The end is nigh: NASA's Mercury probe to plunge to death in 2 weeks

MESSENGER spacecraft images have revealed portions of Mercury never seen by human eyes. Photograph: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

After more than four years of orbiting Mercury, NASA's MESSENGER spacecraft will crash into the solar system's innermost planet in two weeks when it runs out of propellant.

NASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, which was launched in 2004, will impact the planet's surface, most likely on April 30, the US space agency said.

The spacecraft will impact Mercury at more than 3.91 kilometres per second on the side of the planet facing away from Earth.

Artist's concept of NASA's MESSENGER spacecraft in orbit around Mercury. MESSENGER is due to end its mission with a plunge onto the planet's surface on April 30, 2015. Photograph: NASA

Due to the expected location, engineers will be unable to view in real time the exact location of impact.

This week, mission operators in mission control at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, completed the fourth in a series of orbit correction manoeuvres designed to delay the spacecraft's impact into the surface of Mercury.

NASA's Mercury Surface, Space Environment, Geochemistry and Ranging spacecraft -- nicknamed Messenger's image titled "Toc-crater and Fugue" taken with the MDIS Narrow Angle Camera (NAC) shows two named craters imaged by both MESSENGER and Mariner 10. Photograph: NASA/Johns Hopkins University Applied Physics Laboratory

The last manoeuvre is scheduled for April 24.

“Following this last manoeuvre, we will finally declare the spacecraft out of propellant, as this manoeuvre will deplete nearly all of our remaining helium gas,” said Daniel O'Shaughnessy, mission systems engineer at APL.

“At that point, the spacecraft will no longer be capable of fighting the downward push of the sun's gravity,” he said.

Although Mercury is one of Earth's nearest planetary neighbours, little was known about the planet prior to the MESSENGER mission.

Another composite image of Mercury as clicked by MESSENGER as part of it four year long mission to collect data. Photograph: NASA

“While spacecraft operations will end, we are celebrating MESSENGER as more than a successful mission. It's the beginning of a longer journey to analyse the data that reveals all the scientific mysteries of Mercury,” said John Grunsfeld, associate administrator for the Science Mission Directorate at NASA Headquarters in Washington.

The spacecraft travelled more than six and a half years before it was inserted into orbit around Mercury on March 18, 2011.

The prime mission was to orbit the planet and collect data for one Earth year.

The MESSENGER craft will impact Mercury at more than 3.91 kilometres per second on the side of the planet facing away from Earth after having orbited the planet for nearly four years as part of an ongoing mission to collect information. Photograph: NASA

The spacecraft's healthy instruments, remaining fuel, and new questions raised by early findings resulted in two approved operations extensions, allowing the mission to continue for almost four years and resulting in more scientific firsts.

One key science finding in 2012 provided compelling support for the hypothesis that Mercury harbours abundant frozen water and other volatile materials in its permanently shadowed polar craters.