Comet Update! Rosetta’s Philae landed, but not as planned

Now here’s what you’ve been waiting for! You really need more comet, like Christopher Walken/Bruce Dickinson needs more cowbell, so here you go…

In a blog post few months ago, I told you about the European Space Agency’s (ESA’s) Rosetta mission. Nine years after its launch and after four gravity assists, Rosetta reached the comet 67P/Churyumov-Gerasimenko and began to orbit it. On 11th November, Rosetta maneuvered its position and trajectory to eject its washing machine-sized lander, Philae, which sallied forth and landed on the comet the next day, and MADE HISTORY! (Wired‘s apt headline, “Holy Shit We Landed a Spacecraft on a Comet,” beat The Onion, which is known for that sort of thing.) Its landing was confirmed at ESA’s Space Operations Centre in Darmstadt, Germany at 17:03 CET that day.


Above you can see Philae on its fateful journey, and below you can see its first image of the comet, both courtesy of ESA. The landing happened to take place while friends of mine were at a Division of Planetary Sciences meeting in Tucson, Arizona, and we and others discussed the Philae landing at Friday’s Weekly Space Hangout with Universe Today. And if you’re interested in more information than what I’ve written here, then check out the ESA Rosetta blog and posts by Emily Lakdawalla, Matthew Francis, and Phil Plait.


From what we can tell, Philae did initially touch down in its predicted landing ellipse (its planned landing zone) but its harpoons—which were supposed to latch onto the surface—failed to fire, and it bounced! Considering how small the comet is and how weak its gravitational force (about 100,000 weaker than on the Earth), this could have been the end as the lander could then have floated away, never to be seen again. However, after nearly two hours, it landed again…and bounced again, and a few minutes later finally settled on the surface and dug in its ice screws, about 1 km from its intended landing spot on a comet 4 km in diameter. (This would be like trying to land a plane in Honolulu and ending up on another island—it’s unfortunate but at least you didn’t drown.)


At first, it wasn’t clear exactly where Philae actually was; it could have dropped into a crater where it would be nearly impossible to find. But then based on images from the OSIRIS camera and NavCam (navigational camera) on Rosetta, ESA scientists were finally able to locate it a couple days ago. The mosaicked images above came from the OSIRIS Team, and the NavCam image below as annotated by Emily Lakdawalla, to give the larger-scale context. After its last bounce, Philae rotated and headed “east”, finally becoming settled among dust-covered ice at the bottom of a shadowed cliff. It’s not an ideal position but at least it’s not totally precarious. (They considered securing the position with the harpoons, but the momentum from firing them could push the lander back up into space, which would be “highly embarrassing” according to Stephan Ulamec, head of the lander team.)


But the cliff situation is a problem. Philae’s battery had a little more than two days of juice in it, and once that ran out, it would be dependent on its solar panels. However, Philae’s current position only receives about 1.5 hours of light per 12-hour rotation of the comet, much less than hoped. Philae did attempt to run some of its experiments and activities during the time allotted, the battery ran late on Friday. This was @Philae2014’s last tweet: “My #lifeonacomet has just begun @ESA_Rosetta. I’ll tell you more about my new home, comet #67P soon… zzzzz #CometLanding”

Before Philae dreamt of electric sheep, it managed to collect some data using instruments on board. (See this Nature news article.) For example, Philae deployed its drilling system (SD2) as planned, in order to deliver samples to the COSAC and Ptolemy instruments, which probe organic molecules and water (and which I described in my previous Rosetta post). But ESA scientists don’t know how much material SD2 actually delivered to the lander; if the ground is very dense, it’s possible that since Philae isn’t totally anchored, it could have moved the lander rather than drilling into the surface. We do know for sure that some instruments operated successfully, such as the downward-looking ROLIS camera and ROMAP, the magnetic field mapping system.

In any case, scientists have obtained some data already while other data stuck on the snoozing lander will be retrieved later. In the meantime, Rosetta is keeping busy and continues to take observations. Philae has already been a success, and who knowsmaybe it will “wake up” when its solar panels absorb enough sunlight to recharge the batteries.

[Note that the NavCam images we’ve seen so far are pretty good, but I have heard that Rosetta scientists have much better resolution color images that are embargoed and won’t be released for six months. I haven’t confirmed this fact yet, so if you have more up-to-date info, please let me know.]

Finally, I’ll end with some comments about what some people are referring to as #shirtstorm or #shirtgate. (For more info, see this Guardian article and this blog post and this one.) On the day of the worldwide live-stream broadcast last week, Matt Taylor, the Rosetta Project Scientist, wore a shirt covered with scantily clad women. I get the impression that Taylor is a cool guy and wants to get away from the scientist stereotypes people have, but this is completely inappropriate. (And he’s worn this shirt to work before. Apparently none of his colleagues told him to leave it at home.) But it’s not just the shirt; during the middle of his broadcast, Taylor referred to Rosetta as the “sexiest” mission. “She’s sexy, but I never said she was easy.”


We debated many aspects of this on astronomers’ official and unofficial social media, and for the most part, our community is very unhappy about this. You may say that we should focus on the science, and who cares about what this scientist wears or says when he’s excited about his mission’s success. But we have been working really hard to increase diversity in STEM fields and to achieve gender equality in science. Many aspects to working in the current scientific establishment are not particularly welcoming to women, and Matt Taylor’s shirt and poor choice of words are part of the problem. A few days later, Taylor made a heartfelt apology. As far as I know, ESA itself has not issued an official apology yet. The American Astronomical Society made a statement today (Wednesday) that “We wish to express our support for members of the community who rightly brought this issue to the fore, and we condemn the unreasonable attacks they experienced as a result, which caused deep distress in our community. We do appreciate the scientist’s sincere and unqualified apology.”

In any case, our focus is on the science and on this amazing scientific achievement. But Science is for everyone.

2 thoughts on “Comet Update! Rosetta’s Philae landed, but not as planned

  1. Pingback: Rosetta and the Time-scale of Science | Science Political

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