0400 GMT (11:00 p.m. EST)
The Philae lander has been spotted at its first landing site in images taken from the Rosetta orbiter: Read the full story.
0400 GMT (11:00 p.m. EST)
Rosetta's Philae lander managed to return all its stored science data before its battery power dropped to critical levels and it fell silent: Read the full story.
0046 GMT (8:46 p.m. EST)
The connection with Philae stopped at 0036 GMT.
0038 GMT (7:38 p.m. EST)
All the science data is off the lander but power levels have plunged so low that it has entered 'idle' mode, according to Stephan Ulamec, the lander manager. The lander continues to send sporadic housekeeping data. "We can even watch it falling asleep," said Ulamec.
0009 GMT (7:09 p.m. EST)
The flight director estimates there are 45 mins left in this Rosetta/lander communication pass, but the battery might be depleted before then.
2340 GMT (6:40 p.m. EST)
Battery voltages have taken a sudden drop. With the battery producing only 21.5 volts the lander is likely to shut down very soon.
2300 GMT (6:00 p.m. EST)
The elevation and rotation of the lander is now complete. Battery levels are looking good but it is hard to estimate remaining life.
2250 GMT (5:50 p.m. EST)
Science data from Philae has been downloaded and ground controllers will now attempt to move the lander by extending the landing gear and rotating the body.
2237 GMT (5:27 p.m. EST)
Flight controllers report a good signal from Philae!
2220 GMT (4:20 p.m. EST)
A brief signal was just received from Philae but quickly lost. This is not unusual. Hoping to re-establish the link soon
2050 GMT (3:50 p.m. EST)
Trapped in rough, forbidding terrain with its solar panels draped in shadow, the Philae comet lander raced the clock Friday to carry out high-priority science operations, including an attempt to drill into the surface of the nucleus, before exhausting its on-board batteries and effectively losing consciousness. Read the full story.
1305 GMT (8:05 a.m. EST)
Stephan Ulamec, Philae Lander Manager, says the lander's drill has been active today but it won't be known until late tonight if it successfully analyzed samples from the comet's surface.
1255 GMT (7:55 a.m. EST)
ESA press briefing is due to start at 1300 GMT (8 a.m. EST). You can watch it live here.
0940 GMT (5:40 a.m. EST)
ESA mission operations head Paolo Ferri says ground controllers have received good data from Philae overnight but with much of the lander in shade, it could run out of battery power before the end of the day.

The MOPUS instrumented arm, which includes the lander's surface penetrator, will be extended today and there is some hope it might tip Philae into more sunlight, allowing its solar panels to top up the depleted batteries.

Ground controllers still trying to pinpoint Philae's exact location on the comet, which remains unknown after the lander made at least two hops across the nucleus on the day it landed.

All lander instruments with the exception of MOPUS have been able to collect data on the surface and Ferri says they are close to getting 100 percent of their planned data.

ESA will hold a press briefing at 1300 GMT (8:00 a.m. EST).

1250 GMT (7:50 a.m. EST)
ESA is hosting a press conference shortly to provide a status update on the Philae lander. You can watch on this page.
1030 GMT (5:30 a.m. EST)
Europe's Philae lander radioed home Thursday, sending the first picture from the surface of a comet hours after a dramatic descent that apparently culminated in bouncing hundreds of meters across the distant world before coming to rest.

Read our full story.

2115 GMT (4:15 p.m. EST)
After making history Wednesday as the first spacecraft to touch down on a comet, Europe’s Philae lander collected data on the rugged alien world's environment and may have rebounded into space before settling back on the surface, scientists said Wednesday.

Read our full story.

2115 GMT (4:15 p.m. EST)
After making history Wednesday as the first spacecraft to touch down on a comet, Europe’s Philae lander collected data on the rugged alien world's environment and may have rebounded into space before settling back on the surface, scientists said Wednesday.

Read our full story.

1920 GMT (2:20 p.m. EST)
ESA says there will a press briefing shortly to update the status of Philae.
1820 GMT (1:20 p.m. EST)
ESA says there will a press briefing shortly to update the status of Philae.
1755 GMT (12:55 p.m. EST)
As engineers sort out the condition of the lander, the first image from Philae's descent imager has been released. You can see it on our Facebook page.
1658 GMT (11:58 a.m. EST)
Stephan Ulamec, head of the Philae team at DLR, says ground controllers did not receive a signal confirming the harpoons fired. Officials are considering whether to refire the harpoon.

Intermittent signals are being received from the lander at this point, but officials are not sure what this means about the condition of the Philae spacecraft.

Engineers have a couple of hours before they lose the communications link with Philae when the Rosetta orbiter conducts a maneuver and has to break contact with the lander. Rosetta should be in position to listen again later tonight, European time. Watch our interview with Ulamec.

1643 GMT (11:43 a.m. EST)
An official from the Philae lander team reports telemetry data received from the probe did not confirm its anchoring harpoons fired.
1606 GMT (11:13 a.m. EST)
"This is a big step for human civilization," says ESA director general Jean-Jacques Dordain.

"The only way to reconcile risk and success is expertise," Dordain said. "This is why today we have demonstrated that European expertise ... this is the best expertise in the world because we are the first to have done that and that will stay forever."

1610 GMT (11:10 a.m. EST)
"We have confirmed the lander is on the surface," says Andrea Accomazzo, Rosetta flight director.

We're there, and Philae is talking to us," said Stephan Ulamec, Philae team leader at DLR. "The first thing he told us is the harpoons have fired and we are sitting on the surface. We are on the comet!"

1606 GMT (11:06 a.m. EST)
Engineers are analyzing telemetry to determine the status of Philae.
1603 GMT (11:03 a.m. EST)
Mission control has received a signal from the comet!
1555 GMT (10:55 a.m. EST)
Andrea Accomazzo, wearing the blue hoodie in the ESOC control center, is Rosetta's flight director. He said yesterday has spent 18 years working on the Rosetta mission. The lander -- a significant but secondary objective of the Rosetta mission -- is moments away from touchdown.
1530 GMT (10:30 a.m. EST)
Philae's landing window is now open.

Confirmation of landing could come at any time. The most likely touchdown time is expected around 1602 GMT (11:02 a.m. EST), but there is some variability in the predicted moment of landing.

When signals confirming landing do arrive on the ground, Philae will have already been on the comet for more than 28 minutes. That's how long it takes for radio signals to travel more than 300 million miles through space from comet 67P/Churyumov-Gerasimenko to Earth.

The landing is out of the control of engineers on the ground.

"We had many things to do in the last 10 or 20 yrs, in the last months, in the last weeks in the last night as well," said Andrea Accomazzo, Rosetta's flight director at the European Operations Center in Darmstadt, Germany.

"Now it's up to the lander. We need to be a bit lucky. We perfectly know we don't control the touchdown conditions. It's already major success to be able to come to this point."

Stephan Ulamec, head of the Philae team at DLR, says data relayed to Earth via Rosetta indicates the lander is doing fine.

"Everything looks really good," Ulamec said. "We are curious to find out what's happening on the comet."

"It's getting very tense and very exciting now to see the touchdown, get confirmation that the harpoons have been fired, and get the first data from the surface of a comet," Ulamec said.

1450 GMT (9:50 a.m. EST)
Europe's comet-bound Philae probe released from its Rosetta orbiter mothership Wednesday, and the two spacecraft snapped farewell photos as they went separate ways for the first time after a ten-year journey from Earth to comet 67P/Churyumov-Gerasimenko.

Read our full story.

1330 GMT (8:30 a.m. EST)
Officials at the Philae science operations center in Toulouse, France, say they are receiving data from the lander's instruments and imagery from its cameras on the descent to the comet.

Views inside the Toulouse operations room showed scientists huddled around computer monitors that appeared to show images taken by Philae.

Officials said they expected to release farewell images of Rosetta taken by Philae just after separation some time this afternoon, European time.

1230 GMT (7:30 a.m. EST)
Keep track of where Philae should be in its descent with this timeline of key landing events.
1140 GMT (6:40 a.m. EST)
ESA's mission control boss Paolo Ferri discusses the Philae thruster system problem and how it might affect touchdown on the comet in this video interview
1130 GMT (6:30 a.m. EST)
Stephan Ulamec, head of DLR's Philae landing team, says the probe has deployed its landing gear, allowing the lander to stretch its legs for the first time since before launch in 2004. Telemetry continues to be relayed to the ground via Rosetta.
1108 GMT (6:08 a.m. EST)
Paolo Ferri, mission operations chief at ESOC, says Rosetta is receiving signals from Philae, confirming the lander is alive on its descent to comet 67P/Churyumov-Gerasimenko.

"The link is there and now we can follow it," Ferri says.

"Now we can sit down and wait for the initial data to come -- like pictures and other information from the lander -- over the next five hours," Ferri says.

Signals confirming touchdown are expected around 1600 GMT (11 a.m. EST).

Philae will transmit data back to Earth via Rosetta. It does not have the ability to communicate directly with ground controllers in Germany.

"We have an end-to-end link established," Ferri says. "That's exactly what we want."

1050 GMT (5:50 a.m. EST)
Mission control is standing by to receive signals from Rosetta after its post-separation maneuver to begin communications relay duties between Earth and the Philae lander.
0913 GMT (4:13 a.m. EST)
"We lived together for 10 years, and now Philae is gone," says Andrea Accomazzo, Rosetta's flight director.

Cameras on the Philae lander and Rosetta mothership were expected to take photos of each other starting a minute after separation.

Nine minutes after separation, the spacecraft were expected to be 100 meters (330 feet) apart. That is the earliest opportunity for Philae to extend its three landing legs and a magnetometer boom.

A few minutes after extending its legs, the lander is programmed to rotate 14 degrees to get in the correct orientation for touchdown.

Confirmation of these events is not expected until some time after 1053 GMT (5:53 a.m. EST), when Rosetta will re-establish communications with Philae and relay telemetry from the lander to Earth. There is not a direct communications link between Philae and the ground.

The farewell images will also be sent back to Earth before Philae's touchdown. Officials say they should be released 1300 GMT (8 a.m. EST).

0905 GMT (4:05 a.m. EST)
Philae is away!
0844 GMT (3:44 a.m. EST)
"Landing Philae is sexy, but not easy," says Rosetta project scientist Matt Taylor.

The Philae spacecraft should have already been released from Rosetta, but confirmation of this event takes 28 minutes to arrive on Earth. The radio signals travel at the speed of light, and the comet is 510 million kilometers (316 million miles) away from Earth.

The deployment system uses three rotating screws to push Philae away from Rosetta. If the crews don't do the job, there is a backup system to spring eject the lander moments later.

Earlier updates