In late November and early December last year, NASA's Mars Atmosphere and Volatile Evolution (MAVEN) mission made a series of close approaches to the Martian moon Phobos, collecting data from within 500 kilometres of the moon.
Among the data returned were spectral images of Phobos in the ultraviolet.
The images will allow MAVEN scientists to better assess the composition of this enigmatic object, whose origin is unknown, NASA said.
Comparing MAVEN's images and spectra of the surface of Phobos to similar data from asteroids and meteorites will help planetary scientists understand the moon's origin - whether it is a captured asteroid or was formed in orbit around Mars.
Evidence for such molecules has been reported by previous measurements from the ultraviolet spectrograph on the Mars Express spacecraft, according to the US space agency said.
The observations were made by the Imaging Ultraviolet Spectrograph instrument aboard MAVEN.
