The probe is expected to crash into the surface of the innermost planet of the solar system in two weeks time. The Mercury Surface, Space Environment, Geochemistry and Ranging, or MESSENGER, probe will bow out in a fireball on April 30, meeting its end on the surface of the planet it has been studying for years longer than expected, writes Irene Klotz for Discovery.
Mercury – Interesting data informs knowledge
Its mission was to collect detailed geochemical data on Mercury, as well as studying other factors, over the course of a year. MESSENGER has now been in orbit since March 2011, surpassing its intended lifespan, and enabling scientists to better understand the formation and evolution of Mercury, which is one of four rocky planets in the solar system along with Venus, Earth and Mars.
The mission had previously been extended twice, before scientists managed to eke another six weeks out of the probe after engineers worked out how to gain some altitude using the helium used to pressurize its fuel tank. This final boost will take place on April 24, taking MESSENGER from 6 miles above the surface of Mercury to around 12 miles in altitude, allowing another six days for continued studies.
Some of the data collected by the probe has been fascinating, and some incredible discoveries have been made during its last months, including the fact that ice exists on the surface of Mercury, despite its proximity to the Sun. Dark, potentially carbon-rich matter can be seen forming a layer on top of the ice in one crater.
Further discoveries question theory
Scientists were also surprised by the presence of hallows, which are shallow, recently formed depressions, on the surface of Mercury. Such features have also been found on Ceres, a dwarf planet under investigation by NASA’s Dawn spacecraft.
MESSENGER also showed that Mercury reduced in diameter by over 4 miles as its iron core cooled, and volcanic deposits have been found on its surface. Other discoveries include the fact that the planet has an unexpected asymmetrical magnetic field, but perhaps the most important concerns the volatile elements found on the planet.
Scientists previously thought that elements such as potassium and sulfur would have evaporated, but instead have found that the amount of volatile elements is about the same as on Mars, which throws into question the theory of how Mercury formed.