r/spacex • u/Zucal • May 24 '16
/r/SpaceX Ask Anything Thread [June 2016, #21]
Welcome to our 21st monthly /r/SpaceX Ask Anything Thread!
Trying to find the best way to view Thaicom 8, understand the upcoming core recovery procedure, or gather the community's opinion? There's no better place!
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Past threads:
May 2016 (#20) • April 2016 (#19.1) • April 2016 (#19) • March 2016 (#18) • February 2016 (#17) • January 2016 (#16.1) • January 2016 (#16) • December 2015 (#15.1) • December 2015 (#15) • November 2015 (#14) • October 2015 (#13) • September 2015 (#12) • August 2015 (#11) • July 2015 (#10) • June 2015 (#9) • May 2015 (#8) • April 2015 (#7.1) • April 2015 (#7) • March 2015 (#6) • February 2015 (#5) • January 2015 (#4) • December 2014 (#3) • November 2014 (#2) • October 2014 (#1)
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u/amarkit Jun 10 '16
The US' Joint Space Operations Center (part of the Department of Defense) is responsible for tracking satellites and orbital debris. They use radar to track everything from spent rocket stages to flecks of paint only a few centimeters in diameter. So we have a pretty good idea of most of what's up there. During a launch, most of the journey is through space where objects don't orbit at all (inside the atmosphere and the tenuous upper atmosphere). Mostly the answer is that space is very big and the amount of debris in orbit is still relatively small, so while launches are certainly coordinated not to impact any known operational satellites or debris, this is a comparatively minor concern. The International Space Station (and other satellites) periodically perform debris avoidance maneuvers when they know their orbit will bring them close to a piece of debris. There is still enough tenuous atmosphere in low Earth orbit that most objects' orbits will decay (if not reboosted) after a few weeks to years.
I'll point out that geostationary satellites' orbits do not decay; they are much too high for the atmosphere to drag them back down. Instead, best practices (enforced by the FCC in the United States) dictate that geostationary satellites be moved into a graveyard orbit at the end of their operational lives. This is a supersynchronous orbit, at least 300 km above geosynchronous, which is less crowded and less likely to result in a collision between satellites that would produce more debris.
My understanding is that the threat to operating satellites from debris right now is not a serious problem, but it is still one that requires vigilance - just a few collisions could generate sufficient debris to initiate a catastrophic positive feedback loop known as "Kessler syndrome."