Although nearing the end of its lifespan, NASA’s MESSENGER spacecraft is currently providing us the most detailed images of the surface of Mercury ever taken.
MESSENGER, which is just about to run out of propellant, has been orbiting Mercury since 2011. The spacecraft is also the closest it has ever been to the planet’s surface, with only 15 kilometers (roughly 9.3 miles) separating the two.
MESSENGER reveals Mercury’s craters, scarps and hollows
In a series of vivid images released on March 16, we can see ice-encrusted craters, staircase-like ridges and visible surface abrasions that suggest severe space weathering.
Scientists are particularly intrigued by a few choice images that are providing new insights into Mercury’s many craters. According to Nancy Chabot, a planetary scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, MESSENGER has given scientists images of at least a dozen craters located near Mercury’s North and South poles. Although the initial photos only showed craters with blacked-out pits (due to the brightness of the crater rims over-saturating the image), subsequence visual enhancements bring the crater floors into clearer view.
Among the most interesting craters recently captured is the Fuller crater (shown above), named after neo-futuristic architect and visionary Richard Buckminster Fuller. This processed image suggests the existence of some type of carbon-rich material that overlays the ice covering the Fuller crater’s floor. Other features include the appearance of sharply defined black and white areas, which scientists theorize are the result of a space rock that slammed into Mercury, depositing water “in the form of ice with darker material atop it.”
There are also images that show smaller versions of long ridges, or scarps, that have long characterized Mercury’s surface.
These ridges are often hundreds of kilometers long and are thought to be cracks formed when Mercury cooled and shrank over time. These newer, smaller scarps, however, “are so young that they are probably forming today,” says Thomas Watters, a planetary scientist at the National Air and Space Museum in Washington DC.
A final feature MESSENGER’s images are bringing into clearer view are mysterious swaths of brightly lit depressions called “hollows.” These hollows are considered relatively new formations, suggesting Mercury is undergoing a lot of geological and tectonic change.
According to mission controllers, the MESSENGER orbiter has enough fuel for just five more boosts before Mercury’s gravity brings the spacecraft down for a final explosion of obsolescence. Fortunately, the European Space Agency is sending a spacecraft that will reach Mercury in 2024 to pick up where MESSENGER left off.