OSIRIS spots Philae drifting across the comet

How long is Rosetta going to orbit 67P? Indefinitely? We need Rosetta to be able to talk to Philae.

markcerqueira, you, sir, are hellbanned.

Even the moon has significant variations, http://en.wikipedia.org/wiki/File:Moon_gravity_acceleration_...

Yes, yes it would.

If you haven't already, do watch which orbit changes of Rosetta were needed to deploy the lander:

https://www.youtube.com/watch?v=4a3eY5siRRk

Must watch. The video was made by ESA.

A better analogy would be firing a bullet that has the ability to correct its course in flight, which is a far less daunting challenge.

I don't think "we" do take it for granted. It's just that those of us who don't can't think of much more to say than "Woah! on a comet?! wow." This is incomprehensibly amazing to me.

It is stunning.

Thinking about navigating in zero gravity became a lot easier for me when I realised that you can arbitrarily redefine “down” as whatever direction is convenient. Gravity assists and orbits, for example, are simply falling around a bend.

The pic you linked to was taken with a different camera (NAVCAM), the pictures in this article (OSIRIS) are much better, and clearly show the lander before and after touchdown along with marks where it first landed/bounced. What they don't show unfortunately is the final resting place, but that's a bit tricky because of comet rotation, comet shape (not a flat surface), and the parabolic trajectory of the lander.

What's the confusion about the time? Touchdown was at 15:34 UTC (NB UTC), I doubt anyone at ESA is confused about the time, though some of the commenters seem pretty confused on the ESA blog post this BBC article is based on:

http://blogs.esa.int/rosetta/2014/11/17/osiris-spots-philae-...

Philae is getting 1 hour of sunlight about every 12 hours. Right now, it's so cold that it has to warm up the batteries before charging them, and it's getting so little light that it can't even do that. It's possible that the rotation might change, but because the probe is surrounded on 3 sides, that's not likely to help. So we'll have to wait for the temperature to get higher and/or the sunlight to get a lot stronger.

It's estimated to take between 6 and 14 months but still not guaranteed to produce enough current to recharge the lander.

The legs were actually designed to dampen the impact and use that energy to drive ice screws into the comet: https://www.youtube.com/watch?v=-77-Z_DHTlY#t=1m40

Its landing was supposed to be softened by a thruster, which didn't work, and it was supposed to be held fast upon landing by harpoons, but they also failed. They presumably did use some shock absorbtion, but it was probably engineered under the assumption that at least some of the rest of the landing system would have worked.

Really too bad the harpoons failed. Why I wonder?

http://image.slidesharecdn.com/rosettamediabriefing16octbiel...

From the article it seems they assumed the comet surface would be a soft layer of dust, absorbing the impact

You can always reenact it in Kerbal Space Program ;)

That's about as subtle of a Star Wars reference as slicing someone's arm off with a light saber.

The drill probably not (no results for COSAC):

https://twitter.com/erichand/status/534413817040867328

They might have had some results from particles/gases in the atmosphere, not sure, nothing announced yet that I know of but they did say they were taking measurements. It might be weeks/months before they announce results.

I hear some of the instruments were owned by private research institutes rather than European taxpayers (who funded the vehicle) so for some areas may take a while to publish. Might have to wait for proper papers etc

The wifi reception is really shitty up there. Jest aside: More pixels, more bandwidth needed and if you think about how much bandwidth wifi systems were capable of achieving 10 years ago, they're probably at the edge of what they could use without resorting to cutting edge tech. You also have to transmit the data from the lander to the orbiter in a reasonably short timeframe since the lander is not always visible from the orbiter.

Maybe they have higher res pictures still on the orbiter that will download later when there's bandwith left.

Bear in mind it left Earth more than 10 years ago, I'd imagine they did send state of the art tech for the time.

It's because you need to send something that needs to work on very tight energy budgets, after 10 years of radiation exposure and extremely cold temperatures, and on tight bandwidth budgets. They're lifespans and conditions that are rarely considered when designing cutting edge tech.

If you only get one shot at setting up for a mission that won't start gathering data until 10 years later, you probably don't want to take a state of the art camera up there, you want to take a decent camera that you're pretty sure will work well after 10 years.

My guess would be latency, a higher quality camera feed would take longer to transmit.

Note that the final image in this mosaic (labeled 15:43) is not the final resting place for Philae. They still do not know exactly where it landed.

The only way to make it hit at a lower speed would be to have some sort of thruster on the bottom, which could have failed just as the one on the top did. Additional redundancy may have helped, but that would have reduced useful payload for other things, and since the top thruster is more versatile then you may as well go for redundant top thrusters rather than top and bottom.

The gravity and forces we're talking about are tiny. The craft hit the ground moving slower than 1 m/s and then bounced up over 1km before landing again. The forces involved with something moving that slowly and stopping are minuscule.

Think about dropping a golf ball onto concrete vs. sand. The harder surface will result in less loss of energy due to deformation. Thus, the ball bounces higher from the hard surface.

You're missing speeds and acceleration. Comet 67P is a very, very tiny world, with barely the slightest hint of gravity compared to Earth's surface. Consider that an ordinary walking speed is about 1 m/s. That's the escape velocity on 67P. A human could literally jump off the surface under their own power, or they could run into a low orbit (low altitude orbit velocities are 0.7x escape velocities, in general).

The speeds and accelerations that we're used to in the context of bouncing from the surface within the context of Earth are about ten thousand times greater than on comet 67P. The amount of force generated by Philae's collision with the comet's surface was very tiny, but it only takes a very tiny force to throw things long distances across the surface of the comet, due to the extremely low gravity (about 1mm/s^2).

Philae hit the comet at around 0.5m/s. 0.5m/s is a very small velocity. The probe is definitely much elastic than the comet, for start, the legs were designed to be elastic.

You can't tell that from this sequence of photos, since the orbiter was not viewing the descent from directly 'above' the landing site.

After releasing Philae, Rosetta performed a maneuver to establish a new orbit. There are some nice plots of these trajectories here:

http://www.bis-space.com/2014/11/12/13849/about-landing-on-a...

How did you come to this conclusion? The images shown may just be a matter of perspective and the lander still could've had a vertical descent