The team for NASA's Messenger mission to Mercury reported that the spacecraft smashed into the planet's surface as expected on Thursday, capping a successful four-year orbital mission.
After a series of mission extensions, the car-sized probe went down to its unavoidable crash at about 3:26 p.m. ET. The spacecraft was on the side of Mercury facing away from Earth when it hit, so mission managers estimated the end based on calculations of Messenger's orbital path — and the fact that it was no longer sending signals.
The trajectory called for the spacecraft to hit the dirt at more than 8,700 mph (14,000 kilometers per hour) near Mercury's Shakespeare impact basin, leaving a crater that's 52 feet (16 meters) wide.
“Going out with a bang as it impacts the surface of Mercury, we are celebrating Messenger as more than a successful mission,” John Grunsfeld, associate administrator for NASA’s science directorate, said in a statement confirming the mission's end. “The Messenger mission will continue to provide scientists with a bonanza of new results as we begin the next phase of this mission — analyzing the exciting data already in the archives, and unraveling the mysteries of Mercury.”
"Messenger" is an acronym for MErcury Surface, Space ENvironment, GEochemistry and Ranging. The craft was launched in 2004, and in 2011 it became the first human-made object to go into orbit around Mercury.
The probe's instruments produced the first global maps of Mercury, sampled wisps of atmosphere and confirmed that the planet had deep deposits of brimstone as well as trillions of tons of water ice.
The orbital mission was initially scheduled to last just one Earth year, but Messenger's team found ways to conserve the spacecraft's propellant for three years' worth of extensions — including a final one-month extension for low-altitude observations.
Once the fuel ran out, the sun's gravitational pull caused Messenger to sink out of orbit. NASA said the mood was "both somber and celebratory" at Johns Hopkins University Applied Physics Laboratory, which housed Messenger's mission operations center. The Applied Physics Laboratory said the mission's team will continue working with the probe's science data through the scheduled end of the Messenger project in May 2016.
Although Messenger was the first spacecraft to orbit Mercury, it won't be the last: A European-Japanese mission called BepiColombo will launch in 2017 and put two spacecraft into Mercurial orbit in 2024.