The team behind NASA’s 19-year-old Mars Reconnaissance Orbiter (MRO) has been busy teaching an old spacecraft new tricks, persuading the vehicle to perform a 120-degree roll to peer more clearly into the red planet.
The mission team imaginatively calls the maneuvers “very large rolls,” and they involve nearly flipping the spacecraft so that the Shallow Radar (SHARAD) can have a deeper view of Mars than ever before.
SHARAD can peer more than a half mile below the planet’s surface and helps scientists distinguish between materials like rock, sand, and ice. The latter substance is especially important, since it could be a key in-situ resource for any future crewed mission.
The problem is that SHARAD’s antenna segments are located on the “back” of the vehicle, with other instruments, such as the High-Resolution Imaging Science Experiment (HiRISE), in a prime position on the “front.” The radio signals pinged onto the planet by SHARAD can therefore encounter parts of the spacecraft, making for images that aren’t as clear as they could be.
The data returned is still useful, but scientists reckoned that if SHARAD were given an uninterrupted view of the surface, then things could be so much clearer. They found that the maneuver can strengthen the radar signal by ten times or more, making for a much clearer picture of the subsurface of Mars.
The latest trick does involve some risk. The orbiter was originally designed to roll up to 30 degrees in any direction. A 120-degree roll is so large that MRO’s communications antenna is no longer pointed at Earth, and its solar arrays can no longer track the sun.
Reid Thomas, MRO’s project manager at NASA’s Jet Propulsion Laboratory (JPL), said, “The very large rolls require a special analysis to make sure we’ll have enough power in our batteries to safely do the roll.”
Hence, only one or two very large rolls are permitted per year.
MRO was launched almost twenty years ago and has been orbiting Mars for over nineteen years. At this point in its mission, which has gone on for far longer than initially planned, controllers can be forgiven for wanting to try something new in the hope of some bonus science. For example, the European Space Agency’s (ESA) Mars Express sprouted a new instrument after engineers came up with a way of repurposing the Visual Monitoring Camera (VMC) used to monitor the departure of the Beagle 2 lander. The VMC now returns images of Mars.
NASA’s Mars Atmosphere and Volatile EvolutioN (MAVEN) and Mars Odyssey spacecraft are also orbiting the planet. Both are, however, at risk of being canceled should the proposed budget for the US agency be passed by lawmakers. ®