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US experts change forecasts on Phobos-Grunt reentry

November 24, 2011, 13:43 UTC+3

The automatic interplanetary station Phobos-Grunt was launched from the Baikonur Cosmodrome on November 9 by the Zenit-2SB launch vehicle

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MOSCOW, November 24 (Itar-Tass) — The American system of space control has changed its initial forecast on the time of re-entry of Russian’s automatic interplanetary station Fobos-Grunt (Phobos-Soil), predicting it at a later date. This has indirectly confirmed the theory of the station’s self-control in low Earth orbit.

If earlier, according to American calculations, the station was to enter the Earth’s atmosphere on November 26, then now a new possible date - December 12 is named. It is also emphasised that these data will be updated on a permanent basis. For the first time a website subordinated to the US Strategic Command has presented the linear dimensions of the automatic interplanetary station - 16.83 metres.

The automatic interplanetary station Phobos-Grunt was launched from the Baikonur Cosmodrome on November 9 by the Zenit-2SB launch vehicle. The station reached a low-Earth orbit from which it was to be transferred to an escape trajectory from Earth to Mars by two ignitions of its main propulsion system. For unknown reasons, the control system has failed to give the command to the first ignition of the propulsion system.

According to previously available data, since the launch time the station’s orbit has not degraded in height. This is possibly owing to the work of the Sun orientation subsystem that has given relevant commands to the low-thrust engines of the station that maintained the orbit’s altitude.

For a long time, all the attempts to establish communication with the station were unsuccessful. The situation has possibly begun to change over the past two days when the experts of the European Space Agency (ESA) managed able to restore contact with the station. Experts of the ESA and the Russian Federal Space Agency (Roskosmos) are currently preparing a program of further work with the automatic interplanetary station. They have little time left - as the window for Phobos-Grunt to enter the escape trajectory to Mars will be closed by the end November.

Roughly 7.5 metric tons of highly toxic hydrazine and nitrogen tetroxide are on board the station, the head of Roskosmos said earlier. It is mostly fuel for the spacecraft’s upper stage. The amount of fuel is nearly 20 times the amount that was on board the American spy satellite USA-193, which was shot down before re-entry by the US in February 2008. These compounds, with melting points of 2 °C and -11.2 °C, are normally kept in liquid form; if the probe is not rescued but they remain liquid, they are expected to burn out during re-entry. NASA veteran James Oberg said the hydrazine and nitrogen tetroxide “could freeze before ultimately entering.” If Phobos-Grunt is not salvaged, it may be the most dangerous object to fall from orbit. However, the head of Roskosmos says the probability of parts reaching the Earth is “highly unlikely,” and that spacecraft will be destroyed during re-entry.

Fobos-Grunt is the first Russian interplanetary mission since Mars 96, which suffered a launch failure. The last Russian or Soviet interplanetary mission that was successfully launched was the second probe of the Phobos program in 1988. Fobos-Grunt is the first sample return mission to the natural satellite of another planet conducted by mankind. If successful, Fobos-Grunt could pave way to a number of Russian interplanetary missions, including missions to the moons of Jupiter, Saturn and Uranus, and asteroid and comet sample return missions.

The Russian Federal Space Agency has said 90 percent of Phobos-Grunt is made of new and untested elements. The new instruments are being tested and will be tested during the flight. According to lead scientist Alexander Zakharov, the entire spacecraft and most of the instruments are new, although they do draw on the heritance of the three successful Luna sample-return missions of the 1970s. Zakharov has described the Phobos sample return project as “very difficult,” possibly “the most difficult interplanetary one to date.”

The Soviet Union began its Martian program in October 1960. There were two launches in 1960 and three more in 1962. Four launches were abortive, and only Mars 1 went to space on November 1, 1962. However, contact with it was lost. Two automatic interplanetary stations - Mars 2 and Mars 3, were launched in May 1971. Mars 2 delivered a capsule with the Soviet state emblem to Mars. The landing vehicle of Mars 3 touched down on December 2. Nevertheless, no information was collected. Four Mars vehicles came to the Martian orbit in 1974, and Mars 6 landed in the Mars southern hemisphere.

Two Phobos rovers were launched in July 1988 for studying Mars and its moon. The first one was lost on the way to Mars and the other reached the Martian orbit. In two months of its work Phobos 2 transmitted information about temperature fluctuations on the Martian surface and 38 images of Phobos. The latest Martian mission in November 1996 failed. Mars 96 could not reach the designated orbit and was lost.

Phobos-Grunt was launched on 8 November 2011 at 2016 UT on a Zenit 2SB41.1 rocket from the Baikonur Cosmodrome in Kazakhstan into an elliptical Earth orbit. The plan was to use a Fregat upper stage to carry Phobos-Grunt and Yinghuo-1 on an eleven month cruise to Mars. However, the later firings never occurred and the spacecraft remained in Earth orbit, according to NASA. The plan for the mission if it had made it to Mars is as follows: It will orbit Mars for a few months and touch down on Phobos in February 2013. Sample assessment and collection will take place over the next 2 to 7 days. It will collect 15 to 20 separate samples. After the samples have been collected, the springs will propel the return stage away from the lander and the rockets provide the 35 km/hr velocity needed to escape Phobos’ gravity. After the necessary manoeuvres, the return capsule should arrive at Earth in August of 2014. The lander experiments will continue to operate on the surface for a year.

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