Mercury is the smallest planet in the Solar System and has the closest proximity to our sun. As a result, it’s one of the most neglected when it comes to scientific study. While Mars, Venus, Jupiter and Saturn have been probed and photographed in exquisite detail during the space age, the closest planet to the Sun has had to make do with a few flybys from the Mariner 10 spacecraft in the early 1970s.
However, that is now changing thanks to NASA’s Messenger spacecraft. In addition to confirming the existence of ice and organic molecules back in November, the probe has also transmitted thousands of images of the planet over the past year. These have allowed NASA personnel to construct the first high-resolution maps of the planet, its own high-resolution maps, down to the scale of kilometers.
According to David Blewett, a scientist at the Applied Physics Laboratory at Johns Hopkins University and part of the Messenger team, part of the reason it has taken more than 30 years to revisit the planet since the Mariner 10 flybys was because a lack of public interest. Messenger, he claims, has changed all that. Speaking ahead of a briefing on Friday at the annual meeting of the American Association for the Advancement of Science in Boston, Blewett had this say:
“Messenger has revealed Mercury to be a fascinating, dynamic and complex world. We know now that it is an oddball planet. It’s the smallest of the eight planets but has the highest density. The interior structure is different than the other planets. The geologic surface is different to the moon and Mars. The surface composition is enigmatic because … it consists of rock types that we don’t have much experience with. It has a global, Earth-like magnetic field, Venus and Mars do not.”
The new global map is an enhanced image that shows the different compositions of rocks on the surface of Mercury by color-coding them. The more orange areas are volcanic plains while the make-up of the rocks in the deep blue areas is unknown. Though Messenger was able to detect an abundance of individual elements on Mercury’s surface – including iron, titanium, sulphur and potassium – without rock samples to study, scientists cannot determine the exact compounds or minerals in which those elements are arranged.
But the biggest surprise came on the surface, where there was an abundance of relatively volatile elements such as potassium and sulphur was seen to be very high. Most of the models for the formation of Mercury predict that these elements should have evaporated away during the planet’s formation. So in addition to learning more about its surface features, scientists are now presented with the opportunity to study and learn more about the planet’s early history as well.
But of course, much of that information and research are going to have to wait for future generations of Rovers. These are likely to be similar in nature to Curiosity, in that they are remote controlled, networked robots with internal labs. But unlike those currently combing the Red Planet, these ones will have to be able to withstand surface temperatures in excess of 400 C and some dangerous surface activity. Hard to know exactly when NASA will be rolling any of those out, but the simplest answer is, not too bloody soon!
Check out the video of Mercury’s new color map as it rotates to show its fully-detailed surface. And FYI, this bit of breaking news has become my 900th post! Woohoo!