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Can't they aim a bit better while jettisoning stuff or is re-entry that chaotic? It looks like they are relying on stuff burning off as they go through atmosphe

Can't they aim a bit better while jettisoning stuff or is re-entry that chaotic? It looks like they are relying on stuff burning off as they go through atmosphere but I don't see how that can happen for a roundish chunk of metal. But I am no nasa engineer so who knows The earth surface is 70% water, surely you can aim for an ocean

hollerith 2y ago
"The pallet and the batteries were expected to burn up completely in Earth's atmosphere"
- shultays 2y ago
  My question was, is it not better to just "aim" for an ocean.
  - joelthelion 2y ago
    It might not be easy to aim anywhere if the object is expected to do multiple rotations around the earth before ending up anywhere. It would be good to have confirmation from a specialist.
    - hollerith 2y ago
      I agree: specifically, I think that controlling the point of impact is possible but requires equipment (rocket motors, a heat shield, navigation computers) which of courses costs money to get into orbit and can be used only once.
    - evilduck 2y ago
      It was from the ISS three years ago. It made around seventeen thousand orbits before reentry.
  - dghughes 2y ago
    Your question is vague. You're not dropping something off a cliff it's moving and 400km up and 25,000km/h. Any object coming from the ISS will be going 25,000 km/h. I don't think "aim" is the word since the Earth is moving rapidly beneath the object. There's no stationary point to aim at. Plus once the object of whatever shape in the atmosphere drag which causing friction to burn it up is not controllable. It would break apart and each object with different mass now has its own path and velocity. I'm amazed any of it works as well as if does now.
    - wredue 2y ago
      If we can “aim” at mars and generally hit it, then we can definitely “aim” our space junk not at densely populated areas. I really don’t think that the use of the word “aim” here necessitated this level of pedantry.
  - wcoenen 2y ago
    > is it not better to just "aim" for an ocean Anything released from the ISS will initially be in an orbit very similar to the ISS. That's because the initial difference in velocity between the object and the ISS will be measured in meters per second or less (which is small compared to the orbital velocity measured in kilometers per second). Then the orbit of the released object will start to slowly decay because of (at that altitude, a very small amount of) air resistance. The details of that depend on the shape, size and mass of the object. It can even depend on unexpected solar activity which can cause the Earth's atmosphere to puff up minutes[1]. The ISS counteracts this by periodically boosting its orbit. The longer the orbital decay takes, the more the uncertainty adds up. The fix to accurately "aim" an object, is to strap it to a rocket and perform a deorbit burn, to slow down from orbital velocity. This way the reentry process can be more reliably aimed at the middle of the Pacific or something like that. But that's expensive. [1] https://www.smithsonianmag.com/smart-news/solar-storm-knocks-40-spacex-satellites-out-of-orbit-180979566/ https://www.smithsonianmag.com/smart-news/solar-storm-knocks...
- HPsquared 2y ago
  Surprising, given another comment says it's made of Inconel.
taneliv 2y ago
From the article: > "NASA specialists use engineering models to estimate how objects heat up and break apart during atmospheric reentry," they added. "These models require detailed input parameters and are regularly updated when debris is found to have survived atmospheric reentry to the ground." So, yes, they do rely on stuff burning off as it goes, but with some understanding whether that should actually happen.
plg94 2y ago
Yes, for big parts where they know it will come down to the surface they try to aim for water, like they do with all the rocket boosters etc. However that's still risky, so given the choice between (fast descent and aim for ocean) and (slow descent to burn up in atmosphere) they almost always aim for the latter. Plus you can only "aim" something like a rocket booster or a satellite that can still generate a little thrust of its own. This case was more like throwing your heavy backpack from the top of a skyscraper – 3 years ago(!!). That's impossible to control. Plus it has been an emergency solution anyway, see https://www.space.com/space-station-jettisons-huge-space-junk-pallet https://www.space.com/space-station-jettisons-huge-space-jun...
itishappy 2y ago
Reentry is just that chaotic. Atmospheric drag is the main determining factor, and the atmosphere at high levels is thin, but not particularly flat, and difficult to measure. Add in the fact that orbital objects move at ridiculous speeds, and the errors quickly add up. > The batteries, nine in total, were released on 11 January 2021 and will undergo a natural reentry, which is now predicted for around 18:56 CET on 8 March +/- 0.4 days. Half a day of uncertainty! This was a day before reentry! https://www.esa.int/Space_Safety/Space_Debris/Reentry_of_International_Space_Station_ISS_batteries_into_Earth_s_atmosphere https://www.esa.int/Space_Safety/Space_Debris/Reentry_of_Int... The batteries from this incident are typically returned to Earth in a controlled manner via a cargo spacecraft, but a failed launch required an alternative plan. > The uncontrolled disposal of the pallet, however, was not part of the original plan. It was made necessary by a disrupted spacewalking schedule following the failed launch of a Soyuz rocket in 2018, which forced NASA astronaut Nick Hague and Roscosmos cosmonaut Alexey Ovchinin to make an emergency landing in the Kazakh steppe. This event led to a backlog in the disposal of such equipment. Normally, old batteries would be placed inside an HTV and jettisoned from the ISS to burn up on re-entry. https://gizmodo.com/massive-iss-cargo-pallet-reentry-earth-march-2024-1851317508 https://gizmodo.com/massive-iss-cargo-pallet-reentry-earth-m...
- shultays 2y ago
  Oh wow, I had no idea it took 3 years for things to land. Thanks

hollerith 2y ago

"The pallet and the batteries were expected to burn up completely in Earth's atmosphere"

shultays 2y ago
My question was, is it not better to just "aim" for an ocean.
- joelthelion 2y ago
  It might not be easy to aim anywhere if the object is expected to do multiple rotations around the earth before ending up anywhere. It would be good to have confirmation from a specialist.
  - hollerith 2y ago
    I agree: specifically, I think that controlling the point of impact is possible but requires equipment (rocket motors, a heat shield, navigation computers) which of courses costs money to get into orbit and can be used only once.
  - evilduck 2y ago
    It was from the ISS three years ago. It made around seventeen thousand orbits before reentry.
- dghughes 2y ago
  Your question is vague. You're not dropping something off a cliff it's moving and 400km up and 25,000km/h. Any object coming from the ISS will be going 25,000 km/h. I don't think "aim" is the word since the Earth is moving rapidly beneath the object. There's no stationary point to aim at. Plus once the object of whatever shape in the atmosphere drag which causing friction to burn it up is not controllable. It would break apart and each object with different mass now has its own path and velocity. I'm amazed any of it works as well as if does now.
  - wredue 2y ago
    If we can “aim” at mars and generally hit it, then we can definitely “aim” our space junk not at densely populated areas. I really don’t think that the use of the word “aim” here necessitated this level of pedantry.
- wcoenen 2y ago
  > is it not better to just "aim" for an ocean Anything released from the ISS will initially be in an orbit very similar to the ISS. That's because the initial difference in velocity between the object and the ISS will be measured in meters per second or less (which is small compared to the orbital velocity measured in kilometers per second). Then the orbit of the released object will start to slowly decay because of (at that altitude, a very small amount of) air resistance. The details of that depend on the shape, size and mass of the object. It can even depend on unexpected solar activity which can cause the Earth's atmosphere to puff up minutes[1]. The ISS counteracts this by periodically boosting its orbit. The longer the orbital decay takes, the more the uncertainty adds up. The fix to accurately "aim" an object, is to strap it to a rocket and perform a deorbit burn, to slow down from orbital velocity. This way the reentry process can be more reliably aimed at the middle of the Pacific or something like that. But that's expensive. [1] https://www.smithsonianmag.com/smart-news/solar-storm-knocks-40-spacex-satellites-out-of-orbit-180979566/ https://www.smithsonianmag.com/smart-news/solar-storm-knocks...
HPsquared 2y ago
Surprising, given another comment says it's made of Inconel.

taneliv 2y ago

From the article: > "NASA specialists use engineering models to estimate how objects heat up and break apart during atmospheric reentry," they added. "These models require detailed input parameters and are regularly updated when debris is found to have survived atmospheric reentry to the ground." So, yes, they do rely on stuff burning off as it goes, but with some understanding whether that should actually happen.

plg94 2y ago

Yes, for big parts where they know it will come down to the surface they try to aim for water, like they do with all the rocket boosters etc. However that's still risky, so given the choice between (fast descent and aim for ocean) and (slow descent to burn up in atmosphere) they almost always aim for the latter. Plus you can only "aim" something like a rocket booster or a satellite that can still generate a little thrust of its own. This case was more like throwing your heavy backpack from the top of a skyscraper – 3 years ago(!!). That's impossible to control. Plus it has been an emergency solution anyway, see https://www.space.com/space-station-jettisons-huge-space-junk-pallet https://www.space.com/space-station-jettisons-huge-space-jun...

itishappy 2y ago

Reentry is just that chaotic. Atmospheric drag is the main determining factor, and the atmosphere at high levels is thin, but not particularly flat, and difficult to measure. Add in the fact that orbital objects move at ridiculous speeds, and the errors quickly add up. > The batteries, nine in total, were released on 11 January 2021 and will undergo a natural reentry, which is now predicted for around 18:56 CET on 8 March +/- 0.4 days. Half a day of uncertainty! This was a day before reentry! https://www.esa.int/Space_Safety/Space_Debris/Reentry_of_International_Space_Station_ISS_batteries_into_Earth_s_atmosphere https://www.esa.int/Space_Safety/Space_Debris/Reentry_of_Int... The batteries from this incident are typically returned to Earth in a controlled manner via a cargo spacecraft, but a failed launch required an alternative plan. > The uncontrolled disposal of the pallet, however, was not part of the original plan. It was made necessary by a disrupted spacewalking schedule following the failed launch of a Soyuz rocket in 2018, which forced NASA astronaut Nick Hague and Roscosmos cosmonaut Alexey Ovchinin to make an emergency landing in the Kazakh steppe. This event led to a backlog in the disposal of such equipment. Normally, old batteries would be placed inside an HTV and jettisoned from the ISS to burn up on re-entry. https://gizmodo.com/massive-iss-cargo-pallet-reentry-earth-march-2024-1851317508 https://gizmodo.com/massive-iss-cargo-pallet-reentry-earth-m...

shultays 2y ago
Oh wow, I had no idea it took 3 years for things to land. Thanks