ESA’s Rosetta Mission Set To Land On Comet This Morning


If everything goes according to plan, a lander roughly the size of a household washing machine will be touching down on a comet hurtling through space:

London (CNN) — The Rosetta mission to land a probe on Comet 67P is past the point of no return, the European Space Agency (ESA) announced on Wednesday.

“There is no going back now,” the agency said after the spacecraft’s lander was released for its trip to the surface.

If it succeeds it will be the first time a spacecraft as landed on a comet.

The Philae lander separated from the mother ship Rosetta around 3:30 a.m. ET to begin its 7-hour descent.

Philae, which has spent 10 years fixed to the side of Rosetta during the journey across the solar system, cannot be steered. Once it was released, it was on its own.

Before the announcement, ESA lander system engineer Laurence O’Rourke told CNN that the orbiter Rosetta has to be in the right position to allow the craft to “free fall” on the correct trajectory to the chosen landing site.

Scientists are hoping the probe will help us learn a lot more about the composition of comets and how they react when they get close to the Sun.

Weighing in at 220 pounds, it might be the size of a domestic washing machine but Philae is considerably smarter.

It is equipped with an array of experiments to photograph and test the surface of Comet 67P as well as finding out what happens when the roasting effect of the Sun drives off gas and dust.

But first it has to reach the landing site.

O’Rourke explained that hours before separation, Philae’s on-board batteries were prepared and a fly wheel is started to give the probe stability on its journey to the comet surface. Without the gyroscopic effect of the fly wheel there’s a danger that the lander could turn end over end, he said.

Mission controllers now face the long wait for Philae to reach the surface. The comet is so far away that a confirmation signal relayed from Rosetta, which remains in orbit around the comet, will take nearly half an hour to reach Earth.

Scientists should have word around 11 a.m. ET.

NASA TV is live streaming coverage, and has already started doing so even though we’re still about an hour away from the really important part.

Artist’s Depiction via European Space Agency

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Doug Mataconis
About Doug Mataconis
Doug Mataconis held a B.A. in Political Science from Rutgers University and J.D. from George Mason University School of Law. He joined the staff of OTB in May 2010 and contributed a staggering 16,483 posts before his retirement in January 2020. He passed far too young in July 2021.


  1. stonetools says:

    They did it!
    Philae has landed!
    Good on yer, Europe!
    Cue God Save the Queen, the Marseilles, Duetschland uber Alles, and all the various European anthems!
    No monoliths found yet….

  2. Neil Hudelson says:

    From what I can tell of the mission control applause, it was a very successful landing.

  3. stonetools says:

    Guess those tired, effete, socialistic, sclerotic Europeans aren’t done after all…

  4. Mikey says:

    This is an incredible, amazing, fantastic thing. It’s hard to get anywhere in space, let alone land on a celestial body that’s little more than a speck of dust on the cosmic scale.

    I’m really looking forward to the pictures, and the results of the various samplings and experiments. We will learn so much.

  5. Tyrell says:

    This is amazing. What I don’t understand is how that spacecraft is going to hang on to a comet that is zooming through space at huge speeds.

  6. Mikey says:

    @Tyrell: The comet does have gravity, although it is far, far less than Earth’s–if you were to stand on the comet and jump up, you might even hit escape velocity.

    As far as how it’s going to hang on, the Philae probe actually has “harpoons” meant to be fired into the surface of the comet as anchors. At this point it appears they didn’t fire during the landing sequence, and ESA is trying to figure out how to proceed.

  7. Grewgills says:

    In addition to what Mikey said the craft and the comet will not be careening through an atmosphere so there isn’t the resistance you are thinking of when you picture the craft trying to hold on to a speeding train or airplane.

  8. grumpy realist says:

    @Tyrell: Oh good grief….

    Learn some celestial mechanics, dude. If the probe has the same velocity and acceleration as the asteroid, the two of them will fly together in the same orbit, capisce? The harpoon is to keep the bloody thing ON the asteroid so they can use the rest of their sampling equipment.

  9. Tyrell says:

    @grumpy realist: Okay, I get that, but comets are very fast, 100,000 mph and more. Are there rockets that fast ?

  10. Mikey says:

    @Tyrell: OK, so here’s how it works. It’s not like Star Trek where the ship sets a course for something and just flies there. It’s far more challenging than that.

    Take a look at this video and you’ll see the incredible path Rosetta took over more than 10 years to intercept comet 67P. It’s simply amazing.

    The reason Rosetta used so many “gravity assists” is because it couldn’t possibly carry enough fuel to just fly to the comet. It has to match the comet’s orbit in a way that it can intercept the comet.

    Once it got close enough it was able to do some maneuvers that required very little fuel and enter an orbit, from which the probe was launched and landed.

  11. Blue Galangal says:

    @Mikey: xkcd has a great sequence that was funny and explained almost everything I was wondering about: #120 was my favourite.

  12. Mikey says:

    @Blue Galangal: That was wonderful! And the whales really had nothing to worry about.

  13. grumpy realist says:

    @Tyrell: Gravity assist, dude. Also, PLEASE take at least an introductory course in physics, mmmkay?

    (Pounds head against wall.)

  14. Mikey says:

    @grumpy realist: Who needs physics? You can learn all a layman needs to know, and then some, with this:

    One of my favorite computer games ever. Just don’t get attached to the little green dudes, because you will slaughter them wholesale. Not on purpose, of course. It’s just that getting a rocket into space is damned hard.

  15. Tyrell says:

    @grumpy realist: Well, right now I have been reading about and watching videos about quantum physics.

  16. grumpy realist says:

    By the way, has anyone seen Shirtgate ?

    I’m with the “they managed to land a probe on a comet and you’re getting upset about this?!”

    It might have been his Lucky Shirt. Or Last Clean Shirt. Or Closest in the Closet Shirt. But do they think of that? No…..

  17. grumpy realist says:

    @Tyrell: If you really want to learn physics, I’d suggest looking up Lewin’s videos on the MIT site. He is a great, great lecturer (I had physics from him, but it was 8.03 rather than 8.01) And then there’s Feynman, who will take you even further.

    If you want quantum mechanics, two books which are great fun and give a good overview: Mrs. Hudson’s Cat by Colin Bruce, and Strange Story of the Quantum by Banesh Hoffman.

  18. Mikey says:

    @grumpy realist: Well, to be fair, that shirt is pretty awful. I was wondering if he’d lost a bet, or something. Or maybe he was trying to thumb his nose at the ESA higher-ups who’ve told him in the past to cover his tattooed arms.

    Or maybe he was just being a smartass.

  19. grumpy realist says:

    @Mikey: When I consider some of the stuff I ended up schlepping on during mammoth project crunch time, I’m sympathetic. One reason why I now wear straight black black blackitty black. Less hassle and fewer brain problems.

  20. Mikey says:

    @grumpy realist: Yeah, who knows how little sleep that team has gotten the past week. I’d bet they were pretty wrecked by the end.

    I was watching the ESA live feed at work, and cheered along with them when they got confirmation of landing. I think of all that’s happened in human space exploration in my lifetime–the Apollo landings, Skylab, Viking, the Voyager missions, Space Shuttle, Mars rovers, Cassini, probably some I’ve forgotten, and now actually landing a man-made probe on a freakin’ comet…man, I want to throw on something colorful and inappropriate too.

  21. gVOR08 says:

    @Mikey: I still clearly remember standing outside in July ’69 staring at the moon in awe thinking, “Holy ****, there are people there.” Which may remind you of the famous Onion headline that falls outside OTB guidelines, NSFW.

  22. Keith says:

    This event took me back to my childhood, watching the Apollo missions while drinking my orange TANG!