On Wednesday, November 12, 2014, an event that has been almost two decades in the making will finally take place. The Philae robotic lander, one of two components of the Rosetta robotic space probe, is scheduled to land on the comet 67P/Churyumov–Gerasimenko (a comet named after its discoverers) at about 11 a.m. EST.
The attempted comet landing marks the first such attempt in history. The European Space Agency (ESA) launched Rosetta in 2004 in the hopes of learning more not just about the comet, but about the origins of our Solar System and of life on Earth. It’s the most complex mission ever undertaken by the ESA, with more than 2,000 people involved in the project from start to finish.
Here are 10 things you need to know about Rosetta:
- Rosetta will launch Philae at 2:35 a.m. EST on November 12. It will take more than seven hours to free fall about 12.5 miles from the probe to the surface of the comet. When it gets close to the surface, the lander will engage a set of harpoons to prevent it from bouncing back out into space.
- Rosetta had been in space for more than a decade. The probe was launched on March 2, 2004, from Kourou, French Guiana. Originally, Rosetta was intended to be launched on January 12, 2003, and to study the comet 46P/Wirtanen in 2011. The failure of a Ariane 5 carrier rocket during a communications satellite launch in 2002 halted the mission until the cause of the failure could be determined, and made it impossible for the probe to reach its original target. 67P was chosen as a backup because it has a similar orbit.
- In the course of its mission, Rosetta has made flybys of asteroids and Mars, in addition to three flybys of the Earth. In order to conserve fuel and keep the cost of the project down, the probe’s route to the comet has been complex, using gravity assists from the Earth’s pull to essentially slingshot it toward its target. It’s third and final flyby of the Earth occurred exactly five years ago this week, on November 13, 2009. In this, its closest approach of the three, Rosetta zoomed by at an altitude of 1,542 miles, traveling at 29,841 mph.
- The Rosetta mission is controlled from the European Space Operations Centre (ESOC), in Darmstadt, Germany. NASA is assisting with the project, conducting four experiments and providing communications and navigation backup.
- Rosetta reached 67P/Churyumov–Gerasimenko on August 6, 2014 and has been orbiting the comet ever since. It is the first probe in history to successfully orbit a comet. Other probes have performed flyby missions. Until the probe reached the comet, ESA did not know what the surface looked like. Five potential landing sites were identified within a few weeks after the probe began its orbit.
- Rosetta is named after the Rosetta Stone, a slab of stone from ancient Egypt featuring the same passage of text in three different scripts. Philae is named after an island in the Nile where an obelisk bearing Greek and Egyptian inscriptions was discovered. By comparing these two objects, linguists were able to decipher Egyptian writing. Scientists hope the studies performed by these two pieces of equipment will lead to a similar leap in understanding the makeup of our Universe. One of the goals of this mission is to find out whether organic compounds found inside comets could have played a role in promoting life on Earth.
- Rosetta and Philae are carrying 21 instruments between them, including several different cameras, devices for measuring gasses, devices for detecting water, ammonia, and carbon dioxide, radar devices, microscopes, spectrometers (devices that measure and study light), dust accumulators, and more.
- To save on fuel, Rosetta was placed in hibernation mode for 31 months between June 2011 and January 2014 as it cruised toward its eventual rendezvous with the comet. During this period, ESA had no control over or communications with the craft.
- The main body of Rosetta is a little less than 10 feet around, with two 45-foot long wings on either side covered in solar panels to power its instruments. From tip to tip, the spacecraft spans about 105 feet. Rosetta weighs about 6,600 pounds. Philae weighs only 220 pounds.
- Rosetta’s mission is expected to end in December of 2015, at which time it will have orbited the comet for 17 months, completing the most detailed study of a comet ever undertaken. Because it could not carry enough fuel for a return mission, the probe and lander will remain in space.
Photo: Artist’s impression of Rosetta and Philae at the comet. Credit: ESA – C. Carreau/ATG medialab