The
MESSENGER spacecraft, depicted in this artist’s rendering, began
studying Mercury in 2011. Today, its mission ended with its impact on
the far side of the planet. Image Credit: NASA
Here’s MESSENGER by the numbers:
Years since launching: 10+;
Years in Mercury’s orbit: Four;
Number of orbits: 4,105;
Size of its impact crater: Estimated to be 52 feet wide;
Other spacecraft to orbit Mercury in spaceflight history: Zero.
What a long, strange trip it has been: NASA’s MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft is no more. The space agency’s flagship Mercury mission ended at 3:26 p.m. EDT, as it struck the planet’s surface on its far side at an approximate speed of 8,750 miles per hour. By 3:38 p.m., no signal was detected by the Deep Space Network (DSN) station in Goldstone, Calif.; if MESSENGER had somehow survived, it would’ve emerged from behind Mercury at that time. The mission was declared at its end at 3:40 p.m. The time of impact and end of mission were confirmed by mission controllers at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md.
NASA’s John Grunsfeld, associate administrator for the agency’s Science Mission Directorate, stated: “Going out with a bang as it impacts the surface of Mercury, we are celebrating MESSENGER as more than a successful mission. 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’s
final image. From the MESSENGER website: “This afternoon, the
spacecraft succumbed to the pull of solar gravity and impacted Mercury’s
surface. The image shown here is the last one acquired and transmitted
back to Earth by the mission. The image is located within the floor of
the 93-kilometer-diameter crater Jokai. The spacecraft struck the planet
just north of Shakespeare basin.” Image Credit: NASA/Johns Hopkins
University Applied Physics Laboratory/Carnegie Institution of Washington
During its four years of orbital operations, MESSENGER shed light upon one of the Solar System’s most enigmatic planets. Mercury, due to its temperature extremes, proximity to the Sun, and exposure to solar radiation, poses a challenge to spacecraft. The planet was previously only explored in three flybys performed by the Mariner 10 spacecraft during the mid-1970s. Up until 2011, no other spacecraft dared to tackle Mercury as its subject of study.
Enter MESSENGER, launched aboard a Delta II 7925 rocket from Cape Canaveral Air Force Station’s SLC-17B on Aug. 3, 2004. Traveling 6.5 years before it entered Mercury’s orbit, the spacecraft mapped Mercury extensively, and also returned evidence of ice water present near its poles.
MESSENGER also proved itself to be tough enough to brave the harsh conditions of an alien world: “In addition to its momentous scientific findings, MESSENGER also represented a technological breakthrough in spacecraft design, as it survived a harsh environment for a period much longer than its original lifetime. It employed an innovative ceramic cloth sunshade, designed to protect sensitive spacecraft instruments from extreme temperature excursions. In addition, its orientation was fine-tuned to balance heating conditions.”
Sean Solomon, MESSENGER’s principal investigator and director of Columbia University’s Lamont-Doherty Earth Observatory, gave his thoughts about the end of the mission, while underscoring the intrepid spacecraft’s accomplishments:
An artist’s depiction of BepiColombo, ESA and JAXA’s joint Mercury explorers, scheduled to launch in 2017. Image Credit: ESA
While MESSENGER’s time has come to an end, the spacecraft has left researchers with a treasure trove of data concerning the Solar System’s least-explored planet. Its findings will be available in NASA’s Planetary Data System for years to come. In addition, a new Mercury mission is scheduled to launch in late-January 2017 from Europe’s Spaceport in Kourou, French Guiana, aboard an Ariane 5 launch vehicle. BepiColombo, a joint European Space Agency (ESA) and Japan Aerospace Exploration Agency (JAXA) mission consisting of two orbiters, will identify the impact crater left by MESSENGER when it commences orbital operations in 2024, twenty years after the launch of its U.S. predecessor.