We Landed on a Comet

By Mark Hanna 13/11/2014 17


So, last night was exciting. The European Space Agency’s (ESA) robotic spaceship Rosetta arrived at the comet 67P/Churyumov-Gerasimenko in early August, after an amazing journey comprising of over 10 years and four gravity slingshots. Last night, it separated from its lander module, Philae, and sent it to touch down on the surface of the comet.

What I’ve been able to gather from watching the live stream last night and what I saw on Twitter when I woke up groggily for 2 minutes at 5:15 this morning is that not everything went to plan, but the landing seems to have been successful.

Philae (the lander) has several devices to make the landing easier. One of these is a “cold gas thruster”, a small engine to push it gently into the surface of the comet so it wouldn’t bounce off (remember the comet has extremely little gravity relative to something like the Earth or Moon). This engine failed to start working before the spacecraft separated, but the team decided to go ahead with the landing anyway.

Another device Philae has to help with the landing is a pair of harpoons to skewer the surface, but these also failed to fire. As far as I know they’re not sure yet why they failed, but Philae did make it to the surface, so the comet landing was a success.

The ESA be getting data back from Philae but I don’t think they know yet how it landed or where exactly it is relative to the landing site. There’s a danger it could be on its side, for example, which would prevent some of the experiments it’s carrying on board from going ahead. Time will tell, though.

A photo of the comet taken from Philae when it was only 3 km away has been posted to the official Twitter account:

Photo credit to European Space Agency, ROLIS camera on Philae

Photo credit to European Space Agency, ROLIS camera on Philae

UPDATE 2014/11/14

Since the landing a few other things have come to light. First, presumably because the harpoons failed to fire, Philae bounced of the surface twice. Although it bounced pretty much straight up, the comet was rotating beneath it so its final landing zone is a few hundred metres away.

Also, Philae has landed on its side. It’s still taking photographs and sending back data, so that’s good, but the fact that it’s on its side may mean that some of its experiments may not be able to go ahead. Phil Plait has a good write up explaining these updated on Bad Astronomy and Emily Lakdawalla has a more detailed one on her blog the Planetary Society.


17 Responses to “We Landed on a Comet”

  • This is pretty exciting science, in fact it ranks up there with finding new energy sources.
    300 million km away, this is pretty amazing engineering, to get it to land on a spinning rock that is whooshing through space. The harpoons failed to deploy properly and it did bounce but is now settled on it.
    The data that comes back from this should give us a clearer idea of the make up of some of the stuff hurtling around up there.
    As for the beginning of the universe well that is speculation. Space is not an empty vacuum but is instead filled with stuff, how interesting.

    • Even further, they’re actually closer to 500 million km away from Earth at the moment. Far enough that it takes signals travelling to and from the spacecraft at the speed of light a whole 28 minutes to bridge the gap between us.

      Like when Curiosity landed on Mars two years ago, this means the landing sequence needs to be entirely automated, as any commands sent to the spacecraft in response to something it detects wouldn’t arrive until at least 56 minutes after the detection. The same restriction applies when sending driving commands to the rovers on Mars, for example.

      The speed of light makes the vast distances involved in space travel a real game changer.

  • Yes it is amazing that a radio signal can travel 500 million kms in 28 minutes. So they have the 2 radio telescopes working with this ? The californian one as well as the australian one ?
    Can’t wait to see some of the results from the initial tests, do you know if it is using a spectrometer in order to get its results ? I wait in anticipation.

  • The Rosetta Mission is a European Space Agency (ESA) one, not a NASA one (although they do have some involvement). The ESA does have a listening station in New Norcia, Australia, which was one of the stations that was listening for Rosetta’s carrier signal when it “woke up” earlier this year after a period of hibernation as it was too far from the sun to remain powered from its solar panels.

    I’m not sure what stations around the world are relaying signals from Rosetta, although now that I’m looking for information on this I’m guessing it’d be the European Space Tracking network (ESTRACK http://en.wikipedia.org/wiki/ESTRACK). The ESOC, the European Space Operations Centre that is essentially ESA’s Mission Control, is in Darmstadt in Germany.

    Yesterday’s Astronomy Picture Of the Day has a diagram of Philae’s instrumentation: http://apod.nasa.gov/apod/ap141112.html

    From Emily Lakdawalla’s latest update on her blog at the Planetary Society (http://www.planetary.org/blogs/emily-lakdawalla/2014/11131025-philae-status-a-day-later.html) it sounds like because Philae is on its side they won’t be using any of the instrumentation that requires mechanical motion.

    To quote Emily, “That means no MUPUS surface properties experiments, or use of the APXS, and no deliveries to the gas chromatograph mass spectrometers.”

  • Oh it is a shame it has fallen over, all those instruments that can’t be used. To quote Fred Dagg “Bugger”.
    Thanks for all the links very interesting information, please keep us updated.

  • Things have progressed a bit since then. Due to its location being in shade, Philae has gone into hibernation, perhaps forever (but perhaps not – time will tell and either way it’s still been a remarkable success in my eyes). As always, Emily Lakdawalla has a great post on what’s happened here: http://www.planetary.org/blogs/emily-lakdawalla/2014/20141115-now-philae-down-to-sleep.html

    There’s also a post about this on the official ESA blog: http://sci.esa.int/rosetta/54962-pioneering-philae-completes-main-mission-before-hibernation-/

    You can find the photographs taken by Philae’s ROLIS camera on the ESA website as well. Here’s one of them, for example: http://www.esa.int/spaceinimages/Images/2014/11/Welcome_to_a_comet

  • A NASA probe called Deep Impact impacted a comet with a 370 kg impactor (moving at around 37,000 km/hour relative to the comet) on June 29 2005, and the probe observed the impact and the crater. Going from the Wikipedia article (http://en.wikipedia.org/wiki/Deep_Impact_(spacecraft)), there was some surprise at that time about how icy the comet was, but I haven’t been given the impression that the iciness of 67P has been surprising.

    My understanding (which could well be wrong) is that much of the ice that could be expected to be on the surface instead forms the coma, as 67P’s surface is too warm for it to be covered exclusively in ice (http://thewatchers.adorraeli.com/2014/08/01/rosetta-comet-67p-too-hot-covered-ice/). I think there’s still a lot of ice in the interior of the comet, and when it’s uncovered and subjected to the light and heat of the sun this is what causes the outgassing of water vapour that has been observed (http://www.astronomy.com/news/2014/07/rosettas-comet-sweats-two-glasses-of-water-per-second).

    I’m no comet expert though, this is all stuff I’ve found via searching on Google, so take this with a pinch of salt 🙂

  • Thank you, yes comets are fascinating, the organic chemical make up. ” Water is a major volatile component of comets, along with carbon monoxide, methanol, and ammonia”. I take it this is what is in the vapour of this particular comet.
    Philea should give us a fascinating insight into the actual make up of this comet. One thing I would like to know is, are there any measurements made of the electric potential of this comet ? Could it be the water is being made by the comet at 2 glasses per second with the fusion of hydrogen and oxygen ? Any idea of the plasma make up of this comet ?
    Interesting bit of info I found “The scientists think it must be produced in some way by the activity of the comet, as it releases neutral particles into space where they become electrically charged due to a process called ionisation. But the precise physical mechanism behind the oscillations remains a mystery.” Maybe this ionisation (plasmafication?)leads to a fusion process ?
    I too used google and found that here
    http://blogs.esa.int/rosetta/2014/11/11/the-singing-comet/

  • Ok have found an explanation for the production of water from comets in this video go to 54 minutes into this and they explain how water can be produced by a comet.
    This is a great video to watch if you have the time because there is a lot of research into previous comet missions and is conducted in an analytical and factual way.
    https://www.youtube.com/watch?v=34wtt2EUToo
    Fascinating science as it seems to give answers and not unknowns, anyone with time and a questioning of scientific dogma should watch the whole thing.

  • Appearances can be deceiving, and although you may think the photos of 67P look like it’s made of rock, it seems to be predominantly made of ice. They certainly believe that the spot where Philae first touched down is made of hard water ice.

    Here’s a post from right after Philae’s landing on ESA’s Rosetta blog: http://blogs.esa.int/rosetta/2014/11/18/philae-settles-in-dust-covered-ice/

    “Looking at the results of the thermal mapper and the probe together, the team have made the preliminary assessment that the upper layers of the comet’s surface consist of dust of 10–20 cm thickness, overlaying mechanically strong ice or ice and dust mixtures.”

    It also quotes Tilman Spohn, principal investigator for the MUPUS instrument, saying “If we compare the data with laboratory measurements, we think that the probe encountered a hard surface with strength comparable to that of solid ice”.

    I hope you understand that hypotheses are not tested by looking for things that conform to them, but by attempting to prove them false. Dedication to proving an idea to be true, as exhibited on the websites dedicated to the “electric universe” idea which you seem to consistently use as your primary sources, is detrimental to the scientific process. Always be careful not to be more interested in an idea itself than in actually finding out whether or not it is true.

    Do you have any reliable sources, such as ESA itself, saying that 67P/Churyumov-Gerasimenko is likely made of rock rather than water ice? I have been unable to find any.

  • Still waiting for more on comets from mainstream, it seems like the alternative science media is throwing up a few answers. The electrical component of comets is being discovered.
    Whilst the dirty snowball theory remains silent
    Thunderbolts crew with more real science to help you see the big picture
    Comet sliding spring, 67p and more
    https://www.youtube.com/watch?v=D_iUEGct0es

  • Derek it’s very rude for you to comment on an old post just to share a new pseudoscience video only tangentially related to the post itself. I’ve explained this to you before, and I expect you to stop doing it. If you post more comments like this on my articles here, I will be deleting them if they are off topic.

    If you want to share these pseudoscience videos, you are perfectly welcome to do it on your own platform. But please stop hijacking the comments sections of Sciblogs articles.