Asteroid samples escaping from jammed NASA spacecraft • Hacker News Board

Re: Asteroid samples escaping from jammed NASA spacecraft

#11

Post by yetihehe » Tue, Oct 27, 2020, 1:40 PM UTC

SamBorick wrote: post #8

rhn_mk1 wrote: post #7

Earlier quoted context omitted.

Thanks. That means there are two containers: the open one where the samples are now, and the sealed return capsule, where the contents will be transferred soon. In that light, this quote confuses me: > scientists won’t know how much the sample capsule holds until it’s back on Earth. They wanted to spin the spacecraft to measure the mass, but they can't risk losing more samples from an open container. But why can't th…

I recommend the scott manly video another commenter linked to for a more full explanation, but: The sample container that's currently jammed open is on the end of a long arm, while the sample return capsule is mounted on the body of the spacecraft. The only way to measure mass in free-fall is to spin the entire craft and measure where the center of rotation is compered to before the sample capture. The difference is…

Bright side - they have so much material, that weighting it is not really that much of a concern. They were hopeful to get maybe 50 grams of material, they got about 400g, but maybe 100g will be lost. They won't have exact number, but they will have more than expected anyway.

Re: Asteroid samples escaping from jammed NASA spacecraft

#12

Post by yetihehe » Tue, Oct 27, 2020, 1:41 PM UTC

7373737373 wrote: post #9

Is a second touchdown possible?

Second touchdown would be required if they didn't caught enough material first time. Since they got 10x too much, even if they lose half it's not a tragedy.

Re: Asteroid samples escaping from jammed NASA spacecraft

#13

Post by lolbot » Tue, Oct 27, 2020, 1:46 PM UTC

augusto-moura wrote: post #6

JshWright wrote: post #4

As with all "current events in space", Scott Manley has an excellent video on this. https://youtu.be/cmQfWuFbLNg

> Blowing a raspberry in the surface of the asteroid Classic Manley

From TFV:

"In order to be able to perform the landing they needed to update their software to give it optical navigation abilities ..."

Imagine being part of the team that had to do that, fast, chop-chop, or else their billion dollar space mission would fail miserably.

"Oh, you only need us to implement vision. Ok, no biggie."

Re: Asteroid samples escaping from jammed NASA spacecraft

#14

Post by codeulike » Tue, Oct 27, 2020, 1:50 PM UTC

Not really 'jammed', I think they mean 'jam packed'

edit: ok I see, it jammed because it was jam packed

Re: Asteroid samples escaping from jammed NASA spacecraft

#15

Post by peeters » Tue, Oct 27, 2020, 1:57 PM UTC

codeulike wrote: post #14

Not really 'jammed', I think they mean 'jam packed' edit: ok I see, it jammed because it was jam packed

It's jammed. There's a film that was supposed to close on the collector to keep the material inside, but because of debris it wasn't able to close, so material is escaping.

Re: Asteroid samples escaping from jammed NASA spacecraft

#16

Post by Jaruzel » Tue, Oct 27, 2020, 2:00 PM UTC

yetihehe wrote: post #11

SamBorick wrote: post #8

Earlier quoted context omitted.

I recommend the scott manly video another commenter linked to for a more full explanation, but: The sample container that's currently jammed open is on the end of a long arm, while the sample return capsule is mounted on the body of the spacecraft. The only way to measure mass in free-fall is to spin the entire craft and measure where the center of rotation is compered to before the sample capture. The difference is…

Bright side - they have so much material, that weighting it is not really that much of a concern. They were hopeful to get maybe 50 grams of material, they got about 400g, but maybe 100g will be lost. They won't have exact number, but they will have more than expected anyway.

Won't the extra weight require a change in earth re-entry fuel calculation etc. ? Without knowing the exact change in weight, they are going to be firing in the dark, as it were.

Re: Asteroid samples escaping from jammed NASA spacecraft

#17

Post by yetihehe » Tue, Oct 27, 2020, 2:08 PM UTC

Jaruzel wrote: post #16

yetihehe wrote: post #11

Earlier quoted context omitted.

Bright side - they have so much material, that weighting it is not really that much of a concern. They were hopeful to get maybe 50 grams of material, they got about 400g, but maybe 100g will be lost. They won't have exact number, but they will have more than expected anyway.

Won't the extra weight require a change in earth re-entry fuel calculation etc. ? Without knowing the exact change in weight, they are going to be firing in the dark, as it were.

I don't know that much, but I suppose they will do a burn and then some corrections. If mass difference is big enough to be detectable for reentry, it will be detectable when they are going back to earth.

Re: Asteroid samples escaping from jammed NASA spacecraft

#18

Post by rtkwe » Tue, Oct 27, 2020, 2:22 PM UTC

rhn_mk1 wrote: post #2

If the container is open, how are they planning to retrieve the sample without losing it on reentry?

There's a sample return vehicle that detaches with the sample canister inside of it. There's some concern with so much material floating around from the sample head no sealing properly that some bits might get in the way though. Scott Manley has a pretty good video about it as per usual when there's slightly vague space news. I've linked directly to where he's talking about the sample return portion of the mission.

https://youtu.be/cmQfWuFbLNg?t=443

Re: Asteroid samples escaping from jammed NASA spacecraft

#19

Post by rtkwe » Tue, Oct 27, 2020, 2:24 PM UTC

rhn_mk1 wrote: post #7

jimmydorry wrote: post #5

Earlier quoted context omitted.

> "Lauretta said there is nothing flight controllers can do to clear the obstructions and prevent more bits of Bennu from escaping, other than to get the samples into their return capsule as soon as possible." This, I'm guessing. Also, I found these parts interesting: >"Regardless of what’s on board, Osiris-Rex will still leave the vicinity of the asteroid in March — that’s the earliest possible departure given the r…

Thanks. That means there are two containers: the open one where the samples are now, and the sealed return capsule, where the contents will be transferred soon. In that light, this quote confuses me: > scientists won’t know how much the sample capsule holds until it’s back on Earth. They wanted to spin the spacecraft to measure the mass, but they can't risk losing more samples from an open container. But why can't th…

The sample return vehicle is much closer to the center of the vehicle so the change in the moment of inertia will be much smaller than if they had been able to extend the arm as planned. The change would be pretty slight and maybe on the edge of what is meaningfully measurable.

Re: Asteroid samples escaping from jammed NASA spacecraft

#20

Post by moron4hire » Tue, Oct 27, 2020, 2:25 PM UTC

JshWright wrote: post #4

As with all "current events in space", Scott Manley has an excellent video on this. https://youtu.be/cmQfWuFbLNg

"So they actually performed a software upgrade of on the spacecraft to give it optical navigation capabilities..."

God dammit. And here I have trouble getting software updates into a server I have full control over on Earth.