Rosetta Begins Free Fall To Comet 67P Today, Crash Lands Friday

Artist's view of the Rosetta spacecraft settling to the surface of Comet 67P/Churyumov-Gerasimenko tomorrow morning when the mission ends. Credit: European Space Agency (ESA)
Artist’s view of the Rosetta spacecraft descending to the surface of Comet 67P/Churyumov-Gerasimenko tomorrow morning when the mission ends. Credit: European Space Agency (ESA)

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.

Rosetta is far out! The probe, which will crash-land on Comet 67P tomorrow morning is currently far from the sun. That's the main reason the mission is finally coming to an end. Without adequate sunlight to provide electricity from its solar panels, its instruments will soon lose power. Credit: ESA with annotations by the author
Rosetta is far out! The probe, which will crash-land on Comet 67P tomorrow morning, is currently over 354 million miles from the sun. A drop in the intensity of sunlight is the main reason the mission is finally coming to an end: without adequate sunlight to provide electricity from its solar panels, the spacecraft and its instruments will soon lose power. Credit: ESA with annotations by the author

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.esa.int
* http://livestream.com/ESA/rosettagrandfinale
ESA’s Facebook page

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).

The images cover the time period between 31 January (top left) and 25 March (bottom right), when the spacecraft was at distances of about 30 to 100 km from the comet.
If you haven’t met Comet 67p before, this montage of images taken between January 31 (top left) and March 25 (bottom right), will help you get acquainted. Click to download a giant version. Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

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.