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Tag Archives: MESSENGER

From an article on

Mercury has possessed a magnetic field for billions of years, and that field may have once been as strong as the Earth’s.

As NASA’s MESSENGER spacecraft ended its four-year mission at Mercury, it travelled so low over the surface, at altitudes as low as 15 kilometers, that it was able to detect weak magnetism coming from surface rocks in terrain 3.7 to 3.9 billion years old.


Credit: NASA/University of British Columbia

The discovery indicates that Mercury’s magnetic field, generated by liquid rotating in the planet’s core, was that old, helping to constrain scenarios for how Mercury has evolved over time. No trace of magnetism on Earth in rocks older than 3.5 billion years has been found.

Link: article.


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.