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

[vger]

I haven't been this excited about a probe since Sojourner.

[Sky_walker]

UPDATE:

http://blogs.esa.int/rosetta/2014/07/24/hints-of-features/

First surface features begin to appear!

ESA promised that they'll post one image a day from now on (and think that people complained on this forum just a week ago how ESA isn't open enough!)

For those interested: They will share it on a blog and twitter.

[edit]: BTW, it's 12 days till arrival

Edited July 25, 2014 by Sky_walker

[lajoswinkler]

I'm curious about the structural integrity of this lump.

http://blogs.esa.int/rosetta/2014/07/29/cometwatch-28-july/

[Scotius]

Apparently it holds well against centrifugal forces. It will be interesting to see what will happen closer to the Sun - when surface starts to boil off.

[Sky_walker]

Update time!

Here's a full text: http://blogs.esa.int/rosetta/2014/07/31/catching-up-with-the-comets-coma/ - latest photograph of a comet below.

Quick summary:

Scientists speculate that the shape of comet nucleus might come from uneven sublimation, exposure to sun, and original shape of the nucleus. White "neck" is where most of the sublimation occurs. Small, dark spot in top part of the neck on a photograph is most likely a shadow. Also on a top of smaller lob there's a small depression that was observed early on. This, along with the origin of bright, white spots on a surface of the comet are still a subject of debate.

[Streetwind]

Oooh, things are starting to get pretty detailed now.

[Aethon]

Ha! Finally the time zone difference worked in my favor and I got to ninja Sky_walker on a Rosetta story. He's probably upset he didn't get to go into Toshi station to pick up some power converters.

http://www.universetoday.com/113616/rosettas-comet-is-too-hot-for-complete-ice-surface-spacecraft-en-route-reveals/#more-113616

Luke?!... LUKE?!?!

Edited August 1, 2014 by Aethon

[Agamemnon]

new image, from 1000 km

http://blogs.esa.int/rosetta/2014/08/02/comet-at-1000-km/

[vger]

Dirty snowballs never looked so good.

[NovaSilisko]

Shrunken and sharpened a little.

[tygoo7]

Wow that is really detailed. When is Rosetta planned to land on it?

[NovaSilisko]

Wow that is really detailed. When is Rosetta planned to land on it?

Philae will land on it in November.

[tygoo7]

Philae will land on it in November.

Oh yeah, I forgot the spacecraft is Rosetta and the lander is Philae.

[lajoswinkler]

I thought of this earlier, but now I'm sure it reminds me of a winter boot.

[Sky_walker]

ESA today successfully completed 13 minutes burn approaching comet

Thruster temperature graph during burn:

Here's how comet looks like in a frame of NAVigation CAMera from mere 500km away:

NAVCAM is an APS sized CCD camera weighting 10 kg (including lens, lens-shade, heating, shielding and electronics) with a circular field of view equal to 5 degrees - that's comparable to APS-C Nikon*/Sony/Pentax DSLR shooting square photos with a 270mm lens. If you'd try to take a picture of a moon from surface of Earth with that focal length it'd look more-or-less like that:

That's considered wide angle by space-probe-standards .

NAVCAM resolution is 1 MPx (1024x1024px), and photos are taken with exposure time of 30seconds.

NAVCAM sensor doesn't have any color filter array so it takes black-and-white photos capturing a full spectrum (kind of similar to Leica Monochrome - which also has a CCD sensor withouth CFA).

Like all of the temperature-sensitive electronics - NAVCAM needs to be heated, in this case: It's between -25 and 0°C for operations and -50 to +50°C in a sleep mode - but optics also require heating, as glass changes it's optical and physical properties depending on a temperature, so NAVCAM lens needs to be constantly kept at a temperature between -60 and +60°C.

* Nikon designation for APS-C sensors is "DX". Canon DSLRs are using different crop than majority of other DSLRs - x1.6 instead of usual x1.5.

[hugix]

http://sci.esa.int/where_is_rosetta/

Awesome tool to visualize how Rosetta has been flying.

KSP really need a good tool to figure out gravity assists!

[Scotius]

Awesome indeed And precision of gravity assists is astounding.

[vger]

So now, random moron question. Does the comet just have a very weak coma or are they generally so dim compared to the nucleus that short exposure times easily filter it out?

[Karriz]

So now, random moron question. Does the comet just have a very weak coma or are they generally so dim compared to the nucleus that short exposure times easily filter it out?

The comet is probably not "erupting" yet, but it's getting closer to the sun and should start warming up, which should be quite a show to the probe.

[Zapness]

Never heard of this till today. Can someone fill me in on exactly what is happening? Looks awesome.

[Kryten]

Never heard of this till today. Can someone fill me in on exactly what is happening? Looks awesome.

These are images from an ESA comet-studying spacecraft called Rosetta, launched in 2004. It's now on the final approach to it's target comet, the snappily-named 67P Churyumov-Gerasimenko. It's only moving at a few tens of m/s and is only a few hundred km out; it's going to end up in it's planned mapping orbit within a few days. It's equipped with a small lander called Philae, which it is planned to dump on the comet in october-november after thoroughly mapping it.

So now, random moron question. Does the comet just have a very weak coma or are they generally so dim compared to the nucleus that short exposure times easily filter it out?

Both. This is an image of the coma from a few days ago;

note the nucleus is horribly overexposed, and it's covered with cosmic ray flashes due to the long exposure time. Even with that, it's only visible to maybe 50km out at either side, compared to tens of thousands for something like Halley.

Edited August 3, 2014 by Kryten

[Scotius]

I have another question For how long Rosetta will orbit the comet? Is it expected to survive perihelion, when Sun will boil surface of the comet spraying gases and dust everywhere?

[sgt_flyer]

Well, 67P/CG Perihelion is at 1.2429 AU - above earth's orbit. so the sun is not directly the problem for Rosetta the gas / dust tail might still be the main issue, but i think they'll manoeuver rosetta to avoid most of it after delivering the lander.

afterall, the coma gazes will be ejected mostly in the direction opposite to the sun - so it's predictable - and Philae will face much harsher conditions on the comet's surface though

the comet will reach Perihelion on august 13 2015 - and the mission is supposed to last until the end of 2015.

http://sci.esa.int/rosetta/2279-summary/

Edited August 3, 2014 by sgt_flyer

[Sky_walker]

note the nucleus is horribly overexposed, and it's covered with cosmic ray flashes due to the long exposure time. Even with that, it's only visible to maybe 50km out at either side, compared to tens of thousands for something like Halley.

Just to clarify - you can see barely a few cosmic ray flashes. These are short lines between the stars. These weird black-white gradients that you see in a middle are a combination of several pictures at different exposure, enhanced to show the shape of coma. It's so very faint that you wouldn't be able to see much in a single, solid picture - basically: middle would be huge bright spot, and you wouldn't have any idea how large comet is in a context of a whole picture (comet is that small white blob in a very middle).

I have another question For how long Rosetta will orbit the comet? Is it expected to survive perihelion, when Sun will boil surface of the comet spraying gases and dust everywhere?

Rosetta will follow comet as long as possible, even after the end of a mission it'll remain on an orbit around the comet, but in general schedule is as follows:

• In 3 days - orbital insertion burn, basically: arrival to the comet
  
• 2014 November - Philae lands on a surface
  
• 2015 August 13 - Comet perihelion
  
• 2015 December - Planned end of a mission, comet second nearest pass to the Earth
  

It's an extremely risky mission, because noone really knows how comet will behave near sun with spacecraft in such a proximity, and it's most unexpected shape might cause it to break up in half - which would be something unseen ever in a history by humans from so up close. Philae, the lander, will also perform very risky operation - first ever landing on a comet - trying to harpoon into it (yes, Philae will basically be an interstellar Captain Ahab) and then drill-down in a hope to stay steady, but... truth to be said: there's so many unknowns ahead that anything might happen.

That's why this whole thing is so interesting and exciting - this mission will perform numerous studies that never were done in a mankind history, including some very risky operations, boldly going when noone has ever gone before.

Edited August 3, 2014 by Sky_walker

[lajoswinkler]

Are they planning to put the probe into a polar orbit, so that it doesn't get sprayed so often?

I doubt Philae will survive the outgassing. I wonder how are they going to incorporate that into those cartoons.