NASA’s MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) probe will crash into the planet at 8,750 miles per hour (3.91 km/sec), most likely on April 30, after it runs out of propellant.
An artist’s concept shows MESSENGER in orbit around Mercury. Image credit: NASA.
On April 14, MESSENGER mission operators completed the fourth in a series of orbit correction maneuvers designed to delay the spacecraft’s impact into the Mercury’s surface. The last maneuver is scheduled for April 24.
“Following this last maneuver, we will finally declare the spacecraft out of propellant, as this maneuver will deplete nearly all of our remaining helium gas. At that point, the spacecraft will no longer be capable of fighting the downward push of the Sun’s gravity,” said Dr Daniel O’Shaughnessy of the Johns Hopkins University Applied Physics Laboratory.
The spacecraft is currently floating around Mercury in an eccentric orbit, but is passing much closer to the planet than before. Its periapsis altitude – the closest approach to the planet – now ranges from 3.7 to 24.2 miles (6 – 39 km) above the planet’s surface.
Although Mercury is one of Earth’s nearest planetary neighbors, little was known about it prior to the MESSENGER mission.
On August 03, 2004, MESSENGER blasted off from Cape Canaveral for a risky mission that would take the small satellite dangerously close to the surface of Mercury, paving the way for an ambitious study of the planet closest to the Sun. Image credit: NASA.
MESSENGER blasted off from Cape Canaveral, Florida, on August 3, 2004. It traveled 4.9 billion miles (7.9 billion km) – a journey that included 15 trips around the Sun and flybys of Earth once, Venus twice, and Mercury three times – before it was inserted into orbit around its target planet in 2011.
It is only the second spacecraft sent to Mercury. Mariner 10 flew past it three times in 1974 and 1975 and gathered detailed data on less than half the surface.
