On April 24, 2019, NASA’s Mars Odyssey orbiter captured a new thermal image of Phobos, the larger of Mars’ two moons. Each color in the full-moon image represents a temperature range detected by Odyssey’s Thermal Emission Imaging System (THEMIS) camera.
“This new image is a kind of temperature bullseye — warmest in the middle and gradually cooler moving out,” said Odyssey project scientist Dr. Jeffrey Plaut, from NASA’s Jet Propulsion Laboratory.
“Each Phobos observation is done from a slightly different angle or time of day, providing a new kind of data.”
The new, full-moon view is better for studying material composition, whereas earlier half-moon views are better for looking at surface textures.
“With the half-moon views, we could see how rough or smooth the surface is and how it’s layered,” said THEMIS co-investigator Dr. Joshua Bandfield, senior research scientist at the Space Sciences Institute.
“Now we’re gathering data on what minerals are in it, including metals.”
Iron and nickel are two such metals. Depending on how abundant the metals are, and how they’re mixed with other minerals, these data could help determine whether Phobos is a captured asteroid or a pile of Mars fragments, blasted into space by a giant impact long ago.
“These recent observations won’t definitively explain Phobos’ origin,” Dr. Bandfield said.
But Odyssey is collecting vital data on a moon scientists still know little about — one that future missions might want to visit.
“By studying the surface features, we’re learning where the rockiest spots on Phobos are and where the fine, fluffy dust is,” Dr. Bandfield said.
“Identifying landing hazards and understanding the space environment could help future missions to land on the surface.”