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Tag Archives: orbiter

NASA’s MESSENGER orbiter of Mercury ran out of fuel and crashed into Mercury on May 1, 2015, ending a very successful mission. The craft slammed into Mercury’s surface at about 8,750 mph and created a new crater on the planet’s surface.

MESSENGER’s demise went unobserved because the probe hit the side of the planet facing away from Earth, so ground-based telescopes were not able to capture the moment of impact. Space-based telescopes also were unable to view the impact, as Mercury’s proximity to the Sun would damage their optics.

MESSENGER had been in orbit more than four years and completed 4105 orbits around Mercury. Among its many accomplishments, the MESSENGER mission determined Mercury’s surface composition, revealed its geological history, discovered its internal magnetic field is offset from the planet’s center, and verified its polar deposits are dominantly water ice.

The movie below shows a NASA simulation of the spacecraft’s epic voyage.

Links: MESSENGER home, Sky & Telescope’s report, NY Times article, high-resolution image of the crash-site, map of gravity anomoalies measured by deviations of MESSENGER from its predicted orbit.


The European Space Agency’s ExoMars mission is set for launch in 2018.  A rover and a lander are included, to search for evidence of past and present life on Mars. The orbiter, part of the ExoMars 2016 mission, will sample the Martian atmospheric trace gases, such as methane and provide communications. The rover will leave the landing platform and drill into the surface to search for potential fossils, relevant minerals, and organic molecules (with chirality as biomarkers).


Credit: ESA

In addition to its scientific exploration, the mission will help test in-situ technologies that might pave the way for a future international Mars sample return mission.

Links: ExoMars 2018 mission overview; ESA Mars homepage.