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Couple questions (curious if anyone knows...) >> ... averaging 44 satellites per launch. How big are these things and how many can _actually_ be put up in a s

by kylek 8y ago

Couple questions (curious if anyone knows...) >> ... averaging 44 satellites per launch. How big are these things and how many can _actually_ be put up in a single launch? >> However, SpaceX intends to use this to their advantage by gradually replacing inactive satellites ... What happens to inactive satellites? Do they de-orbit themselves in safe locations? Or just stay as space junk?

ceejayoz 8y ago
They’ll be in low orbit, so they deorbit on their own in months/years due to atmospheric drag. The ISS requires regular boosting for this reason. 44 in one launch is very doable. They’ve done 64 in a launch before: https://www.google.com/amp/s/phys.org/news/2018-12-spacex-satellites.amp https://www.google.com/amp/s/phys.org/news/2018-12-spacex-sa...
- kylek 8y ago
  >> carrying 15 micro-satellites and 49 CubeSats IANASJ (I am not a space junkie) but this makes those ones sound unusually tiny and brings me back to the first question - are the Starlink birds similarly sized?
  - mrep 8y ago
    Most people on r/spacex are guesstimating that each falcon 9 will launch 25 satellites. 44 has been discounted because many think the falcon 9s fairing will be volume limited when launching that many satellites. That being said, no official number has been given out by spacex so this is all guesswork and this article did not cite a source for the "44 satellites per launch".
  - ceejayoz 7y ago
    SpaceX's two test Starlink satellites were of the "micro-satellite" size, which typically means sub-100kg: https://space.skyrocket.de/doc_sdat/microsat-2.htm https://space.skyrocket.de/doc_sdat/microsat-2.htm
- kohtatsu 8y ago
  Non-AMP: https://phys.org/news/2018-12-spacex-satellites.html https://phys.org/news/2018-12-spacex-satellites.html
SECProto 8y ago
> What happens to inactive satellites? Do they de-orbit themselves in safe locations? Or just stay as space junk? I believe they plan to use the last bit of their propellant to lower the perigee into the atmosphere, which will then naturally deorbit. They recently submitted documents to the FCC stating a change to materials to ensure everything burns up and wont impact the earth. [1] [1] https://www.nasaspaceflight.com/2019/03/spacex-higher-necessary-safety-starlink-constellation/ https://www.nasaspaceflight.com/2019/03/spacex-higher-necess...
- acchow 8y ago
  What do the compounds turn into when they burn up? There are metals too.
  - manicdee 8y ago
    Vapour in the upper atmosphere, though some materials with low ballistic coefficient might break free and drift down intact. There has been at least two cases of people being “hit” by insulation from reentered satellites and spacecraft. The objects were basically paper or cardboard in terms of density.
    - gpm 8y ago
      For the first 75 (or less) satellites there are some components that SpaceX thinks might survive re-entry. They've redesigned latter satellites such that they should burn up entirely. Nice article (the relevant portion is near the end, but if you're interested in this you might as well read the whole thing): https://www.nasaspaceflight.com/2019/03/spacex-higher-necessary-safety-starlink-constellation/ https://www.nasaspaceflight.com/2019/03/spacex-higher-necess... Raw source: https://licensing.fcc.gov/myibfs/download.do?attachment_key=1636825 https://licensing.fcc.gov/myibfs/download.do?attachment_key=...
manicdee 8y ago
Each Starlink satellite is likely to be in the range of 200–300 kg. Roughly the size of ~220L fridge when panels are folded. The plan for active decommissioning is to drop perigee into “atmosphere” but there are also plans for passively deorbiting satellites that fail while in higher orbits which would otherwise take Millenia to de orbit on their own.
martythemaniak 8y ago
They're only a few hundred pounds each. Falcon 9 can launch 50,000 lbs to LEO in expandable mode, so probably about 30,000 lbs when reusable, meaning they could launch close to 100 if they weighed 300lbs (there'd also be a deployment structure etc). 44 seems very doable, and they'd just burn up like any other satellite.

by kylek 8y ago

ceejayoz 8y ago

They’ll be in low orbit, so they deorbit on their own in months/years due to atmospheric drag. The ISS requires regular boosting for this reason. 44 in one launch is very doable. They’ve done 64 in a launch before: https://www.google.com/amp/s/phys.org/news/2018-12-spacex-satellites.amp https://www.google.com/amp/s/phys.org/news/2018-12-spacex-sa...

kylek 8y ago
>> carrying 15 micro-satellites and 49 CubeSats IANASJ (I am not a space junkie) but this makes those ones sound unusually tiny and brings me back to the first question - are the Starlink birds similarly sized?
- mrep 8y ago
  Most people on r/spacex are guesstimating that each falcon 9 will launch 25 satellites. 44 has been discounted because many think the falcon 9s fairing will be volume limited when launching that many satellites. That being said, no official number has been given out by spacex so this is all guesswork and this article did not cite a source for the "44 satellites per launch".
- ceejayoz 7y ago
  SpaceX's two test Starlink satellites were of the "micro-satellite" size, which typically means sub-100kg: https://space.skyrocket.de/doc_sdat/microsat-2.htm https://space.skyrocket.de/doc_sdat/microsat-2.htm
kohtatsu 8y ago
Non-AMP: https://phys.org/news/2018-12-spacex-satellites.html https://phys.org/news/2018-12-spacex-satellites.html

SECProto 8y ago

> What happens to inactive satellites? Do they de-orbit themselves in safe locations? Or just stay as space junk? I believe they plan to use the last bit of their propellant to lower the perigee into the atmosphere, which will then naturally deorbit. They recently submitted documents to the FCC stating a change to materials to ensure everything burns up and wont impact the earth. [1] [1] https://www.nasaspaceflight.com/2019/03/spacex-higher-necessary-safety-starlink-constellation/ https://www.nasaspaceflight.com/2019/03/spacex-higher-necess...

acchow 8y ago
What do the compounds turn into when they burn up? There are metals too.
- manicdee 8y ago
  Vapour in the upper atmosphere, though some materials with low ballistic coefficient might break free and drift down intact. There has been at least two cases of people being “hit” by insulation from reentered satellites and spacecraft. The objects were basically paper or cardboard in terms of density.
  - gpm 8y ago
    For the first 75 (or less) satellites there are some components that SpaceX thinks might survive re-entry. They've redesigned latter satellites such that they should burn up entirely. Nice article (the relevant portion is near the end, but if you're interested in this you might as well read the whole thing): https://www.nasaspaceflight.com/2019/03/spacex-higher-necessary-safety-starlink-constellation/ https://www.nasaspaceflight.com/2019/03/spacex-higher-necess... Raw source: https://licensing.fcc.gov/myibfs/download.do?attachment_key=1636825 https://licensing.fcc.gov/myibfs/download.do?attachment_key=...

manicdee 8y ago

Each Starlink satellite is likely to be in the range of 200–300 kg. Roughly the size of ~220L fridge when panels are folded. The plan for active decommissioning is to drop perigee into “atmosphere” but there are also plans for passively deorbiting satellites that fail while in higher orbits which would otherwise take Millenia to de orbit on their own.

martythemaniak 8y ago

They're only a few hundred pounds each. Falcon 9 can launch 50,000 lbs to LEO in expandable mode, so probably about 30,000 lbs when reusable, meaning they could launch close to 100 if they weighed 300lbs (there'd also be a deployment structure etc). 44 seems very doable, and they'd just burn up like any other satellite.