Spectrometer - OMEGA
This instrument will determine the mineral content of the Mars'surface and the composition of the atmosphere by analyzing sunlight reflected and heat radiation emitted from the surface.

Planetary Fourier Spectrometer - PFS
PFS will measure the global atmospheric distribution of water vapor and other minor components with great accuracy.

UV and IR Atmospheric Spectrometer - SPICAM
SPICAM will measure smaller volumes of the atmosphere than PFS, and measure ozone. It will also use the technique of stellar occultation to measure the vertical profiles of carbon dioxide, temperature, ozone, aerosols and clouds.

Works Cited:

1) Mars Society
2) JPL NASA
3) Beagle2.com
4) sci.ESA.int

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