[HN Gopher] FCC Approves 5 Year Satellite Deorbiting Rule
___________________________________________________________________
 
FCC Approves 5 Year Satellite Deorbiting Rule
 
Author : sebg
Score  : 137 points
Date   : 2022-09-30 15:41 UTC (7 hours ago)
 
web link (payloadspace.com)
w3m dump (payloadspace.com)
 
| Dracophoenix wrote:
| When exactly did the FCC's jurisdiction extend to the heavens?
| There should be a lot more concern than there currently is over
| an agency granting itself powers over private property in space.
 
  | rzimmerman wrote:
  | FCC approval is required to communicate with a (US-based)
  | satellite in space, so effectively they can apply rules like
  | this one. It's less of a power grab/nefarious plot and more a
  | utilitarian kind of thing - the FCC has historically been the
  | only agency that has authority to exert this pressure, so the
  | work falls on them. It's admittedly odd that it's not the FAA
  | or Space Force, but that's how it is.
 
    | Dracophoenix wrote:
    | If one were to launch satellites over the United States that
    | communicate with transponders set up in Mexico, the
    | Caribbean, Greenland, and Canada, would that be outside scope
    | of the FCC's jurisdiction?
 
      | bluGill wrote:
      | In general those countries have their own rules that while
      | different amount to the same with different details. The
      | smaller countries generally copy what the US does (or
      | possibly what the EU does).
      | 
      | While you might be able to find a country to let you pick
      | your own rules, you will only be able to talk to your
      | satellite which means you can't do much with it. Most
      | satellite are used for communicating to people on the
      | ground and if you can't communicate to the US the satellite
      | is much less valuable.
 
  | frostburg wrote:
  | They're friends with other people with guns and rockets.
 
  | enraged_camel wrote:
  | Well, various government agencies have jurisdiction over, say,
  | private cars that drive on public roads, so why couldn't you
  | apply similar logic to the FCC with regards to satellite
  | regulation?
 
    | Dracophoenix wrote:
    | No country has any recognized territorial claims to space.
    | Roads are built within and between territories. I don't know
    | of a road built on unclaimed territory that grants a far away
    | government jurisdiction over every car traveling through the
    | said territory, even if these cars used other paths or went
    | off-trail.
 
      | l33t233372 wrote:
      | The FCC's jurisdiction only applies to satellites
      | communicating with US based ground stations.
 
        | Dracophoenix wrote:
        | The FCC derives its powers from the Communications Act of
        | 1934 (before Sputnik) and a few Supreme Court cases, none
        | of which have to do with satellite communication. That
        | the FCC has jurisdiction over terrestrial radio spectra
        | does not give it the right to create additional
        | requirements for communication with orbital satellites
        | even if there are US-based ground stations involved.
 
        | dragonwriter wrote:
        | > The FCC derives its powers from the Communications Act
        | of 1934 (before Sputnik)
        | 
        | ...which has many post-Sputnik amebdments, but
        | specifically the FCC role regarding policy for
        | communication satellites comes from the Communication
        | Satellites Act of 1962.
 
| MichaelCollins wrote:
| > _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 require a de-orbit burn.
| 
| Companies that use very low satellites are impacted less, since
| atmospheric drag does more of the work.
 
  | teawrecks wrote:
  | 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?
 
    | benslavin wrote:
    | I'm aware of Astroscale (https://astroscale.com/). They're a
    | Japanese company with a presence in the US and UK that's
    | commercializing this sort of service. I'm not sure if they
    | have plans for multi-satellite de-orbit services, but they do
    | have single-satellite plans.
    | 
    | Among other things, they're promoting a standardized docking
    | adapter (https://astroscale.com/docking-plate/) to give
    | satellite operators a path to either life extension
    | (refueling and/or orbit raising) or de-orbit.
 
    | tejtm wrote:
    | Woz seems to think so.
    | 
    | https://www.cnn.com/2022/03/01/tech/space-junk-steve-
    | wozniak...
 
      | MichaelCollins wrote:
      | Given Woz's post-Apple track record, that's not a good
      | sign..
 
    | loeg wrote:
    | It would cost more than reserving some propellant.
 
    | bryanlarsen wrote:
    | Going from travelling at Mach 25 in one direction to
    | travelling at Mach 25 in a different direction takes an
    | amount of energy comparable to going from 0 to Mach 25. Being
    | outside of atmosphere helps a lot, and being able to use the
    | less powerful but more efficient electric ion propulsion
    | engines helps a lot, but 10 satellites per mission is usually
    | not feasible. 3 per mission is the number I've heard.
    | 
    | Some companies approaching this problem are hoping to utilize
    | refueling depots. It adds another expensive rendezvous but it
    | does help.
 
    | apendleton wrote:
    | With a vehicle, probably not. Moving form one satellite's
    | orbit to another is extremely fuel-intensive (you'd typically
    | need ~thousands of km/h of velocity change to do it), so it's
    | not really practical to have a single vehicle up there moving
    | from satellite to satellite.
    | 
    | But maybe there'd be some other way to do it? There have been
    | proposals for de-orbiting little pieces of debris from the
    | ground with lasers, and I suppose it's possible that those
    | approaches would scale to bigger objects (or maybe you could
    | do it with lasers from other satellites whose orbits were
    | fixed, or something).
 
      | dmckeon wrote:
      | A set of satellites that could do laser ablation of debris
      | or EOL sats would be great, but would need safeguards to
      | not become a weapon of economics or war.
      | 
      | Avoiding splash-over or collateral damage to other sats in
      | or near the line-of-sight would be an issue, especially if
      | any of those other sats might have capabilities that their
      | nation/owner might want to keep secret. Perhaps an
      | arrangement of vetos over particular ablation shots would
      | suffice. Countries wanting to hide their interests in some
      | sats could veto N times as many shots as needed, making
      | uncovering which sats are special more difficult.
      | 
      | In any case, laser ablation would need much less delta-V
      | than the usual imagery of plucky space-cowboys chasing
      | errant sats with a net, or some such. Who knew that
      | _Planetes_ would have such a strong effect on our
      | collective imagination.
 
      | MichaelCollins wrote:
      | In the far future, perhaps orbit-cleaners could eat dead
      | satellites and space debris, atomizing the debris and
      | turning it into reaction mass.
 
  | s1artibartfast wrote:
  | How does this FFC rule work in an international market? I
  | assume it applies for US companies with US based launches.
  | 
  | Does it apply to US satellite companies with ex-US launches?
  | 
  | Are US companies free to purchase service/bandwidth from ex-US
  | launched satellites which are not compliant?
 
    | MichaelCollins wrote:
    | US companies launching satellites with foreign launch
    | providers still need to get a license from the FCC if their
    | satellite uses radio communications.
 
      | bryanlarsen wrote:
      | How about foreign satellites on foreign launch systems that
      | wish to communicate with ground stations in the US? I
      | assume they also need an FCC license.
 
        | MichaelCollins wrote:
        | Yes, satellites communicating with ground stations in the
        | US need licenses from the FCC, regardless of where
        | they're launched or where the owner is based. US
        | satellites that exclusively communicate with ground
        | stations outside of the US might not, but I'm not sure
        | about that. Satellites launched by other US government
        | agencies (NRO, etc) might also be exempt.
 
  | wumpus wrote:
  | > De-orbiting faster means reserving more propellant for the
  | final de-orbit burn.
  | 
  | One new technology is releasing a sail to increase drag.
  | 
  | Example: http://www.parabolicarc.com/2021/08/23/millennium-
  | space-syst...
 
  | pessimizer wrote:
  | If rules didn't cause inconvenience to someone, they wouldn't
  | have to be written.
 
    | MichaelCollins wrote:
    | I was thinking more along the line of the new rule giving
    | another commercial advantage to SpaceX. Starlink will be
    | effected, their satellites already deorbit faster than 5
    | years. But many other satellite operators will have to launch
    | more frequently, and SpaceX is positioned to meet that
    | growing demand.
 
      | chousuke wrote:
      | I don't really see it as "giving" a commercial advantage to
      | anyone if the new rule's purpose is to prevent something
      | harmful and someone happens to benefit because they're
      | already not doing that harmful thing.
      | 
      | In my view it's really a separate issue if SpaceX has too
      | many advantages and that levelling the playing field
      | somehow would be useful; allowing companies to grow too
      | powerful does cause problems, and I don't think there's a
      | moral requirement for regulators to be "fair" when dealing
      | with corporations. They are not humans.
      | 
      | The need for that sort of intervention should not keep us
      | from instating otherwise beneficial rules, though.
 
        | MichaelCollins wrote:
        | > _In my view it 's really a separate issue if SpaceX has
        | too many advantages_
        | 
        | That's not what I was saying. I was offering an
        | observation, not a critique. I think this new rule is
        | good.
 
        | chousuke wrote:
        | Oh, I didn't really read it as a critique; mostly just
        | the phrasing of "giving another commercial advantage"
        | made me want to comment since it can be read as if that's
        | the (or even just a) purpose of the rule.
 
      | xani_ wrote:
      | > But many other satellite operators will have to launch
      | more frequently, and SpaceX is positioned to meet that
      | growing demand.
      | 
      | Read the article. It's about deorbiting after mission is
      | finished.
      | 
      | If you have enough fuel on board you're free to keep your
      | satellite for 50 years on the orbit. You just have to
      | deorbit it within 5 after you stopped using it.
 
  | Me1000 wrote:
  | To be honest, this seems quite reasonable. Space is obviously a
  | unique environment, but to use an imperfect analogy: we don't
  | let cars that break down just sit in the middle of the road,
  | and we don't let dilapidated buildings sit unattended until
  | they collapse.
  | 
  | There's an externality to leaving a EOL'd satellite in LEO, now
  | these new rules require that externality be priced in. Either
  | through the cost of reserving enough propellant for a de-orbit
  | burn, or perhaps, one day, for more expensive satellites, a new
  | industry could emerge for refueling/boosting/servicing to
  | extend the sat's life.
  | 
  | This regulation seems like a good sign that the commercial
  | space industry is starting to mature in a healthy way.
 
    | JaggedJax wrote:
    | The future is here! I know of at least one company, Orbit
    | Fab, who already has signed contracts for their in-orbit
    | refueling service. It's a bit early to see how successful or
    | profitable this will be though.
 
| danieldbird wrote:
| I know how small the debris is relative to the earth. But the
| sheer number. Would that have any effect on the sun reaching
| earth and it's heating / cooling?
 
  | gpm wrote:
  | No.
  | 
  | To have an effect you need to launch multiple orders of
  | magnitude more mass than we have, and that mass would need to
  | be optimized towards having as large as an effect as possible
  | by being very very thin film positioned so that it is
  | consistently between earth and the sun (or you could add on a
  | few more orders of magnitude).
  | 
  | You can look at proposal for doing this intentionally to get a
  | sense for the scale:
  | https://en.wikipedia.org/wiki/Space_sunshade
 
  | xani_ wrote:
  | Nope
 
  | ultra_nick wrote:
  | No, that's like trying to cool your house with a pinch of dust.
  | 
  | Bus = 0.0002 km2
  | 
  | Earth = 510.1 million km2
  | 
  | (Earth / Bus) / 100 = 25,000,000,000 bus sized satellites
  | needed to cover 1% of the sky.
 
| jmount wrote:
| The previous "de-orbing 25 years after mission completion" sound
| a deliberately unenforceable rule.
 
  | rzimmerman wrote:
  | It was enforced during licensing. In order to obtain a license
  | from the FCC (which is effectively required to launch a
  | satellite, unless you never want to communicate with it), you
  | had to prove it would either deorbit naturally in < 25 years or
  | that you had a system to do so at the end of the mission. The
  | rule was generally to have a plan and an ability to deorbit
  | after 25 years. A lot of satellites fail in ways that prevent
  | using a propulsion system.
 
  | kobalsky wrote:
  | I'm not sure but I think has to do with parking the satellite
  | in a lower orbit such that the atmospheric drag will force it
  | to reenter within 25 years, not that the operator has 25 years
  | to deorbit the satellite at some point.
  | 
  | I think this has to do with the amount of fuel the need to save
  | to reach the disposal orbit.
 
  | mikepurvis wrote:
  | I expect that's less about having to reserve fuel or have a
  | specific plan for it, and more that to get approval, you have
  | to be able to plausibly show a model where the device will
  | deorbit on its own within 25 years of no maintenance burns.
 
| Eleison23 wrote:
| One day we will need to pass laws against celebratory satellite
| launches on holidays and the urban microphone networks will be
| calibrated to detect heavy-lift launches by gangstas. New nations
| will enshrine the right to launch satellites in their
| constitutions. Elementary schools will go on lockdown when a
| student is discovered to have built a satellite and fuelled their
| boosters.
 
| kortex wrote:
| I wanted to know if this affects "graveyard orbits". Seems like
| this applies only to satellites in LEO, while MEO/GEO are exempt.
| 
| > The Report and Order adopted today requires satellites ending
| their mission in or passing through the low-Earth orbit region
| (below 2,000 kilometers altitude) to deorbit as soon as
| practicable but no later than five years after mission
| completion.
 
| causi wrote:
| I'd like to see a breakdown of deorbiting fuel requirements with
| 25 years vs 5 years vs, say, 30 days.
 
  | rzimmerman wrote:
  | I'd expect the fuel required is generally the same, but this
  | changes the altitude range for the question "do I need
  | propulsion at all?" Satellites that would decay naturally in
  | 6-10 years due to atmospheric drag would have satisfied the old
  | rule. Now they need to install a propulsion system.
  | 
  | The actual impact is probably small - there aren't that many
  | satellites launching to those altitudes, and most of them
  | probably have a propulsion system anyway. But for a university
  | satellite this could be a big obstacle.
 
| karaterobot wrote:
| I wonder if they could do a "debris offset credits" type thing,
| where you could extend the life of your satellite by clearing out
| existing debris. So if you wanted a 25-year orbit, you could
| clear out maybe 5-10x the cross-sectional area, or mass, or
| whatever the relevant number is.
 
  | itp wrote:
  | The new rule is 5 years after mission completion, so this
  | already allows for a 25-year orbit (as long as you're still
  | operating).
 
| T3RMINATED wrote:
 
| nonethewiser wrote:
| Good improvement. What is China's rules for de-orbiting?
 
  | Someone1234 wrote:
  | It wouldn't surprise me if they wound up just copying this,
  | making it a de-facto international standard. Space junk is an
  | international problem, nobody wins by it continuously becoming
  | worse.
  | 
  | De-orbiting requirements add costs, but space junk damage and
  | or avoidance systems are even more expensive, so this is the
  | cheap solution in the medium to long term.
 
    | bluGill wrote:
    | I would expect that they put their own rules in places that
    | are different enough to be annoying if you need to permission
    | from both countries, but for practical purposes the end
    | result is the same. It may or may not be possible to satisfy
    | the letter of both countries rules though.
 
| rzimmerman wrote:
| I think this is generally a good thing to do, with some caveats
| that I hope the FCC considers.
| 
| For most satellites below ~450km, this is really a non-issue.
| Atmospheric drag will generally be sufficient to deorbit the
| satellite in a few years. For big Earth-observing constellations,
| Starlink and friends, and many small missions, this doesn't
| change anything. Debris don't really accumulate dangerously in
| this zone and collision avoidance is a well-studied problem with
| a lot of people doing great work. The 18th SDS with the US Space
| Force, LeoLabs, Starlink/SpaceX, and a lot of other constellation
| operators take this very seriously and do a good job.
| 
| For satellites in the 800km+ range, this is also not a meaningful
| change. The 25-year rule meant that these satellites needed a
| deorbit plan anyway. 800km is a rough estimate, in real life it
| depends on the satellite mass + geometry and the solar cycle.
| 
| For satellites in the 450-800km range (again - hand waving here)
| this is actually a big deal. Satellites that would decay
| naturally between 5 and 25 years now need an active deorbit plan
| or need to launch lower and keep themselves up with propellant.
| Small satellite propulsion is becoming cheaper and more
| available, so this isn't that onerous for commercial operators.
| But I do worry a little about educational and non-profit
| launchers of satellites. They'd be excluded from using launches
| to this orbital range unless the FCC allows waivers (which I'm
| hopeful they will).
| 
| Overall I don't think this has a particularly big impact. It's a
| sensible revision of an old rule that was a little too lax. But
| there aren't that many satellites launching at the high end of
| the 450-800km range without propulsion. The 1000km-2000km area is
| a more important area for debris mitigation and that was really
| already covered.
| 
| As for the FCC having this jurisdiction vs. the FAA or the USSF,
| as Spock would say - "it is not logical, but it is true."
 
  | ortusdux wrote:
  | Several companies have been developing deorbit add-on modules,
  | and I hope this requirement spurs on this growing industry. I
  | would love it if it became the norm that satellites have a
  | passive failsafe deorbit system that activates at after a set
  | amount of time or if ground communications fail for a set
  | duration.
  | 
  | https://www.nasa.gov/smallsat-institute/sst-soa/deorbit-syst...
 
  | elliekelly wrote:
  | > Debris don't really accumulate dangerously in this zone and
  | collision avoidance is a well-studied problem with a lot of
  | people doing great work.
  | 
  | I think this line of thinking is dangerously incorrect. Sure
  | it's not a problem _right now_ but we're poised to have a lot
  | more stuff in orbit than we've ever had before. Plastic waste
  | didn't initially "accumulate dangerously" either but once it
  | became more widely used (and _did_ accumulate dangerously) it
  | was much more difficult to try to reign it back.
 
    | bryanlarsen wrote:
    | Debris does not accumulate in LEO, it reenters naturally.
    | This isn't like plastic waste, it's more like organic waste
    | that naturally decays. Sometimes the law says you have to
    | clean up organic waste, but sometimes it's better to let it
    | rot on its own.
 
      | mikeyouse wrote:
      | The timeframe varies _widely_ based on the shape of the
      | object and the altitude. There are something like 5 orders
      | of magnitude pressure difference between an object at 100km
      | and one at 500km which is the difference between deorbiting
      | in days vs years.
 
        | bryanlarsen wrote:
        | There's probably more than 5 orders of magnitude
        | difference between throwing an apple core into the woods
        | and a city's worth of sewage, but both are organic waste.
        | I think the analogy is fairly sound.
 
        | Retric wrote:
        | Huge constellations with stable orbits under active
        | control are irrelevant. It's really the a pair of
        | uncontrolled satellites colliding that's a meaningful
        | risk, and that risk grows exponentially with age. To the
        | point where the difference between 1 day and 1 year is
        | effectively meaningless while the difference between 5
        | years and 50 years is huge.
 
        | mikeyouse wrote:
        | If we're launching 15k satellites per year as some people
        | expect, the difference between 1 day deorbit and 5 years
        | deorbit is something like 75,000 satellites.
 
        | Retric wrote:
        | If the risk of collisions in both scenarios is sub
        | 0.0001%, is it a meaningful difference? Very quickly the
        | risk is dominated by being launched into the wrong orbit.
 
        | s1artibartfast wrote:
        | yes, but if deorbiting in years is sufficient, the
        | difference in time is not relevant.
 
        | mikeyouse wrote:
        | What? Starlink eventually wants 40,000 satellites - with
        | 5 year lifetimes that'll be 8,000 per year... there are
        | numerous other planned constellations, so figure
        | something like 15,000 LEO per year within a few decades.
        | 
        | 15k satellites per year with a 5 year lifespan and a
        | 1-year decay means you'll be stable at 75k satellites. 5
        | year lifespan with a 3-year decay means you'll eventually
        | be stable at over 100k satellites in orbit with 30,000 of
        | them 'dead' and decaying. That's a massive difference in
        | collision risk.
 
        | bisby wrote:
        | The rule is 5 years. You've given 2 examples under 5
        | years. If everything is going to re-enter within 5 years
        | without boosting then your point is moot, because even in
        | your "massively more collision risky" example, it still
        | abides by the rules.
        | 
        | If something was going to deorbit within 1 minute, or was
        | going to deorbit within 4 years, 6 months... It doesn't
        | matter to the creator, because they don't have to change
        | their design at all to meet the rules.
        | 
        | If something was going to deorbit within 8 years (because
        | they previously had a 25 year allowed limit), they now
        | have to rework the design.
        | 
        | There's plenty of room for debate about if 5 years is
        | adequate, but as it stands, _most_ things (under 500km)
        | will naturally deorbit within the legal time frame anyway
        | even without special consideration.
 
        | mikeyouse wrote:
        | Just responding to a comment that said "If deorbiting in
        | years is sufficient, the difference in time is not
        | relevant" where it's obviously relevant.. this doesn't
        | seem remotely controversial.
 
        | s1artibartfast wrote:
        | Let me put this another way, if I use my computer to send
        | emails, it doesn't matter to me if my ping is 10
        | milliseconds or 10 femtoseconds.
        | 
        | One time is 10^12 times longer, but the difference does
        | not matter to me. My emails are still sent and received
        | faster than I can possibly perceived.
 
        | bisby wrote:
        | You're arguing a different thing. The topic was satellite
        | design for satellites under 450km.
        | 
        | If deorbiting in years is sufficient, the difference in 1
        | minute vs 4 years is NOT relevant -> to a satellite
        | builder worried about the law.
        | 
        | If everything deorbits within 5 years, the only way for
        | more things to accumulate is to launch things faster. But
        | that's a separate discussion. If everything launched
        | today is deorbited within 5 years, then in 5 years, all
        | satellites will be new satellites launched after today.
        | If everything launched today is deorbited within 5
        | months, then in 5 years, all satellites will be new
        | satellites launched after today. Deorbit speed under a
        | threshold has no bearing on accumulation beyond that
        | threshold.
        | 
        | If SpaceX launches a trillion Starlink satellites, and
        | they all deorbit within a year, then yes. it's going to
        | be a very crowded year, and we'll have to drastically
        | rethink how much stuff we have in LEO, but at the same
        | time SpaceX would not be in violation of the 5 year
        | deorbit window, so the issue is about how much stuff
        | we're sending up, and not how fast it de-orbits.
        | 
        | "Amount of junk below 450km, total" and "Amount of junk
        | below 450km, that hasn't deorbited after 5 years" are
        | very different things. You're making points about total,
        | while the original point was about deorbit speed.
 
        | s1artibartfast wrote:
        | >That's a massive difference in collision risk.
        | 
        | Is it? It's a big difference in absolute numbers but that
        | doesn't mean it's a meaningful difference in Risk.
        | 
        | If both numbers are quite small relative to the level of
        | concern, the difference can still be irrelevant.
        | 
        | My point is that it takes more than just looking at the
        | number of satilites to understand risk. You need to do
        | the work to show how the collision chance compares to
        | what an acceptable limit might be. Both cases could be
        | very acceptable (or both cases could be unacceptable).
 
    | hinkley wrote:
    | 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 though, do we really build satellites that are
    | expected to only work for 5 years? Are we disincentivizing
    | people from building 20 year satellites this way?
 
      | Fatnino wrote:
      | I assume it means deorbit within 5 years after the
      | satellite is decommissioned.
 
      | ntrz wrote:
      | The article says "5 years after completing their mission",
      | not 5 years after launch.
 
        | hahajk wrote:
        | time to assign 25 year missions to satellites built to
        | last 10 years!
 
    | MichaelCollins wrote:
    | https://www.youtube.com/watch?v=mQT5aMa_7iI
    | 
    | "Gabbard Diagram for Low Earth Orbit 1959-2021"
    | 
    | See how the stuff in the lower left corner speeds up towards
    | the lower left corner? That's low flying debris falling out
    | of space.
 
      | wpietri wrote:
      | I am generally allergic to video, but that was fascinating
      | to watch. Thanks for sharing it.
 
    | rzimmerman wrote:
    | I didn't mean to imply orbit debris isn't a real problem. But
    | for the low end of LEO:
    | 
    | - Most debris deorbits naturally in a few years. Any debris
    | causing events or accumulation naturally clears out in a
    | reasonable time frame. It's not like debris at 800-2000km
    | which is the real "Kessler Syndrome" concern where it takes
    | decades or centuries.
    | 
    | - Debris mitigation efforts that are already in place are
    | effective. Limiting debris release during launch and
    | deployments has had a huge positive impact over the last few
    | decades.
    | 
    | - "Traffic control" is a lot easier at these altitudes and
    | debris in this range is well tracked. Obviously this doesn't
    | extend to small stuff (<5cm), but due to active mitigation
    | and natural decay this is less of an issue. Also ground
    | radars are getting better and can actually see a lot of these
    | objects now.
 
  | hinkley wrote:
  | 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 the atmosphere on the way
  | back down, but in the meantime any other satellite that crosses
  | paths with it is effectively hitting a wall of stationary
  | debris, creating a new cone that ladders up higher. Is there
  | enough space that the ladder stops, or does it just keep
  | building?
 
    | FairlyInvolved wrote:
    | I don't think debris 'going higher' isn't much of a problem.
    | Whenever this happens the orbit is going to be more eccentric
    | - meaning a lower periapsis, and consequentially lots of drag
    | that will cause a rapid deorbit.
    | 
    | On the second point about parabolic orbits I also find that
    | probably relatively low risk because we are only talking
    | about a fraction of an orbit for a collision to occur so
    | unless the debris field was massive the chance of another
    | collision is probably still low. Remember when we are
    | modelling orbit collisions normally we are often talking over
    | 25+ years - 100,000 + orbits.
    | 
    | I think the main problem is busy orbits (e.g. sun-synchronous
    | polar orbits at popular altitudes) where most of the debris
    | remains roughly in the same orbit following an acute
    | collision but has a lot of other potential collision targets.
    | Also as satellites are disabled by a collision they lose the
    | ability to avoid other objects already in the same crowded
    | orbit - i.e. the fraction of objects able to take avoidance
    | decreases increasing the chance that future collisions are
    | from 2 incapacitated satellites, removing the possibility of
    | avoidance.
 
    | jessaustin wrote:
    | Angular momentum is subject to a conservation law.
 
| exabrial wrote:
| It's a bit weird the FCC is ruling on this... not really a space
| agency... but regardless, it's a good move!
 
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