Early on the morning of March 29 2011, the Messenger captured this extraordinary image of Mercury. It may look like just another image of a barren planet but this image is the first ever obtained from a spacecraft in orbit around our solar system's innermost planet. This is history.
It gets better: here is what you might call the money shot of the whole mission. Another first - Messenger has returned the first ever color photograph from a spacecraft orbiting the planet. The spacecraft was launched six years ago. Since then, Messenger has travelled through the inner solar system and has conducted flybys of Earth, Venus and now Mercury. Its ultimate mission was to be the first spacecraft to orbit the closet planet to the sun, Mercury. Now data is returning to Earth, the first since the Mariner mission over three decades ago. That, after all was what it was supposed to do. The name is an acronym – Messenger stands for MErcury Surface, Space ENvironment, GEochemistry, and Ranging.
Of course, Messenger has done a flyby of Mercury before – back in 2008. The amazing image above was taken then but it is not what we would see were we Borrowers in Space aboard Messenger. The information here shows information about how different types of rock are distributed on the surface of Mercury. However, the new pictures that Messenger will now return to us from orbit will be at a much better resolution – improved by a factor of three.
This photograph was taken as Messenger moved northward along its first orbit of Mercury. This was the first orbit during which Messenger’s MDIS was on. The Mercury Dual Imaging System (MDIS) is fairly straightforward – it is of a pair of color cameras. The first is a narrow angle imager, the second a wide angle imager. It will take pictures of Mercury in visible and near-infrared light. It is planned that a global topographic map of Mercury will be created by the action of the MDIS.
This remarkable (and now annotated!) first orbital image of Mercury was acquired thirty seven years to the day after Mariner 10’s historic first flyby of the innermost planet. Labels have been added to indicate several craters that were named based on Mariner 10 images, as well as Debussy, Matabei, and Berkel, which were named based on Messenger flyby images. The surface contained in the white lines is terrain previously unseen by spacecraft, and the star indicates the location of the South Pole.
Let’s take a closer look at the Debussy crater. This image was taken on March 29 2011 and shows where the impact ejecta landed from the initial strike. You can see the large systems of rays spreading out from Debussy in the sort of detail that no one has ever seen before this year. They stretch out for hundreds of kilometers across the surface of the planet.
There are large portions of Mercury that have never been seen by a spacecraft, let alone human eyes. Here, as Messenger passed low over the north polar region of the planet (see the star at the base of the annotated picture above), the Mercury Dual Imaging System pivoted to take an image of this never before seen terrain. As Messenger continues its orbit of the planet we can look forward to some even more extraordinary images.