Anyone watching the comet landing?

[Speakpigeon]

Indeed; ESA's initial reports of success were premature. Looks like it was a bouncing instead of a landing.

I told you: dirty trick!

But from whom!?
EB

 

[Speakpigeon]

An example of the importance of the distinction of mass vs weight... Nothing weighs anything in kilograms and it's important to be careful in a situation where you can be misunderstood.

67P has mass around 10¹³kg, and can be (very) roughly approximated as a sphere around 2km in diameter. That means that the acceleration due to gravity at the surface is approximately 0.00015m/s².

The lander weighs around 1000N on Earth but it only weighs around 0.015N on the comet. In kilogram-force, that's around 100kgf vs 1.5gf.

I understand that one idea is that 67P was at some point two bodies orbiting each other that later came together into one body. So perhaps the approximate shape is more like two spheres with a really small area of contact due to low gravity. So, if Philae had landed near this "middle" point, my guess is that gravity there would be nearly zero as there would be basically a broadly symmetrical distribution of matter around that small area, like being at the exact mass centre of the Earth. There Philae would weigh much less than 1g, say maybe 0.001g.
EB

 

[dx713]

I heard an ESA representative describe the comet's shape as "rubber duck like" and the intended landing point as "on top of the duck's head".

 

[dystopian]

Calling this a failure isn't anywhere close to the truth. Despite the lack of drilling, they're pulling in quite a lot of data. Plus, some of the pictures we've gotten are truly stunning:

https://www.flickr.com/photos/europeanspaceagency/sets/72157638315605535/ for more of 'em

 

[Derec]

Actually, it weighs around 100kg or 220lbs and has two systems to anchor itself to the comet;

Actually its mass is 100kg and it weighed 220 lbs on Earth. Given the weak gravity of the comet the probe is now nearly weightless.

harpoons that seem to have failed and footscrews that appear to have worked.

Good to know. Does that mean the probe has enough anchoring to drill for samples?

 

[Derec]

Anyone know why they opted for solar panels instead of a radioisotope generator? That would have avoided the danger of the lander landing in shade (as unfortunately happened) or that the solar panels would be damaged (being that they are necessarily on the outside and thus exposed).

 

[dystopian]

Anyone know why they opted for solar panels instead of a radioisotope generator? That would have avoided the danger of the lander landing in shade (as unfortunately happened) or that the solar panels would be damaged (being that they are necessarily on the outside and thus exposed).

Probably too big for the lander. There's also the risk of radiation leaks contaminating readings.

 

[beero1000]

An example of the importance of the distinction of mass vs weight... Nothing weighs anything in kilograms and it's important to be careful in a situation where you can be misunderstood.

67P has mass around 10¹³kg, and can be (very) roughly approximated as a sphere around 2km in diameter. That means that the acceleration due to gravity at the surface is approximately 0.00015m/s².

The lander weighs around 1000N on Earth but it only weighs around 0.015N on the comet. In kilogram-force, that's around 100kgf vs 1.5gf.

I understand that one idea is that 67P was at some point two bodies orbiting each other that later came together into one body. So perhaps the approximate shape is more like two spheres with a really small area of contact due to low gravity. So, if Philae had landed near this "middle" point, my guess is that gravity there would be nearly zero as there would be basically a broadly symmetrical distribution of matter around that small area, like being at the exact mass centre of the Earth. There Philae would weigh much less than 1g, say maybe 0.001g.
EB

Rubber ducky! Philae is on the top of the smaller lobe, probably a bit farther than 2km from the center of mass.

It's hard to say precisely what it weighs, regardless of where it landed, due to varying densities and whatnot (the comet is irregularly made of ice and rocks - not even close to uniformly distributed). As a first estimate, I would guess 1.5gf is pretty close, to within an order of magnitude or so. I'm sure the ESA has a much better model of gravity on the comet and I've seen news reports saying that it weighs about a gram.

 

[barbos]

Not a complete failure.

True, but for the most part it is. ESA does not have the same amount expertise NASA has with robots.
Well, Cassini-Huygens was huge but NASA has had nothing but constant stream of raging successes with robots lately.

 

[dystopian]

Some people have a very odd definition of 'failure'. It's not remotely a failure; quite the opposite: it is primarily a success.

In fact, it has now completed its primary mission; having drilled into the comet's surface and sending the information back. It's done what we sent it out there to do. The fact that it didn't have a perfect landing doesn't make it any less of a success.

 

[Angry Floof]

Some people have a very odd definition of 'failure'. It's not remotely a failure; quite the opposite: it is primarily a success.

In fact, it has now completed its primary mission; having drilled into the comet's surface and sending the information back. It's done what we sent it out there to do. The fact that it didn't have a perfect landing doesn't make it any less of a success.

My thoughts exactly. I didn't know that less than 100% success meant 0% success.

 

[thebeave]

I would very much call it a success, especially given that this is the first time anything like this has ever been attempted. A very long journey with lots of things that have to happen just right, or the craft doesn't even get to the comet in the first place. I think it exceeded expectations of the scientists and engineers involved. Very interesting to see a comet close up. I was expecting it to look more like a typical egg shaped meteor, with a few pock marks here and there. Had no idea there was so much interesting terrain and features to it.

Kinda shitty, though, that the SJWs had to turn a joyous technical achievement for scientist Dr. Matt Taylor into silly, tear-filled shaming episode just because the shirt he wore got a few uptight people offended.

http://www.theguardian.com/science/video/2014/nov/14/rosetta-scientist-matt-taylor-breaks-down-apology-offensive-shirt-video

 

[barbos]

In my book success is more than 90% of the mission, 50% is not a success and they don't have 50%.

Now, I don't know the details but I am surprised they have not had an option of simply dropping damn thing on asteroid - long legs with dampeners - no bouncing.

 

[barbos]

http://www.theguardian.com/science/video/2014/nov/14/rosetta-scientist-matt-taylor-breaks-down-apology-offensive-shirt-video

Someone should have told him that shirt was not at all appropriate for the moment. I am sure he has E=MC^2 shirt somewhere.

 

[fromderinside]

In my book success is more than 90% of the mission, 50% is not a success and they don't have 50%.

Now, I don't know the details but I am surprised they have not had an option of simply dropping damn thing on asteroid - long legs with dampeners - no bouncing.

Quibble here. It launched without blowing up. I successfully traversed the gap between earth and the comet. It landed, is on the comet. Its light gathering package deployed. It is getting some sunlight for recharging. It drilled into the comet. It took pictures both from above and from on the comet, That's pretty successful. So its decelerating thrusters failed. It still landed in tact. So its hooks failed to inject. Its on the comet. Successful.

 

[skepticalbip]

http://www.theguardian.com/science/video/2014/nov/14/rosetta-scientist-matt-taylor-breaks-down-apology-offensive-shirt-video

Someone should have told him that shirt was not at all appropriate for the moment. I am sure he has E=MC^2 shirt somewhere.

I think there would be people miffed at any message on a shirt. This is the one that apparently puckered some's butts:



I wonder how many butts would have puckered if he had worn this one:

 

[barbos]

In my book success is more than 90% of the mission, 50% is not a success and they don't have 50%.

Now, I don't know the details but I am surprised they have not had an option of simply dropping damn thing on asteroid - long legs with dampeners - no bouncing.

Quibble here. It launched without blowing up. I successfully traversed the gap between earth and the comet. It landed, is on the comet. Its light gathering package deployed. It is getting some sunlight for recharging. It drilled into the comet. It took pictures both from above and from on the comet, That's pretty successful. So its decelerating thrusters failed. It still landed in tact. So its hooks failed to inject. Its on the comet. Successful.

No

 

[dystopian]

In my book success is more than 90% of the mission, 50% is not a success and they don't have 50%.

They landed on a comet. They performed the mission they went there to perform (drill into the comet); they've done lots of other science on there with their other equipment too. The only things that failed are the landing mechanisms to make it a perfect landing, which hasn't prevented them from doing the science they came there to do. Yes, the landing resulted in problems with power due to solar orientation... however, they will get another shot once the comet is sufficiently rotated, and again... they did what they came there to do. That isn't "not even 50%", that's actually "100% but we didn't get the 110% we might've otherwise gotten."

Now, I don't know the details but I am surprised they have not had an option of simply dropping damn thing on asteroid - long legs with dampeners - no bouncing.

So you feel confident enough to criticize the project as a failure (even though it did everything it set out to do)... but don't even know enough about the project to understand why your option for the landing would never work?

 

[thebeave]

Someone should have told him that shirt was not at all appropriate for the moment. I am sure he has E=MC^2 shirt somewhere.

I think there would be people miffed at any message on a shirt. This is the one that apparently puckered some's butts:

View attachment 1545

I wonder how many butts would have puckered if he had worn this one:

View attachment 1547

The interesting part of this is that interest in buying his shirt has skyrocketed. Whoever designed that shirt is going to be rich quick.

 

[Angry Floof]

But it ended up sitting crooked with less sunlight than we wanted! FAIL