Nasa’s Mars Reconnaissance Orbiter (MRO) reached its destination 10 March, 7 months after launch, and is now in position to gradually descend into a low science orbit around the Red Planet. Its mission to pave the way for future rover and crewed missions will end late in 2010.

Exceptional Mars mission

Weighing 2.18 t, MRO is the heaviest spacecraft ever to orbit Mars. Its fuel tank alone holds more than 1.22 t of propellant.

Ultimately, MRO will also generate very-high-resolution imagery (30 cm/px), making it in every way an exceptional mission that will send back more data to Earth than any previous Mars orbiter.

Friday 10 March, MRO successfully accomplished a crucial phase of its mission when it put itself into an elliptical orbit with a periapsis of 350 km above the planet’s surface.

Its final working science orbit will be 20% lower than the other satellites already in orbit around Mars: Nasa’s Mars Global Surveyor and Mars Odyssey, and Esa’s Mars Express.

25 months of observation

Aerobraking operations to lower MRO’s orbit will be completed by end September, when the orbiter will begin its 25-month science mission in low-altitude, circular polar orbit.

The science mission’s objectives are to:

  • Improve our understanding of Mars’ climate and search for signs of water: MRO is equipped with a spectrometer to detect minerals, a ground-penetrating radar and a radiometer to analyse atmospheric dust and water vapour, and measure temperature profiles.

  • Identify and define possible landing sites for future Mars rover missions.

  • Serve as a communications relay for 2 future Mars missions: the Phoenix lander, scheduled to land at Mars’ north pole in 2008; and the Mars Science Laboratory (MSL) to be launched in 2009.

  • Observe the planet with 3 cameras: the 1st of MRO’s cameras has the largest objective lens (50 cm) ever flown on a planetary mission. It will be able to clearly distinguish rocks and layers of terrain less than 2 m wide. A 2nd camera will increase tenfold the number of spots surveyed close-up. A 3rd camera will map Mars weather.

Scientists will start poring over all these data from November to gain a closer insight into the variations in Mars’ atmosphere and the phenomena that have shaped the planet’s geology.

MRO’s mission is scheduled to end late 2010, but fuel reserves should be sufficient to extend the mission for much longer.