Final farewell: MESSENGER mission ends with impact on Mercury

The probe's mission has ended after two extensions to continue gathering data.
By Andrew McDonald | Apr 30, 2015
According to a statement from the Johns Hopkins University Applied Physics Laboratory, NASA's MErcury Surface, Space ENvironment,GEochemistry, and Ranging (MESSENGER) probe has met its end after an extremely successful mission. At 3:26 p.m. EST on April 30, MESSENGER plummeted into the surface of Mercury.

Its fuel depleted and lacking any means of rising to higher altitudes, MESSENGER was pulled into Mercury's surface by the influence of the Sun's gravity. Traveling at about 8,750 miles per hour, the probe blasted out a fresh crater as much as 52 feet wide.

Final confirmation of MESSENGER's demise came at 3:40 p.m. EST, when the Deep Space Network did not pick up a signal from the probe when it would have reemerged from the far side of Mercury, had it not struck the surface.

MESSENGER performed so admirably that, after the conclusion of its main science mission in March 2012, its operation was extended twice in order to take advantage of the probe's lower-altitude orbits. MESSENGER acquired data and images in extraordinary resolution.

In March 2015, the second and final mission extension, dubbed XM2, commenced, with MESSENGER coming to between five and 35 miles from Mercury's surface. On April 28, the last orbital correction maneuver was carried out; this maneuver was part of a series that had kept MESSENGER orbiting for the extra month of April. During this lease on life, MESSENGER gathered data on magnetic anomalies in Mercury's crust and the planet's polar craters, which cradle areas of ice.

Sean Solomon, MESSENGER's Principal Investigator and Director of Columbia University's Lamont-Doherty Earth Observatory, delivered the mission's eulogy:

"Today we bid a fond farewell to one of the most resilient and accomplished spacecraft ever to have explored our neighboring planets. Our craft set a record for planetary flybys, spent more than four years in orbit about the planet closest to the Sun, and survived both punishing heat and extreme doses of radiation. Among its other achievements, MESSENGER determined Mercury's surface composition, revealed its geological history, discovered that its internal magnetic field is offset from the planet's center, taught us about Mercury's unusual internal structure, followed the chemical inventory of its exosphere with season and time of day, discovered novel aspects of its extraordinarily active magnetosphere, and verified that its polar deposits are dominantly water ice. A resourceful and committed team of engineers, mission operators, scientists, and managers can be extremely proud that the MESSENGER mission has surpassed all expectations and delivered a stunningly long list of discoveries that have changed our views not only of one of Earth's sibling planets but of the entire inner solar system."

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