In a tweet on February 28, MESSENGER’s science team announced that the entire surface of Mercury had been mapped with its Dual Imaging System (MDIS).
The milestone comes just shy of MESSENGER’s (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) beginning its third year at the closest planet to the sun. The task of mapping Mercury was accomplished using the wide-field camera component of its Mercury Dual Imaging System, which has a resolution of approximately 250m/pixel. The mapping process was begun in a series of flybys by Mariner 10 in 1974 but due to orbital geometries, that probe only mapped 45% of the surface. The modern effort of mapping the planet began with MESSENGER’s first flyby in January 2008, and got going in earnest upon entering orbit in March 2011.
Since MESSENGER entered orbit, the probe has completed over 1750 orbits around Mercury. The amount of time taken to map the planet was due in part to Mercury’s spin-orbital resonance, in which Mercury completes three rotations for every two orbits. The resonance leads to a complex motion of the sun in Mercury’s sky, meaning areas where imaging conditions ideal for mapping new terrain move very slowly across the planet’s face.
In other MESSENGER news, the probe’s twitter feed (which posts updates from the probe’s point of view) has been active in the last couple of days with updates from the probe’s 29th science team meeting, which discusses details of the probe’s current health and upcoming operations. The tweets hinted that planning for the end of MESSENGER’s mission were among the topics of discussion at the meeting. One possibility mentioned in the twitter feed is “lithobraking”, suggesting that the probe may be crashed into the planet for scientific observations. As one tweet read, “At some point I will either run out of fuel or funding. Just like every great spacecraft, one cannot last forever.”
MESSENGER was planned to operate in Mercury’s orbit for a year after it arrived at the planet in 2011. The mission was extended last year in part to help study the solar cycle. That extension ends this year, but another extension may be granted for the mission until 2015. Whether or not the mission is extended past 2013 will likely depend on NASA’s budget situation, although existing probes generally take precedence over missions currently being planned. Time will tell, and an announcement regarding the probe’s future may be made at the Lunar and Planetary Science Conference, which takes place from March 19-23.
I’ll leave you with video highlighting some of the interesting things that MESSENGER’s narrow-field MDIS imager has observed. The video was released through MESSENGER’s twitter feed on February 27.
Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington