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FCC Approves 5 Year Satellite Deorbiting Rule

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Re: FCC Approves 5 Year Satellite Deorbiting Rule

#111

Post by tlamponi »

londons_explore wrote: post #103

It seems there is an easy loophole.... Just declare the satellite mission to be super long. Eg. This spacecraft will act as a Comms satellite for 10 years and will then go into a low power mode where it switches to 'gamma ray burst detection mode' which will be active for 150 years, upon which it will then deorbit within 5 years as regulated.

Meh, can be blocked from starting at all due to:

1. Pretty easy to detect for most cases, especially as blunt in your (exaggerated, I know) example. Agencies should have a rough idea about realistic time frames for mission times in near earth orbits depending on what the satellite does.

2. They still need to have the propulsion unit integrated in the satellite, as otherwise they cannot guarantee the 5 years after mission time in higher orbits. They'll also need to prove that the propulsion unit used is very likely to actually work after mission time, e.g., your 160 year in radiation ridden space, which may be much more expensive than constructing one for the shorter, actual mission time.

Re: FCC Approves 5 Year Satellite Deorbiting Rule

#112

Post by bryanlarsen »

saghm wrote: post #98
bryanlarsen wrote: post #95

Earlier quoted context omitted.

WTF? Space is incomprehendibly big. The number of potential landfill locations are very limited.

Isn't this thread discussing a very specific orbital range? The 450k-800k range is big, but I'm not sure I'd classify it as "incomprehensibly big".

Anything orders of magnitude larger than the Pacific Ocean deserves that title IMO.

Re: FCC Approves 5 Year Satellite Deorbiting Rule

#113

Post by Retric »

Ferrotin wrote: post #110
Retric wrote: post #96

Earlier quoted context omitted.

It seems like it should be quadratic in that double the satellites should get 4x the number of collisions, but satellite orbits don’t start out random. Without stationkeeping initially clear orbits become chaotic in that slight differences in initial position and velocity result in wildly different orbits. That transition results in an exponential increase in risk. This is most obvious with geostationary orbit. Over…

I see your point that it’s not random but an exponential increase wouldn’t result from chaotic changes in orbit. That randomizes, making it quadratic. It looks like inactive geostationary satellites will drift to the same longitudes, and tilt their axis away from the pole. If you have a set of geostationary satellites in that situation, the risk of collision is still quadratic in growth. The risk is the sum of the pa…

Thinking about it more, it could probably be modeled by the intersection of random walks that are initially unable to come into contact. I was thinking that was exponential but it’s presumably some polynomial function with a large exponent that’s eventually bound by a different quadratic function for sufficient values of time.

Re: FCC Approves 5 Year Satellite Deorbiting Rule

#114

Post by hinkley »

ntrz wrote: post #67
hinkley wrote: post #63

Earlier quoted context omitted.

In this case it's policy reflecting Little's Law: population = arrival rate X duration of visit If suddenly someone wants to launch twice as many satellites, you either have to reduce tenancy or accept a higher population in the system. If you have a policy that's at most 25 years and a lot of satellites de-orbit in say 15 years on average, you can still triple your launches by pulling that down to 5. I am worried th…

The article says "5 years after completing their mission", not 5 years after launch.

Wait, really? What orbital mechanics take five years to achieve? Lunar assisted orbital insertion burns only take a year or two, right? Why wouldn’t the deorbit burn start the day after decommissioning?

Re: FCC Approves 5 Year Satellite Deorbiting Rule

#115

Post by hinkley »

jessaustin wrote: post #75
hinkley wrote: post #65

Earlier quoted context omitted.

How high can the debris loft after a particularly nasty collision? Two satellites hitting at an acute angle should produce a cone of debris in front of them, of which about a third deorbits and a third goes up into a higher orbit that's an average of the two. Two satellites that hit at an obtuse angle, well, they pancake and produce a donut of debris. The stuff headed straight up is on a parabolic orbit that will hit…

Angular momentum is subject to a conservation law.

What does angular momentum have to do with Kessler syndrome?

Re: FCC Approves 5 Year Satellite Deorbiting Rule

#116

Post by zardo »

hinkley wrote: post #114
ntrz wrote: post #67

Earlier quoted context omitted.

The article says "5 years after completing their mission", not 5 years after launch.

Wait, really? What orbital mechanics take five years to achieve? Lunar assisted orbital insertion burns only take a year or two, right? Why wouldn’t the deorbit burn start the day after decommissioning?

If it takes 5 years, there is no deorbit burn.

Re: FCC Approves 5 Year Satellite Deorbiting Rule

#117

Post by WalterBright »

simonh wrote: post #108
WalterBright wrote: post #85

One way to deorbit a satellite that doesn't require fuel is to deploy a simple sail, which could increase the drag on the satellite by 10x or more.

A system like that has already been used.

I figured someone would tell me it was a dumb idea. I'm glad to be wrong about that!

Re: FCC Approves 5 Year Satellite Deorbiting Rule

#118

Post by dotnet00 »

teawrecks wrote: post #9
MichaelCollins wrote: post #2

> The rule shortens the time required for satellite operators to deorbit LEO satellites to no more than 5 years after completing their mission, from 25 years. De-orbiting faster means reserving more propellant for the final de-orbit burn. Since the lifespan of satellites is already generally determined by how much propellant they have, this new rule effectively reduces the lifespan of any satellite high enough to req…

I'm no rocket scientist, but could there be a service which knocks satellites out of orbit for people? I wonder how cost effective such a service could get. Could one mission knock 10 satellites out of orbit?

Astroscale is trying to push a standardized docking adapter for that purpose and Northrop Grumman has a vehicle that was able to dock to the engine of another satellite to serve as a life extension vehicle, so assuming that can be easily adapted to other satellites, they too can provide a deorbiting service.

Clearing out several satellites with one vehicle is not practical though, would need too much fuel. At best one might launch several such vehicles on one launch, or if orbital fuel depots really take off soon, it may be possible to have depots in convenient locations such that deorbiting vehicles can always make a relatively cheap visit to a depot to refuel and wait for another deorbiting target. In such a setup the deorbiter would just lower one end of the orbit to speed up decay rather than dragging it all the way down to Earth.

Re: FCC Approves 5 Year Satellite Deorbiting Rule

#119

Post by Ferrotin »

Retric wrote: post #113
Ferrotin wrote: post #110

Earlier quoted context omitted.

I see your point that it’s not random but an exponential increase wouldn’t result from chaotic changes in orbit. That randomizes, making it quadratic. It looks like inactive geostationary satellites will drift to the same longitudes, and tilt their axis away from the pole. If you have a set of geostationary satellites in that situation, the risk of collision is still quadratic in growth. The risk is the sum of the pa…

Thinking about it more, it could probably be modeled by the intersection of random walks that are initially unable to come into contact. I was thinking that was exponential but it’s presumably some polynomial function with a large exponent that’s eventually bound by a different quadratic function for sufficient values of time.

It would seem to be exponential after the first collision, at least.
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