Wooo it's up! New paper alert! I will write a summary thread about this paper tomorrow morning when I'm not quite as mentally exhausted!
"An Orbital House of Cards: Frequent Megaconstellation Close Conjunctions" by Thiele, Heiland, Boley, & Lawler arxiv.org/abs/2512.09643
Not recommended for reading right before bed. It's real bad up there in Low Earth Orbit, folks.
An Orbital House of Cards: Frequent Megaconstellation Close Conjunctions
The number of objects in orbit is rapidly increasing, primarily driven by the launch of megaconstellations, an approach to satellite constellation design that involves large numbers of satellites paired with their rapid launch and disposal.arXiv.org
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Jason Nishiyama
in reply to Prof. Sam Lawler • • •Mallory's Musings & Mischief
in reply to Prof. Sam Lawler • • •ItsDoctorNotMrs
in reply to Prof. Sam Lawler • • •Fabian Egli
in reply to Prof. Sam Lawler • • •rexi
in reply to Prof. Sam Lawler • • •(Especially since our back-up system gets defeated by big fishing trawlers with sharp anchors and an agenda.)
for reference:
en.wikipedia.org/wiki/Kessler_…
cited from arXiv:2512.09643
"Our calculations show the CRASH Clock is currently 2.8 days, which suggests there is now little time to recover from a wide-spread disruptive event, such as a solar storm. This is in stark contrast to the pre-megaconstellation era: in 2018, the CRASH Clock was 121 days."
planetary low-orbit debris hazard
Contributors to Wikimedia projects (Wikimedia Foundation, Inc.)Eggs now in different baskets.
in reply to Prof. Sam Lawler • • •The image that came into my mind on reading your toot was the start of a game of pool, where the triangle of balls is split and the balls then ricochet in all directions, some disappearing into the pockets.
It must be noted that the collisions that occur on a pool table tend to happen in two dimensions as opposed to the three dimensional collisions that can occur in space.
RaymondPierreL3
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to Prof. Sam Lawler • • •This paper started with a plot showing the density of satellites in orbit vs. altitude that Aaron Boley (professor at UBC) made. I knew this was probably bad, but what does 10^(-7) objects per cubic km really even mean when everything is flying around at 7km per second? It doesn't sound very scary.
I re-made the plot in a hand-wavy way assuming circular orbits, and looking at it in terms of 1km close-approaches instead, and it was a lot scarier. So scary, it was time to write a paper!
Prof. Sam Lawler
in reply to Prof. Sam Lawler • • •Two incredibly talented students led the project. We figured out a much less hand-wavy analytical way to calculate close approach rates using real data from public catalogues. And then we also ran n-body simulations to double check. They agree very well! And are really scary!!
In the densest part of LEO (Starlink), there are closer than 1km approaches every 15 minutes. 1km sounds like a lot, but remember everything in LEO is moving at 7km PER SECOND
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Prof. Sam Lawler
in reply to Prof. Sam Lawler • • •SpaceX Gen1-Gen2 Semi-Annual Report (7!1!25)
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Simon
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to Prof. Sam Lawler • • •We also did this calculation for the catalogue of satellites, trackable debris, and rocket bodies from 2018, before megaconstellations, showing just how much less safe megaconstellations like Starlink have made orbit.
The densest part of orbit in 2018 had a closer than 1km approach a little more frequently than once a day. Now it's more frequently than once every 15 minutes.
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Prof. Sam Lawler
in reply to Prof. Sam Lawler • • •How do you summarize how unsafe orbit is? This is where I get to tell you about my new favourite forced astronomy acronym, which I spent quite a while thinking about.
We needed a metric. I originally wanted to do something like "Kessler Countdown" or "Kessler Clock" but this isn't a countdown to Kessler Syndrome, it's just showing how bad things are in orbit, and how quickly they could get worse. So, our name for this metric is...
Collision Realization And Significant Harm: the CRASH Clock!
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dwardoric
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to Prof. Sam Lawler • • •The CRASH Clock uses the current density in altitude bins (averaged over eccentric orbits) of satellites, rocket bodies, and tracked debris, assuming typical cross sections for each type and orbital speeds. This calculation tells us how long to a collision if all orbital maneuvers were to suddenly stop.
The CRASH Clock is currently* at 2.8 days.
In 2018 it was 121 days.
*This is actually for June 2025 because that's when we ran it. Will update soon!
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Prof. Sam Lawler
in reply to Prof. Sam Lawler • • •We set up a CRASH Clock website here: outerspaceinstitute.ca/crashcl…
Note that this is a probabilistic calculation. A catastrophic collision could happen sooner than 2.8 days of no maneuvers. In our (extremely computationally expensive) collision simulation, just by random chance we actually got the first collision just 3 hours in.
We are currently well inside the Caution Zone. The probability of collisions happening if no avoidance maneuvers occur is >10% in any 24 hour period.
CRASH Clock – Outer Space Institute
outerspaceinstitute.caProf. Sam Lawler
in reply to Prof. Sam Lawler • • •This really highlights how incredibly dependent we are on Starlink's continued perfect collision avoidance maneuvers. So far they've done it, but they keep adding more satellites and making it harder.
Other megaconstellations are now launching as well, and they all need to communicate PERFECTLY in order to not crash. Will China talk to Starlink? Will the US gov't secret satellites talk to OneWeb? This is all incredibly important so that we don't destroy LEO.
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Prof. Sam Lawler
in reply to Prof. Sam Lawler • • •"In the short term, a major collision is more akin to the Exxon Valdez oil spill disaster than a Hollywood-style immediate end of operations in orbit. Indeed, satellite operations could continue after a major collision, but would have different operating parameters, including a higher risk of collision damage."
This is why I did a poll here about name recognition for Exxon Valdez a few months ago! (You young'uns go read about it because many of you don't know)
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Estarriol, Terrorist Dragon
in reply to Prof. Sam Lawler • • •torre canyon for europeans and older readers!
Biggest issue on a collision is IF it cascades by altering expected paths. Shudders.
Prof. Sam Lawler
in reply to Prof. Sam Lawler • • •reshared this
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Prof. Sam Lawler
in reply to Prof. Sam Lawler • • •I'll end with the last paragraph of the paper:
"In addition to the dangerously high collision risks calculated here, we are already experiencing disruption of astronomy, pollution in the upper atmosphere from increasingly frequent satellite ablation, and increased ground casualty risks. By these safety and pollution metrics, it is clear we have already placed substantial stress on LEO, and changes to our approach are required immediately."
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Legit_Spaghetti
in reply to Prof. Sam Lawler • • •Fantastic work. I need to set aside some time to read the full paper.
One tiny, tiny note from one professional communicator to another: The closing paragraph does a good job of summarizing the risk, but could emphasize what humankind stands to lose a bit more plainly and directly. If I'm a very wealthy US lawmaker who doesn't care about science or the environment, why should I care? (HINT: Catastrophic and irreparable economic damage on top of everything else.)
Well done!
Chris Johnson
in reply to Prof. Sam Lawler • • •Great work and a great thread!
Thank you so much for taking the time to summarize your work and type it in here.
goomba 🇨🇦
in reply to Prof. Sam Lawler • • •Evo Terra – #RhRR
in reply to Prof. Sam Lawler • • •Great analysis as always, Sam.
A hypothetical: Would it be possible—forget how and why for a moment—to use the collision avoidance thrusters on one (or more) of these mega cluster satellites to move it/them down where there’s enough atmospheric drag to cause it/them to fully deorbit?
Prof. Sam Lawler
in reply to Evo Terra – #RhRR • • •Evo Terra – #RhRR
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to Evo Terra – #RhRR • • •Evo Terra – #RhRR
in reply to Prof. Sam Lawler • • •WesDym
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to Evo Terra – #RhRR • • •varx/social
in reply to Prof. Sam Lawler • • •Out of curiosity, how hard would it be for a bad actor to *intentionally* induce Kessler Syndrome? (That is, are we crowded enough that it could happen with a single collision or chaff bomb?)
[EDIT] I guess this would have to be conditioned on the *time frame* in which the bad actor wanted to disable a large number of satellites, given how long the cascade could take.
Prof. Sam Lawler
in reply to Prof. Sam Lawler • • •2 interviews lined up to talk about the CRASH Clock so far!
And I usually say yes to just about every interview request I get, but I got 1 interview request on a non-urgent, non-time-sensitive astronomy topic late on a Friday afternoon asking to talk today or tomorrow. I think I will have to blow that one off and focus on other things.
Jimmy
in reply to Prof. Sam Lawler • • •econads
in reply to Jimmy • • •Jimmy
in reply to econads • • •econads
in reply to Jimmy • • •Jimmy
in reply to econads • • •@econads I grew up in an area that was easy to navigate where we had a teenage habit of random driving, so the only reason you needed a street guide was to locate the general area of your target. But then I got kind of footloose and learned to navigate by highway numbers and the sun, and eventually rode from Seattle to NYC using a Rand McNally road atlas and dead reckoning.
Now I live in a place where the streets were laid out by a drunk goat with a paintbrush on his tail.
Prof. Sam Lawler
in reply to Jimmy • • •Jimmy
in reply to Prof. Sam Lawler • • •Thanasis Kinias
in reply to Prof. Sam Lawler • • •@jhavok @econads
jz.tusk
in reply to Prof. Sam Lawler • • •@jhavok @econads
Why, whatever do you mean?
Brian Smith
in reply to Prof. Sam Lawler • • •The CRASH Clock is ticking as satellite congestion in low Earth orbit worsens
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Barbara Monaco
in reply to Brian Smith • • •We hear the sonic booms.
Farhan Ahmed
in reply to Brian Smith • • •Prof. Sam Lawler
in reply to Farhan Ahmed • • •Display Name
in reply to Prof. Sam Lawler • • •Mastodon Migration
in reply to Display Name • • •Yes.
Each such episode further increases the probability of future collision events.
It does not mean that instantaneously low earth orbit will become unnavigable, but we are on that path.
Edit: For more information see this article on Kessler Syndrome: spectrum.ieee.org/kessler-synd…
Kessler Syndrome Space Debris Threatens Satellites
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Ian K. Rogers ikr?╭ರ_ಠ
in reply to Mastodon Migration • • •Mastodon Migration
in reply to Ian K. Rogers ikr?╭ರ_ಠ • • •Not sure where you are getting this information.
Jo - pièce de résistance
in reply to Display Name • • •I’m curious about this too. It feels to me like it’s actually a prison that is being built for humans to never leave this planet.
Display Name
in reply to Jo - pièce de résistance • • •Anyway, it sounds like one more externalized billionaire cost that we'll either live with it or pay to clean up.
Prof. Sam Lawler
in reply to Display Name • • •Display Name
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to Prof. Sam Lawler • • •It's been interesting putting up a high-impact (hopefully no pun there) paper and getting lots of feedback! One (highly respected!) scientist graciously showed us a small error in our calculation, which we have fixed. It's like crowd-sourced peer-review. Interesting.
So, with that fix, the CRASH Clock is now at 5 days instead of 3 days. (If you think that extra time means there's no problem, you missed the point here!)
New from Scientific American: archive.ph/6BwqQ
Prof. Sam Lawler
in reply to Prof. Sam Lawler • • •I've seen some truly bad headlines related to this paper. Clearly LLM-written and not checked well. The funniest (saddest) ones seem to imply that 3 days from now, there will definitely be a crash in orbit.
I'm glad conversations are happening as a result of this paper. I hope the right conversations happen with the right people, and maybe some regulations will happen? Probably not fast enough. But I'm still holding out hope (and writing lots of letters to the FCC).
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Bruce Acton 🇨🇦🇨🇦🇨🇦
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to Prof. Sam Lawler • • •Oh hey look, a Starlink satellite "experienced an anomaly" and ejected a bunch of debris. Explosion? Debris hit? Either way, not good..
pcmag.com/news/starlink-satell…
editing to add snark (because that's how I deal with bad news I guess): Don't worry everyone, SpaceX says it'll reenter in a few weeks and totally won't crash into anything! Please ignore the spray of debris that's at basically the exact same altitude as the ISS!
Starlink Satellite Malfunctions, Ejects Debris Fragments
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James
in reply to Prof. Sam Lawler • • •Emily_S
in reply to Prof. Sam Lawler • • •Curioso 🍉 🇺🇦 (jgg)
in reply to Prof. Sam Lawler • • •Dan Sugalski
in reply to Prof. Sam Lawler • • •Dr. Eric J. Fielding, PhD
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to Dr. Eric J. Fielding, PhD • • •Prof. Sam Lawler
in reply to Prof. Sam Lawler • • •Dr. Eric J. Fielding, PhD
in reply to Prof. Sam Lawler • • •AI6YR Ben
in reply to Dr. Eric J. Fielding, PhD • • •@EricFielding
Someone lost a satellite
Kessler syndrome will be a delight
To color the holidays skies with sparkling trails
Of humanity's hubris as spaceflight fails
Never mind the satellite fragments flying around
Just listen for the sonic boom sound
What a festive atmosphere
As satellites fall here and there
Sparkly sparkly streaks in the sky
Tell me tell me tell me why
A billionaire gets to own outer space
Why do we have to keep looking at his face
Anyway if it's not this time maybe soon
When the only working satellite left will be the moon
And the skies will be lit up every night
With re-entering broken satellites
#poem #kesslersyndrome #space (human poem)
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Prof. Sam Lawler
in reply to AI6YR Ben • • •AI6YR Ben
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to AI6YR Ben • • •@ai6yr @EricFielding Hahahah I wasn't interpreting your poem as advocacy for Kessler! But it hits a little different when you re-read it that way hahahahaha
Thank you.
jakllsch
in reply to AI6YR Ben • • •Steve's Place
in reply to AI6YR Ben • • •@ai6yr @EricFielding Uh-oh. I just put another one of your poems to music.
Had to cut the "satellite" before "fragments," but it otherwise pretty much survived unscathed, lol.
AI6YR Ben
in reply to Steve's Place • • •Steve's Place
in reply to AI6YR Ben • • •@ai6yr @EricFielding There may be a few minor rearrangements to suit the meter. It has a bit of a Neil Young feel.
In the queue. I guess I should start recording soon. I have acoustic guitar-ready callouses now.
AI6YR Ben
in reply to Steve's Place • • •Muro deGrizeco
in reply to AI6YR Ben • • •@ai6yr
Have you heard the Strangler's "The Last Men on the Moon" ?
"Degrading satellites abound
Spiralling their way to the ground
There'll be a reckoning
And we all know it's due"
(Oops. Ok, edited to make Public)
MsMerope
in reply to AI6YR Ben • • •@ai6yr @EricFielding
Space debris
Space debris
Falling on our head
Wish us luck
Remember to duck
Or we might end up dead
(To the tune of Jingle bells)
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Rupert V/
in reply to AI6YR Ben • • •@ai6yr @EricFielding
But say a prayer
Pray for the satellites
At Christmastime
It's hard when you're having fun
There's a world above your rooftop
And it's a world of dread and fear
Where the only water flowing
Is @sundogplanet's tears
And the Christmas stars that shine there
Are blotting out the Moon
Well tonight thank God it's them
Instead of you
And there won't be snow in LEO this Christmas
The greatest gift they'll get this year is life
Where nothing ever grows, no rain or rivers flow
Do they know it's Christmas time at all?
Prof. Sam Lawler
in reply to Rupert V/ • • •Rupert V/
in reply to Prof. Sam Lawler • • •Dr. Eric J. Fielding, PhD
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to Prof. Sam Lawler • • •MikeH
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to MikeH • • •Emily_S
in reply to Prof. Sam Lawler • • •out of curiosity, do we know what the smallest bits of space junk we can track are?
It's the little bits that come off in an event like this that worry me.
Prof. Sam Lawler
in reply to Emily_S • • •@emily_s Yeah. 10cm is about the smallest pieces that can be radar-tracked from the ground, maybe a little smaller at this relatively low altitude. But there are smaller pieces that are untrackable and could still hit other satellites with damaging force.
Which is perhaps what happened to this Starlink satellite. Runaway collisions suck....
Emily_S
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to Prof. Sam Lawler • • •SpaceWeather.com -- News and information about meteor showers, solar flares, auroras, and near-Earth asteroids
spaceweather.comPlay Ball and Fight Fascists
in reply to Prof. Sam Lawler • • •G.I. Robot
in reply to Prof. Sam Lawler • • •Otter-Matic
in reply to Prof. Sam Lawler • • •Sensitive content
Dr. Eric J. Fielding, PhD
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to Dr. Eric J. Fielding, PhD • • •Norcal Gma 2
in reply to Prof. Sam Lawler • • •CheapPontoon
in reply to Prof. Sam Lawler • • •AkaSci 🛰️
in reply to Prof. Sam Lawler • • •FYI - in case you have not written about this - theverge.com/news/844502/starl…
"A collision in space was narrowly avoided last week when a newly deployed Chinese satellite came within a few hundred meters of one of the roughly 9,000 Starlink satellites currently operating in low Earth orbit. SpaceX is laying the blame on the satellite operator for not sharing location data."
This is yet another unknown in the equations for the CRASH Clock.
Starlink and Chinese satellites nearly collided last week
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Gordon J Holtslander
in reply to Prof. Sam Lawler • • •The movie Gravity does a memorable dramatic illustration
youtu.be/VDeZyRtPJvI
Gravity – Collision (full scene)
YouTubeGemma ⭐️🔰🇺🇸 🇵🇭 🎐
in reply to Prof. Sam Lawler • • •Joshua Barretto
in reply to Prof. Sam Lawler • • •Zombie Gopher 🇨🇦
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to Zombie Gopher 🇨🇦 • • •Chitchat
in reply to Prof. Sam Lawler • • •It seems one 'solution' is creating a lower level orbit: theconversation.com/the-next-f…
Business as usual, polluting a different place 🙄
The next frontier in space is closer than you think – welcome to the world of very low Earth orbit satellites
The ConversationProf. Sam Lawler
in reply to Chitchat • • •Matt Hall
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to Matt Hall • • •Matt Hall
in reply to Prof. Sam Lawler • • •That's my misunderstanding then... I thought the majority of Starlink satellites _were_ cubesats.
Thanks for the clarification! ❤
Prof. Sam Lawler
in reply to Matt Hall • • •Matt Hall
in reply to Prof. Sam Lawler • • •Matt Hall
in reply to Prof. Sam Lawler • • •So they're just sling'n Honda Odysseys into low-earth orbit.
Shiiiit.
Prof. Sam Lawler
in reply to Matt Hall • • •@401matthall And then burning them up in the atmosphere! Adding all that metal and plastic to the stratosphere! It's currently 1-2 a day, will ramp up to 23 per day if they actually get to 42,000 like they said.
Oh and sometimes they don't burn up completely. Whoopsies. cbc.ca/news/canada/saskatchewa…
AstraLuma
in reply to Prof. Sam Lawler • • •@401matthall space.com says there's 8800 starlink satellites currently in orbit, with wikipedia plotting about 2500 launched in 2024.
Wikipedia says there's been 2300 CubeSats ever (launched between 1999-2023), and about 300 have been launched a year since 2021.
Prof. Sam Lawler
in reply to AstraLuma • • •Jonathan's Space Report | Space Statistics
planet4589.orgMatt Hall
in reply to Prof. Sam Lawler • • •@astraluma
That's absolutely gobsmacking...
Medea Vanamonde 🏳️⚧️
in reply to Prof. Sam Lawler • • •Catelli
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to Catelli • • •Roy -- the dull one
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to Roy -- the dull one • • •David Penfold
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to David Penfold • • •David Penfold
in reply to Prof. Sam Lawler • • •David Penfold
in reply to David Penfold • • •D2
in reply to David Penfold • • •Prof. Sam Lawler
in reply to D2 • • •Jonathan's Space Report | Space Statistics
planet4589.orgDavid Penfold
in reply to Prof. Sam Lawler • • •I vaguely remember hearing the figure of 2,000 in 2011, so we're looking at a 7 to 8-fold increase or thereabouts.
Although that graph would indicate it was closer to 1,000.
WildRikku
in reply to Prof. Sam Lawler • • •So there's a lot of collision risk calculation going on all the time?Is that why you stress the importance of keeping maneuvers up - because they'd stop if calculation stopped working?
David J. Atkinson
in reply to Prof. Sam Lawler • • •@davep The mathematics of a system guaranteed of collision-free orbits in LEO would be very difficult, especially due to atmospheric drag and other physical effects. I don’t think anyone really knows how to compute the max density of satellites. Unless you intend to build a shell and that certainly won’t be popular.
When the automobile first became popular, the accident rate was quite high when a certain density of auto traffic in cities was reached. That’s when traffic laws and road standards were invented. I don’t think we can wait for accidents in LEO due to the danger of a runaway collusion scenario.
Axomamma, Antifa's cousin*
in reply to Prof. Sam Lawler • • •Anthony
in reply to Prof. Sam Lawler • • •Manda
in reply to Prof. Sam Lawler • • •Yeah.
See. I feel like some people think throwing things where they want them is the whole business model. There is no thought out plan.
James Helferty
in reply to Prof. Sam Lawler • • •LionelB
in reply to Prof. Sam Lawler • • •When a collision takes place, debris will distribute randomly and that debris will cause new collisions etc. etc.
Have those patterns of secondary disruption been modelled?
Prof. Sam Lawler
in reply to LionelB • • •LionelB
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to LionelB • • •LionelB
in reply to Prof. Sam Lawler • • •simonbp
in reply to Prof. Sam Lawler • • •doragasu
in reply to Prof. Sam Lawler • • •bewilderbeast23
in reply to Prof. Sam Lawler • • •Carolyn
in reply to Prof. Sam Lawler • • •Kpl Klink
in reply to Prof. Sam Lawler • • •ChookMother 🇦🇺🦘
in reply to Prof. Sam Lawler • • •Epic Null
in reply to Prof. Sam Lawler • • •That seems worse than advertised.
Maneuvers in space rely on fuel (like in most places). But in space... it's not so easy to refuel.
If these satellites are constantly maneuvering... how long until they can't? Does that time make a collision practically guaranteed?
Prof. Sam Lawler
in reply to Epic Null • • •BashStKid
in reply to Prof. Sam Lawler • • •Ms. Que Banh
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to Ms. Que Banh • • •Ms. Que Banh
in reply to Prof. Sam Lawler • • •Knud Jahnke
in reply to Prof. Sam Lawler • • •@PhoenixSerenity
Chernobyl over here. 14 year old me standing at my window, not being allowed to go outside, because it was raining – likely with radioactive fallout...
I still remember that view.
GLC
in reply to Prof. Sam Lawler • • •Also interested in the times orders to launch nuclear weapons were issued within the Soviet military command but not executed (Arkhipov and Petrov) along with the time we accidentally bombed North Carolina but one of the four safety switches held.
On the other hand, Chernobyl got a TV series. So that's good for a while. I understand the containment at the site was breached the other day.
crazyeddie
in reply to Prof. Sam Lawler • • •@PhoenixSerenity I think I was in my 20's when that happened? Maybe still teens...
I'm actually only vaguely aware of it too. Kinda remember the ducks and stuff. Dawn. But it barely registers and the memory has faded considerably. So much has happened.
crazyeddie
in reply to Prof. Sam Lawler • • •Michael Slade
in reply to Prof. Sam Lawler • • •Just Tom... 🐁
in reply to Prof. Sam Lawler • • •Martin Vermeer FCD
in reply to Just Tom... 🐁 • • •@tompearce49 I don't think it would prevent space travel or the use of space, only the resource called LEO would be lost for a time that will depend on the height of the orbit.
During that time, it would not be possible to safely place satellites there, but I think it could be relatively safely traversed quickly. Large fragments could be tracked, tiny fragments protected against by micrometeorite shielding.
Prof. Sam Lawler
in reply to Martin Vermeer FCD • • •Martin Vermeer FCD
in reply to Prof. Sam Lawler • • •@tompearce49
researchgate.net/figure/Predic…
Prof. Sam Lawler
in reply to Martin Vermeer FCD • • •nen
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to nen • • •The Enduring Dangers of Anti-Satellite Weapons and Space Debris - The National Interest
Lauren Kahn (The National Interest)Nick
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to Nick • • •zenkat
in reply to Prof. Sam Lawler • • •What's the expected lifetime of propellant onboard, especially with increased maneuvers required to avoid ever-more-probable collisions? ie, What are the chances that a satellite loses the ability to avoid its neighbors before burning up in the atmosphere?
I also assume that a corollary of this chart is the likelihood of a snowballing chain reaction where one collision creates multiple pieces of uncontrollable (and untrackable?) debris that increase the likelihood of further collisions?
Prof. Sam Lawler
in reply to zenkat • • •@zenkat Starlink satellites only have lifetimes of 5 years. I have no idea how much propellant they start with or how much they use. They wouldn't tell me if I asked, anyway.
Yeah, and modelling the collisions is a very different kind of paper. This is just likelihoods.
lp0 on fire
in reply to Prof. Sam Lawler • • •Brian Tatosky
in reply to Prof. Sam Lawler • • •I think this is a great page to have.
If I could make one totally unsolicited opinion; If there were a way to feature this number more Doomsday clock style for the clicks and publicity of it, since I entirely think it is info that needs to be spread far and wide and get attention.
Thank you for doing the research and keeping us informed.
tobychev
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to tobychev • • •Earthling
in reply to Prof. Sam Lawler • • •Qybat
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to Qybat • • •Qybat
in reply to Prof. Sam Lawler • • •Now I'm imagining launching a giant deployable sheet into retrograde orbit, to collide with and de-orbit everything it hits, before its own ratio of cross-section to mass brings it down.
I will file this idea as 'cool, but probably not practical.'
Prof. Sam Lawler
in reply to Qybat • • •Qybat
in reply to Prof. Sam Lawler • • •Martin Schröder 🇺🇳
in reply to Prof. Sam Lawler • • •Erik Beck
in reply to Prof. Sam Lawler • • •Knud Jahnke
in reply to Prof. Sam Lawler • • •Emily_S
in reply to Prof. Sam Lawler • • •dear goddess we're a datacenter failover from disaster if they were doing that in realtime.
Wonder how far in advance they get scheduled. 😬
David Schuetz ** looking for work **
in reply to Prof. Sam Lawler • • •Atz
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to Atz • • •Atz
in reply to Prof. Sam Lawler • • •Andy
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to Andy • • •Efi (nap pet) 🦊💤
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to Efi (nap pet) 🦊💤 • • •Efi (nap pet) 🦊💤
in reply to Prof. Sam Lawler • • •I forgor
John Lusk
Unknown parent • • •Is that mv^2/2? All that energy comes from rocket fuel, right? 1/1,000th seems like a lot.
Daniel Lakeland
in reply to Prof. Sam Lawler • • •cool paper, your description here had me thinking about a dimensionless measure for collisions.
density is in 1/length^3 and speed is length/time, typical cross section of a satellite is length^2 and a useful time scale is the design life of a payload
there are 4 measures and 2 dimensions, so we should get 2 dimensionless groups
cross section * speed *density*lifetime should give a dimensionless measure of lifetime collision danger
John Lusk
Unknown parent • • •@thomasfuchs
Right. And the velocity comes from...?
@sundogplanets
Prof. Sam Lawler
in reply to John Lusk • • •John Lusk
in reply to Prof. Sam Lawler • • •I'm assuming the velocity comes only from the energy used to boost the thing into orbit at the velocity needed to stay there. There's no gravitational slingshotting or anything that adds extra energy, right? So it's 100% from chemical rocket fuel burn, right? What am I missing?
(Actually, I guess climbing the gravitational well by itself requires even more energy, so there's even more energy in the burn than orbital velocity, right?)
@thomasfuchs
Prof. Sam Lawler
in reply to John Lusk • • •How Do We Launch Things Into Space? | NASA Space Place – NASA Science for Kids
spaceplace.nasa.govJohn Lusk
in reply to Prof. Sam Lawler • • •Right. So... all propellant, right? No other energy source. That's a lot of chemical energy.
(I did major in physics, several decades ago, but I might have missed something big.)
@thomasfuchs
Jeroen Franssen 🇧🇪
in reply to Prof. Sam Lawler • • •nachtet
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to nachtet • • •nachtet
in reply to Prof. Sam Lawler • • •Fällt uns der Weltraumschrott auf die Füße? - 42 - Die Antwort auf fast alles - Die ganze Doku | ARTE
ARTEProf. Sam Lawler
in reply to nachtet • • •nachtet
in reply to Prof. Sam Lawler • • •David GaladíEnríquez 🐀
in reply to Prof. Sam Lawler • • •Prof. Sam Lawler
in reply to David GaladíEnríquez 🐀 • • •David GaladíEnríquez 🐀
in reply to Prof. Sam Lawler • • •Bernard
in reply to Prof. Sam Lawler • • •indeed like any comments earlier, there's much more to this. Like this: economist.com/science-and-tech…
archive.ph/28lC0
AkaSci 🛰️
in reply to Prof. Sam Lawler • • •RE: mastodon.social/@NewSpaceEcono…
@sundogplanets
Coverage of the CRASH Clock at
fosstodon.org/@NewSpaceEconomy…
Fosstodon
fosstodon.orgNew Space Economy
2025-12-19 02:04:22
Prof. Sam Lawler reshared this.
Prof. Sam Lawler
in reply to AkaSci 🛰️ • • •Of Bookish Things
in reply to Prof. Sam Lawler • • •@AkaSci
👍
My first reaction to the image was an AI Bubble Crash. Perhaps computer folks can use AI to design an AI Bubble Crash. The AI would then spread messages to the other AI telling them to repent/reboot, the end is near. 😱
AkaSci 🛰️
in reply to Prof. Sam Lawler • • •More headlines -
'Crash Clock' reveals how soon satellite collisions would occur after a severe solar storm — and it's pretty scary - space.com/space-exploration/sa…
Crash clock says satellites in orbit are three days from disaster - newscientist.com/article/25087…
New ‘CRASH Clock’ Warns of 2.8-Day Window Before Likely Orbital Collision - gizmodo.com/new-crash-clock-wa…
'Crash Clock' warns Earth orbit is nearing disaster as megaconstellations push space traffic to brink - accuweather.com/en/space-news/…
New 'CRASH Clock' Warns of 2.8-Day Window Before Likely Orbital Collision
Ellyn Lapointe (Gizmodo)Mastodon Migration reshared this.