The orbit of NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft sometimes crosses the orbit of the planet’s inner moon, Phobos. This image shows the configuration of the two orbits in early December 2015, when MAVEN’s Phobos observations were made. Image credits: CU/LASP and NASA.Orbiting a mere 3,700 miles (6,000 kilometres) above the surface of Mars, Phobos is closer to its planet than any other moon in the solar system. Mars’ gravity is drawing in Phobos, the larger of its two moons, by about 6.6 feet (2 metres) every hundred years. Scientists expect the moon to be pulled apart in 30 to 50 million years.
Other than gathering evidence of its eventual fate, NASA scientists are also closer to solving the mystery of how Mars’ moon Phobos formed.
In late November and early December 2015, NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) mission made a series of close approaches to the Martian moon Phobos, collecting data from within 300 miles (500 kilometres) of the moon.Phobos as observed by MAVEN’s Imaging Ultraviolet Spectrograph. Orange shows mid-ultraviolet (MUV) sunlight reflected from the surface of Phobos, exposing the moon’s irregular shape and many craters. Blue shows far ultraviolet light detected at 121.6 nm, which is scattered off of hydrogen gas in the extended upper atmosphere of Mars. Phobos, observed here at a range of 300 kilometres, blocks this light, eclipsing the ultraviolet sky. Image credits: CU/LASP and NASA.The observations were made by the Imaging Ultraviolet Spectrograph instrument aboard MAVEN. 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.
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. The MAVEN data, when fully analysed, will also help scientists look for organic molecules on the surface. Evidence for such molecules has been reported by previous measurements from the ultraviolet spectrograph on ESA’s Mars Express spacecraft.
Decisions on the future of a joint robotic mission between NASA and the European Space Agency to demonstrate the ability to deflect an asteroid on a collision course with Earth have been put off until later this year after European governments declined to fully fund their part of the project in December.
NASA’s Hubble Space Telescope helped an international team of astronomers find that an unusual object in the asteroid belt is, in fact, two asteroids orbiting each other that have comet-like features. These include a bright halo of material, called a coma, and a long tail of dust.
Astronomers say an object observed speeding through our solar system last month has an unexpected cigar-like shape and originated from another star, making it the first confirmed interstellar asteroid.