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 may be closer to solving the mystery of how Mars changed from a world with surface water billions of years ago to the arid Red Planet of today. A new analysis of the largest known deposit of carbonate minerals on Mars suggests that the original Martian atmosphere may have already lost most of its carbon dioxide by the era of valley network formation.
Mars’ seasonal cap of carbon dioxide ice has eroded many beautiful terrains as it sublimates (goes directly from ice to vapour) every spring. In the region where the High Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter took this image, we see troughs that form a starburst pattern.
The young crescent Moon’s nightly motion from 31 December 2016 to 3 January 2017 carries it past dazzling planet Venus and first-magnitude Mars. A small telescope also reveals outermost planet Neptune, which passes just 0.02 degrees from Mars around 7h UT on 1 January, offering observers around the world a New Year’s Day treat.
