Confused Mercury Crater Looks Icy, But May Be Evaporation Evidence

At first glance, you’d think that white stuff on the floor of Kertesz crater is ice, especially since that substance has been confirmed on its home planet — Mercury. This new shot of the 19-mile (31-kilometer) crater in the Caloris basin shows off irregular depressions, or hollows, that jump out in this color-enhanced picture taken by NASA’s MESSENGER spacecraft. More close-up pictures from previous passes are below the jump.

“The bright material on the floor of Kertész crater is not the water ice recently confirmed to be in craters near Mercury’s poles, but it might well be behaving as ice would on another planet,” NASA wrote in 2012.

“Mercury’s daytime temperatures are so hot at most latitudes that rocks that would be stable at other places in the Solar System may essentially evaporate on Mercury. That is one theory for the formation of these bright, irregular features known as hollows seen here and in many other craters on Mercury.”

There’s still much to learn, so scientists are probably grateful that MESSENGER is still working beyond its design lifetime. It was originally supposed to conclude in 2011, but its mission was extended further to see the effects of the solar maximum on the solar system’s closest planet to the sun.

This photomosaic shows the Kertesz crater on Mercury on the planet's Caloris Basin, as seen by NASA's MESSENGER mission. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
This photomosaic shows the Kertesz crater on Mercury on the planet’s Caloris Basin, as seen by NASA’s MESSENGER mission. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
A side view of  Kertész crater on Mercury, as imaged by NASA's MESSENGER spacecraft. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
A side view of Kertész crater on Mercury, as imaged by NASA’s MESSENGER spacecraft. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
A 3-D view of Kertesz crater in Mercury's Caloris Basin. Mosaic from NASA's MESSENGER spacecraft. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
A 3-D view of Kertesz crater in Mercury’s Caloris Basin. Mosaic from NASA’s MESSENGER spacecraft. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Take a Spin Around Mercury

Created by the MESSENGER mission team at the Johns Hopkins University Applied Physics Laboratory and the Carnegie Institution of Washington, this animation gives us a look at the spinning globe of Mercury, its surface color-coded to reflect variations in surface material reflectance.

Thousands of Wide Angle Camera images of Mercury’s surface were stitched together to create the full-planet views.

While the vibrant colors don’t accurately portray Mercury as our eyes would see it, they are valuable to scientists as they highlight the many different types of materials that make up the planet’s surface. Young crater rays surrounding fresh impact craters appear light blue or white. Medium- and dark-blue “low-reflectance material” (LRM) areas are thought to be rich in a dark, opaque mineral. Tan areas are plains formed by eruption of highly fluid lavas. Small orange spots are materials deposited by explosive volcanic eruptions.

At this point, over 99% of the Solar System’s innermost planet has been mapped by MESSENGER. Read more about the ongoing mission here.

Image/video credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington