After over a decade of planetary exploration, NASA's MErcury Surface, Space ENvironment, GEochemistry and Ranging (MESSENGER) spacecraft is set to end its mission by smashing into the surface of Mercury. The collision will take place on April 30, with the probe traveling at a speed of roughly 8,750 mph (14,082 km/h).
Mercury is the smallest planet in our solar system. With an equatorial circumference of only 9,525 miles (15,329 km), it is only a little larger than Earth's Moon. The surface of Mercury has been left scorched by its close proximity to the Sun, with temperatures varying between 800 °F (430 °C) and -290 °F (-180 °C) on a day/night cycle.
Launched in August 2004, MESSENGER undertook a six-and-a-half-year journey to travel to Mercury, and unlock the secrets of the desolate little planet. Protected by a cutting-edge sunshade, MESSENGER's suite of eight scientific instruments have succeeded in determining Mercury's surface composition, characterizing the planet's magnetosphere, and taking detailed readings of her intricate internal structure.
Furthermore, in 2012 the spacecraft was responsible for uncovering deposits of water in the form of ice hidden deep in the perennially-shaded craters, in a discovery that had profound implications for our understanding of how planets like Earth gained large bodies of water, and with it the building blocks for life.
However, the fuel reserves that have allowed MESSENGER to continue exploring the rocky planet for years after its primary mission have expired and are expected to be depleted this Friday – as the probe undertakes the last of four maneuvers designed to prolong its life.
"For the first time in history we now have real knowledge about the planet Mercury that shows it to be a fascinating world as part of our diverse solar system," states John Grunsfeld, associate administrator for the Science Mission Directorate at NASA Headquarters, Washington. "While spacecraft operations will end, we are celebrating MESSENGER as more than a successful mission. It’s the beginning of a longer journey to analyze the data that reveals all the scientific mysteries of Mercury."
With its supply of propellant gone, MESSENGER will be allowed to crash into the surface of the planet that it has spent its operational life studying. Unfortunately, the spacecraft is predicted to impact the surface on the far side of the planet from Earth, meaning that those who have spent the last decade administering to the ground-breaking probe will be unable to follow its final moments.