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

[PakledHostage]

As dorky as it is, I love the little details in these cartoons. Like the badge on Philae's backpack:

[BagelRabbit]

Another sequel of a fantastic cartoon series.

I'm going to have to make another Low-Budget Animation about Rosetta and Philae in KSP!

(For those who want to see my last one, which was about MAVEN: I'm shamelessly going to promote it. The video is here. It's not all that good, but it was a lot of fun to make )

[Hydrazine_Soup]

I'm going to have to make another Low-Budget Animation about Rosetta and Philae in KSP!

(For those who want to see my last one, which was about MAVEN: I'm shamelessly going to promote it. The video is here. It's not all that good, but it was a lot of fun to make )

I've lost the count how many times I've watched that video just to hear the kerbal singing KSP main theme lol

[lajoswinkler]

More talk on OSIRIS camera.

http://blogs.esa.int/rosetta/2014/11/06/into-the-shadows-of-comet-67pc-g/

The camera is much better than any camera any of us has probably ever seen, so now we can conclude that our typical high end DSLRs would suck when confronted with this task.

[VirtualCLD]

As dorky as it is, I love the little details in these cartoons. Like the badge on Philae's backpack:

http://i.imgur.com/NSSMErh.jpg

I can't wait for part two, when Philae realizes s/he is stranded there for the rest of its years like Spirit was! Of course Philea will orbit/float free when the comet breaks up, but when that will happen is anybody's guess.

[Dkmdlb]

The camera is much better than any camera any of us has probably ever seen, so now we can conclude that our typical high end DSLRs would suck when confronted with this task.

Eh, I don't think so. Rosetta was launched more than 10 years ago, and the technology inside is even older, and it's not like the camera spent those 10 years boxed up in someone's closet - it's been in space. I'm pretty sure a high-end DSLR would make better pictures.

[Camacha]

Eh, I don't think so. Rosetta was launched more than 10 years ago, and the technology inside is even older, and it's not like the camera spent those 10 years boxed up in someone's closet - it's been in space. I'm pretty sure a high-end DSLR would make better pictures.

I am not sure how a DSLR would fare after 10 years in space - electronics seem to have a tough time up there.

[VirtualCLD]

Eh, I don't think so. Rosetta was launched more than 10 years ago, and the technology inside is even older, and it's not like the camera spent those 10 years boxed up in someone's closet - it's been in space. I'm pretty sure a high-end DSLR would make better pictures.

Also, I think the camera is an IR camera, in which case it is a lot more expensive and complex than a DSLR camera. It probably is one of the best scientific IR cameras we've seen.

[goldenpeach]

Just a little question, the landing is expected to take place the 12 november, the confirmation of the landing(or the crash :\) is expected to arrive at 11:02 EST.

My question is: where can I know if it has landed or not as soon as possible?

Will there be a "live" stream(there is a lot of delay) or the landing? A live stream of the mission control room?

Just a internet page where the result will appear when the signal arrive?

[PakledHostage]

You need to look at the article that Lajos linked to. There are details in it about the camera's dynamic range. Despite being 10 years old, the article says that the Osiris camera is a 16-bit camera. I assume, by that, that they mean it uses a 16-bit ADC to acquire analog data from the camera's sensor. I'm also inferring that it is a "black and white" camera in so far as it only encodes data from one "colour" channel.

In comparison, my modern DSLR camera has a DIGIC 5+ image processor. That image processor was only developed in the last couple of years, but its ADC is only 14 bits per colour channel. A higher number of bits means you have more discrete values that the processor can "sense" from each color channel. Put another way, more bits means more "shades" of a given colour.

Note: I realise that most PCs encode colours in combinations of red, green and blue, encoded in three 8 bit fields, so can't display all the nuances of colours aquired using a 14 bit or 16-bit ADC.

[Streetwind]

Just a little question, the landing is expected to take place the 12 november, the confirmation of the landing(or the crash :\) is expected to arrive at 11:02 EST.

My question is: where can I know if it has landed or not as soon as possible?

Will there be a "live" stream(there is a lot of delay) or the landing? A live stream of the mission control room?

Just a internet page where the result will appear when the signal arrive?

Quickly typing the keywords "philae", "landing" and "livestream" into Google and pressing "I'm feeling lucky" turned up this page: http://blog.longnow.org/02014/11/03/rosetta-probe-landing-live-stream-breakfast-event/

Does this answer your question?

[Sky_walker]

The camera is much better than any camera any of us has probably ever seen, so now we can conclude that our typical high end DSLRs would suck when confronted with this task.

Define "better".

And typical camera would "suck" mostly because typical camera would die pretty much instantly in space. DSLRs are build to work on a surface of the earth, which makes task MUCH easier. But if you'd, say, sit inside of a manned spacecraft and take a photo through the cupola with a latest high-end DSLR - it'd work just fine, actually: it would give you better results than the OSIRIS.

[lajoswinkler]

Eh, I don't think so. Rosetta was launched more than 10 years ago, and the technology inside is even older, and it's not like the camera spent those 10 years boxed up in someone's closet - it's been in space. I'm pretty sure a high-end DSLR would make better pictures.

Read the article.

Define "better".

And typical camera would "suck" mostly because typical camera would die pretty much instantly in space. DSLRs are build to work on a surface of the earth, which makes task MUCH easier. But if you'd, say, sit inside of a manned spacecraft and take a photo through the cupola with a latest high-end DSLR - it'd work just fine, actually: it would give you better results than the OSIRIS.

Ignoring the ionizing radiation issue, which is true, our DSLRs can't capture that much shades. Confronted with the comet, they'd have trouble getting such details as OSIRIS which has one channel with all 16 bits dedicated to it. You'd have to resort to multiple exposures of the same scene (impossible with rotating comet and orbiting probe) to do a HDR process.

[Sky_walker]

You'd have to resort to multiple exposures of the same scene to do a HDR process.

Yes, that pretty much was the idea, combined with much higher angular resolution and brighter lens (OSIRIS has only an f/5.6 lens) it'd capture significantly higher amount of details. Dynamic range and though would still be a concern as you rightfully pointed out. Another edge that OSIRIS got is an option to change color filters at will. But sensor technology made an enormous progress since late '90s when OSIRIS was designed and in many ways modern cameras are much better than what Rosetta has onboard.

(impossible with rotating comet and orbiting probe)

Depends on an exposure time, distance to the nucleus, speed of a spacecraft in relation to the surface. OSIRIS got another limit in that regard that DSLRs don't - 3.4 second sensor readout time during which you cannot capture another photo, so it's not really suitable for making up-close multiple exposure shots.

[PakledHostage]

But if you'd, say, sit inside of a manned spacecraft and take a photo through the cupola with a latest high-end DSLR - it'd work just fine, actually: it would give you better results than the OSIRIS.

This is something of a silly argument because we're comparing apples and oranges, but Lajos' point is valid. The article talks about OSIRIS's dynamic range and its 16-bit ADC. In that regard, the OSIRIS camera is still a better camera than a modern high-end DSLR. As I mentioned in my post on the previous page, my camera's very recent technology DIGIC 5+ image processor only has a 14 bit ADC. Although my camera isn't a top of the line DSLR camera, the same DIGIC 5+ image processor is used in Canon's current crop of top of the line cameras like the 5D Mark III and 1D-X. My camera, like all DSLR cameras, struggles to correctly expose shots that contain a combination of very bright and very dark areas. You can compensate by adding filters and/or by stacking multiple shots to create a HDR image, but my read of the various references suggest that OSIRIS does a better job natively. It is this combination of OSIRIS's image processor's 16-bit resolution ADC and the dynamic range of the sensor that make it impressive for its age.

[Squelch]

Quickly typing the keywords "philae", "landing" and "livestream" into Google and pressing "I'm feeling lucky" turned up this page: http://blog.longnow.org/02014/11/03/rosetta-probe-landing-live-stream-breakfast-event/

Does this answer your question?

Here is the proposed timeline of the landing, and details on where the results are available straight from the horse's mouth

http://blogs.esa.int/rosetta/2014/11/07/landing-operations-the-most-critical-moments-you-should-watch-for/

http://blogs.esa.int/rosetta/2014/11/07/rosetta-and-philae-landing-timeline/

I've set time aside for this, and will be watching with baited breath. Will Philae be able to attach itself, or will it bounce?

Edited November 8, 2014 by Squelch

[Streetwind]

It all depends on whether or not it separates and comes down properly.

Philae is essentially a cubic octagonal strut with science instruments and OX-STAT panels taped to all sides. There is no RCS or control gyroscope... just a single flywheel for stability and a tiny cold-gas thruster on top that can fire for 10-15 seconds to press it straight down to the surface while the harpoons catch hold and the legs begin drilling themselves into place. And yes, they're "landing" this thing by practically throwing it at the comet from orbit... in precisely such a trajectory that at the time of intended touchdown, Philae will be moving along exactly the same vector as the surface of the comet rotating below it, effectively negating lateral velocity for a single instant. If it fails to grab on then, that was it. No second chances.

Even the thought of having to sit there as an involved scientist, after ten years of waiting, essentially watching a 7-hour coinflip in slow motion deciding the fate of the entire project, makes me weep. I bet they simulated this a thousand times though. Here's to you, team Philae - may the odds ever be in your favor!

[Camacha]

Even the thought of having to sit there as an involved scientist, after ten years of waiting, essentially watching a 7-hour coinflip in slow motion deciding the fate of the entire project, makes me weep. I bet they simulated this a thousand times though. Here's to you, team Philae - may the odds ever be in your favor!

The time you have to second guess your previous decisions seems the worst to me. Oh yeah guys, you know that thing we came up with 12 years ago? I am not too sure that is actually going to work.

[Squelch]

The expectation of a "regular" dirty snowball probably shaped the decisions back then. The revelation that the surface may be rocky must have the ice harpoon and anchor drill designers worried. It will be an incredible feat if they pull it off. Perhaps a lasso should have been included to snag a boulder too?

Velcro is very good too apparently...

Exciting times, even more so with the new technical challenges.

Edited November 10, 2014 by Squelch
Wrong video link

[Motokid600]

Honestly, what does everyone think Philae's chances are? 50/50? Either the anchors work or they don't I figure..

If the anchors don't work.. and Philae bounces... Wouldn't the probe make its way back to the surface anyway?t Or is that bounce enough to send it out and away?

Edited November 10, 2014 by Motokid600

[Kryten]

The escape velocity and landing speed figures I can find are the same (1m/s), so it would depend on the margins of error on both of those and how 'bouncy' the surface is. Without a way to correct it's attitude, it would make little difference either way.

[Streetwind]

Honestly, what does everyone think Philae's chances are? 50/50? Either the anchors work or they don't I figure..

If the anchors don't work.. and Philae bounces... Wouldn't the probe make its way back to the surface anyway?t Or is that bounce enough to send it out and away?

The bouncing off thing is more a worry in terms of how exactly Philae comes down. For instance, it may have too much lateral velocity (try landing on the Mun while sliding sideways and see what happens). Or it may not come down legs first, because something went wrong... after all, beyond a single axis flywheel, it has zero control authority, and it'll be coasting for seven hours prior to touchdown.

If Philae comes down legs first and slow enough to not roll over, then I'd wager the landing will be a success regardless of whether or not the harpoons and leg drills catch a reliable hold. The thruster designed to keep it pushed against the surface for ~15 seconds will make sure of that. Although the comet's gravity is tenuous, if all velocity is zeroed out it will be enough to keep Philae where it is... for now. But it may well get ejected later-on when the comet nears the sun and significantly increases its gas emissions. To hold on in that environment, the screws and harpoons are likely not optional.

If there is significant lateral velocity involved, the harpoons will be necessary to arrest that.

Also note that the screws and harpoons are also parts of multiple scientific experiments. It would be unfortunate if they failed to dig in.

[dharak1]

While on the topic of speed what is the orbital speed of the probe? What kind of orbit is it even in? How many Km above the surface is it?

[Streetwind]

While on the topic of speed what is the orbital speed of the probe? What kind of orbit is it even in? How many Km above the surface is it?

Short answer: It's complicated. Rosetta came as close as 8.x km to the surface (10km from center of gravity) and orbited there for a while, but it has since swung back further out to prepare for the landing.

Long answer: http://blogs.esa.int/rosetta/files/2014/11/Rosetta_s_trajectory_October_December.jpg

As far as I understood it:

Rosetta is being maneuvered a good distance away from the comet, then deorbited. Shortly after, Philae is released with a precisely calculated ejection force to put it exactly on the right trajectory. Then Rosetta does another burn to re-enter orbit, while Philae continues to fall towards the comet. Its trajectory will be such that its periapsis is a few centimeters above the surface of the landing site, and the landing site (on the rotating comet) will arrive under that periapsis point at the same time as Philae reaches it. Furthermore, at the instant of periapsis, the movement speed of the rotating surface below Philae will match the speed of Philae itself, temporarily canceling out all lateral velocity for just one brief moment (this is possible due to the very low gravity of the comet). That is when Philae will launch its harpoons and fire its little downpress thruster in an attempt to cling onto the comet.

The success of this maneuver is reliant on a.) making sure Philae's landing legs face the surface at the instant of periapsis and b.) succeeding in zeroing out lateral velocity at the instant of periapsis through carefully calibrating the trajectory. If either goes wrong, Philae will probably fail to hold on.

To make an analogy, they throw a velcro ball from orbit and hope it sticks

After the landing, Rosetta's orbit will be adjusted as necessary to serve as a relay station for Philae's data downlink to Earth. It will also cooperate with the lander in various co-op experiments, which will likely require orbital adjustments again.

Edited November 11, 2014 by Streetwind

[lajoswinkler]

If it bounces, it will enter a suborbital trajectory and later smack into one of the lobes of a rotating comet. Anyhow, it's gonna be interesting.