It’s tiny, it’s pockmarked, and it’s got almost no atmosphere. So it’s probably small wonder that we cared so little for poor Mercury that we couldn’t be bothered to check out a whole half of the planet until 2008.
—Image courtesy NASA/Johns Hopkins University Applied Physics Laboratory/Arizona State University/Carnegie Institute of Washington
But when we did send a probe to scope out the scene, boy did we find some doozies!
Last October the MESSENGER probe had its second sweep past the planet as it settles into an eventual orbit. Not to waste the opportunity, scientists programed the craft to collect all kinds of data during the brief flyby.
The latest issue of Science describes a whole slew of neat findings from the October visit, including:
- Magnetic activity that generates invisible “twisters”
- Surprise magnesium in the thin atmosphere
- A global [and colorful!] picture of Mercury’s surface geology
- A really big freakin’ impact basin
I personally loved the magnetic twisters, which I found cool enough to assign as a news story that was deftly reported by our own Rebecca Carroll.
But that last one is also pretty impressive.
As impact basins go, the newly named Rembrandt is a sizable feature—430 miles (700 kilometers) wide, or big enough to stretch from D.C. to Boston if it was on Earth.
—Image courtesy NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington/Smithsonian Institution Copyright: Smithsonian Institution
For something so large, it really surprised the research team to find that the floor of the basin has remained largely unchanged for 3.9 billion years.
“This is the first time we have seen terrain exposed on the floor of an impact basin on Mercury that is preserved from when it formed,” the Smithsonian’s Thomas Watters said in a statement. “Terrain like this is usually completely buried by volcanic flows.”
Being almost bare-bottomed means that researchers can see the patterns of ridges and troughs criss-crossing the basin floor, including evidence of a thrust fault that would rival the San Andreas in California.
“The pattern of tectonic landforms in the Rembrandt basin is truly extraordinary,” Watters said. “It is unlike anything we have seen before in other impact basins on Mercury, the Moon or Mars, or in basins formed on the icy moons of the outer planets.”