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.
A survey of ten hot, Jupiter-sized exoplanets conducted with NASA’s Hubble and Spitzer telescopes has led a UK-US team to solve a long-standing mystery — why some of these worlds seem to have less water than expected. The findings offer new insights into the wide range of planetary atmospheres in our galaxy and how planets are assembled.
Using data from NASA’s Fermi Gamma-ray Space Telescope and other facilities, an international team has found the first gamma-ray binary in another galaxy and the most luminous one ever seen. The dual-star system, dubbed LMC P3, contains a massive star and a crushed stellar core that interact to produce a cyclic flood of gamma rays.
At half the diameter of Pluto, Charon is the largest satellite relative to its planet in the solar system. NASA’s New Horizons spacecraft has returned the best colour and the highest resolution images yet of Charon, showing a landscape covered with mountains, canyons, landslides, surface-colour variations and more — all evidence of a surprisingly complex and violent history.
