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.
Scientists celebrated another success with Japan’s Hayabusa 2 spacecraft late Wednesday (U.S. time), when the robot explorer accomplished a second pinpoint touch-and-go landing on asteroid Ryugu, this time to collect a sample of pristine dust and rock excavated by an explosive impactor earlier this year.
NASA’s Mars Curiosity rover has started drilling in a clay-bearing unit on the slope of Mount Sharp where rocks formed in the presence of water are expected.
A hundred days have passed since Mars was closest to Earth this year, but the Red Planet can still be seen in the early evening sky close to the jewel of the solar system, Saturn. If you wish to identify this pair of planets, then a convenient celestial marker in the form of the waxing crescent Moon passes by on the evenings of 8—9 September in the UK and Western Europe.
