Jim Sharkey
February 11th, 2018
Artist’s depiction of NASA’s Mars Reconnaissance Orbiter above the Red Planet. Image Credit: James Vaughan / SpaceFlight Insider
Since arriving in orbit above the Red Planet in 2006, NASA’s Mars Reconnaissance Orbiter (MRO) has observed Mars with it scientific instruments and provided a vital communications link for mission on the Martian surface. The spacecraft has already operated for more than twice its planned mission lifetime. NASA is planning to keep using it well into the 2020’s to support upcoming missions. The space agency is currently taking steps to increase the orbiter’s longevity.
MRO’s solar array prior to the launch of the spacecraft. Photo Credit: NASA / KSC
One potential way to extend MRO’s life expectancy would be to increase reliance on the spacecraft’s star tracker and less on its aging gyroscopes. Another way to potentially increase the spacecraft’s life would be to squeeze more power from the orbiter’s batteries.
“We know we’re a critical element for the Mars Program to support other missions for the long haul, so we’re finding ways to extend the spacecraft’s life,” said MRO Project Manager Dan Johnston of NASA’s Jet Propulsion Laboratory stated via a release. “In flight operations, our emphasis is on minimizing risk to the spacecraft while carrying out an ambitious scientific and programmatic plan.”
MRO completed its final full-swapover test using only stellar navigation to maintain its orientation in early February. The mission team is studying the results of this test and plans to shift to “all-stellar” mode in March.
Until the “all-stellar” capability was uploaded as a software patch last year, MRO had always used an inertial measurement unit containing gyroscopes and accelerators for attitude control. The space carries a primary and a spare inertial measurement unit. The mission team switched from the primary to the backup unit when the primary began to show signs of limited life after about 58,000 hours of use. The spare is still functioning after 52,000 hours of use, but will need to be conserved for when it is needed most.
The star-tracker, which also has a spare on board, uses a camera to image the sky and pattern-recognition software to determine which bright stars are in the field of view. This enables the system to discern the orbiter’s orientation. Repeated observations at a rate of several times per second provides accurate measurements of the rate and direction of attitude change.
“In all-stellar mode, we can do normal science and normal relay,” Johnston said. “The inertial measurement unit powers back on only when it’s needed, such as during safe mode, orbital trim maneuvers, or communications coverage during critical events around a Mars landing.”
The MRO team is conditioning the spacecraft’s two batteries to hold more of a charge in order to reduce demand on the batteries and prolong battery life. The team also plans to reduce the time the spacecraft spends in the shadow of Mars during each orbit. Currently the orbiter spends about 40 minutes of each two-hour orbit in the shadow of Mars. The batteries are recharged by MRO’s solar panels as the spacecraft passes over then sunlit side of Mars.
“We are counting on Mars Reconnaissance Orbiter remaining in service for many more years,” said Michael Meyer, lead scientist of NASA’s Mars Exploration Program at the agency’s headquarters in Washington D.C. “It’s not just the communications relay that MRO provides, as important as that is. It’s also the science-instrument observations. Those help us understand potential landing sites before they are visited, and interpret how the findings on the surface relate to the planet as a whole.”
Video courtesy of NASA/JPL-Caltech
Jim Sharkey
Jim Sharkey is a lab assistant, writer and general science enthusiast who grew up in Enid, Oklahoma, the hometown of Skylab and Shuttle astronaut Owen K. Garriott. As a young Star Trek fan he participated in the letter-writing campaign which resulted in the space shuttle prototype being named Enterprise. While his academic studies have ranged from psychology and archaeology to biology, he has never lost his passion for space exploration. Jim began blogging about science, science fiction and futurism in 2004. Jim resides in the San Francisco Bay area and has attended NASA Socials for the Mars Science Laboratory Curiosity rover landing and the NASA LADEE lunar orbiter launch.
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