ISS to throw "piano" overboard

MeteorWayne · Nov 20, 2006

James Oberg NBC News space analyst This week, a spacewalking cosmonaut will tee up a golf ball just outside the international space station and let loose with a publicity-generating drive – a shot that has already generated a debate over the dangers posed by orbital debris. But if you think one foam-rubber “golf ball” is a cause for concern, how about a concert grand piano? That’s roughly the size and weight of the piece of equipment NASA plans to throw over the space station’s side next spring — if they can figure out which way it’ll go once it’s cast away. link <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

pioneer0333 · Nov 20, 2006

Will they try to record re-entry? <div class="Discussion_UserSignature"> </div>

CalliArcale · Nov 20, 2006

Hey, they're finally gonna do the golf shot? Cool! Jettisoning the unit does seem like the best solution in the circumstances. Bringing it back wouldn't be easy. Interesting challenge. <div class="Discussion_UserSignature"> "People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff." -- The Tenth Doctor, "Blink" </div>

MeteorWayne · Nov 20, 2006

They haven't even figured out which direction to shove it. Because it is so much denser than the ISS, it's orbit will decay much more slowly, which means there's a danger of it hitting the station. It's a complicated calculation, and you can't screw up. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

erioladastra · Nov 20, 2006

"They haven't even figured out which direction to shove it. Because it is so much denser than the ISS, it's orbit will decay much more slowly, which means there's a danger of it hitting the station. It's a complicated calculation, and you can't screw up. " I am not sure where you got your information but we figured out a loooong time ago which way to throw it. Since the ballistic number is nearly the same as ISS, the safest way is retrograde and that is what will be done. Posigrade and you could have problems in the future if you have to do a reboost for debris avoidance and you only delay the intersection. ISS will have a minimum of 2.5 days to reboost to get out of the way, and likely 5-7 depending on the jettison speed the astronaut gets. It will be done from the end of the arm. It will probably be done during 13A but during the stage is still an option (and a back up option should it not get done during 13A). The attachment point to the ISS is degrading so it is not ceritifed beyond Aug 2007 and must be removed prior to P6 relocation anyway. it is too dangerous to bring back and not worht it.

erioladastra · Nov 20, 2006

"Will they try to record re-entry? " Doubt it - but we will video the jettison.

vogon13 · Nov 20, 2006

Could the shuttle carry it down to a lower altitude (lower than the ISS is ever allowed to drift), and then jettison it prior to closing the payload doors? <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

MeteorWayne · Nov 21, 2006

e, All I knew was what was in the Oberg article. It didn't mention anything about the reboost. Glad this has been thought out well, and decisions made. That's why we appreciate you guys here, so we can get the facts instead of media hype and speculation! Thanx MW <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

erioladastra · Nov 21, 2006

"Could the shuttle carry it down to a lower altitude (lower than the ISS is ever allowed to drift), and then jettison it prior to closing the payload doors? " That was discussed - but the biggest problem with that is that the fixture you would grab it by the arm is what is failing so your risk it breaking free before then. You also have the problem that the SSRM is required for late inspection of the tiles after undock and before reentry so the arm is not free.

erioladastra · Nov 21, 2006

"All I knew was what was in the Oberg article. " yeah, sorry, I read his article after the post and I should have question where he got his info <img src="/images/icons/smile.gif" /> (and I didn't mean it to sound snappy if it did). Don't get me wrong - it is not trivial and a lot of work ahead but not as dire as Oberg indicates.

nexium · Nov 21, 2006

Near Earth Orbits that come close to Earth more than a few times per century require considerable energy to establish from LEO or GEO, so we need to designated several. Others are likely to be perturbed into re=entry orbits, so this may be a good idea, even if it is costly. The value as salvage is doubtful as recycle and reuse on Earth is typically not profitable without subsidies. Neil

MeteorWayne · Nov 21, 2006

steve, he's been here for two years. Where've you been? Never mind, I know the answer to that. We've been dishing out questions to he and shuttle_guy and getting great answers for quite a while. Not to slight any of the others in the space program, these two just seem to help us the quickest. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

MeteorWayne · Nov 21, 2006

"That & lacking much informative contribution." Now that's an ad homenim. Back to the subject at hand. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

erioladastra · Nov 21, 2006

stevehw33, Well I think there are two populations here. Stuff being jettisoned from ISS is destined for re-entry. In fact, it can't be jettisoned if it doesn't because the danger and cost of manpower/reboost fuel is too much. Hence the initial concern over the original golf ball to be hit (now a lighter one is being used). While putting it in a parking orbit is noble the cost is prohibitive. The debris that hit the orbiter was likely from a rocket or satellite that broke up, either intentially or not. But yes, it is a very dangerous issue that needs more attention.

erioladastra · Nov 21, 2006

Hey guys, Stevehw33 was trying to be nice, lets not make a big deal of who said what or why. Otherwise, the S/N will go down so much that those of us who are trying to help here will go elsewhere. <img src="/images/icons/smile.gif" />

tony873004 · Nov 22, 2006

Could they just attach a parachute or other drag-increasing attachment to it, ensuring that it will decay faster than ISS?

erioladastra · Nov 22, 2006

"Could they just attach a parachute or other drag-increasing attachment to it, ensuring that it will decay faster than ISS? " Yes we discussed that. But then you increase the risk of the parachute snagging. That would suck - throw it away, have it snag on your foot restraint, bounce off in some direction, the cord break and...well bad day. We also looked into venting some of the ammonia from it but that is dangerous too (e.g., you get it on your suit, go back into the airlock, repress, take off your helmet and die).

tony873004 · Nov 22, 2006

How about a remotely-deployed parachute? Wait until the thing was a few km away from the ISS, press a button and deploy a simple parachute. Even if the parachute didn't deploy smoothly, it would still be like driving a car with a bedsheet hanging out the trunk, flapping in the wind. That should bring it down pretty quick. I imagine that even if this thing were tossed away in any random direction that the odds that it would ever impact the ISS would be extremely slim. Does anyone know what the odds are? I'm not suggesting we do that. I'm only curious. There's gotta be a point in which the odds are so low that the treat can be considered ignorable.

MeteorWayne · Nov 22, 2006

I don't think there's time to develop, test, build, and deploy such a parachute system before this thing has to be dumped, in less than a few months. Random directions are not good, as even a one in a thousand chance of impact would utterly destroy the space station if it happened, and likely destroy the usefulness of low earth orbit for centuries. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

cretdob · Nov 23, 2006

Why not have a rummage sale instead?

erioladastra · Nov 24, 2006

"I imagine that even if this thing were tossed away in any random direction that the odds that it would ever impact the ISS would be extremely slim. Does anyone know what the odds are? I'm not suggesting we do that. I'm only curious. There's gotta be a point in which the odds are so low that the treat can be considered ignorable. " Well it depends on the Ballistic Number (BN) of the EAS. If it is the exact same as ISS, then the probability is 100%. However, depending on how it tumbles and how full it is it may be just above or just below then it is lower but still significant. And ISS is a big articulating vehicle (i.e., its BN is changing). Makes it very hard to predict at this point. But we plan for the worst case (e.g., the astronaut can't get a good push on it or the angle is bad).

MeteorWayne · Nov 24, 2006

Good thing the golf ball was only three grams, since he shanked it! <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

SpaceKiwi · Nov 24, 2006

This is likely to be considered a stupid question by the many experts resident here, so I apologise in advance for that, but why is the item being thrown in a retrograde direction? If the object of the exercise is to have it burn up in the atmosphere ASAP, why is it not thrown in the nadir direction? I'm obviously missing something here, can someone please explain the reasoning for going in a direction which (admitedly in worst-case scenario) has the mass come past ISS again? <div class="Discussion_UserSignature"> Who is this superhero? Henry, the mild-mannered janitor ... could be!-------------------------------------------------------------------------------------------Bring Back The Black! </div>

tony873004 · Nov 25, 2006

I worked out the math in an earlier thread when an astronaut lost a spatula while on a spacewalk. Here's a link to the thread. It shows you why retrograde is best: http://orbitsimulator.com/BA/spatula.htm

erioladastra · Nov 26, 2006

"This is likely to be considered a stupid question by the many experts resident here, so I apologise in advance for that, but why is the item being thrown in a retrograde direction? If the object of the exercise is to have it burn up in the atmosphere ASAP, why is it not thrown in the nadir direction? " No it is not a stupid question. Basically the answer is "orbital mechanics are funky" <img src="/images/icons/smile.gif" />. This has been worked out and Tony has a good link to try to explain.

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