Rosetta, Philae and Comet 67P/Churyumov-Gerasimenko.

[Specialist290]

Friendly moderator reminder: Let's keep the discussion on the technical details of the mission itself, and not on the cosmological implications, as that is technically off-topic and runs the risk of devolving into a discussion of pseudo-scientific theories which aren't allowed on this forum.

[GregA]

On the surface yes. Sunlight causes sublimation, this is very basic stuff. If what you were saying was right, deep impact shouldn't have detected any water at all.

Water is liberated when you heat Carbonacious condrite, which is composed of about 22% water. This also happens to match exactly what Deep impact found in the debris field.

There is no water ice on comets. The evidence is now overwhelming.

Edit: mod is this post ok?

[Kryten]

Water is liberated when you heat Carbonacious condrite, which is composed of about 22% water. This also happens to match exactly what Deep impact found in the debris field.

Distribution of water within the plume supports a separate layer below carbonaceous material, and your model fails to explain why there is any distinguishable distinction between comets and c-type asteroids.

[GregA]

Distribution of water within the plume supports a separate layer below carbonaceous material, and your model fails to explain why there is any distinguishable distinction between comets and c-type asteroids.

Comets are negatively electrically charged. As they move through the Suns electric field, a sputtering process carves material off of the surface. A standard asteroid spends no time in the outer solar system, as a result, it is electrically neutral with regards to the electrical field of the sun.

[Boomerang]

So whats the deal with Philae's feet/achors? The probe landed three times so did the anchors make an attempt to grab hold three times? Or where they one and done and if they couldn't grab hold the first time then that's it.. Im just curious as to how the rover bounced without the anchors being deployed.

There are two separate anchoring systems you might be confusing. There are the two harpoons mounted below the main body of Philae. The three landing legs have auger bits built into them (separate from the sampling drill). The idea was that the the thrust on top of the craft and/or the harpoons would provide a downward force so that the augers could anchor the landing legs to the comet, assuming the surface is soft enough for them to penetrate.

From what I've heard, the ESA is saying that the harpoons never fired and there were issues with the thruster. My guess would be that Philae bounced due to a lack of downward, anchoring force from either of those two devises, so the augers never had a chance to anchor to the surface. I would also imagine that the augers attempting to drill into the surface under such low gravity would have pushed the craft off the surface, if it weren't held to the surface by the harpoons/thruster. Again though, that's conjecture on my part.

Also, maybe we could stop feeding the 40-post account making utterly absurd claims about the validity of particular fields of science based on nothing more than blind-ass guessing?

Edited November 14, 2014 by Boomerang

[Camacha]

Those auger shaped ones that are on the lander? Yes. Yes, an auger shaped drill bit is incapable of of penetrating rock. If I were drilling in rock or concrete I would use either a masonry bit, with a hardened steel tip. Or alternatively I would use a core drill, with a diamond carbide tip.

I would never use an auger bit on rock.

The auger bit I use, I use to cut holes in ice when I go ice fishing.

Augers do not work on hard surfaces - they are intended to screw into, not drill. That are two different approaches. About any matter that is not solid or hard will accept an auger - dust, loose gravel, ice, all that jazz. And, don't forget, we did not know what comets were made of exactly - it is kind of the point of this whole mission - so we knew it was probably not going to be very hard stuff and prepared as best we could for whatever the rest could turn out to be.

This is science in its purest form - discovering things you did not know and going places you have not seen. That inherently means you have only a vague idea of what you are doing. If we knew what we were doing, it would not be called research - it would be engineering.

[Tommygun]

There is something I'm not clear about.

Do the augers have electric motors to rotate them or is it the downward force that makes them rotate?

Something like those old style mechanical screw drivers.

[Camacha]

Does anyone know what the future of Cherry-Gerry will be? It has been pushed inward by Jupiter, but I am not sure that will happen again.

Do the augers have electric motors to rotate them or is it the downward force that makes them rotate?

I am speculating, but I thought that the downward force was created by the augers. The give in the suspension system would pull the vehicle down and against the comet.

Edited November 14, 2014 by Camacha

[MajorThomas]

So where is the ksp Esa cooperation? Similar to ksp nasa.

I think there is/was a major opportunity lost in ksp viral marketing here. Asteroid redirect vs comet landing. Seems all the major game sub components were available for a quick win.

Just my opinion...

Still an opportunity... have ESA consult on adding COMETS to KSP. They can first appear way out there, near Jool or Eeloo. As they pass the orbit of say Duna they start sublimating, steaming, etc. Will need a new landing part, not quite a grappler, to facilitate landings for SCIENCE.

[Camacha]

Will need a new landing part, not quite a grappler, to facilitate landings for SCIENCE.

No landing parts will be supplied, since we still don´t really know what a suitable solution is

[Streetwind]

They should do the CONSERT test before it dies.

The CONSERT experiment is long finished - they switched that on the very first day. They used it, among other things, to estimate where Philae actually came to rest (as it bounced and left its preferred landing area).

There is something I'm not clear about.

Do the augers have electric motors to rotate them or is it the downward force that makes them rotate?

Something like those old style mechanical screw drivers.

They have electric motors, activated by pressure against the landing gear upon impact on the surface. They activated fine, which is why ESA originally thought the lander was anchored properly. But they likely did not actually screw in on initial impact because they did not get a grip on anything; they would have needed the pressure from the cold-gas thruster and the harpoon winches to be able to do so. However, neither of these two systems worked. So basically, the only anchoring system that worked was the one that was reliant on the other two that didn't work, and therefore Philae has no anchoring at all right now.

I am speculating, but I though that the downward force was created by the augers. The give in the suspension system would pull the vehicle down and against the comet.

They are screws. They cannot exert a downward force - that was the job of the cold-gas thruster and the harpoon winches. They can, however, get a secure grip on something, IF there is a downforce present when they attempt to do so.

To understand how this works, take a screw, a screwdriver and a wooden board and attempt to get said screw into the board with and without downforce.

[Camacha]

They are screws. They cannot exert a downward force - that was the job of the cold-gas thruster and the harpoon winches. They can, however, get a secure grip on something, IF there is a downforce present when they attempt to do so.

They were intended to exert a downward force. The harpoons and thruster were just intended to give the initial push - as someone stated correctly earlier that you need a little push to make augers catch and dig in. After that the screws were supposed to pull the craft towards the comet. Just check out the clip ESA made, you see the craft dip a little as the augers screw themselves into the comet and apparently load the landing gear this way.

Edited November 14, 2014 by Camacha

[Tommygun]

They have electric motors, activated by pressure against the landing gear upon impact on the surface. They activated fine, which is why ESA originally thought the lander was anchored properly. But they likely did not actually screw in on initial impact because they did not get a grip on anything; they would have needed the pressure from the cold-gas thruster and the harpoon winches to be able to do so. However, neither of these two systems worked. So basically, the only anchoring system that worked was the one that was reliant on the other two that didn't work, and therefore Philae has no anchoring at all right now.

They are screws. They cannot exert a downward force - that was the job of the cold-gas thruster and the harpoon winches. They can, however, get a secure grip on something, IF there is a downforce present when they attempt to do so.

To understand how this works, take a screw, a screwdriver and a wooden board and attempt to get said screw into the board with and without downforce.

They were intended to exert a downward force. The harpoons and thruster were just intended to give the initial push - as someone stated correctly earlier that you need a little push to make augers catch and dig in. After that the screws were supposed to pull the craft towards the comet. Just check out the clip ESA made, you see the craft dip a little as the augers screw themselves into the comet and apparently load the landing gear this way.

Edit: ninja'd same video.

Thanks, I came across this interesting video of the landing sequence. At least in the video there is a short delay between the impact and the screws going down. I thought the harpoons fired higher up too.

It also shows how some of the science instruments are deployed.

[AgentMOO]

The CONSERT experiment is long finished - they switched that on the very first day. They used it, among other things, to estimate where Philae actually came to rest (as it bounced and left its preferred landing area).

Citation?

It could have begun the moment they started receiving telemetry from Philae. However it would take several orbits of varying paths to complete the experiment. I could not find anywhere stating the length of Rosetta's orbit around 67P therefore I can not estimate how many orbits it's done since telemetry was received(if that's when the experiment started). I hope your correct, but again I ask for a citation.

[Streetwind]

"Exert a downward force" implies that the screws actively press the lander against the surface. That is not their job. They are there to keep the lander from leaving the surface again - after drilling in, the screws just sit there. They are not exerting any force at all, in any direction. They are simple mechanical devices that resist forces applied to them from elsewhere. This is achieved by friction (inhibiting any movement of the screw) and by material strength (of the locking pin that inhibits what rotation the screw would achieve after friction is overcome), but not by exertion of force.

Compare the thruster: it's only job was to actively press the lander against the surface. For its entire operation time, it was meant to actively exert a force, directed downwards, as necessary for the rest of the anchoring systems to catch on without destabilizing the lander. That's a very different operation principle.

This may seem like it's a matter of semantics - you're of course free to define for yourself how you want to use certain words. But you need to be careful that your conversation partner(s) are understanding the same thing that you're trying to communicate, and that's why sometimes, precision in language can be important. In science more so than in other areas, perhaps.

[Streetwind]

Citation?

Source 1: Wednesday's landing event livestream where the speakers on stage confirmed that CONSERT was already running.

Source 2: Thursday's press event where they presented results from the first CONSERT pass.

There's to be another press event today - maybe they'll present additional info I'm sure they'd like as many passes as they can get, but on the other hand they're on a very short energy budget right now, and have other experiments to run.

Hmmm... isn't the forum supposed to combine multiple posts in a row into one? Oh well...

Edited November 14, 2014 by Streetwind

[Camacha]

This may seem like it's a matter of semantics - you're of course free to define for yourself how you want to use certain words. But you need to be careful that your conversation partner(s) are understanding the same thing that you're trying to communicate, and that's why sometimes, precision in language can be important. In science more so than in other areas, perhaps.

I have been as clear as I could and intended to be. The screws, as is obvious in the clip, exert a downwards force on Philea. That you choose to interpret this as a continuous force is a case of PEBCAK, I am afraid

Note that the landing gear apparently was intended to apply continuous pressure, as it looks like the screws tension (the spring in) the legs a bit after landing. I guess that is a bit like what a spring washer does for a nut, though I would like to see it confirmed that it was intended to work that way, as it makes screwing the augers in a little big harder and will not really work in loose stuff.

[AgentMOO]

Source 1: Wednesday's landing event livestream where the speakers on stage confirmed that CONSERT was already running.

Source 2: Thursday's press event where they presented results from the first CONSERT pass.

There's to be another press event today - maybe they'll present additional info I'm sure they'd like as many passes as they can get, but on the other hand they're on a very short energy budget right now, and have other experiments to run.

Hmmm... isn't the forum supposed to combine multiple posts in a row into one? Oh well...

I watched the live-stream (all of it), and listened to to the lead investigator talk about the instrument. I don't remember him saying it was already active. As for Thursdays press update... I missed it, but I found some of it here. I'll watch it now.

[Kryten]

Comets are negatively electrically charged. As they move through the Suns electric field, a sputtering process carves material off of the surface. A standard asteroid spends no time in the outer solar system, as a result, it is electrically neutral with regards to the electrical field of the sun.

Philae and Rosetta have multiple instruments for measuring 67p's ionic environment and it's interaction with the sun; so did Deep Impact, so did the Halley armada. It would be obvious if something like this was happening. It is not.

[AgentMOO]

I watched the live-stream (all of it), and listened to to the lead investigator talk about the instrument. I don't remember him saying it was already active. As for Thursdays press update... I missed it, but I found some of it here. I'll watch it now.

Didn't take long to get to the good bit! So it is running. But by no means is it finished (multiple orbits). Looking forward to the next update. It's going to take some time to interpret that data too. Thanks Streetwind.

[Camacha]

It's going to take some time to interpret that data too.

These kinds of missions typically generate enough data to keep swathes of scientists occupied for years.

[Andersenman]

What would you suggest? Superglue?

That's perhaps not as crazy as it sounds. Would you mind sharing your thoughts?

[AgentMOO]

Google hangout with ESA @ 1300 GMT : https://plus.google.com/events/c78o050l93ub7cm4kcoltjnt424

Could the gyro be used to "walk" the lander around?

[Funeh]

Do we have composed panorama picture into one? With some higher resolution?

[Sky_walker]

Nice report on the BBC world service I caught on my commute from work explained that Philae has the capacity to reactivate if the sunlight should increase due to Cherry- Gerry moving closer to the sun. If it receives more solar energy it can warm itself up and reactivate it's systems.

Yes, that's true. There's some hope for that, but obviously it's preferred to keep on continuous operations instead of hoping for miracle. Next 24 hours will be critical. They'll try to get larger solar panel on Philae pointing towards sun, hopefully getting more energy, there's a chance they'll try some more risky stuff... we'll see... things change every hour.

Do we have composed panorama picture into one? With some higher resolution?

Resolution is limited to the resolution of cameras.

We won't have complete panorama unless lander rotates. Terrain features are too close to the cameras. As said above - they'll try to move Philae, so there is hope for a full panorama, but can't tell anything for sure (at the moment there are more important experiments going on than photographs)

Edited November 14, 2014 by Sky_walker