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Phobos-Grunt

NSSDCA/COSPAR ID: 2011-065A

Description

The Phobos-Grunt spacecraft did not perform its scheduled burn to begin its trajectory to Mars and could not leave Earth orbit. It re-entered Earth's atmosphere on 15 January 2012.

Phobos-Grunt (alternatively Fobos-Grunt) was a Russian mission designed to land on the martian moon Phobos and return a sample to Earth. The primary scientific objective was to analyze the sample on Earth to understand the origin and reconstruct the history of Phobos. Specific objectives were to analyze the composition of the material returned and to determine how it related to other material in the solar system, if it contained any particles ejected from the martian surface, protosolar matter, or organic material, if it had been differentiated and to what degree, and the ages of the sample. A robotic arm would have collected approximately 100 to 200 grams of samples and deposit them in a return capsule which will be launched back to Earth. Phobos-Grunt was launched with a Chinese Mars orbiter mission, Yinghuo-1.

Spacecraft and Subsystems

The lander comprises a short cylindrical body with three landing legs and two solar panel wings. Total dry mass of the lander cruise stage is 730 kg. Instruments, the sample return vehicle, and the robotic arm are mounted on top of the structure. Communications are achieved via the Onboard Radio Complex, which operates in X-band and has a data rate of 16 Kbit/sec. Power is supplied by the solar panels, which have a total area of 10 square meters and provide a maximum power of 150 W for the payload. The cruise stage will carry 870 kg of Unsymmetrical Dimethylhydrazine (UDMH) propellant and will be run by the BKU flight control system. Spacecraft attitude and control are achieved using a star tracker unit (BOKZ-MF), optical sun trackers (OSD), the Baseless Inertial Unit (BIB-FG), and a Television System of Navigation and Observation (TSNN). A radar system, the Dopler Measurer of Velocity and Range (DISD), will be used for final approach and landing on Phobos.

The scientific payload has a total mass of 50 kg. It comprises a number of instruments mounted on the spacecraft to evaluate the regolith at the landing site. These are the FOGS Gamma Spectrometer, the MAL-1 Mass Spectrometer, the Termofob Thermodetector, and the Seismo-1 Seismometer. Phobos-Grunt also carries a Meteor-F cosmic dust detector. The sampling unit consists of a robotic arm, a shifting device, an inlet capsule, and TV cameras for visual control. The area around the lander will be assessed and samples chosen. The robotic arm consists of a cylindrical scoop which can open, with a piston inside to push the samples out into the cylindrical inlet container. A photo-diode will be used to determine if a sample has been deposited. The samples will fall into the interior of the sample return capsule. Samples can be up to 1.3 cm in size.

The return stage is mounted on springs on top of the lander. It has a dry mass of 106.66 kg and a fueled mass of 296 kg. The springs will eject the return stage and propel it to a safe distance above the lander before the rockets ignite, to prevent damage to the instruments on the lander. Power is provided by 1.64 square meters of solar panels. It is also equipped with a star tracker, sun tracker, and inertial unit. The propulsion unit has a thrust of 130.5 N and uses UDMH from a pressure-fed propellant supply system. Attitude control is achieved using 16 small 0.08 kg nitrogen gas thrusters. The craft is spin-stabilized during its flight back to Earth. The reentry capsule has a mass of 7.5 kg.

Mission Profile

Phobos-Grunt 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 occured and the spacecraft remained in Earth orbit. It reentered the atmosphere on 15 January, 2012.

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 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 maneuvers, the return capsule should arrive at Earth in August of 2014. The lander experiments will continue to operate on the surface for a year.

Spacecraft image for illustrative purposes - not necessarily in the public domain.

Alternate Names

  • Fobos-Grunt

Facts in Brief

Launch Date: 2011-11-08
Launch Vehicle: Zenit
Launch Site: Tyuratam (Baikonur Cosmodrome), Kazakhstan
Mass: 730.0 kg
Nominal Power: 150.0 W

Funding Agency

  • Unknown (Russia)

Discipline

  • Planetary Science

Additional Information

Questions or comments about this spacecraft can be directed to: Dr. David R. Williams.

 
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