Mercury probably lost its outer layers in a brawl with another rocky world, orbital observations suggest. The new data also shows that its magnetic field is curiously top heavy, stronger in the northern hemisphere than the southern, and leaves open the possibility that the sun-baked world may harbour ice in some of its polar craters. The data comes from NASA's Messenger probe, which became the first spacecraft to go into orbit around Mercury in March. Members of the mission team announced the latest results at a press briefing on Thursday. Studies of the composition of the surface have already ruled out two of the main theories for how Mercury came to have such a high density, with an enormous two-thirds of its mass made up of its metal core. Read more
The planet closest to the sun appears to have more ice at its poles than does Earth's moon.
Despite their proximity to the sun, portions of the surface of Mercury appear to be covered in ice, scientists said Thursday after analysing about 20,000 new images of the solar system's smallest planet. The pictures beamed to Earth by the Messenger spacecraft strongly suggest that frozen water - and perhaps other frozen substances - coat portions of impact craters near the planet's north and south poles. Permanently enshrouded in shadow, these surfaces are typically 300 degrees below zero Fahrenheit. Read more
Major-element composition of Mercury surface materials
Credit: NASA/The Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
Major-element composition of Mercury's surface materials, depicted on the same graph, as measured by the MESSENGER XRS. Mercury has lower Al/Si and higher Mg/Si than typical lunar surface materials and terrestrial basalts, indicating a lower fraction of the common mineral plagioclase feldspar.
MESSENGER Data from Mercury Orbit Confirm Theories, Offer Surprises
After nearly three months in orbit about Mercury, MESSENGER's payload is providing a wealth of new information about the planet closest to the Sun, as well as a few surprises. The spacecraft entered orbit around Mercury on March 18, 2011, becoming the first spacecraft ever to do so. Its instruments are performing the first complete reconnaissance of the planet's geochemistry, geophysics, geologic history, atmosphere, magnetosphere, and plasma environment. Tens of thousands of images of major features on the planet - previously seen only at comparatively low resolution - are now available in sharp focus. Measurements of the chemical composition of Mercury's surface are providing important clues to the origin of the planet and its geological history. Maps of the planet's topography and magnetic field are revealing new clues to Mercury's interior dynamical processes. And scientists now know that bursts of energetic particles in Mercury's magnetosphere are a continuing product of the interaction of Mercury's magnetic field with the solar wind. Read more
NASA Releasing First Ever Spacecraft Orbital Views Of Mercury
NASA will host a news conference at 1 p.m. EDT on Thursday, June 16, to reveal new images and science findings from the first spacecraft to orbit Mercury. The event will be held in the NASA Headquarters auditorium located at 300 E St. SW, in Washington. NASA Television and the agency's website will broadcast the event. Read more