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Question about the second stages: Are these left in orbit or are they deorbited?

• deleted 10y ago
  [deleted]
• walrus01 10y ago
  Depends on the launch. There is no remaining fuel in a second stage for any Delta v to lower its orbit into the atmosphere in most launches. A launch to GTO at 350 x 36,000 km will eventually decay. In some satellite launches there is a third stage (like a fregat, but not the same thing) which performs the final circularization of the orbit. In others the satellite itself does this. In a launch to an MEO orbit like 1500x1500 km the 2nd stage is going to stay up there pretty much forever as dead debris.
  • ygra 10y ago
    SpaceX doesn't do GEO launches as far as I know, only GTO. I don't know whether from a lack of capability or whether they're not allowed/certified for that, though. I guess an expendable F9 should easily be able to get to GEO.
    • toomuchtodo 10y ago
      SpaceX does GEO since December 2013. http://www.spacex.com/press/2013/12/03/spacex-successfully-completes-first-mission-geostationary-transfer-orbit http://www.spacex.com/press/2013/12/03/spacex-successfully-c...
      • InclinedPlane 10y ago
        SpaceX doesn't do direct GEO insertion, only boosting to a Geostationary Transfer Orbit (GTO) which is the norm for satellites headed to GEO. The satellite itself does the circularization, which isn't hugely costly fuel wise but requires a stage that can restart after coasting all the way to GEO altitude (several days), which SpaceX currently lacks (the 2nd stage runs on batteries).
        • walrus01 10y ago
          Yes, exactly this. GEO requires an engine that is low kN thrust but can be restarted many times. The Wikipedia page for the Russian fregat which is commonly used as a 3rd or 4h stage for their launches is a good example of such hardware. If you're patient you can even circularize a GTO with ion engines, which has been done on some partially-failed telecom satellite launches.
          • the8472 10y ago
            It has also been done by design instead of a fallback. http://www.boeing.com/features/2015/01/bds-702sp-01-26-15.page http://www.boeing.com/features/2015/01/bds-702sp-01-26-15.pa...
          • InclinedPlane 10y ago
            Several of the most advanced GEO commsats use that as their main way to get into orbit. By beefing up the ion engine enough to circularize the orbit at GEO you make for cheaper launch costs and a longer lived vehicle.
      • the8472 10y ago
        that's GTO. the payload itself will have to to provide the rest of the thrust to circularize that to GEO. But they can do so cheaply with ion engines since they don't need to fight the atmosphere.
    • walrus01 10y ago
      Something like 95% of the commercial for profit launch market is for geostationary telecom satellites. In terms of launches per decade o3b is an aberration. GTO is the highly elliptical transfer orbit for a hohmann transfer to geostationary. This is of course a drastic oversimplification.
    • InclinedPlane 10y ago
      Lack of capability, the 2nd stage doesn't live long enough to do it (yet). They could make the modifications to do direct GEO missions but it's a niche market and not particularly worth it, at least not yet.
• InclinedPlane 10y ago
  Some are deorbited immediately (such as on ISS resupply flights) others are left in orbit but so far they all have fairly low perigees so they re-enter after a few months at most.
  • JshWright 10y ago
    s/months/years/ There are still a couple upper stages from 2014/2015 up there.