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Does SpaceX have any concerns about the Kessler Syndrome [0] or any plans to mitigate it? [0] https://en.wikipedia.org/wiki/Kessler_syndrome https://en.wikiped

Does SpaceX have any concerns about the Kessler Syndrome [0] or any plans to mitigate it? [0] https://en.wikipedia.org/wiki/Kessler_syndrome https://en.wikipedia.org/wiki/Kessler_syndrome

walrus01 10y ago
Things in very low earth orbit will re-enter on their own, if left unattended, from atmospheric drag.... At orbits of 450-600 km or less the lifetime of any satellite is very much finite. Satellites in much higher (like the MEO O3b satellites) will not re-enter due to atmosphere drag even on a 500+ year time scale.
mikeyouse 10y ago
Of course they do, it's a well-known problem for the satellite industry. From the technical addendum: > Each satellite in the SpaceX System is designed for a useful lifetime of five to seven years. SpaceX intends to dispose of satellites through atmospheric reentry at end of life. As suggested by the Commission,50 SpaceX intends to comply with Section 4.6 and 4.7 of NASA Technical Standard 8719.14A with respect to this reentry process. In particular, SpaceX anticipates that its satellites will reenter the Earth’s atmosphere within approximately one year after completion of their mission – much sooner than the international standard of 25 years. After the mission is complete, the spacecraft (regardless of operational altitude) will be moved to a 1,075 km circular orbit in its operational inclination, then gradually lower perigee until the propellant is exhausted, achieving a perigee of at most 300 km. After all propellant is consumed, the spacecraft will be reoriented to maximize the vehicle’s total cross-sectional area, a configuration also stable in the direction of aerodynamic drag. Finally, the spacecraft will begin to passivate itself by de-spinning reaction wheels and drawing batteries down to a safe level and powering down. Over the following months, the denser atmosphere will gradually lower the satellite’s perigee until its eventual atmospheric demise. http://licensing.fcc.gov/myibfs/download.do?attachment_key=1158350 http://licensing.fcc.gov/myibfs/download.do?attachment_key=1...
- int_handler 10y ago
  Interesting. Thanks!
- Osmium 10y ago
  > "for a useful lifetime of five to seven years" Isn't that a relatively low lifetime for so many satellites? Doesn't that mean they'll need to make a lot of launches just to keep the fleet operational?
  - arijun 10y ago
    I think the idea in the first place is to lower the per unit cost. Then spending millions more for longer life doesn't make as much sense.
  - gozur88 10y ago
    Depends on how they do it. The lifetime may be low because it doesn't carry much fuel. But if it's small enough they can launch dozens at a time.
  - JshWright 10y ago
    This plan is obviously predicated on viable first stage reuse. Estimates vary (and I'm sure even SpaceX doesn't know what the eventual number would be), but it's conceivable that their per-launch cost would be in the low double digit millions. These are also relatively small satellites, so you can pack quite a few of them on a dedicated launch, as well as sending one or more uphill as secondary payloads for launches that have useful trajectories.
  - nbarbettini 10y ago
    Yes. They are going for a very different model compared to "traditional" comsats. Instead of launching very heavy, very expensive birds that need to last for 10-20 years (to justify the huge development and launch costs), they want to launch cheap and light satellites that can be replaced much more quickly. As someone stated above, this all hinges on first stage reuse proving to be viable. If a customer buys a flight and they recover and reuse the booster, it's almost a "free" flight for them.
jimmcslim 10y ago
In my opinion, the Kessler Syndrome, or a Carrington Event, are the two most underrated yet likely causes of TEOTWAWKI.
- alanh 10y ago
  The End Of The World As We Know It. (I had to google. Interestingly, my Mac’s dictionary has TEOTWAWKI as an alias for “Survivalism”.)
  - nathancahill 10y ago
    AIFF: And I feel fineeeee!!
- ddoolin 10y ago
  For the uninitiated (incld. myelf...), "The end of the world as we know it."
- arijun 10y ago
  Why would a Kessler cascade be so devastating? Most of our comsats and all our GPS satellites are above LEO.
  - wmf 10y ago
    But would it prevent launching any more?
  - walrus01 10y ago
    It would completely fuck up the viability of all earth-sciences and imagery satellites (Hello google earth, google maps, bing maps, etc) which mostly orbit as low as reasonably possible and in 90 degree inclined polar orbits. It would also kill Iridium (either the current generation of satellites, or the next generation which will be in generally the same orbital configuration) because it depends on low earth orbit, highly inclined polar orbit satellites. Iridium is incredibly important to maritime users and aircraft users, in addition to its massive US DoD use.

Does SpaceX have any concerns about the Kessler Syndrome [0] or any plans to mitigate it? [0] https://en.wikipedia.org/wiki/Kessler_syndrome https://en.wikipedia.org/wiki/Kessler_syndrome

walrus01 10y ago

Things in very low earth orbit will re-enter on their own, if left unattended, from atmospheric drag.... At orbits of 450-600 km or less the lifetime of any satellite is very much finite. Satellites in much higher (like the MEO O3b satellites) will not re-enter due to atmosphere drag even on a 500+ year time scale.

mikeyouse 10y ago

Of course they do, it's a well-known problem for the satellite industry. From the technical addendum: > Each satellite in the SpaceX System is designed for a useful lifetime of five to seven years. SpaceX intends to dispose of satellites through atmospheric reentry at end of life. As suggested by the Commission,50 SpaceX intends to comply with Section 4.6 and 4.7 of NASA Technical Standard 8719.14A with respect to this reentry process. In particular, SpaceX anticipates that its satellites will reenter the Earth’s atmosphere within approximately one year after completion of their mission – much sooner than the international standard of 25 years. After the mission is complete, the spacecraft (regardless of operational altitude) will be moved to a 1,075 km circular orbit in its operational inclination, then gradually lower perigee until the propellant is exhausted, achieving a perigee of at most 300 km. After all propellant is consumed, the spacecraft will be reoriented to maximize the vehicle’s total cross-sectional area, a configuration also stable in the direction of aerodynamic drag. Finally, the spacecraft will begin to passivate itself by de-spinning reaction wheels and drawing batteries down to a safe level and powering down. Over the following months, the denser atmosphere will gradually lower the satellite’s perigee until its eventual atmospheric demise. http://licensing.fcc.gov/myibfs/download.do?attachment_key=1158350 http://licensing.fcc.gov/myibfs/download.do?attachment_key=1...

int_handler 10y ago
Interesting. Thanks!
Osmium 10y ago
> "for a useful lifetime of five to seven years" Isn't that a relatively low lifetime for so many satellites? Doesn't that mean they'll need to make a lot of launches just to keep the fleet operational?
- arijun 10y ago
  I think the idea in the first place is to lower the per unit cost. Then spending millions more for longer life doesn't make as much sense.
- gozur88 10y ago
  Depends on how they do it. The lifetime may be low because it doesn't carry much fuel. But if it's small enough they can launch dozens at a time.
- JshWright 10y ago
  This plan is obviously predicated on viable first stage reuse. Estimates vary (and I'm sure even SpaceX doesn't know what the eventual number would be), but it's conceivable that their per-launch cost would be in the low double digit millions. These are also relatively small satellites, so you can pack quite a few of them on a dedicated launch, as well as sending one or more uphill as secondary payloads for launches that have useful trajectories.
- nbarbettini 10y ago
  Yes. They are going for a very different model compared to "traditional" comsats. Instead of launching very heavy, very expensive birds that need to last for 10-20 years (to justify the huge development and launch costs), they want to launch cheap and light satellites that can be replaced much more quickly. As someone stated above, this all hinges on first stage reuse proving to be viable. If a customer buys a flight and they recover and reuse the booster, it's almost a "free" flight for them.

jimmcslim 10y ago

In my opinion, the Kessler Syndrome, or a Carrington Event, are the two most underrated yet likely causes of TEOTWAWKI.

alanh 10y ago
The End Of The World As We Know It. (I had to google. Interestingly, my Mac’s dictionary has TEOTWAWKI as an alias for “Survivalism”.)
- nathancahill 10y ago
  AIFF: And I feel fineeeee!!
ddoolin 10y ago
For the uninitiated (incld. myelf...), "The end of the world as we know it."
arijun 10y ago
Why would a Kessler cascade be so devastating? Most of our comsats and all our GPS satellites are above LEO.
- wmf 10y ago
  But would it prevent launching any more?
- walrus01 10y ago
  It would completely fuck up the viability of all earth-sciences and imagery satellites (Hello google earth, google maps, bing maps, etc) which mostly orbit as low as reasonably possible and in 90 degree inclined polar orbits. It would also kill Iridium (either the current generation of satellites, or the next generation which will be in generally the same orbital configuration) because it depends on low earth orbit, highly inclined polar orbit satellites. Iridium is incredibly important to maritime users and aircraft users, in addition to its massive US DoD use.