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

[lajoswinkler]

What we perceive =/= albedo

[Camacha]

What we perceive =/= albedo

The discussion is a little broader than just albedo, though you also really need to be a bit more specific if you want to use coal as a comparison. Common anthracite coal is actually pretty shiny.

[Aethon]

December 9 ...........................................................................January 8

The changing comet.

http://www.universetoday.com/118708/rosetta-sees-fascinating-changes-in-comet-67p/

Edited February 3, 2015 by Aethon

[Tommygun]

Are those really cracks or just shadows on little embankments left after the "sand" like material moved.

Or just the light angle changing enough to cast shadows across them now.

Edited February 3, 2015 by Tommygun

[monstah]

I think the boulders' shadows change too little to justify those disappearing cracks as different lighting conditions...

[Aethon]

Why comets are like deep fried ice cream.

http://www.nasa.gov/jpl/rosetta/why-comets-are-like-deep-fried-ice-cream/index.html#.VNzMQfnF-Yd

[michaelsteele3]

Why comets are like deep fried ice cream.

The solution:

[PB666]

Spaceflight is not very fast .

Try an earth reentry from a circumsolar retrograde orbit using a breaking ION drive. Whats the DV, 50000 m/s.

I think your ejecta would probably produce a nice gamma ray burst on shortly before your craft ionized in earths upper atmosphere.

[Tommygun]

Why comets are like deep fried ice cream.

http://www.nasa.gov/jpl/rosetta/why-comets-are-like-deep-fried-ice-cream/index.html#.VNzMQfnF-Yd

..........Yum, rotten eggs and ammonia flavored ice cream, mmmmmmmm............

[Aethon]

On February 14, Rosetta passed within 6km of Comet 67p.

http://www.universetoday.com/118981/the-first-images-are-in-from-rosettas-valentines-day-comet-flyby/

[lajoswinkler]

11 cm/px, Rosetta's shadow in the photo taken on February 14th.

http://www.esa.int/spaceinimages/Images/2015/02/14_February_close_flyby

[PakledHostage]

Does anyone know if they've narrowed down Philae's location? Are there any efforts planned to photograph the spots where it might have come to rest?

[Frida Space]

Does anyone know if they've narrowed down Philae's location? Are there any efforts planned to photograph the spots where it might have come to rest?

This is the latest data they have, as far as I know they had to decide between Rosetta's science and Philae and for the moment they have chosen to focus on the first. I was at a conference of Philae's drill's P.I. last week.

[Tommygun]

I found this on the ESA website and it was posted prior to Philae's landing.

Could activity on the comet's surface damage or destroy the lander?

Survival of the lander depends on a number of factors, such as power supply, temperature, or surface activity on the comet. For example, dust may cover the solar panels, preventing the battery from recharging. In any case, by March 2015, when the comet is closer to the Sun, it is likely that the lander will become too hot to operate.

I haven't been following Philae's status the last few months, so I don't know if ESA still has any real hope of hearing from it again or not.

Would this heat just prevent Philae from operating/reactivating or could it actually damage it?

I'm assuming that if it's getting this hot in March, the comet must be getting more sun light than before and Philae has not reactivated yet, that it's not looking good at all.

Well in the next few weeks at least since March has just started.

[Frida Space]

Would this heat just prevent Philae from operating/reactivating or could it actually damage it?

I'm assuming that if it's getting this hot in March, the comet must be getting more sun light than before and Philae has not reactivated yet, that it's not looking good at all.

Actually, the main problem is the cold, not the heat. Most of Philae's vital instruments will die below -210 (plus/minus 15) Kelvin. Surface temperatures can drop as low as 180 Kelvin, but in certain areas they reach 230 Kelvin. It all depends on how cold Philae's landing site is.

[lajoswinkler]

ESA has started to release NAVCAM images to the general public.

http://blogs.esa.int/rosetta/2015/03/06/introducing-the-navcam-image-browser/

[monstah]

...and are now getting ready to attempt communicating with Philae for the first time since touchdown(s):

http://blogs.esa.int/rosetta/2015/03/10/waiting-for-a-signal-from-philae

I shoudn't be, but I am SO OPTIMISTIC (or, at least, hyped). They'll begin attempting communication tomorrow, and try continually until the 20th.

Even if they don't listen to any response this time, they will try again when the stars are right.

[Frida Space]

Plus, good thing is Philae needs only a tiny amount of energy to start a one-way communication. That is, Rosetta can send Philae signals to change its orientation ect. in order to increase the amount of sunlight riceaved without Philae having to answer! Unfortunately, two-way communication will require a bit more energy.

[monstah]

I was thinking about this too: is there sufficient information on its current position, so as to change it to receive more light by dead reckoning?

[Kryten]

And exactly how is it supposed to do that?

[Streetwind]

It can raise and lower each of its three legs individually, and rotate 360 degrees on the vertical axis above the legs.

The solar panels are not uniformly distributed around its body; some sides are slightly larger than others, some regions have openings for instruments instead of panels etc. Getting a side with more panel area into the sun will increase the amount of energy available to the lander.

[KerikBalm]

Didn't they already try that?

Anyway, its battery is dead now, they can't do any of what you just said unless it receives enough light to re-activate...

And if it does re-activate, what you just described wouldn't be necessary.

[monstah]

Didn't they already try that?

Anyway, its battery is dead now, they can't do any of what you just said unless it receives enough light to re-activate...

And if it does re-activate, what you just described wouldn't be necessary.

Responding to Rosetta and doing any useful science, as well as staying awake during night time, takes a LOT more power than turning it just a bit to get a little bit more sun, and that little bit more sun may pay off in regard to the things above!

- - - Updated - - -

Besides, the batteries aren't dead, they're empty. Tho they may be actually dead (due to intense cold), they might still be able to recharge.

[Aethon]

The Deep Space Network Goldstone Dish is communicating with Rosetta now.

https://eyes.nasa.gov/dsn/dsn.html

[Streetwind]

Didn't they already try that?

They did that during the science collection last year. By now the orientation of the comet with respect to the sun might have changed significantly enough to warrant readjustment.