Good morning from the European Space Operations Centre, ESA’s mission control in Darmstadt, Germany. Today, ESA attempt to land on comet 69P/Churyumov-Gerasimenko.
This is the first time a landing on a comet has ever been attempted. It is a risky mission. This blog will run live all day following the action. You can also follow me on Twitter for additional updates.
Overnight there have been two more go/nogo decisions. Both were ‘go’ but the Philae lander team needed an additional hour before they confirmed that they were indeed ‘good to go’.
The reason for the delay has not yet been confirmed but there was a computer glitch in Philae when it was switched on 24 hours earlier. Read more about that here.
Rosetta were pronounced ready at 00:00GMT. Philae’s confirmation came at 02:35GMT.
A fourth and final go/nogo takes place sometime between 6:35 and 7:35GMT this morning. If Rosetta and Philae are pronounced good to go at this point, the landing attempt will take place today.
Sometime in the next hour, Rosetta will perform the ‘pre-separation manoeuvre’. This is a thruster burn to place it on course for the separation point, when it will release Philae.
The burn is expected to last about 6 minutes. It will alter Rosetta’s velocity by about 0.46m/s and send it heading in towards the comet.
The fourth and final go/nogo will determine whether the burn has taken place successfully and Rosetta is on the right track. It will also make a final assessment of the two spacecraft, the ground stations, the ground systems and the teams. All must be ready for landing.
Following separation, Rosetta will manoeuvre again to move away from the comet, but keeping Philae and the landing site in view.
The landing has just become riskier. The cold gas thruster appears not to be working on Philae. This thruster is on top of the lander and is designed to push the spacecraft onto the comet as the harpoons and drills anchor Philae to the surface. Without the thruster, the risk of Philae bouncing off the surface is increased.
The truster problem is the reason for the delay in last night’s third go/nogo. At one point, Paolo Ferri, Head of Mission Operations, European Space Agency, ESOC, said that it looked as if the third go would not be given. When the confirmation came, it was an hour later than originally planned.
All other systems on the lander are working as expected. Philae must now depend upon three screws to drill the legs into the surface, and two harpoons that it will fire into the comet as well.
About three decades ago, Rosetta began as an idea for a mission that would bring a sample back from a comet. That proved too expensive. So, according to Gerhard Schwehm, Former Rosetta Project Scientist, they decided that if they couldn’t bring comet samples back to a laboratory, they would build a laboratory to send to a comet. The result is Rosetta. The laboratory is Philae. It lands today.
London (CNN) -- The comet probe Philae may have bounced when it landed, the European Space Agency (ESA) said Wednesday.
It is the first time a soft landing has been achieved on a comet -- but there was a hitch.
Comet 67P has a very weak gravity, so anchoring harpoons were designed to shoot into the comet to fix the spacecraft to the surface. They failed to fire and Philae is not firmly secure, ESA says.
Philae lander manager Stephan Ulamec said the probe may have lifted off again and turned.
Rosetta team celebrates landing
Rosetta: The comet chaser
Comet landing an 'engineering miracle'
Lander snaps goodbye picture of Rosetta
"So maybe we didn't land once -- we landed twice," he told a news conference.