Almost a week on from the excitement of Philae’s landing on Comet 67P/Churyumov—Gerasimenko, and the dust has settled, just about (damn low gravity on that there comet). What a rollercoaster ride. My live feed to ESA decided to cut out right at the very moment that the landing was confirmed, so I missed the punch-the-air happy moment, but it was still such a wow-wow-wow moment, learning of the touchdown via ESA’s twitter feed rather than seeing and hearing about it. So fantastic. And then came the delay in getting the photos of the comet’s surface that we had been promised not long after Philae had touched down. Something was up, but ESA wasn’t telling, for a while at least. Then came the news that the scientists thought the harpoons hadn’t secured Philae to the surface—we already knew that the booster that would help force the probe on to the surface wasn’t going to work—and it might have bounced.

Photo taken by Philae from about 40 metres above the surface of the comet, just prior to Philae’s landing.

X marks the spot: Philae’s initial landing place on the comet.

Philae’s initial landing place on the comet, before the first of its two bounces.  In the right hand shot, Philae and its shadow can be seen on the surface.

The next morning came the news that it had indeed bounced – twice. The gravity is so low on the comet’s surface that the first bounce is thought to have been in the region of 1 km high.

Philae’s first bounce, taken from Rosetta.

Then came pictures of the surface. Staggering shots, the first ever showing a close up of the surface of a comet. But the scientists still didn’t know where exactly on the comet Philae was.

The first image sent back by Philae from the surface of the comet. Part of the lander can be seen in the foreground.

Then came the news that Philae had landed with one of its legs up in the air, and in shadow for much of the time. Not good news for either its stability (needed for the scientific tests) or more importantly for its life – if it didn’t get sun, the solar panels would not be able to recharge the batteries and the probe would shut down.

Panoramic image series taken by Philae, with a sketch of the lander itself superimposed indicating its probable orientation.

Then Philae’s location was established. Time was running out, and the scientists decided to run the tests and hope that Philae would have enough power to get the results back to Rosetta, for it to send the data back to us. Success!

And then Philae ran out of power, and shut down.

In its journey around the sun, there may come a time when the sun falls on Philae and it awakens and can talk to us and hopefully perform more science tasks. Rosetta will be accompanying the comet on its travels, and so will be able to send messages to and from earth. There is a plan to land Rosetta on the comet when its useful life is done: a fitting grave, close to little Philae. Together they will wander through the solar system, on their long orbit around the sun. I love this thought. It reminds me a little of the ending of one of my favourite films, Dark Star.

So much amazing science, such a tremendous achievement, such a heart-stopping few days full of highs and lows. Wow, what a great, great week for science.

Update: organic molecules have been detected by Philae on the surface of the comet!

So, so happy right now. Philae is safely down on the surface of the comet, “Its landing gear has been drawn back into the lander and it is sitting on the surface!” “It’s talking to us”.

Just waiting now for the first photos from the surface …

Such a massive, extraordinary achievement. I can’t say how proud I am of all the ESA scientists and engineers and others involved.

Shortly after parting from Rosetta, the lander Philae took a shot of its mothership, Rosetta, here seen above the sun flare.

Philae soon after separation, photographed from Rosetta.

Philae on its way, photographed from Rosetta.

Last shot of Philae from Rosetta.

Before today, humankind had landed spacecraft on only six other celestial bodies: the moon, Mars, Venus, Titan (one of Saturn’s moons) and two asteroids.* This is the seventh. An amazing, stunning, superb achievement. Congratulations.

* (in 2005 NASA’s Deep Impact mission intentionally crashed an impactor into comet Tempel 1 in order to study the resulting debris cloud; it doesn’t quite count as a ‘soft landing’, and no data was sent back from the surface of the comet). 

The countdown for the release of the Philae probe from the Rosetta spacecraft, and its 7 hour journey down to the surface of comet Comet 67P/Churyumov-Gerasimenko, has begun. This is a historic and quite mind-boggling mission. Rosetta, the European Space Agency’s robotic spacecraft, spent the last 10 years travelling from earth to to rendezvous with the comet. It then spent a few months in orbit around the c. 6 km long comet, mapping its terrain to establish the likely safest landing place for Philae, the probe it is carrying.

But not for much longer! If all goes to plan, at around 8.35 am GMT/UTC tomorrow, Philae will separate from Rosetta and head off down to the surface of the comet. The descent will take some seven hours. Once it makes touchdown, it will secure itself to the icy surface of the comet using harpoons and screws. The signal that the mission has succeeded should be received back on earth at about 4.00 pm GMT/UTC the same day.

The targeted landing place for the Philae probe on Comet 67P/Churyumov–Gerasimenko. Photo by ESA, taken from Rosetta.

The risks are great—Philae may not even touch down on the comet. It may make a bad landing and fall over, and it has no means of righting itself should this happen.

If it does succeed, it will then commence the varied scientific analyses it is equipped for. First and foremost, it will photograph its landing spot. This will be the first ever photograph taken on the surface of a comet. Amazing!

Jagged terrain on the comet. Not the landing spot!

More rough terrain on the comet. Also not the landing spot!

Much smoother terrain on the comet. Not the landing spot, but similar to the sort of place that has been chosen, with fewer obstacles.

The BBC has provided a schedule of tomorrow’s activities (all times in GMT/UTC):

• Rosetta delivery manoeuvre – shortly after 06:00
• Latest Go/No-go decision – before 07:35
• Philae separates from Rosetta – 08:35
• Confirmation signal at Earth of separation – 09:03
• Rosetta’s post-delivery manoeuvre – 09:15
• Radio connection established – 10:30
• First data from descending Philae after 12:00
• Landing of Philae on 67P – after 15:30
• Confirmation signal at Earth – around 16:00

There is a much more detailed one at ESA’s website.

I will be watching and waiting with bated breath. The landing is being broadcast live by ESA: it can be viewed here, right now!