Space agency NASA launched MESSENGER (an acronym of MErcury Surface, Space ENvironment, GEochemistry, and Ranging) in August 2004 to study Mercury, the closest planet to the Sun. The robotic spacecraft successfully entered Mercury’s orbit on March 17, 2011. Since then, it has been studying the planet’s chemical composition, geology, and magnetic field. And now, it’s been reported that MESSENGER is going closer to Mercury than ever before to study the planet more deeply.
MESSENGER has already explored vast chemical diversity on the planet’s surface. MESSENGER has also found new evidence for water ice at Mercury’s poles. Besides, until now MESSENGER has captured more than 200,000 images of Mercury. MESSENGER has done this all from being a safe distance. But on July 25, MESSENGER moved closer to Mercury than any spacecraft has before, dropping to an altitude at closest approach of only 100 kilometers (62 miles) above the planet’s surface.
The latest observational campaign includes closer looks at polar ice deposits, unusual geological features, and the planet’s gravity and magnetic fields “in ways that have never been possible“. Such closeness of MESSENGER to Mercury is allowing the NASA scientists “see Mercury up close and personal for the first time.”
MESSENGER Mission Design Lead Engineer Jim McAdams has confirmed that because of progressive changes to the orbit over time, MESSENGER’s minimum altitude will continue to decrease. On August 19, the minimum altitude will be cut in half, to 50 kilometers. Closest approach will be halved again to 25 kilometers on September 12.
McAdams said, “Soon after reaching 25 kilometers above Mercury, an orbit-correction maneuver (OCM-10) will raise this minimum altitude to about 94 kilometers. Two more maneuvers, on October 24 and January 21, 2015, will raise the minimum altitude sufficiently to delay the inevitable – impact onto Mercury’s surface – until March 2015.”