Rosetta's comet mission discussion thread

[marcus]

This YouTube describes the Rosetta mission


Here is the print version:
http://science.nasa.gov/science-news/science-at-nasa/2012/02feb_rosetta/

Rosetta is a European (ESA) mission with some Usa instruments on board. It carries a lander that will descend onto the comet surface, take pictures at the surface, and study the comet.

Rosetta will continue to orbit the comet for about 16 months, while the comet goes in close to the sun, evaporates some making a tail, and then swings out away from the sun again.

The lander's feet will have to drill into the comet material in order to be anchored firmly, because the gravity is very slight.

 

[marcus]

http://science.nasa.gov/science-news/science-at-nasa/2014/26aug_rosetta/

Landing is expected in mid-November.

The article says that 3 of the five sites are on the small lobe, and 2 on the large lobe (which surprised me).

So they have narrowed the choice down to a "short list".

I'd be interested to know if you understand what criteria were used in the selection, other than a level patch clear of obstacles.

 

[marcus]

This ESA page discusses each of the 5 sites separately. (scroll down)
http://www.esa.int/Our_Activities/Space_Science/Rosetta/Rosetta_Landing_site_search_narrows

It's interesting to learn about the pros and cons of each site.

 

[Dotini]

It's interesting to learn about the pros and cons of each site.

So very cool to be able to do this comet landing! I like site A. It's got the best view of these jets out-gassing from the waist nucleus.
http://www.universetoday.com/114334/new-mosaic-reveals-jets-blasting-from-rosettas-comet/

 

[Dotini]

An interesting study of ruggosities, lights and shadows.

http://www.esa.int/var/esa/storage/...481-1-eng-GB/Comet_on_26_September_NavCam.jpg

It will be even more interesting if and when this thing splits in two.

 

[Dotini]

They may well attempt the landing tomorrow, November 11.
http://rosetta.jpl.nasa.gov/

The landing looks almost impossibly difficult. IMO, they will need plenty of luck. But I wish them well.

 

[marcus]

I too! The landing time I see projected is for Wednesday 12 November.

"Rosetta will deploy Philae on November 12 at 12:35 AM PST. Confirmation of the landing will arrive at ground stations around 8:03 AM PST."

"Rosetta will deploy Philae on November 12 at 3:35 AM EST. Confirmation of the landing will arrive at ground stations around 11:03 AM EST.

"Rosetta will deploy Philae on 12 November at 08:35 UTC from a distance of 22.5 km. Confirmation of the landing will arrive at ground stations around 16:00 UTC"
the chosen landing site used to be called "Site J" and is now renamed Agilkia, after an island in the Nile.
http://sci.esa.int/rosetta/54870-farewell-j-hello-agilkia/

Here is a beautiful photograph of terrain on the comet:
http://blogs.esa.int/rosetta/2014/10/31/cometwatch-28-october/

 

[Greg Bernhardt]

The time has come!

Tomorrow, a Spacecraft Will Try to Land on a Comet for the First Time Ever
http://www.wired.com/2014/11/rosetta-philae-attempt-comet-landing/?mbid=social_fb

 

[Windadct]

Hello Everyone - 2 links for your enjoyment...

The EESA live stream... http://new.livestream.com/esa/cometlanding

and a neat audio recording of Rosetta - https://soundcloud.com/esaops/a-singing-comet

Enjoy!

 

[dipole]

Wow this is really exciting. This will be the first time (that I know of) humans will ever get a close-up view of the surface of an object of such low gravity.

 

[berkeman]

Here is a beautiful photograph of terrain on the comet:

Wow, pretty amazing! :-)

 

[mfb]

Wow this is really exciting. This will be the first time (that I know of) humans will ever get a close-up view of the surface of an object of such low gravity.

Itokawa is smaller, and we have samples on earth. I didn't see pictures directly taken from the surface, however.

It will be the first landing on comet.

Philae can’t steer

That doesn't sound good, but apparently they are confident Philae will make it. Well, the escape velocity is tiny.

 

[marcus]

Wow, pretty amazing! :)

Glad you liked it, Berkeman! That terrain was photographed just recently, on 28 October. In case anyone new to the thread hasn't seen it, here's the link:
http://blogs.esa.int/rosetta/2014/10/31/cometwatch-28-october/

About the landing site, formerly called "Site J" and now renamed after an island in the Nile river (Agilkia) that plays some role in the the Rosetta stone story, that landing site is on the very top of the duck's head if you imagine the comet as a toy plastic duck the large roundish lobe being the body and the smaller lobe being the head.
And interestingly, the way the comet is rotating it tumbles head over heels so the top of the head comes swinging by you, in the animation, and it looks like a question of precise timing to land on it.

 

[marcus]

Here is an animation that shows the rapidly tumbling comet and the orbit being traced out by the Rosetta spacecraft .
http://www.esa.int/spaceinvideos/Videos/2014/10/Rosetta_close_orbits_to_lander_deployment
Around 45 seconds into the clip they shift to slo-mo. And they show the lander's path as it is released and descends to the surface (at Site J aka Agilkia, the very top of the duck's head).
The landing occurs at around 54 seconds into the video.

After that, Rosetta makes some complicated orbit changes in order to be positioned well for communication with the lander and for serving as a relay.

Incidentally the lander will need to plant two small harpoons into the comet surface material in order to be anchored securely, given the comet's weak gravity.

 

[marcus]

Churyumov-Gerasimenko rotates once every 12.7 hours, or about twice in an Earth day.
The landing site (on top of the duck's head) is about as far out from the center of gravity as any part of the comet surface, so it would be rotating as fast or faster than any other part of the surface. (the axis of rotation corresponds to a minimal width). My guess is that its radial distance from the center of rotation is at least 2 km. So if my estimates are right the landing site if moving at least 4π kilometers in 12.7 hours. That is at least 1 kilometer/hour.

Well that's not too bad.

 

[DennisN]

ESA seem to be broadcasting live here:
(Quote: "Waiting for confirmation of landing. Expected at around 16:00 UTC")
http://rosetta.esa.int/

 

[OmCheeto]

Current UTC

And Philae made NASA's Picture of the Day.

She has her own twitter account, as does Rosetta.
Philae's last name is Lander. I did not know that.

Philae Lander @Philae2014 · 15m
.@ESA_Rosetta I will send you hundreds of postcards from #67P :) #CometLanding

ESA Rosetta Mission @ESA_Rosetta · 25m
.@Philae2014 :) My back is chilly now you’ve left, but I'm in a better position to watch you now. Send me a postcard! #CometLanding

Philae Lander @Philae2014 · 20m
.@ESA_Rosetta WOW! I feel like I’m floating! And #67P is closer and closer… #CometLanding

Philae Lander @Philae2014 · 24m
Finally! I’m stretching my legs after more than 10 years. Landing gear deployed! #CometLanding​

 

[Dotini]

I have heard from BBC radio that the important "down" thruster has failed.

A big question is the nature of the surface. It may turn out that pitons and jam nuts are more useful than harpoons and ice screws.

 

[enorbet]

In just a few minutes NasaTV and other sites will be posting Live Coverage. Someone already knows if it made it safely as it would have radio'd back almost an hour ago. Prior to that, during descent it the lander radio'd back to Rosetta and seemed to confirm that pictures will be sent. The last I read, it is still given 75% chance of success. I can hardly sit still.

 

[Greg Bernhardt]

Watching the announcement
http://new.livestream.com/esa/cometlanding

The main guy looks a bit stressed!

 

[Greg Bernhardt]

The feed just died! :L Does that mean it landed?

 

[Greg Bernhardt]

You can also follow the twitter hashtag which may be the first to announce and as I hear the video is delayed
https://twitter.com/hashtag/Rosetta?src=tren

 

[Greg Bernhardt]

Someone just said it touches down in 5 minutes!

 

[Greg Bernhardt]

THEY DID IT!

 

[Greg Bernhardt]

That was the most exciting video of watching a bunch of people stare at computer screens ever!

 

[marcus]

The live video of the control room was just showing people cheering and hugging each other
http://new.livestream.com/esa/cometlanding

"We are on the comet"

Harpoons have been fired (to anchor)

Now there are congratulatory statements by dignitaries and leaders

 

[jerromyjon]

Are the harpoons temporary until the legs drill?

 

[Borg]

Awesome! Looking forward to all of the pictures and data. :w

 

[mfb]

I now have to leave our #CometLanding party to go drive a rover on Mars. If that isn't proof we live in the future, I don't know what is.

Source

We finally got revenge for all those unannounced #cometlanding on Earth for past 4.5 billion years.

Source

Edit: "Hollywood is good, but Rosetta is better" - Livestream a minute ago.

 

[Dotini]

Source

On Sony Playstation 3, you can load GranTurismo 6 and drive a lunar rover.

 

[jerromyjon]

On Sony Playstation 3, you can load GranTurismo 6 and drive a lunar rover.

I just want to fly a predator drone... landers and rovers are just too "20th century" for me.

 

[enorbet]

Didn't die for me. It landed and "phoned Home". Whew! What a day!

 

[jerromyjon]

Congratulations! Well done for humanity!

 

[marcus]

Are the harpoons temporary until the legs drill?

What I think now is that all they have to anchor with is the two harpoons they have been talking about.

I don't have a clear picture of the mechanism. Also I heard a disconcerting bit of news announced from the Lander control room at Köln.

They had an unexpectedly soft landing, which seems good. But when they tried to fire the harpoons, either they did not fire, or they fired but did not take hold. The speaker said they were now studying the situation and considering whether to try again.

Does anybody have a diagram of the anchor mechanisms?

EDIT: I followed a link that Greg gave and found this:
https://twitter.com/hashtag/Rosetta?src=tren
If that link works it is a diagram that indicates that the screws in the footpads start drilling in as soon as there is contact.
Also there is a thruster on the top to give it a temporary downwards push.
And the two harpoons are under the belly of the thing. there seems to have been a problem with the harpoons. I have not heard anything about the drills or screws in the footpads, whether they were successful or not.

Do very much hope the lander gets a firm grip.

Looking forward to the chemistry analysis!

 

[marcus]

...
Edit: "Hollywood is good, but Rosetta is better" - Livestream a minute ago.

: ^D
Yes, I heard that on Livestream too. Was it the Swiss guy? ...wood good, ...etta bettah
sums it up deftly and succinctly.