The end is near! The European Space Agency’s Rosetta spacecraft is set to complete its historic mission in a controlled descent to the surface of Comet 67P early tomorrow morning September 30. Touchdown, or more like crunch-down, should happen within 20 minutes either side of 5:40 a.m. Central Daylight Time (10:40 a.m. Greenwich Time). Because Rosetta and the comet are over 446 million miles (718 million km) from Earth, confirmation of the impact will take an additional 40 minutes due to the time it takes the radio signal to travel such a vast distance.
Confirmation of the landing time will be made between 4:55-5:05 a.m. CDT (9:55-10:05 GMT) Friday morning. You can go to ESA’s Facebook Page to get an update as soon as the return signal is received. Live coverage of the event runs from 5:30-7:30 a.m. CDT (10:30-12:30 GMT) Friday at these three sites:
Rosetta’s final orbit and track to the the comet’s surface
After orbiting and studying the comet up close for two years, Rosetta will begin a 14-hour-long free-fall to the comet’s surface from an altitude of 11.8 miles (19 km) starting this afternoon. During its descent to the dumbbell-shaped comet’s smaller lobe, the spacecraft’s OSIRIS cameras (both narrow- and wide-angle) will first image the regions of the large lobe that it passes over. As the spacecraft approaches the small lobe, the cameras will target the walls of the Ma’at pits. The very high resolution photos will show the fine, goosebump-like structures within the pits that may be some of the earliest ‘cometesimals’ or icy snowballs that stuck together in the days of the early solar system to form the comet.
This descent visualization shows how Rosetta will descend to comet 67P. When it contacts the surface, all communication with the probe will cease. Because the comet’s gravity is slight, the spacecraft won’t come smashing down but rather strike the surface and perhaps bounce before finally settling into place. Parts of the Rosetta are expected to break off and crack during the impact.
In order to fire off the highest possible number of photos in the limited time available before the spacecraft impacts the surface, the images will be highly compressed, up to 20 times compared with ‘normal’ images. On top of compressing, the images will also be downsized. The cameras weren’t designed to photograph the comet from this close, so as Rosetta descends to the surface, the photos will become increasingly blurred below 650-1,000 feet (200-300 meters).
Select images from the descent will be posted at various points during our live broadcast including the very last image downloaded from the spacecraft. We should see that one within about 10 minutes of the confirmation of end of mission. Service to your door!
Other instruments will collect data on the density and composition of gas around the comet, measure the surface temperature, get detailed measurements of 67P’s gravity field and examine how dust grains are shot away from the comet before the final curtain is drawn. Don’t miss this historic event.