REPLAY – Rosetta & Philae mission update 14 Nov

REPLAY NOW AVAILABLE: Follow our ESA Hangout live today starting at 13:00 GMT / 14:00 CET. Rosetta and Philae teams will provide an update on mission progress.



  • Uday says:

    Great Achievement! My heartiest congrajulations to ESA and its entire staff.

  • Gerben Mulder says:

    I assume that the landing was a failure. So far only animations and fake photo’s.

    • Luca D'Andria says:

      Failure? Fake photos? What are you talking about?

    • Frank Beinersdorf says:

      @Rosetta Team: Amazing work! Thx!

    • Michel says:

      Haven’t you noticed they’re having problems ? They’re telling us from the beginning.

      The world does NOT work only thru Yes/no, True/false good/bad success/failure binary reductionnism..

    • William says:

      *slow clap*

      the speeds are too slow for lots of photos flooding the airwaves now.. as well as the issues of battery life.. whats more important to you? the composition of the comet or pretty pictures?

      the pictures ive seen seem pretty legit to me. guess you know exactly what the comet “should” look like right?

      speed from earth to rosetta is about 28kbps when there is a link. science data first then pretty pictures is im sure the priority.

      as to the animations… yips.. i dont think there is a camera crew in deep space to record the moving bits for us…. sorry for the much disapont

    • Dan says:

      @Gerben.. Uh, no. It was a resounding success – though it didn’t quite land as they intended it to, it’s definitely down and working fine, and despite the problems and challenges the ESA is facing, nobody would consider it even close to any kind of failure. Any animations or fake photos you see are artists conceptions, and quite a few real photos have been released. It’s, shall we say, pretty obvious and easy to find out what the current status of Rosetta is. After all, you’re at the right site for it!

    • Massimo says:

      How the people can be so ……….
      Thanks to Rosetta’s team we (all) made a great progress !
      Not a failure ! Big success of all of us (even for Mr. Mulder)

    • Christian W says:

      Fake fotos? Only animations? What do you want? a 1080p HD live feed from 500 million km away?

      And give the team time to figure out what is going on. They have only two short time windows per day for communication and they have a commmand / response delay of 1 hour. So everything takes its time…

    • Jacob Nielsen says:

      No photo = it didn’t happen? :-D:-D

    • Andy says:

      Of course….and the whole thing is being produced in a Hollywood film set just like the fake moon landings. How can the whole world not see that?

    • Jaime Diaz T. says:

      Failure???, how can you say that of geting 3 landings in a row?. even the telemetry of the bounces is scientific data.
      Vale, no salieron las cosas como estaban planeadas, pero suele pasar cuando se hace algo por primera vez, y mas si vas a donde nunca se ha estado. ¿ cuantos exploradores han fallado aquí en este planeta?, es mas ¡cuantos han convertido un traspiés en un rotundo éxito!.
      Para mi que Philae esta apoyado en un lado, esto por supuesto limita mucho lo que se puede hacer, pero de nada vale lamentarse por lo que no se puede hacer, mejor es aprovechar al máximo lo que si se puede.
      Y recordemos que aun sin impulsores, Philae tiene volantes de inercia, y en unos meses estará mucho mas cerca del Sol, así que hay esperanza de recargar baterías.
      Es mas, ¿ que tal si en un año intentan otro descenso?, Rosetta tiene una cantidad limitada de hidracina, propongo usar el último aliento para descender al cometa y seguir haciendo ciencia; cuando se aleje del Sol, hibernar, y tratar de restablecer contacto en la próxima aproximación.

    • Kenny says:

      Why do you say the landing was a failure? Which photos are fake then?

    • Peter Lindqvist says:

      I was wondering when the conspiracy theorists would arrive, spicing things up with unfounded tinfoilhattery. Well done.

    • David C says:

      How do you know the photos were faked?

    • Richard Liu says:

      And, for the longest time, it was assumed that the earth was flat. It’s difficult to imagine a more cataclysmic clash of science and ignorance than that represented by the above remark embedded in the website of an organization devoted to science.

    • Blackscale says:

      Actually no, it wasn’t. Here are the pictures you’ve obviously missed:
      Just because not everything’s going perfectly according to plan doesn’t make it a failure. After a ten years voyage of more than 8 Billion km, _some_ small mechanical mishaps might well be expected. We all should be very impressed by this achievement. Also, excellent use of our taxes, thank you 🙂
      (I’m not associated with ESA, I’m not even a scientist, btw)

      • Blackscale says:

        It’s ‘only’ 6.5 billion km so far of course. Guess I’ve been carried away a bit.

    • Tyler says:

      It’s almost like the lander can only send back black and white photos of things it can see or something, whoa /sarcasm

      There are “only animations” because nothing took a video of the landing that happened about 3x further away from us than the sun is.

    • Maxi says:

      do you think that everything is a fake?

      • Rossano says:

        That’s right.
        Because who will beliebe we, humans, could calculate speed, traveling without air resistance and also drop just same speed or almost suficient to not destroy the satelite?! oh, come on everbody, you guys are watching a lot of science fiction movies.
        Give me a break.

    • Steve Goodey. says:

      No, a great success. You need to look harder, and visit a few news websites.

    • MacMan says:

      The landing was not a failure, Its on the comet. Its just on its side and the photos are not fake

    • x says:

      Fake photos? Why would they lie?

    • greg says:

      the opposite of failure , it was pure poetry of science fiction in reality

    • Sean says:

      What information would convince you?

    • Scully says:

      Yes, Mulder, the answer is somewhere up there! *lol*

    • Nicolas says:

      Why are you here if you don’t believe then?

      But seriously, would you believe more if you had excellent images, and a very successful mission? Is the partial failure and difficulties as seen not the best proof of it being happening?

    • Robert Labar says:

      @Gerben Mulder I say who does care about your opinion about the landing? Do you need movies?
      I assume you have no idea about what is the meaning of research.
      So please just go write your comments on some other places.

      This is simply the biggest step every made by the mankind.

    • rui says:

      Dear Gerben,
      LEt me close the gap in the information you seem to lack:
      -Philae touched down in the intended site J. However, neither the thrust nor the harpoons designed to keep it in place functioned appropriately. Thus, Philae bounced back at about half the incoming speed, and flew for another 2 hours. After another bounce, it finally landed in a place near site B – still to be confirmed
      -Philae is probably lying sideways (as hinted by the pictures received),, resting on two feet and the body, and with one foot on “air”, in a poorly illuminated área
      -Most of the experiments can still be proceeded even in this position – so the mission goes on
      -It can still be put in the upright position using an internal flywheel – so the next pictures are likely to be better
      -The lack of informations is due to Rosetta going out of communications horizon – it should be resumed shortly and even improved with some orbital corrections underway
      -One major source of concern is the illumination received, possibly insuficient to recharge the batteries and allow extending operations beyond their 60 hour capacity. But Philae can even be put in hibernation until the comet aproches the sun and higher illumination is received.
      In summary, the mission goes on, and is by no means a failure, even if wth some hickups. What is most amazing is the capability of still controlling these contingencies from 500 million km.
      Bravo ESA!!!

    • MrMxyzptlk says:

      The landing was a success. But there are problems, the harpoons did not shoot, so the lander bounced and got into a position there is not enough sunlight to recharge the lander, so most probably the lander will be lost from the next few hours to the next few days, they don’t know for sure. So let’s see. This is what I understoof

    • Greg says:

      You must be joking.

    • Optimistic says:

      I am more optimistic and supportive – Great Success with some issues – temporary we hope

    • dario says:

      The staff is working on the boundaries of the human exploration. PHILAE IS LANDED, so great success, no doubt!

    • THOMAS says:

      The images acquired by Rosetta/Philae are certainly not fake, nor is the way they are being presented by the Rosetta/Philae science teams.

      What certainly IS fake, on the other hand, is the opportunistic way certain respected TV channels (and probably other media) are using those images in their reporting of events. On Wednesday evening, for example, the main state-owned French TV channel showed the famous close-up picture of the Keops boulder, published several weeks ago, as having been taken during Philae’s descent…. It certainly looks much sexier than the pictures Philae actually took, but it’s just another example of the scandalous way serious science is being “reported” to the public.

    • Rossano says:

      Truly agree with you. Totaly fake

  • Paul Chapman says:

    If only there had been GoPro’s available in 2004!

  • Graeme says:

    Fake photos? That’s quite an accusation. I’m assuming you can prove the released photos were faked?

    And I must say – how many comets have you landed probes on?

    Stop belittling the ESA’s achievement with nonsense.

    I bet you think the moon landings were faked too.

  • Mario Mohr says:

    Dr. Mr Gerber

    Let be a little positive I hope your life does’t carry such a negativity around you and the people with whom you interact!

    You should be happy for such a result so far…


    And yes…I don’t work at ESA, I am just a normal citizen has any other which is happy for such a science breakthrough!…

  • It was a success, have got several images now which were presented in yesterday’s even.

    This was the first one received from the surface.

    However, after landing in an ideal site, it failed to tie itself down because the harpoons didn’t fire – and it bounced 1 km up in the air, and then did a second much smaller bounce – and ended up a km or so away from the original landing site.

    It seems to be next to a cliff – or in a ditch or hole. Nobody was quite sure yesterday, so hope to find out more today! It’s getting 1.5 hours of sunlight a day- which may be enough to keep the instruments above the -58C temperature needed to be able to wake up from hibernation – but if they can’t find a way to get more sunlight then it will go into hibernation at least, with some possibility it might wake up as the comet gets nearer the sun.

    But they may be able to move it – because it is so light, just 1 gram in weight in the low gravity – its onboard instruments just by moving around may move it, also it can use its landing gear to “hop”

    however on the other hand it landed awkwardly this final time with one leg in the air – so they will be cautious, and they don’t know where it is exactly yet – if it moves who knows, might end up in a worse place. Find out more today!

  • Neil Choi says:

    Hope ESA and Philae find the way out to get power sooner as he can.

  • Hugo Rosado says:

    Using the drill and other ‘movement’ type instruments could bring us some interesting news today regarding a new possible mini-jump’. People, cross your fingers!

  • GT says:

    Fake photo’s?

    No more fake than your apostrophe: perfectly real but not in the right place.

  • GT says:

    It’s amazing that Philae was landed at all, and the scientific results will be unique and valuable regardless of whether all the lander’s experiments have the opportunity to be run. Well done all!

  • Snick says:

    I assume that you think that having a 6.5 billions trip, landing on a comet and send back pictures and sience datas is a failure..probably you expected that all is easy, even in deep space! Or maybe you expected some green-body creatures running in circles in front of the camera.. I wonder what we get back if you were the chief of this mission..
    I looks like everyone became astrophysics in the last few days..

  • Christina Scully says:

    How can you possibly say that?

  • Peter_ray says:

    @esa congrats!! This is an historical achievement, you guys brought us with you in the deep space and let us being part of something special. Thank you!

    @Gerben i’m sorry if you’re feeling frustrated. The guys from esa will uncover and share all the informations with us asap as they
    Always did. We’ve been waiting for ten years, we can wait for ten hours more without being mean to them 😉

  • joe R says:

    woow really cool. I wonder what this means for our knowledge and what we can make of this

  • Peter Yates says:

    I wouldn’t say it was a failure. It certainly made contact with the comet’s surface, though I’m not sure if you could call it a landing! … Anyway, you can see the first photo on this page: … It doesn’t show any signs of being a fake.

  • max says:

    Based on what, does it?

  • Stuart Atkinson says:

    Always one, isn’t there….

  • Gijs says:

    I assume that you haven’t had the time to examine the facts they have presented in relation to the difficulty of this operation. It started as a big but daring gamble and most of the goals are achieved:
    – Rosette in orbit of a comet achieving a lot of data
    – a lander on the surface of a comet!!!
    – scientific data from the lander
    – a few photos from the surface
    You must realize that this mission is not a show for the public, but a scientific operation.

  • Mattia Terzaghi says:

    I think is too-early to say that this Landing was a failure. It wasn’t as expected and now there could be lots of problems. But problems doesn’t exist, what exist are solutions… Let’s see…

  • @Gerben Mulder You call this a failure? There have already been tons of science data received, from the radio-“röntgen” experimient e.g.. I assume, that it will take the scientists some time, to evaluate these – and make these available for the public. Research like this is one of the best sources for the positive development – thank you, everybody, who helped to make this successful!

  • J Walker says:

    Please give us some real information. We saw nothing of the landing or the landing data!
    Were there any pictures of approach?
    How did you know she had landed? Or bounced?
    Does Philae have rockets or orientation control or measurement?
    is Rosetta taking photos? If so from how far and at what spatial resolution?
    How much energy is available? What percentage of power is being generated? what does the generation graph look like? how tightly have you located Philae?
    what measurements are taking place? in what order? to find out what?

  • Ashley Gaunt says:

    No its not a failure! How is it you think they are fake? Congrats to all there, i’m sure there is not much sleep happening though while they work out how to move it into the light.

  • Terry says:

    Brilliant, pure science not tainted by politicans or greed.

  • Dave says:

    It is wonderful to see the world reaching together.

  • Zhdophanti says:

    Uhhh fake photos, so how you know they are fake?

  • Redgy Devos says:

    First of all my congratulations to the team’s who are doing great work in difficult circumstances and with probably little time left in wich to do them. Although I sincerely hope that an unforeseen event may extend the landers life. I am convinced that a significant part of the world looked in awe of what you all have done ,and rightly so. And finally regarding comments about fake photo’s and animations,please remember that everyone in the whole world can see what you are posting…

  • Greg Robison says:

    Quite the contrary, they released a panoramic view yesterday. Unfortunately the lander bounced several times so they aren’t where they wanted to be. Also, Philae is oriented with one of the landing feet pointing towards the sky rather than all three feet on the comet. They’re getting data though!

  • Harrie says:

    The sound quality is horrible

  • Stephen says:

    Each time I read comments like the one from Gerben Mulder, I lose faith in humanity.

    Space exploration is complicated stuff, and what they have achieved so far is simply spectacular.


  • John Spillett says:

    Awful sound on HANGOUT. Unintelligible

  • Luke Little Horn says:

    Yeah, it all was a setup and fake. You really see through it!

  • Adrian says:

    Next time use nuclear power for the next space probe! It should last for hundred of years.

  • David Sebastio says:

    Can you reduce the volume of the microphones in the main room? the voices are distorted!!

  • Giuseppe Cappai says:

    What about the power supply to Philae? Do you think that Philae can continue to work for long time as expected, or there could be problems due to lack of energy provided by solar panels?

  • Baznr says:

    Has Philae something like a simple flashing led to help the identification of her position, or perhaps another more sophisticated system for this purpose?.

  • Martyn says:

    I am 72 years old, your Rosetta Mission, is the most inspiring of my life; congratulations, to all the team.


  • Tim O'Rourke says:

    Can the power be reduced to allow recharging battery with limited sun light available?

  • Karl Nelson says:

    Gerben, I don’t understand how you can consider the landing a failure. It didn’t go exactly to plan, but what an amazing overall success! Have you seen the initial REAL imagery? Cheers, Karl

  • Andreas Kröll says:

    Wouldn’t it be possible to find Philaes landing site by analyzing the communication window with Rosetta? At least the area should be narrowed down by such an analsys.

    By the way: You are doing a great job. We are proud of you!!! 🙂

  • Vassily says:

    Guys you are doing a great job! I can’t believe we humans can actually do something good from time to time (between wars and politics).
    Fingers crossed and I can’t wait for the info you will give humanity 🙂

  • David Daniels says:

    It causes me great amusement that ESA can communicate with a spacecraft 511 million km away … but the audio on a streamed earthbound video-conference is …. shall we say … rather poor.
    However, it does show that priorities are correct.

    Totally transfixed by the whole project.

  • CrashTack says:

    Trying to find something that bumped into a speeding, rotating body, floated a kilometre up and then drifted down some range, followed by another bump and drift. All hundreds of millions of kilometres from earth. Would love to be in that room.

  • tolis christou, armagh observatory, UK says:

    as the comet approaches perihelion is it also possible
    that seismic activity, a gas jet or even a change in the surrounding landscape improves the lighting situation?

  • Ernst Schnieder says:

    Why did the harpoons not deploy?

  • lionel says:

    Dear all,

    Do you intend as a last (desperate) move to move Philae before the non-rechargeable battery is depleted? Be with Harpons, legs or drill? So that we can get a better illumination?

  • Philippe says:

    On which techncal criteria did you initially claim a successful landing on 12/11/14 at 17h03 ?

  • Terran says:

    Sigh, the same usual conspiracy theorists popping out from their holes. I wish they would stay in their closed off little worlds. I think they just fear such missions and science in general for some reason and try to run this success down for us.

  • Delafield DuBois says:

    2 quasi haiku

    On dunes sans harpoons
    The drill would turn the craft
    But wedged it might work

    # 2 is about something only slightly mentioned, maybe mistaken, but it made me think.

    Powder to solid
    As snow in an avalanche
    A dirty snowball

  • David Chapin says:

    Have their been any surprises from the preliminary data?

  • julio Finalet says:

    congratulations to you all. This is great!
    my question is : could eventually the drill be used as an anchor if necessary?

  • Holger says:

    Fascinating things happen up there.

    At least streaming done by youtube works.
    The ESAstream had to be restarted every 15s.

    Thank you for this.

  • Hervé says:

    One should not assume… It leads often to wrong thinking … your comment is a perfect example

  • Padraig Meehan says:

    The horizon in the panorama does not surround the orbiter, but intersects it. Surely this means the orbiter is on its side?

  • julio Finalet says:

    you are probably from the United States, right?

  • mihai says:

    Question: why the harpoons failed to fire and who is responsible?

  • Could you some how triangulate position of Philae from Rosetta? I can imagine it would help to resolve situation if you would know where exactly is Phelae, 2130

  • Lindsay Ward says:

    You only have to look back as far as Apollo 8 in 1968 and a snapshot taken by William Anders entitled Earthrise to see how this type of research changes the way we think. This mission will also change the way that we think about our place in the universe. Cost! what cost this mission has been in profit since the day it was conceived in terms of knowledge, hope and what it really means for humanity! The comet landing is one of those seminal moments which humanity needs from time to time in order to make sense of it all and hopefully become a better species more in harmony with ourselves and the cosmos which we inhabit. I must admit to shedding tears along with the team that succeeded in putting Philae on the surface of Comet 67P/Churyumov-Gerasimenko and to share in that moment of history with them was a rare privilege . The realization of just what this team had achieved is difficult to comprehend and unusually the more you know the harder it seems, Totally outstanding, untold billions of children will learn about this mission and will be inspired. The fact that this little craft travelled four billion miles and landed on a Comet traveling at fifty thousand kilometers an hour is a miracle! Now it will sift through ashes of the supernova that spawned our solar system and the solar systems in our vicinity we will know so much more. Knowledge comes from being built up, knowledge on the back of knowledge if you like. Thank you so much ESA! After seeing war, disease and crime reports on the news, you give tangible hope that we are better than that. You mission has humbled us and that’s a good thing.

    • Frank Beinersdorf says:

      @Lindsay: Thanks for putting in words what many of us think or at least can agree with, but are not able to write it down in the thoughtful way you did. Good job.

  • Loic says:

    Yes! Thanks a lot for sharing all this with us, it is really great!

  • maureen says:

    We are crossing all what we have!!! You all make a great job the last days! Keep going, all come to a good end and the lander get sun for new energy!

    Best greetings from Germany

  • Pv says:

    Is this an actual Google+ hangout? Are Rosetta & Philae on Google+?

  • David says:

    Thanks for that, very informative! I really hope that A. the Philae tele link is established again (tonight) and that it can send some more useful data (icing is B. that the drill worked and that a sample was chewed thoughtfully by COSAC and that this data is sent). If ex-communicado from now I will obviously look forward with extreme interest to interpretations of the already received data but will probably even so listen to Down in a Hole with Alice in Chains at least once tonight.

  • Homo stupidus says:

    Imagine, how many situations in 10 years could have led to big failures, ending in a Mission catastrophy. Now see, what the results are:

    – The orbiter is working fine, which was the primary goal anyway as far as I understood. The chance for the lander to work was calculated 50:50 and it’s now 100%.

    – Philae was landed and is transfering scientific data from many experiments

    – One of the most important experiments could have been started – the drilling – to get comet material for analysis (results about a success tonight or tommorrow)

    – Philae could possibly been brought into a new position or at minimum its solar panels could be to make it available the next days

    – AND: Next year in summer when the comet is near to the sun, Philae is in a good position and could hopefully be awakened by much more sunlight, also illuminating the hole, where it is seemably sitting in. Possibly this hole is a big luck as it covers the lander from being pushed away or somehow being destroyed.

    … and then Philae will look over the rim of this hole and observe “the hell” on the surface as Holger Sierks said today and hopefully sends many data and some pictures as it seems to watch the “comet sky” already 😉

    Isn’t this terrific?!


  • prathamesh says:

    assuming the 3 bounces on the comet does it
    guarantee the integrity and successfullness of the tests being conducted on d comet

  • MICHELLE says:

    congratulations Emily on an interesting hangout. thankyou for bringing questions and answers that us mere mortals, who arent scientists but just in awe of everything that this mission has accomplished, can understand. Very interesting, and Matt we love that you look like an ordinairy bloke who just loves what they do, there needs to be more like you in the world!!

    • Robin Sherman says:

      Well said Michelle. Can’t wait until Matt has got some coherent conclusions to enthuse about. Its pretty difficult when there are only bits and pieces of evidence to try and give the bigger picture. My thanks to Emily, Claudia and Daniel for their efforts too, with such a fluid, ever changing event like this, such up to date information that we got, and being able to read what other people are thinking and experiencing, made the whole experience even more gripping. It was wonderful to see the support and messages from around the world.

  • Loph says:

    This is so exciting! Really hope Philae has sufficient battery power to send back its results

  • bob bonwitt says:

    why was Philae’s energy system based on solar and not radioisotope thermoelectric generator?

    • Piot says:

      Let usguess why:
      – American and not European Technology.
      – Not really environment friendly in case of rocket failure, or Earth fly-by.
      – I am not sure, but may be too heavy for Philae anyway. It has been considered for Rosetta because it flies far away form the Sun, but was abandonned quickly because of the first point.
      That is another place where geopolitic meets space !

    • Justin says:


    • hank says:

      Asked and answered in the video

  • Michael Logan says:

    Not that they will read and respond, but can they contract Rosetta’s orbit in the hope of locating Philae?

  • Luis Arocha says:

    WOW!!!!! Congrats! Keep doing your magnificent job.

  • Colin Brazier says:

    Brilliant job. Congratulations to the whole team. Matt, you have my support – awesome job!

  • Vincenzo says:

    Probably a dumb question but, can’t the lander “switch off” during shadow hours and charge batteries when in sunlight?
    After a few cycles that could possibly build up enough energy in the battery to carry on some activity.
    It would be slow but there’s plenty of time, isn’t it?

  • John Wood says:

    Was it hard to decide to stay and use the remaining battery power than try another hope and hope for an improved position

  • Al Rocker says:

    You can land a probe on a comet 10 years after launch, but you can’t get the sound right on your broadcasts 🙂

  • Dave Mills says:

    Congratulations to the brilliant people who planned and executed this amazing Rosetta mission. We are all ESA today, even in Wyoming, USA.

  • Synge says:

    Bravo à tous, ça c’est du rodéo !

  • Christian Vassie says:

    Congratulations! Very much looking forward to hearing the science next month when everyone has had some sleep and time to review all the data. Brave Europe.

    • THOMAS says:

      Brave new world! I mean the comet.

      Can’t wait to hear the science results either.

  • Christian Vassie says:

    Of course my comment should have ended Bravo Europe …

  • roberta says:

    it is so heartening to realize that objective problem solving rationality still exists! after the siege of the media in all other arenas, with fault finding, finger pointing and political correctness enforcement, SCIENCE, as you practice it, making the best effort, and the best thinking aimed at optimizing the PHENOMENAL opportunity and rejoicing at even the set backs as an opportunity to problem solve and rethink solutions for the future. that “‘throwing around of ideas” as Valentina and so many of the PHILAE scientists put it, that exploration of what is so, using logic and unbiased data inputs is the justification in deed of the gift of speech given us by God. i love hearing you all. yes i see the sadness at the losses experienced, but more than that the appreciation of the incredible feat accomplished and the eagerness to make the most of what remains, and the reasoning and knowlege applied to solutions, not destructive conversation. My psyche thanks you and my god given soul thanks you for putting forth the best examples of what i am grateful for in you. your team and solution oriented humanity.

  • Mike Wilhelm says:

    Congratulations on your historic achievement. Looking forward to the advances in human knowledge that will certainly be forthcoming.

  • Emily, the German pronunciation of ‘Ulamec’ is ~~ U-la-mets ~~ , not ~~U-la-metch~~ . Much as this is a trivial point, you might want to consider this in future broadcasts. I realize that pronunciation of names is language-dependent, but when in the presence of the person you are naming, it is preferable to use his/her preferred way of saying his name.

    Thanks for this hangout! It was very informative and helped answer my question about rotation of the comet underneath the bounced Philae, after the first landing. The horizontal movement from that first landing spot J to its final place of rest could have been partly due to the normal rotation of the comet underneath the flying Philae. Of course, some of the momentum of Philae during its two jumps may have due to its brief contact with the surface of 67P/C-G, which has a rotational period of 12.4 hrs. During the first jump of Philae, about 2 hours long, the comet went through 1/6 of its rotation.

    • I meant to say “may have been due”, not “may have due” 🙂

    • By my calculation, a point on the outer surface of the landing area (on the smaller lobe of the comet) would have moved about 2.6 km in the 2 hour period, during the first jump by Philae lander. This comes from the comet’s intrinsic rotation.

      This means that if Philae rebounded straight upwards from the surface with no horizontal vector of motion of its own, it would come down at a distance of 2.6 km from its first point of contact, simply due to the movement of the comet’s surface during those 2 hours. As it appears to have only moved 1-2 km horizontally, the lander may have had a horizontal momentum of its own in the opposite direction to the comet’s rotation.

      • Correction! >> I meant to say that the comet might have imparted some of its rotational momentum to the spacecraft after Touchdown #1, thereby reducing the horizontal distance that Philae covered during the first jump. If Philae had momentum opposite to the comet’s rotation, that would have INCREASED the distance of the trajectory from first point of contact, not decreased it! It’s all relative.

        • Simply stated, Philae should have fallen off the comet, if it had zero or more forward momentum (in an ‘easterly direction). As the comet is rotating in a westerly direction we can assume that in the 1 hour 50 min of the first bounce , Philae would travel >2.3 km east, thus falling off the end of the comet’s head lobe. This would put it onto the larger body lobe, or it may have disappeared into space.

          As it was, Philae probably had received a backward momentum in its two contacts with the comet surface, as the comet continuously rotates in a ‘westerly’ direction (counter-clockwise when viewed from the head of the comet). This rotation is at 35 cm/s and would impart a force to the landing spacecraft in the direction of the comet’s rotation. This helped to put a brake on Philae’s forward momentum, as it was falling to its first landing spot J. This explains why the final resting place was less than 2.6 km from the original landing spot (the distance travelled by a point on the surface of the comet in that time).

  • Congratulations to the Rosetta team and ESA for this amazing and important accomplishment! Even if the lander dies today, the mission will go down in history as an important step in our understanding of the evolution of the solar system. How wonderful that there are people smart enough and bold enough to undertake such a challenge!

  • Aaron says:


  • nw says:

    Depending on the number of countries and tax payers involved, I’m guessing the cost to me was about $300.00 US. +/-. Regardless the science derived from the effort, for me the mission was worth it simply for the last 72 hours of nail biting entertainment. Couldn’t afford this form of entertainment every year, but I’m OK w/ this expense.

  • Antonie says:

    Congratulations with the success.

    Latest from twitter…

    Philae has tilted the right way 35 degrees.
    Great news.

  • What’s interesting is that the rotational speed of a point on the surface of the nucleus is actually 35 cm/s, which is close to the rebound velocity of Philae on its first jump (38 cm/s). It was also astonishing to learn that in the first bounce, Philae almost reached escape velocity for this comet. We came that close to losing Philae into empty space!

    If Philae travelled about 1 km after its first bounce, then it must have gained some momentum in the same direction as the comet’s rotation, which also prevented it from falling over the edge of the head portion of the comet.

    Luck was certainly on the side of the Philae lander team.

  • rajan says:

    human hands reached near of the GODzone
    thanks rosetta—

  • Why are two of my recent comments awaiting moderation? I don’t see any problems with them. They are simply a factual analysis of what happened during the bounces of Philae, when it landed. I am trying to understand what happened just as much as everyone else, including the team. Holger Sierks said “we have a bit of an issue understanding this.” So, I am just trying to add to the discussion. What is the problem with that?

    • emily says:

      Hi Stephan – each comment has to be approved manually, sorry for the delay!

      • Emily, thanks for posting my comments. I was just making sure this article was still being monitored! I really enjoyed your hangout, and learned a lot.

        We need more enthusiastic people like you, to promote the wonders and fascination of space science and astronomy. I just realized that you even have a Ph.D. in Planetary Science and are a published author. Congratulations!

  • Rmckissock says:

    how does a lander bounce in almost zero gravity, then how do they compensate for the bounce when it takes 30 minutes for information to travel to Earth ? and then 30 minutes to send information back ?

  • After reading some comments on another blog, I realized that the direction of the comet’s rotation (counter-clockwise towards the east) is the same direction as Philae took during its bounces (easterly). If the intrinsic speed of Philae during the bounces averaged 0.5 m/s and the comet was rotating at its nominal speed of 0.35 m/s then the relative speed of Philae to ground was 0.15 m/s. In two hours it would have travelled 1.08 km, which turns out to be the estimated distance it travelled from its original touchdown spot (J). The motion vectors of Philae would depend on the angle of its path relative to the rotational path of the comet, as well as variations in gravitational pull along that path. However, the path would generally follow a trajectory going up to about 1 km in height, before descending to a 2nd smaller bounce and a final stopping place.

    I’ll leave it up to the Philae lander team to figure out where Philae finally came to rest. At any rate, it was probably still somewhere on the head lobe of the comet.

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