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By Yuri MARKOV, writer
The launch of a space probe late in the evening is a truly breath-taking and impressive sight. In the gathering twilight you suddenly see a huge column of fire, accompanied by the roar of the powerful engines. Seconds later, when the cigar-shaped launcher enters the sun-lit upper atmosphere, it starts glittering in its bright radiance. That was the sight observed by the crews of the Baikonur Cosmodrome on June 2, 2003. A quarter of an hour before midnight the Russian SOYUZ-FREGAT carrier rocket lifted the MARS-EXPRESS probe on its mission to the Red planet.
Interplanetary ballistics is an exact science. Long before the launch our space experts knew that the probe would reach Mars on the 20th of December, after a flight of a little more than half a year.
- An obvious question from the reader would be-why call the probe EXPRESS? As we know, all probes sent to Mars along an energy-saving trajectory also travel for about half a year. And that was the question I put at that time to colleagues from the European Space Agency.
- The name of the project-they explained-reflected the record-brief period of its preparation. The MARS-EXPRESS interplanetary probe consists of two sections: an orbiter (of the same name) and a lander BEAGLE-2, named in honor of the ship used by Charles Darwin on his round-the-world voyage in 1831. This prompted the great natural scientist to writing his famous "Origin of the Species by Means of Natural Selection".
Five days before reaching Mars the sections of the probe will separate, with the first becoming an artificial satellite of the Red planet and the second going straight on for a soft landing on the plane at Isidis Planitia.
Incidentally, some of the mass media distort the above sequence of maneuvers, misinforming the public about the station going first into an orbit around Mars and then performing the landing of BEAGLE-2. This sequence has indeed been used several times in studies of the Moon and other planets, causing addition-
al losses of energy since it was necessary to first slow down and then spin this massive probe around the heavenly body. And descent from orbit and focusing on the required region also cause additional energy losses.
Faced with what they call a mass deficit of MARS-EXPRESS, scientists choose the strategy of separation of sections of the probe. Incidentally, its total weight, including the fuel, is a little over 1,100 kg.
And there were other requirements which the authors of the project had to bear in mind. The orbit parameters of the MARS-EXPRESS were as follows: inclination-86, apogee altitude-11,560 km, perigee altitude-259 km, period of revolution-7.5 h. After 440 days of initial studies this orbit will undergo correction-the altitudes will be changed to 11,107 km and 298 km respectively, and the period to 6.7 h.
Studies of the mysterious planet will be performed with 3 sets of instruments. The first HRSC (high resolution stereocamera, OMEGA mapping spectrometer and MARS IS sub-surface sounding radar altimeter) will be used for studies of the surface and subsurface layer; the second (PFS-planetary Fourier-spectrometer, SPICAM- ultraviolet and infrared atmospheric spectrometer and ASPERA-energetic neutral atoms analyzer) will begin studies of the atmosphere and ionosphere; and the third (a set of radio transmitters) will be engaged on an experiment of radio-probing of the atmosphere of Mars. These transmitters will be emitting radiowaves from board the satellite in the direction of the Earth through the martian atmosphere. The signals received will help scientists understand the structure of the atmosphere of Mars at different altitudes.
At this point in our conversation my "reader-interlocutor" interested in studies of space says: I beg your pardon, but I think I have already read something about the OMEGA, ASPERA and SPICAM.
- Yes, this is not impossible, because the five instruments on board the MARS- EXPRESS had been developed for experiments within the Russian project MARS- 96 * . Engaged in these preparations were experts of the RAS Institute of Space Studies, the Vernadsky Institute of Geochemistry and Analytical Chemistry and other research centers of this country.
Unfortunately, MARS-96 probe failed to enter the planned trajectory of its flight to Mars. Since then the cause of the failure has been identified-it was a burnout in the engine of the booster unit "D" of the PROTON carrier rocket. But the MARS-96 project left behind a wealth of useful gear and some of this legacy is being used in the present European project. The men charge of the current mission to the Red Planet make no secret of the participation of our experts in the preparation of each of the seven experiments as well as their intellectual assessment of the mission objectives. And bearing in mind that the international station was set on its route to Mars by the SOYUZ-FREGAT Russian carrier rocket and the participation of the TRANSMASh agency from St. Petersburg in the development of the BEAGLE-2 lander, it would be quite fair to call the MARS-EXPRESS project an European-Russian venture.
One should also bear in mind that its success will depend to a large extent on the skill of experts managing the flight of the orbiter. Suffice it to say that every planned experiment requires special conditions. Thus, photos by stereocamera have to be taken only by day, but not at midday, and the camera has to be rocked slightly in order to obtain sharp pictures. As for the radar-altimeter, the preferable operating time is night. And what they call the atoms analyzer, it sometimes requires nadir orientation (anti-zenith) for one whole spin, and so on.
The sounding of the Red planet from board the station will be conducted mainly from the pericenter of the orbit, while during the rest of the orbit the probe will be transmitting recorded data to the ESA ground station in Perth (Australia).
Also planned are remote studies of the martian satellite Phobos. During the two-year mission the station will be approaching it at a distance of 3,000 km and less during which time all of the instruments will be "targeted" at the satellite.
Now, let's take a closer look at the BEAGLE-2 lander. And let us begin by saying that while the building of the platform of an orbiter is no news for specialists, the making of a small, but very complicated landing probe is a "novelty". Apprehension was even expressed that it might
* See: Yu. Markov, "Joy with a Smack of Gall", Science in Russia, No. 4, 1998. - Ed .
not be ready in time for the launch. But the "babe" managed to "jump the train".
The BEAGLE-2 probe was designed by British experts led by Prof. Colin Pillinger (Open University, Milton-Cains) and the head of the whole MARS-EXPRESS project is Prof. Rudi Schmidt (ESA).
The process of the soft-landing, which can hardly be called as such, is a rather complicated procedure: after the protective screen damps down the huge aerodynamic and thermal loads, the parachute system is activated. The probe itself will be placed inside three inflatable air cushions (the procedure was designed by experts of the Korolev R&D center, and it was first put into practice by experts of the Babakin R&D Bureau during the soft landing on the Moon of the LUNA-9 probe on February 3, 1966). After jumping on the surface of the planet, the air cushions will scatter away, leaving behind a very compact structure. The probe will "open up" like a budding flower, unfolding its solar batteries and numerous instruments. The main objective of BEAGLE-2 is to try and detect some signs of life, or what they call-paleolife. This means looking for water and methane in martian atmosphere, organic and inorganic compounds, studies of the structure of carbonic compounds and the quantitative ratios of carbon isotopes.
To be able to cope with all of these tasks the system is equipped with a manipulator with a stereo camera, microscope, turning and drilling lathe and a tiny semi-automatic robot for gathering soil samples. BEAGLE-2 is also equipped with a gas analyzer and instruments for energy measurements and registration and for meteorological observations. The weight of the probe is only 60 kg.
On areas of the martian surface, where rock is covered with rust, the soil samples will first be "cleaned" and then gathered by drilling for further measurements.
The probe will communicate with the Earth through the MARS-EXPRESS radiorelay or the MARS-ODYSSEUS unit which was placed into martian orbit by the Americans quite some time ago.
Very carefully chosen by experts was the landing site of BEAGLE-2. It is located at 10 North of the Isidis Planitia. The place is relatively warm which is important for the operation of the probe in the conditions of the early martian spring. The site has but a few dangerous rocks and its increased atmospheric pressure will permit the parachute system to reduce the landing velocity more effectively.
In conclusion, it should be pointed out that preparations for the MARS-EXPRESS mission (its cost approaches 300 mln Euros) have become an arena of broad international cooperation. The list of participants in the mission to the Red planet, which continues to keep its secrets, includes experts from Austria, Belgium, Great Britain, Germany, Denmark, Ireland, Italy, Spain, Netherlands, Norway, Russia, the United States, Finland, France, Switzerland and Sweden. Bearing in mind that the mission is linked with the Japanese NOZOMI project (the space probe reaching Mars in January 2004) and the designer of the drill on board BEAGLE-2 is a dentist from Hongkong (T. S. Ng), it would be no exaggeration to say that preparations for the mission have involved talents on a global scale.
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