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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!
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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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!
We set up a CRASH Clock website here: https://outerspaceinstitute.ca/crashclock/
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.
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We set up a CRASH Clock website here: https://outerspaceinstitute.ca/crashclock/
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.
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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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.
"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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"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)
One of the scariest parts of this project was learning more about Starlink's orbital operations. I had always assumed they had some kind of clever configuration of the satellites in the orbital shell that minimized conjunctions, and we would see the number of conjunctions grow over time in our simulations. But no! It's just random! There's no magic here, it's just avoiding collisions by moving a Starlink satellite every 2 minutes. This is bad.
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One of the scariest parts of this project was learning more about Starlink's orbital operations. I had always assumed they had some kind of clever configuration of the satellites in the orbital shell that minimized conjunctions, and we would see the number of conjunctions grow over time in our simulations. But no! It's just random! There's no magic here, it's just avoiding collisions by moving a Starlink satellite every 2 minutes. This is bad.
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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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."
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.
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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.
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: https://archive.ph/6BwqQ
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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: https://archive.ph/6BwqQ
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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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).
Oh hey look, a Starlink satellite "experienced an anomaly" and ejected a bunch of debris. Explosion? Debris hit? Either way, not good..
https://www.pcmag.com/news/starlink-satellite-malfunctions-ejects-debris-fragments
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!
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Gli ultimi otto messaggi ricevuti dalla Federazione
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@Otttoz mah, in USA quell'uscita ha toccato un nervo scoperto grosso così. E questo commento spopola tra i MAGA.
Ricordo quella volta che stavo tornando in Italia da Denver, avevo addosso una maglietta che avevo comprato in riserva Navajo con scritto "Navajo Nation". Non dimenticherò mai lo sguardo d'odio viscerale che mi ha lanciato in aeroporto un vecchio vestito da texano, mi ha lasciato basito, manco mi fossi messo la maglietta di Che Guevara negli studi di Cologno Monzese insomma.
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Milano: presidio vietato a lavoratrici e lavoratori degli hotel in concomitanza delle olimpiadi. “saremo in piazza comunque!”
@anarchia
Mancano ormai meno di due giorni all’inaugurazione delle Olimpiadi di Milano-Cortina 2026 e si moltiplicano le proteste e le contestazioni contro un evento che risulta ormai
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@mdione yeah, keeping the audience pretty much the same as the conversation grows seems very natural to me, too.
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@joel LOL can totally relate. Me: "always take a snapshot of your instance before installing anything new or updating apps"... me IRL: forgets to take a snapshot and is horrified when things go wrong 😅 (thankfully it rarely happens)
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@evan It isn't intended as condescension. The common saying of "you can't know until you know" applies. Until you run across what you can unsee or unthink it isn't a possibility.
The Kathy Sierra debacle that was the final push that got Twitter to have their private accounts in the manner the put in place (as a stop gap) was a brutal wake-up call for many. The frailty of that system also was problematic and those, like Kathy, ended up leaving in the tens of thousands.
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@LunaDragofelis @evan I think we have two different mental models about discussions on Mastodon (and social media more generally). And different people use different mental models, yet often assume everyone else sees things the way they do..
One model sees a “thread” or a “discussion” as belonging to the person who created the first note and sees subsequent reply notes linked to the thread as being part of Alice’s (the original note’s author) thread. The other model sees a thread as a collection of individual notes, linked together, with each reply note in the discussion belonging to the reply’s author.
In the model where Bob and Carol and Dawn and Eve are just replying to Alice’s thread, one might expect those reply Notes to go to whatever group of people Alice had originally sent her note to. In the model where each author owns their own notes, one would expect reply Notes to honor the audience specified in the reply Note itself.
The confusion is made worse because the audience settings mean different things in different circumstances, and none of the clients are yet showing what those audiences actually mean for any given Note.
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@ZenHeathen so, for Bob's followers, "Yes" with no context is worthwhile and interesting? That's what they followed Bob for -- to hear his half of a private conversation?
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Your condescension is unearned.
