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

[eRe4s3r]

Why would it crash? It made a touchdown at less than 1 m/s into low density material. Even with its 100 kg, there should be no damage.

Couldn't it have flipped over? With 3 legs only 1 touching ground in a bad angle would have been enough or not?

[Streetwind]

Yes. During the press conference they explained that Philae is oriented horizontally. It's a very rough terrain with large boulders - that's why people find it difficult to catch bearings based solely on the images.

Oh.

Then you might want to edit your press conference recap here, because you accidentally wrote "vertical" instead

That's what confused me.

[Sky_walker]

Oh.

Then you might want to edit your press conference recap here, because you accidentally wrote "vertical" instead

That's what confused me.

I'm sorry. I got it right in a brief, but wrong in the comment you quote. On a video from the press conference it's around 12:00-13:00. Speaker clearly says "vertical".

Edited November 13, 2014 by Sky_walker

[Sky_walker]

ESA just publish panorama on Flickr:

https://www.flickr.com/photos/europeanspaceagency/15756945086/

https://www.flickr.com/photos/europeanspaceagency/15756945166/

[m_robber]

Does anyone know if the "hop" maneuver is possible with only two legs connecting to the ground? I would have thought there would be a considerable risk of it turning over, at least if there is nothing to compensate.

[AndreyATGB]

Does anyone know if the "hop" maneuver is possible with only two legs connecting to the ground? I would have thought there would be a considerable risk of it turning over, at least if there is nothing to compensate.

That's likely one of the main reasons they haven't tried it yet. I'm not sure if it has stabilizers of sorts, but if it did they would take a while to arrest a rotation. Luckily it is relatively difficult to damage the probe with the kinds of velocities involved.

[JedTech]

My question is: Why do they keep calling the landing a success?

Harpoons: FAILED

Ice Screws: FAILED

reaction wheel: FAILED

Thruster:FAILED

Off Target ~0.6 miles

3 bounces

Landing orientation: sub-optimal

Landing Location: shady

Before the landing they kept talking about how delicate things were and if even one thing went wrong it would lead to a mission failure. It seems to me that everything went wrong and they are still calling it a success? Do they even have primary/secondary/tertiary mission goals?

[Kryten]

They're still able to use most of the science for the primary mission. The battery has enough charge to support the full primary mission duration with no input from the panels.

[Sky_walker]

Does anyone know if the "hop" maneuver is possible with only two legs connecting to the ground? I would have thought there would be a considerable risk of it turning over, at least if there is nothing to compensate.

It's not a question if it's possible. It's a question if it lands upright as it is now, or will it flip up side down? What landing spot will it end up on? (You can't see it from a cameras). That's also why they're so reluctant to attempt firing the harpoons - even if they anchor in the ground, team can't tell if force from firing them won't flip the lander.

Edited November 13, 2014 by Sky_walker

[Funeh]

Well I think its success becasue the module IS on the surface and is comunication is established and its the first landing on comet so... i think its a success, maybe not 100% but definitely a success.

[Sky_walker]

My question is: Why do they keep calling the landing a success?

Cause:

Landing: SUCCESS

Science data: GATHERED.

You must distinguish between mission goals and everything else. What you list as FAILED is IRRELEVANT as long as these two above are accomplished.

Harpoons: FAILED

Ice Screws: FAILED

reaction wheel: FAILED

Thruster:FAILED

Off Target ~0.6 miles

3 bounces

Landing orientation: sub-optimal

Landing Location: shady

Ice screws worked, but it's still not 100% sure whatever they anchored after a final touchdown or not (most likely not)

Reaction wheel did not fail, it was intentionally turned off, just as planned.

3 Bounces are actually beneficial to the mission, it's not an obstacle on it's own. Landing in imperfect position is an obstacle. Bounces are really good and add to the value of a mission. Philae actually is equipped to jump on it's own (again: imperfect landing currently is an obstacle in doing that, but it was always considered a tertiary goal)

Location will be determined, don't worry.

It seems to me that everything went wrong

It did not. Vast majority of stuff went VERY right.

Do they even have primary/secondary/tertiary mission goals?

Yea, they do. At a very least 80% of primary goals will end with a complete success, and part of secondary and tertiary goals will be completed as well. (Much depends on a power - these huge boulders are really not helping, but team does everything it can do achieve as much as possible!)

---

I'll allow myself to edit this post now, and leave this thing here:

Edited November 13, 2014 by Sky_walker

[hansen]

They're still able to use most of the science for the primary mission. The battery has enough charge to support the full primary mission duration with no input from the panels.

Yeah, but in my opinion this is also PR-blabla. I mean they get so much media attention which is not common for ESA (as it isn't for any other space agency today...). They want to keep up the good faith, the emotions etc. For me its pretty impressive that they did indeed land on the asteroid, in a kerbal-way at least. The probe will hopefully gather some data. But if I remember correctly the plan was to stay connected to the probe while the asteroid gets closer to the sun and emits particles from the core that can be gathered and analyzed. So after 10 years of waiting a mission that was planned to last for months risks to be over after 2 days, well, I wouldn't call that a success but tragic.

Honestly, there is a lot of hazardous stuff going on in space and a probe withstanding all those influences for 10 years is probably not an easy thing to build. But I don't really get how they could fail technically like this.

[Fingal]

Honestly, there is a lot of hazardous stuff going on in space and a probe withstanding all those influences for 10 years is probably not an easy thing to build. But I don't really get how they could fail technically like this.

It's a failure when your probe burns up in a place that's been visited many times because there's been confusion between imperial and metric measurements. It's not a failure when you land on a completely new object even though not everything worked perfectly.

By some definitions going around here Apollo 11 was a failure.

[Sky_walker]

Yeah, but in my opinion this is also PR-blabla.

It's not a PR-blabla, it's a scientific fact. Battery can support full mission, and majority of data from Philae instruments is already here on Earth.

For me its pretty impressive that they did indeed land on the asteroid,

It's not an asteroid.

The probe will hopefully gather some data.

It already did and it keeps on gathering them every minute.

But if I remember correctly the plan was to stay connected to the probe while the asteroid gets closer to the sun and emits particles from the core that can be gathered and analyzed.

That was never the plan. Philae was never build to last longer than few days, maybe a few weeks. But noone had a real hope for much more than that - assuming ideal landing.

So after 10 years of waiting a mission that was planned to last for months risks to be over after 2 days

Mission has 2 components: Orbiter and lander. Lander was to be alive only for as long as battery allows - anything above that was just a bonus. Orbiter is the main portion of a mission, it will accompany the comet all the way to it's Pe and back away from the sun.

But I don't really get how they could fail technically like this.

Again: IT DID NOT FAIL.

[JedTech]

Yea, they do. At a very least 80% of primary goals will end with a complete success, and part of secondary and tertiary goals will be completed as well.

Loss of any Primary objectives typically constitutes a failure of the mission.

Secondary objectives are "Expected"

Tertiary objectives are "Desired"

[hansen]

It boils down to the definition of success or failure. Thanks for the correction, its a comet, not an asteroid, why didn't ksp teach me about the difference? I see where you are going and it is a success that the probe has landed an can take samples from the surface. On the other hand its mentioned in the wiki-article that the probe is also meant to gather data over time (http://en.wikipedia.org/wiki/Rosetta_%28spacecraft%29#Philae_lander) which is what I remember to be one big goal of the mission. I know that rosetta is doing its observations anyway but why all the fuss about the "rescue" of philae from its probably early lack of functionality?

[Sky_walker]

Loss of any Primary objectives typically constitutes a failure of the mission.

We don't know if any loss occurred. And definition of mission failure is when critical objectives fail. They did not. Critical objectives were to land on a comet and receive scientific data from the lander - both succeeded.

It boils down to the definition of success or failure.

Yes, it does, and by that definition - it was a success.

On the other hand its mentioned in the wiki-article that the probe is also meant to gather data over time

Which is what Philae is doing as we speak.

I know that rosetta is doing its observations anyway but why all the fuss about the "rescue"

I didn't hear any fuss about the "rescue". All they want to do now is to get lander solar panels in more sunlight, and ensure that drilling can be done safely (they don't want to push the lander away from a surface) - which are two major matters being studied right now as far as problems go.

Edited November 13, 2014 by Sky_walker

[Sky_walker]

Quick update: MUPUS, the surface penetrator, will be deployed to 2/3 of it's length which should insert it into the surface of a comet. It was one of two experiments scientists were very hesitant about today, but recent data indicate it'll be safe to run it.

It'll run today, before midnight UTC.

Edited November 13, 2014 by Sky_walker

[Jeroen D Stout]

Quick update: MUPUS, the surface penetrator, will be deployed to 2/3 of it's length which should insert it into the surface of a comet. It was one of two experiments scientists were very hesitant about today, but recent data indicate it'll be safe to run it.

It'll run today, before midnight UTC.

Out of interest, where are you following this news?

[hansen]

Yes, basically every process happens over time, but I don't think they meant to gather data over 64 hours when a lot of interesting stuff will happen during the next months. As far as I follow the media coverage the extension of the lifespan is one primary objective. Aligning the solar panels, reorienting the probe, get out of the crater: thats not only about working experiments but guaranteeing the electric resources to keep the probe running for longer than battery capacity would allow.

[Sky_walker]

Yes, basically every process happens over time, but I don't think they meant to gather data over 64 hours when a lot of interesting stuff will happen during the next months.

Few cometary days was a realistic period of observations over time. As Kryten already pointed out - all primary goals can be run on battery alone - so it'll be possible to achieve without recharging (orbital period of a comet is 12.4 hours). The maximum predicted life span for Philae was 5 months, but it was unlikely to achieve that, even with a perfect landing. It's a comet, not a stable asteroid. Some hoped 4 months, but even that was speculated to be too optimistic.

As far as I follow the media coverage the extension of the lifespan is one primary objective.

I can't comment on that. Never read any of these media you speak of. According to the informations I have - extended mission was just that: extended. Never a primary goal.

Aligning the solar panels, reorienting the probe, get out of the crater: thats not only about working experiments but guaranteeing the electric resources to keep the probe running for longer than battery capacity would allow.

It's mostly about power. They want their lander to live for as long as it's possible But very rough terrain is not helping.

Experiments will run anyway (guys say that drilling - a last experiment that was threatened by imperfect lander orientation - will be attempted as the last one, so even if it would cause problems to the lander - it wouldn't affect the other experiments)

Edited November 13, 2014 by Sky_walker

[Technical Ben]

Who here has not landed up side down on the Mun and still called it a success?!

[AcidSludge]

Who here has not landed up side down on the Mun and still called it a success?!

Yeah! My very first probe crashed with about 30m/s or something and I rejoiced "Yeah, nearly there!". Full success!

[AppleDavidJeans]

Philae did NOT FAIL. Just you know, in a sub-optimal place, but still good enough for SCIENCE!

And ESA landing on a comet? BADASS

[Linear]

The whole point of the mission was to learn about Comets and the early Solar System. This will be done. Sure, slow battery charging may limit that - but we will learn. Primary success.

Considering a lot of the probes tech is 80's/early 90's era, it's a miracle it even landed. It's even more awesome that it bounced and survived. The solar panels may be in the shade a little, but there's a good chance it can be fixed somewhat.

The human race just landed a man-made object on a comet and people are arguing over primary objectives? Sometimes i question humanity. Be grateful it even got off the damn ground.