Spacewalking astronauts lose a piece of shield needed for International Space Station

[Just_Victor]

Source: LA Times
http://www.latimes.com/science/sciencenow/la-sci-sn-astronaut-floats-away-20170330-story.html

Spacewalking astronauts lost an important piece of cloth shielding needed for the International Space Station on Thursday when it floated away.

Astronaut Peggy Whitson immediately reported the mishap to Mission Control, which tracked the bundle as it drifted off. NASA said it would be monitored to make sure it doesn't come back and hit the station.


The shielding protects against micrometeorite debris. It was one of four pieces that Whitson and Shane Kimbrough were installing over the spot left by a relocated docking port. NASA spokesman Dan Huot said the three remaining shields were installed to cover the most vulnerable spots.

It was a disappointing turn of events in a record-setting spacewalk for Whitson, the world's oldest and most experienced spacewoman. It was the eighth spacewalk of her career, the most performed by a woman. There was frustration in her voice as she informed Mission Control.

Huot said it was not immediately clear who let the shield go or how it got away; it's supposed to be tethered to the station or spacewalker at all times.

Spacewalkers have lost objects before, but usually the items are small, like bolts. In 2008, an astronaut lost her entire tool kit during a spacewalk.

Each fabric shield weighs 18 pounds. When unfolded, it is about 2 inches thick and measures about 5 feet by 2 feet, according to NASA. The entire 250-mile-high space station is protected, in some fashion, against possible debris strikes.

more...

Ooops.  Joining the ranks of infamous crewmembers who have "Rossed" flight hardware.

[Cripplecreek]

That's a pretty good sized chunk.

Anybody care to calculate the force that would have it it hit you at 17,000 mph or so?

[Just_Victor]

That's a pretty good sized chunk.

Anybody care to calculate the force that would have it it hit you at 17,000 mph or so?

Fortunately it's in the same orbit as space station.  It's the stuff going the other direction that really causes damage.  The nature of orbital mechanics means that after a few orbits, it will likely bump back into the ISS.  If they can figure out when maybe they can arrange a space walk to go back out and grab it.

[EC]

That's a pretty good sized chunk.

Anybody care to calculate the force that would have it it hit you at 17,000 mph or so?

62,000 newtons or so. Basically it'd be like being underneath a falling tank.

[Cripplecreek]

Fortunately it's in the same orbit as space station.  It's the stuff going the other direction that really causes damage.  The nature of orbital mechanics means that after a few orbits, it will likely bump back into the ISS.  If they can figure out when maybe they can arrange a space walk to go back out and grab it.

Yeah, more of a danger to other things in low earth orbit.

Actually something similar could actually be used to clean up a lot of the small space junk. After all its made to absorb micrometeorite impacts. It might be kind of cool to snag it in a few years and see what its managed to collect.

[Elderberry]

You wouldn't think it would have drifted off very fast. They need to be able to "jet pack" over to it and fetch it back.

[r9etb]

You wouldn't think it would have drifted off very fast. They need to be able to "jet pack" over to it and fetch it back.

That thing was an absolute nightmare to maintain, apparently....

As for the cloth thingy, it's pretty light and its orbit will no doubt decay quite rapidly.

[Elderberry]

That thing was an absolute nightmare to maintain, apparently....

As for the cloth thingy, it's pretty light and its orbit will no doubt decay quite rapidly.

And they haven't redesigned and replaced it since 1984?

[Just_Victor]

And they haven't redesigned and replaced it since 1984?

The MMU was not useful for actual work in space.  Crewmembers need to be anchored to structure to be able to accomplish anything.  And they used what was learned from the MMU to design the SAFER.  Simplified aid for EVA rescue.  Same idea but stowed at the bottom of the backpack and deployable.

[geronl]

She is 57 and he is 50. If anyone is wondering.

[Elderberry]

  Crewmembers need to be anchored to structure to be able to accomplish anything. 

How far do they need to go? It's not "Rocket Science"? Or is it?

[Smokin Joe]

Yeah, more of a danger to other things in low earth orbit.

Actually something similar could actually be used to clean up a lot of the small space junk. After all its made to absorb micrometeorite impacts. It might be kind of cool to snag it in a few years and see what its managed to collect.

The orbit would change. I'd bet one of the whiz kids at JPL could get together with the folks who track space junk and figure out orbits for cleanup satellites that would decay as they pick up junk and plot target paths to 'sweep' low earth orbit...maybe even boost to a new orbit and make multiple passes and get rid of some of that crap--(maybe even recover it and sell it on eBay to help defray mission costs).

[Smokin Joe]

The MMU was not useful for actual work in space.  Crewmembers need to be anchored to structure to be able to accomplish anything.  And they used what was learned from the MMU to design the SAFER.  Simplified aid for EVA rescue.  Same idea but stowed at the bottom of the backpack and deployable.

Is that the thing that looked a lot like a spray wand that they used back when? You'd think they'd have something in case one of the astronauts got separated from the station.

[Cripplecreek]

The orbit would change. I'd bet one of the whiz kids at JPL could get together with the folks who track space junk and figure out orbits for cleanup satellites that would decay as they pick up junk and plot target paths to 'sweep' low earth orbit...maybe even boost to a new orbit and make multiple passes and get rid of some of that crap--(maybe even recover it and sell it on eBay to help defray mission costs).

I'm thinking something like this made out of energy absorbing material. Its got a lot of surface area exposed in all directions. Unless something hits it at a very shallow angle and passes through a single layer it should be fairly effective at capturing debris. In fact the steeper the angle of impact the better the chance of the debris embedding in the material and staying with it.

[Just_Victor]

Is that the thing that looked a lot like a spray wand that they used back when? You'd think they'd have something in case one of the astronauts got separated from the station.

That's exactly what the SAFER is.  EVA rescue.

Doesn't work for long, but it will stabilize a crewmember and allow them to get back to structure.

[InHeavenThereIsNoBeer]

I'd think it would be a lot safer to keep the oven on the inside of the ISS.  Maybe they're worried about fire?

[r9etb]

I'm thinking something like this made out of energy absorbing material. Its got a lot of surface area exposed in all directions. Unless something hits it at a very shallow angle and passes through a single layer it should be fairly effective at capturing debris. In fact the steeper the angle of impact the better the chance of the debris embedding in the material and staying with it.

Nah.  The problem with all of that debris is that basically every piece of it is in its very own orbit plane...  The orbital mechanics says that either you'd have to expend a tremendous amount of delta-V to do plane matching, or you're going to have to absorb high-speed collisions with that ball of stuff without generating any additional orbit debris.  By "high speed," I mean, faster than a speeding bullet. 

And to actually manage any given collision would take some rather finicky orbit determination and maneuver targeting. 

It's hard to imagine any fool-proof way to get at all of that debris....

[Smokin Joe]

Nah.  The problem with all of that debris is that basically every piece of it is in its very own orbit plane...  The orbital mechanics says that either you'd have to expend a tremendous amount of delta-V to do plane matching, or you're going to have to absorb high-speed collisions with that ball of stuff without generating any additional orbit debris.  By "high speed," I mean, faster than a speeding bullet. 

And to actually manage any given collision would take some rather finicky orbit determination and maneuver targeting. 

It's hard to imagine any fool-proof way to get at all of that debris....

Oh, you won't ever get it all, the idea is to clear a safe lane. Aerogel casing, ...lower mass, less energy to change orbit, and will stop a speeding bullet. The idea would not be so much to get rid of it all, but even as something which could shadow and protect critical craft it might be good.

[Cripplecreek]

Oh, you won't ever get it all, the idea is to clear a safe lane. Aerogel casing, ...lower mass, less energy to change orbit, and will stop a speeding bullet. The idea would not be so much to get rid of it all, but even as something which could shadow and protect critical craft it might be good.

Definitely not going to get it all but that's why a passive low cost means of getting what we can is best.

[r9etb]

Oh, you won't ever get it all, the idea is to clear a safe lane. Aerogel casing, ...lower mass, less energy to change orbit, and will stop a speeding bullet. The idea would not be so much to get rid of it all, but even as something which could shadow and protect critical craft it might be good.

No such thing as a "safe lane," either.  At best you could decrease the density of the debris some.  The thing is, the logistics of an object such as you describe would be daunting.  To have any reasonable (and still tiny) chance of intercepting debris it would need to be huge, and it would have to be reasonably dense and therefore heavy.  Good from the standpoint of staying in orbit, and absorbing impacts, but not so good from the standpoint of trying to launch/assemble something big enough to be useful.

Supposing it's up there: there's no point in trying to capture anything.  Small stuff might well vaporize on contact.  For bigger pieces, if something blew through the aerogel it might slow the debris down enough to lower the perigee of the debris into deeper atmosphere, and that would cause the debris to burn in sooner.

[Smokin Joe]

No such thing as a "safe lane," either.  At best you could decrease the density of the debris some.  The thing is, the logistics of an object such as you describe would be daunting.  To have any reasonable (and still tiny) chance of intercepting debris it would need to be huge, and it would have to be reasonably dense and therefore heavy.  Good from the standpoint of staying in orbit, and absorbing impacts, but not so good from the standpoint of trying to launch/assemble something big enough to be useful.

Supposing it's up there: there's no point in trying to capture anything.  Small stuff might well vaporize on contact.  For bigger pieces, if something blew through the aerogel it might slow the debris down enough to lower the perigee of the debris into deeper atmosphere, and that would cause the debris to burn in sooner.

It is still one of those problems that eventually may have to be addressed, and is interesting to try to find a viable solution to. Considering there are approx 19,000 bits rattling around up there, that's a lot, even if the space is vast and being in motion makes intentional 'collisions' to collect it difficult, and reduces the likelihood of unintentional ones.

Of course, if you don't want to get hit, Murphy kicks in...


https://visibleearth.nasa.gov/view.php?id=40173