European Space Agency’s Rosetta mission has landed its Philae probe on the surface of Comet 67P/Churyumov–Gerasimenko. The signal confirming the successful touchdown arrived on Earth yesterday at 11:03 a.m. EDT (8:03 a.m. PDT, 4:03 p.m. GMT, 5:03 p.m. CET).
Philae is safely on the surface of the comet, as this image confirms; one of the lander’s three feet can be seen in the foreground. Image credit: ESA / Rosetta / Philae / CIVA.
“Our ambitious Rosetta mission has secured a place in the history books: not only is it the first to rendezvous with and orbit a comet, but it is now also the first to deliver a lander to a comet’s surface,” noted Jean-Jacques Dordain, Director General of the European Space Agency (ESA).
“With Rosetta we are opening a door to the origin of planet Earth and fostering a better understanding of our future. ESA and its Rosetta mission partners have achieved something extraordinary today.”
Rosetta was launched on 2 March 2004 and traveled 6.4 billion km through the Solar System before arriving at the comet on 6 August 2014.
The landing site, named Agilkia and located on the head of the bizarre double-lobed object, was chosen just six weeks after arrival based on images and data collected at distances of 30–100 km from the comet.
Following a period spent at 10 km to allow further close-up study of the chosen landing site, Rosetta moved onto a more distant trajectory to prepare for Philae’s deployment.
Deployment was confirmed at 4:03 a.m. EDT (1:03 a.m. PDT, 9:03 a.m. GMT, 10:03 a.m. CET), at a distance of 22.5km from the center of the comet.
During the seven-hour descent, which was made without propulsion or guidance, Philae took images and recorded information about the comet’s environment.
Touchdown was planned to take place at a speed of around 1 m/s, with the three-legged landing gear absorbing the impact to prevent rebound, and an ice screw in each foot driving into the surface.
Matt Taylor, ESA Rosetta project scientist, said: “Rosetta is trying to answer the very big questions about the history of our Solar System. What were the conditions like at its infancy and how did it evolve? What role did comets play in this evolution? How do comets work?”
“Today’s successful landing is undoubtedly the cherry on the icing of a 4 km-wide cake, but we’re also looking further ahead and onto the next stage of this ground-breaking mission, as we continue to follow the comet around the Sun for 13 months, watching as its activity changes and its surface evolves.”
First comet panoramic from the imaging system on Philae, with an indication of the lander orientation superimposed on top of it. Image credit: ESA / Rosetta / Philae / CIVA.
Over the next 2.5 days, Philae will conduct its primary science mission, assuming that its main battery remains in good health.
An extended science phase using the rechargeable secondary battery may be possible, assuming Sun illumination conditions allow and dust settling on the solar panels does not prevent it. This extended phase could last until March 2015, after which conditions inside the lander are expected to be too hot for it to continue operating.
Next year, as the comet grows more active, Rosetta will need to step further back and fly unbound ‘orbits’, but dipping in briefly with daring flybys, some of which will bring it within just 8 km of the comet center.
The comet will reach its closest distance to the Sun on 13 August 2015 at about 185 million km, roughly between the orbits of Earth and Mars.
Rosetta will follow it throughout the remainder of 2015, as they head away from the Sun and activity begins to subside.
