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The iss jettisoned 2.6 tons without a reentry vector? That seems crazy to me. There was no way to give it a Pacific ocean reentry delta v? Yes I know reaction

The iss jettisoned 2.6 tons without a reentry vector? That seems crazy to me. There was no way to give it a Pacific ocean reentry delta v? Yes I know reaction mass is precious in space, but, come on.

tekla 3y ago
With what?
- AtlasBarfed 3y ago
  Basically, if you're getting shipments (I understand this situation was caused by a lack of a shipment/rocket), and you might need to dump stuff, you'd send some "disposal rocket". But I get it, until Starship changes the game, every kilogram is precious. As for people discussing breakup uncertainty or inability to target the Pacific, I mean, the pacific ocean is 12,000 miles wide. I get that reentry isn't a perfect parabola/piece of cake with all the sci-fi hooks about "bouncing off the atmosphere". Anyway, they "jettisoned" it, which to me implies some sort of delta-v, some awareness of its vector/orbit, etc.
  - extraduder_ire 3y ago
    They did not have the pallet removed in time to put it on the departing JAXA HTV cargo spacecraft, which has some control over where it burns up. It would not fit on any craft operated by NASA. (I haven't checked if it would fit into a cygnus, but I doubt it) "Jettisoning" things from the ISS is actually pretty straightforward, you just drop or throw it out the back (aft) and its orbit should decay faster than your spacecraft. (IIRC, you really don't want to throw it straight down) JAXA has an airlock that takes great advantage of this for launching cubesats.
fred_is_fred 3y ago
Is it possible to actually aim a pallet of trash to a specific area? I assume it will break up into pieces on reentry with each piece being made of different materials and having a different profile, falling to different spots. I wonder how accurate something like this could reasonably be done.
- appplication 3y ago
  Beyond that, there’s a “skipping stone” effect of re-entry that makes it quite difficult to predict where a reentering object will land.
- itishappy 3y ago
  > It is notoriously difficult to predict where a piece of space junk will reenter the atmosphere. US Space Command precisely tracks tens of thousands of objects in Earth orbit, but the exact density of the upper atmosphere is still largely an unknown variable. Even a half-day before the reentry, US Space Command's estimate for when the battery pallet would fall to Earth had a window of uncertainty spanning six hours, enough time for the object to circle the planet four times.
- bell-cot 3y ago
  Yes...so long as you're willing to invest the needed delta-v. But in this case, they had run out of the latter, so...

The iss jettisoned 2.6 tons without a reentry vector? That seems crazy to me. There was no way to give it a Pacific ocean reentry delta v? Yes I know reaction mass is precious in space, but, come on.

tekla 3y ago

With what?

AtlasBarfed 3y ago
Basically, if you're getting shipments (I understand this situation was caused by a lack of a shipment/rocket), and you might need to dump stuff, you'd send some "disposal rocket". But I get it, until Starship changes the game, every kilogram is precious. As for people discussing breakup uncertainty or inability to target the Pacific, I mean, the pacific ocean is 12,000 miles wide. I get that reentry isn't a perfect parabola/piece of cake with all the sci-fi hooks about "bouncing off the atmosphere". Anyway, they "jettisoned" it, which to me implies some sort of delta-v, some awareness of its vector/orbit, etc.
- extraduder_ire 3y ago
  They did not have the pallet removed in time to put it on the departing JAXA HTV cargo spacecraft, which has some control over where it burns up. It would not fit on any craft operated by NASA. (I haven't checked if it would fit into a cygnus, but I doubt it) "Jettisoning" things from the ISS is actually pretty straightforward, you just drop or throw it out the back (aft) and its orbit should decay faster than your spacecraft. (IIRC, you really don't want to throw it straight down) JAXA has an airlock that takes great advantage of this for launching cubesats.

fred_is_fred 3y ago

Is it possible to actually aim a pallet of trash to a specific area? I assume it will break up into pieces on reentry with each piece being made of different materials and having a different profile, falling to different spots. I wonder how accurate something like this could reasonably be done.

appplication 3y ago
Beyond that, there’s a “skipping stone” effect of re-entry that makes it quite difficult to predict where a reentering object will land.
itishappy 3y ago
> It is notoriously difficult to predict where a piece of space junk will reenter the atmosphere. US Space Command precisely tracks tens of thousands of objects in Earth orbit, but the exact density of the upper atmosphere is still largely an unknown variable. Even a half-day before the reentry, US Space Command's estimate for when the battery pallet would fall to Earth had a window of uncertainty spanning six hours, enough time for the object to circle the planet four times.
bell-cot 3y ago
Yes...so long as you're willing to invest the needed delta-v. But in this case, they had run out of the latter, so...