NASA’s Mars Reconnaissance Orbiter (MRO) is still achieving fresh milestones after nearly two decades of service, as evidenced by a large roll maneuver that has allowed the spacecraft to capture images almost upside down since 2023, according to findings detailed in a new paper.
Engineers on Earth managed the feat of coaxing the orbiter to roll over, gaining a better viewing angle in the search for liquid and ice water on the Red Planet. The spacecraft was initially designed to accommodate small 30-degree rolls, yet the team has successfully achieved much larger 120-degree rolls over the past two years.
“Not only can you teach an old spacecraft new tricks, you can open up entirely new regions of the subsurface to explore by doing so,” said Gareth Morgan of the Planetary Science Institute in Tucson, Arizona, one of the paper’s co-authors.
Rolling Above Mars
Rolling to some degree is a necessary function for an orbiter, enabling it to view landing sites, impact craters, and other surface features of interest. The five onboard instruments also require adjustments, as pointing one directly at the surface generally moves the others into poor viewing angles.
“We’re unique in that the entire spacecraft and its software are designed to let us roll all the time,” said Reid Thomas, MRO’s project manager at NASA’s Jet Propulsion Laboratory in Southern California.
Given the complexities of reorienting the Mars Reconnaissance Orbiter, weeks of planning go into each roll, following negotiations between the various teams that use the orbiter for different studies. A computer algorithm determines the orbiter’s position relative to the Martian surface and controls the maneuver, all while maintaining alignment between the spacecraft’s solar arrays and the Sun to ensure a continuous power supply.
Advanced Maneuvers
The new, larger rolls have allowed for a tenfold increase in MRO’s radar signal strength but require more meticulous planning. The Shallow Radar (SHARAD) instrument gained its best-ever view of Mars, penetrating between half a mile and a mile beneath the surface to identify subsurface sand, rock, and water. Its readings provide essential data for future astronauts to tap into Mars’ local water resources. Beyond providing liquid nourishment, Martian water could be used for rocket fuel and for studying the planet’s climate.
The maneuver does have one major drawback: it places the orbiter in such a position that its solar arrays cannot collect sunlight, meaning the orientation can only be maintained for a relatively short time before power runs low. As a result, the team limits the large rolls to only one or two per year to allow proper recharging.
“The very large rolls require a special analysis to make sure we’ll have enough power in our batteries to safely do the roll,” Thomas said.
SHARAD Instrument
Balancing the needs of all five instruments aboard the orbiter during the design phase was tricky, requiring trade-offs. One of these was mounting SHARAD’s antennas on the rear of the spacecraft to avoid blocking the HiRISE camera. Unfortunately, this positioning leads to interference with SHARAD’s radio signals, degrading image quality. The new large rolling maneuver flips the orbiter around to give SHARAD a much more direct view, resulting in a significant increase in signal strength.
“The SHARAD instrument was designed for the near-subsurface, and there are select regions of Mars that are just out of reach for us,” said Morgan, a co-investigator on the SHARAD team. “There is a lot to be gained by taking a closer look at those regions.”
SHARAD users aren’t the only beneficiaries of the maneuvers. The Mars Climate Sounder, a radiometer that monitors Mars’ atmosphere, is also better positioned, as the gimbal it once used to pivot has failed—making rolls the only way to aim the instrument effectively.
“Rolling used to restrict our science,” said Mars Climate Sounder’s interim principal investigator, Armin Kleinboehl of JPL, “but we’ve incorporated it into our routine planning, both for surface views and calibration.”
The new paper, “SHARAD Illuminates Deeper Martian Subsurface Structures with a Boost from Very Large Rolls of the MRO Spacecraft,” appeared on June 11, 2025, in The Planetary Science Journal.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.