Rosetta Scientists Set a Date for Philae’s Comet Landing
On November 12, 2014, the Philae lander will make its way from the Rosetta mother ship to the surface of Comet 67P/Churumov-Gerasimenko and make history at the same time. It will be the first soft landing on a comet, and if all works as planned, Rosetta mission scientists will have a chance to finally sample the surface of one of the solar system’s oldest objects. The area where Philae will land is called “Site J”, and the team is planning on a public contest to help rename the site, which will be announced on October 14th.
So, what is J like? From the image, it all looks rather dangerous to a spacecraft. When I first looked at this site, I was reminded of the confidence that the Apollo mission planners had for the first human landing on the Moon, only to have that attitude “busted” when astronauts Neil Armstrong and Buzz Aldrin actually GOT to the proposed landing site but had to maneuver a bit to find a REALLY safe place to put down their landing module.
It’s sort of the same situation with Philae. Mission planners didn’t find any broad, flat plain that said, “Here!! Land on ME!!!” Each region of the comet’s surface has challenges for a spacecraft, and even settling down on a small boulder could damage the spacecraft. So, they found six possible sites, narrowed it down to two “least of all evils” choices, and then selected the J site as the one with the least problems. The mission planners found it more compelling scientifically and procedurally than any of the other sites.
This image shows the landing site, just above the jagged shadowed area at the center. Most of the surface area within a square kilometer landing target is relatively flat, or has slopes of less than 30 degrees. Also, the area has only a few large boulders, and it receives enough sunlight to recharge Philae regularly. Renewing the lander’s power by sunlight is important — its battery pack has enough juice for about 64 hours before, which will power the lander for the time the scientists and spacecraft are settling in and calibrating and testing the onboard instruments.
Of course, there’s some chance that Site J will turn out to be unworkable. In that case, the Rosetta mission planners have a backup site, called “C”. It also promises good science and relatively good solar illumination for the spacecraft’s power system.
By the way, just to give you an idea of what the scientists are facing in searching out a landing site: this comet is an active one! It’s tumbling as it moves through space AND there are jets shooting out from beneath its surface.
The final decision about the site and landing will be made on October 14th, based on the latest available data and images taken by Rosetta’s cameras. I can’t wait to see where they finally end up landing, and, of course, the cool pictures! We know there ARE many cool images already taken, but they haven’t yet been released to the public. Yet. Not sure when they will be. But, in any case, stay tuned! A spacecraft landing on a comet is NOT something you don’t see every day!