Good stuff happening! Wish I could watch it by I will be out for the day...
ScienceInsiderBreaking news and analysis from the world of science policy
By Eric Hand
12 November 2014 4:00 am
Update: 12:12 pm CET / 6:12 am ET
After a tense wait, relief spreads through the control room as ESA re-establishes contact with both Rosetta and Philae, which are now talking to each other. Mission control managers can now watch Philae through its slow, unpowered descent.
Update: 10:30 am CET / 4:30 am ET
Where is Philae going? This is a picture of Agilkia, the 1-kilometer wide circle that is the target area for the lander. Most of that uncertainty comes from errors in the velocity at which Philae was shoved off of Rosetta; the remainder comes from errors in the known position of Rosetta's orbit. You can see that the landing zone is by no means completely flat and smooth. There are boulders and sheer slopes that could upset the lander. On Monday, Philae project manager Stephan Ulamec told me that 20% of this landing terrain is pitched at angles greater than 30 degrees, slopes that could pose a problem. Add in the threat of boulders, and most mission managers are talking about a probability of success of around 75%. But no one really knows. The problem with the gas thrusters -- which are supposed to press the lander to the surface while its harpoons and footpads fix themselves to the ground -- cannot help. Decades of work are going to come down to a crapshoot.
Update: 10:13 am CET / 4:13 am ET
The 7-hour descent to the comet surface has begun. Applause burst out in the ESA control room upon receiving confirmation that Philae had indeed separated from the Rosetta spacecraft. "It's on its path down to the comet," says flight director Andrea Accomazzo. Stephan Ulamec, the Philae project manager, said he was feeling "released, or relieved". "The lander is on its own now," he says. It will be a long wait in the meantime. We are hoping that we will get a farewell image of Rosetta taken by CIVA, the lander's panoramic camera, at about the halfway mark, around 2 pm CET.
Update: 8:10 am CET / 2:10 am ET
The pre-delivery burn was a success! And the landing sequence is going ahead. Rosetta's release of Philae comes in less than two hours. But there is a problem: the cold nitrogen gas thrusters that were supposed to press the lander against the surface appear not to be working. Philae will have to rely on its other two tools needed to stick the landing. It still has two harpoons, and spinning screws in the tips of each of the lander's three feet. The harpoons are to puncture harder, icy materials, and the screws are to burrow into the surface if it is softer. But part of the point of the thrusters was to prevent any rebound that might occur because of the harpoons. Couldn't the landing be attempted again in two weeks time? Project manager Fred Jansen says that they made two separate attempts to measure a rise in pressure in the gas tanks that would have signaled them being ready to fire. Making that measurement again in two weeks time wouldn't make any difference, he says.
Update: 7 am CET / 1 am ET
Good morning! There are some bleary eyes here in the European Space Agency's control room in Darmstadt, Germany. But that is surely outweighed by the momentous activities that await. First up: we're expecting to learn soon about a 6-minute-long "pre-delivery burn" on the Rosetta spacecraft. This would put the orbiter in a position to drop the Philae lander in a few hours. This terrific video explains the orbital mechanics of what's about to happen much better (the burn in question happens at the 47 second mark).
[iframe width="560" height="315" src="http://www.youtube.com/embed/4a3eY5siRRk" frameborder="0" allowfullscreen=""][/iframe]
DARMSTADT, GERMANY—On Wednesday, 12 November, the Rosetta spacecraft's Philae probe is set to attempt an historic landing on a comet, known as 67P/Churyumov-Gerasimenko. In a technological tour de force, the probe will slowly approach the comet, then attempt to touch down and use harpoons to secure itself to the surface. A suite of onboard instruments will be taking scientific measurements.
ScienceInsider's Eric Hand is at Rosetta mission control in Germany, following the action, and will be updating this blog with the latest news, starting at 1 a.m. Wednesday morning U.S. Eastern Standard Time. Please join us.
Rosetta officials are scheduled to make a "go/no-go" decision on the landing attempt at about 2:35 a.m. Wednesday (U.S. EST). If it's "go," the lander will separate from Rosetta at 4:03 a.m. and start sending images of the landing at 10:01 a.m. Touchdown is expected at 11:02 a.m. But the terrain is diffcult, and success is not assured.
The European Space Agency will be webcasting the event: http://rosetta.esa.int/
NASA TV online will be covering Rosetta starting at 9 a.m.: http://www.nasa.gov/multimedia/nasatv/index.html
You can read our collected Rosetta coverage here. |
