Happy Landing

Today, 12 Nov 2012, around 16:00 GMT, after a 6 or 7 hour journey from the Rosetta mothership, the Philae lander is due to touch down on Comet 67P/Churyumov–Gerasimenko, in (I think) the red circle shown below:

chury1 Another view with landing site shown:


At launch, the Rosetta mothership will be about 22 km from the comet, and since the lander will approach it at a speed of 1 metre/second, it will take it 6 or 7 hours to cover the distance.

As you can see, the comet has a narrow waist between two lobes.  The landing site is on the smaller lobe, which is 2.5×2.5×2 km. So it looks like the ‘plateau’ with the landing site on it is 2.5×2 km. And the landing site doesn’t look very flat:


I think the above photo shows an area approximately 1 km x 1 km. The deep crater next to the landing site is partly shown at the bottom.

And the lander doesn’t have a motor. So it seems that it’s just going to be given a shove to get it up to speed, hopefully in the right direction.

And the comet is spinning end over end with a rotation period of 12.4 hours. So that when it’s launched, the landing site will be on the other side of the comet.

And they don’t know what the surface is like. They’re going to try and fire a couple of harpoons into it to hold on with, given that escape velocity from the comet is 0.5 metres/second. So if it lands and bounces off, it’ll never be able to land again.

If they completely miss the target smaller node, they’re going to try to land on the larger node instead.

The scientific goals of the mission focus on “elemental, isotopic, molecular and mineralogical composition of the cometary material, the characterization of physical properties of the surface and subsurface material, the large-scale structure and the magnetic and plasma environment of the nucleus.

It also has cameras on board.

There’s going to be a webcast tomorrow covering the mission.

On 11 & 12 November, all segments broadcast by ESA TV will also be webcast here. These include: Media briefing 11.11-20:00CET || GO/NOGO decision points 1-4 (11-12 Nov) || Separation, science updates & landing (12 Nov). The webstream will remain live all the way until 19:00 GMT / 20:00 CET on 12 November with a permanent view of ESOC Mission Control Room in between the listed sequences. Complete list is available via: http://www.esa.int/esatv/Television

I’m sure they were expecting something a bit easier to land on than this. Last I heard, comets were supposed to be ‘dirty snowballs’. It doesn’t look a bit like a snowball to me. It looks like solid rock, with sand here and there. But if it is rock, it’s apparently as light as pumice stone. If you put it in a tub of water, it would float.

I read a few days ago that they reckon they have a 70% chance of a successful landing. I think that’s a bit optimistic. There seem to me to be any number of things that could go wrong. To me it looks like trying to land a glider on a very lumpy deck of a spinning aircraft carrier, blindfolded


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24 Responses to Happy Landing

  1. castello2 says:

    Looking good so far at midnight California time PST. Thanks for the heads up.

  2. Rose says:

    Real science in a genuine quest for information.
    I shall certainly be watching and on the edge of my seat.

    • Frank Davis says:

      I’m going to be on the edge of my seat too.

      ESA http://blogs.esa.int/rosetta/

      NASA http://www.nasaspaceflight.com/?s=Rosetta

      Sky reports:

      There were cheers and hugs in the European Space Agency (ESA) control room when the probe’s detachment from the Rosetta spacecraft was confirmed shortly after 9am.

      The agency tweeted: “SEPARATION CONFIRMED #SEP ESA confirms @Philae2014 Lander has separated from @ESA_Rosetta. Lander now enroute to #CometLanding”.

      The first signal from the detached lander came two hours later.

      It said Philae would now have deployed its landing gear, ready to fire its harpoons and latch on to the giant ball of dust and ice.

      Bad news:

      Scientsts fear that Rosetta’s probe Philae could bounce off the comet because its thrusters have broken.
      After a tense night, scientists at the European Space Agency cleared the lander for separation at 2.35am this morning and the probe, called Philae, detached from the mothership Rosetta at 8.35am.
      However last night the ESA admitted that a crucial part of the landing process cannot be activated. Because the comet is so small, gravity is weak and there is a risk that the probe will rebound at the moment of touchdown.
      Thrusters were built in to keep the probe at the surface, but they are no longer working. The lander will have to rely on a system of harpoons to keep it locked to the surface. However there is a fear that when the harpoons are launched, the probe may fly up and be lost.
      “The cold gas thruster on top of the lander does not appear to be working so we will have to rely fully on the harpoons at touchdown,” says Stephan Ulamec, Philae Lander Manager at the DLR German Aerospace Center. “We’ll need some luck not to land on a boulder or a steep slope.”

  3. Frank Davis says:

    Telegraph Live Blog has lots about it.

    I reckon it’s going to bounce off. I’m going to see whether Philae might go into orbit around the comet after bouncing off, using my orbital simulation model.

  4. Frank Davis says:

    It looks like it was a happy landing after all, given the way they’re all smiles and hugging each other at ESA

  5. nisakiman says:

    You see Frank. That’s the difference between real scientists and junk ‘scientists’.

    That project required not only brains, but also the willingness to take risks, the antithesis of the so called ‘experts’ who spend their lives trying to remove all risk and all joy from everyone’s lives.

    I’m really pleased for them that they succeeded.

    • Rose says:

      So am I.

      Real science understands the concept of success or failure, not an endless stream of maybes, mights and coulds riding on a raft of hearsay and wishful thinking.

  6. Frank Davis says:

    Amazing. I really didn’t think they had I hope in hell.

    Maybe the comet is soft and sticky?

    • nisakiman says:

      Yes, quite amazing. Particularly considering the top thruster wasn’t working. The precision required must have been staggering.

      I have to admit to being a tad disappointed to find that the live stream was of the control room. I was rather hoping that the lander would have a live cam feed. Now that would have been spectacularly exciting! Oh well, can’t have everything I guess… :)

    • garyk30 says:

      Maybe the comet is soft and sticky?

      Green cheese like the Moon?

  7. beobrigitte says:

    When I heard about Rosetta’s 10 year journey, the first thing that came to my mind was: I hope that this time they all agreed on the units of measurements thus getting their calculations right!

    I must admid that I wasn’t exactly optimistic, especially when it was announced that there was a problem with a thruster.

    Now the Philae is sat on Comet 67P/Churyumov–Gerasimenko’s surface. Well, on one half of it.
    (How long does it take for the data that will be sent to reach earth?)
    I hope the people involved in this project do take an hour or so out to have a celebratory drink (?and cigar) before at 23:00 hrs Rosetta is in position to receive and send data. Then a lot of work begins.

    Real science understands the concept of success or failure, not an endless stream of maybes, mights and coulds riding on a raft of hearsay and wishful thinking.

    In REAL science ‘could’, ‘might’, ‘preliminary suspicions indicate that’ translate into: DO NOT KNOW and therefore should NOT be acted upon.

    • Rose says:

      Brigitte, we can be sure that the Rosetta scientists considered all possible confounders rather than just ignore the ones they didn’t like.

      • beobrigitte says:

        Indeed! Anything that involved “might”.. “could” .. “indicates” must have been disregarded and only “it does” or “it does not” have led to the success (so far; apparently the harpunes did not work!) of the first landing on a comet.

        I am hoping to see more pictures tonight!

  8. The Blocked Dwarf says:

    What interests me about it -and the question of where the water on Earth comes from doesn’t-is the fact that , according to radio4, it is 80s technology, which in computing terms is just after the last Ice Age and before the discovery of Fire.

    Amazing that it all worked as well as it did and maybe I’ll dig my BBC Acorn out of the Cupboard Of Doom tonight to celebrate…oh that’s right, I can’t cos I donated it to a Computer MUSEUM in Germany this spring.

  9. Frank Davis says:


    19.10 So it appears that the Philae lander bounced when it hit the comet and lifted off once more before settling somewhere away from original touchdown site. Scientists have also lost the radio link because the probe is now below the horizon and will not be contactable until tomorrow morning.

    “It’s complicated to land on a comet. It’s also complicated to understand what has happened during he landing. What we know that we touched down and we landed on the comet. We had a very clear signal and we also recieved data from the lander. That is the very good news

    The not so good news is that the anchoring harpoons did not fire. So the lander is not anchored to the surface. Did we just land in a soft-sand box and everything is fine? Or is there something else happening. We still do not fully understand what has happened.

    Some of the data indicated that the lander may have lifted off again. It touched down and was rebouncing. We saw data on the solar generator which could be interpretre that the lander lifeted off and started to turn itself. About two hours later this information of turning stopped. So maybe today, we didn’t just land, we landed twice.

  10. harleyrider1978 says:

    Westminster store owners hope to extinguish proposed tobacco ban Boston Herald 10:59



    Should Westminster ban tobacco sales?

    Yes. Tobacco causes cancer. 9%

    No. This is America. Enough with the Nanny State already. 85%

    Yes. We need to keep tobacco away from kids. 1%

    No. It’s going to hurt local businesses. 4%

    Westminster store owners and their supporters — fuming over their Health Board’s first-in-the-nation plan to ban tobacco sales — plan to pack a public hearing on the controversial proposal tonight that they say will crush business in the sleepy central Massachusetts town.

    “People are in an uproar,” Westminister Liquors manager Michael Fratturelli said.

    More than 1,000 people in the town of just 7,700 have signed a petition to snuff out the ban. Many of them plan to get fired up at a 4:30 p.m. rally outside Vincent’s Country Store on Main Street before heading to the board’s 6:30 p.m. meeting, which has been moved from Town Hall to Westminster Elementary School to accommodate the expected crowd.

    “This ban is going to greatly affect not only tobacco retailers, but every other business in town,” said store owner Brian Vincent, who admits to lighting up the occasional cigar. “People are going to drive five minutes out of town to buy cigarettes, and while they’re there, they’re going to buy their gas, their groceries and anything else they need. It’s going to crush commerce in Westminster.”

    Town health agent Elizabeth Swedberg could not be reached yesterday, but said earlier this week the board hopes that if it enacts the ban, loyal customers will support local businesses by buying more non-tobacco products. And she thinks stores could see another benefit: “For people who are trying to quit, it could be a better place for them to shop, because they wouldn’t be confronted with tobacco.”

    Citing a report from the U.S. surgeon general, Swedberg said that if tobacco use continues unabated, 5.6 million American children who are younger than 18 today will die prematurely because of smoking. Change, she said, “has to start somewhere.”

    “The tobacco companies are really promoting products to hook young people,” she said, citing 69-cent bubblegum-flavored cigars, electronic cigarettes and a new form of dissolvable smokeless tobacco that resembles Tic Tac candies. “The board was getting frustrated trying to keep up with this.”

    But Fratturelli, who estimated tobacco products account for 
5 to 7 percent of the store’s revenue, said there are alternatives the board could consider, such as banning flavored cigars and raising the minimum age required to buy tobacco products.

    “If this ban is meant as a protective measure but there’s so much opposition to it, why not let people vote on it?” he said.

    Colleen Conner lived in Westminster for 15 years before moving to neighboring Gardner in 2011, but she still stops at Vincent’s Country Store nearly every day to buy a pack of American Spirits and some groceries.

    The ban “isn’t about cigarettes,” Conner said. “It’s about the government coming in and taking away my right to buy them. Cigarettes are very bad for your health, but so are a lot of other things you can buy. A ban’s not going to deter people from smoking. I’ll just go somewhere else.”

    • harleyrider1978 says:

      No. This is America. Enough with the Nanny State already. 85%

      Just imagine in Massachusetts even getting to the 80%tile range with a answer like that…….It has to be a Nazis greatest fear!

      Worse yet only 9% believe smoking causes cancer…………..Where did the Propaganda machine go wrong after 60 plus years of daily Lies!

  11. Frank Davis says:


    After two bounces, the first one about 1km back out into space, the lander settled in the shadow of a cliff, 1km from its target site.


    Lander project manager Stephan Ulamec told the BBC that he was very wary of now commanding the harpoons to fire, as this could throw Philae back off into space.

    He also has worries about drilling into the comet to get samples for analysis because this too could affect the overall stability of the lander.

    “We are still not anchored,” he said. “We are sitting with the weight of the lander somehow on the comet. We are pretty sure where we landed the first time, and then we made quite a leap. Some people say it is in the order of 1 km high.

  12. Frank Davis says:

    06:00, 15 November 2014

    The comet probe Philae is “asleep”, scientists said, after its batteries ran out and were unable to recharge as it lay in the shadow of a crater wall.

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