Mastodawn

Tommy Weir Oct 17, 2023

Prof. Sam Lawler

Not worried enough about corporate over-development of orbit yet? New article: companies have now filed asking for a total of ONE MILLION satellites: https://www.science.org/doi/10.1126/science.adi4639

Non-paywalled version here: https://www.outerspaceinstitute.ca/docs/One%20million%20(paper)%20satellites%20-%20Accepted%20Version%20.pdf

There is no way we can have anywhere near one million satellites in orbit without going into full Kessler Syndrome and destroying everything in orbit - making satellite science, communication, and interplanetary exploration impossible for decades.

Prof. Sam Lawler Oct 15, 2023

Wowee there is a lot of mansplaining going on in the replies to this thread now. Muting!

Just a reminder that I have a PhD in astrophysics, and my specialty is orbital dynamics. You really don't need to explain to me how orbits work.

Pauline von Hellermann Oct 15, 2023

@sundogplanets i get so much mansplaining on here too. Certain type that is particularly active on Mastodon. Yes, just mute!

WndlB Oct 15, 2023

@sundogplanets Like this? https://music.youtube.com/watch?v=PGNiXGX2nLU&feature=shared

Dead Or Alive - You Spin Me Round (Like a Record) (Official Video) - YouTube Music

Official 4K Video for "You Spin Me Round (Like a Record)" by Dead Or Alive Listen on Spotify - http://smarturl.it/DeadOrAlive_Spotify Listen on Apple Music ...

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Burrito Justice Oct 15, 2023

@sundogplanets ok how about they can launch a million satellites but only if they require that a mansplainer has to go up with each one

Fred Moyer Oct 15, 2023

@burritojustice while listening to “Round and Round” by Ratt

glasspshr Oct 15, 2023

@sundogplanets 🤣🤣🤣

🦆Oct 15, 2023

@sundogplanets I got this too any time I talk orbits. I think commercial space fans of a certain type just look for anyone to bombard on the topic.

Chris White finds this vexing Oct 15, 2023

@sundogplanets I swear some people think playing kerbal space program turns them into physicists

Wigglepig Oct 15, 2023

@sundogplanets orbital dynamics is something I have been very interested in for years but have not so far found a decent primer on.

Justin Buist Oct 15, 2023

@Wigglepig The game Kerbal Space Program is a good learning tool. Generally only about $20 on Steam and Windows, Mac, Linux compatible.

Pair it up with Youtube tutorials by Scott Manley and you get a pretty good idea how to work with conic section orbits. Add Principia for n-body physics and whoa boy.

GoatsLive Oct 13, 2023

@sundogplanets So they don't even want us to be able to see the moon? 😁

Dr. Jürgen Knödlseder Oct 13, 2023

@sundogplanets It’s rather centuries, not decades. At 1000 km a satellite stays up there for 1000 years.

Prof. Sam Lawler Oct 13, 2023

@jknodlseder I'm thinking Starlink altitudes, but yeah, you are right, and some debris will end up on higher orbits light that if we do indeed enter this worst-case scenario ugh.

Do you have a good scientific reference for drag/deorbit time vs. altitude?

Dr. Jürgen Knödlseder Oct 13, 2023

@sundogplanets Unfortunately not. I got the 1000 km - 1000 years rule from an expert on orbital debris from the French Space Agency who gave a talk at our lab.

Dr. Alexandre Santerne 🌍Oct 13, 2023

@jknodlseder @sundogplanets I thought it was few years for LEO, few decades for MEO and few centuries for GEO (likely the same source).

Bottom line: exact time doesn’t matter, it’s way too long anyway.

Dr. Jürgen Knödlseder Oct 14, 2023

@AlexSanterne @sundogplanets I guess once you are in GEO you basically stay up there

robryk Oct 15, 2023

@jknodlseder @AlexSanterne @sundogplanets

What's the green line (and why does the "debris" line end there)?

Dr. Jürgen Knödlseder Oct 15, 2023

@robryk @AlexSanterne @sundogplanets The green line is the ISS altitude, I guess the calculations were just stopped here (there exists another version of the plot where the debris line continues)

Cogito Ergo Disputo Oct 15, 2023

@jknodlseder @sundogplanets unless you push them down. We will need a company or supranational entity with a space drone capable of pushing decommissioned satellites down. Then there's all the space debris that needs to be removed.

Michael Busch Oct 13, 2023

@jknodlseder @sundogplanets Orbital lifetime up that high depends a lot on eccentricity (higher e meaning more drag at perigee) and inclination, right?

e.g. I recall discussions about deliberately disposing of MEO satellites by inducing eccentricity oscillations.

But that supposes that the operator of the satellite acts responsibly. Which neither Starlink nor the various other aspiring LEO megaconstellations are.

Steffen Christensen Oct 14, 2023

@michael_w_busch @jknodlseder @sundogplanets If only there were a sufficiently well-resourced space agency that had regulatory oversight capabilities and could look ahead 30 years or so for the welfare of all humanity.

Oh well. Kessler it is, then.

Michael Busch Oct 14, 2023

@Wikisteff @jknodlseder My assumption has been that the money backing LEO megaconstellation plans will eventually be cut off - Starlink has run through a few billion dollars and is losing hundreds of millions per year; OneWeb as it now exists has bankrupted multiple companies; etc. ( The article @sundogplanets linked does emphasize overfiling.)

But that's in no way an excuse for the failure of regulation.

Especially since when a company goes bankrupt, who becomes liable for the satellites?

Steffen Christensen Oct 14, 2023

@michael_w_busch @jknodlseder @sundogplanets I wonder who you can sue when your firm's LEO satellite gets Kesslered?

Michael Busch Oct 14, 2023

@Wikisteff @jknodlseder @sundogplanets If there is no company to sue; you can sue the country that the spacecraft was launched from - but only if your own country lets you do that: https://en.wikipedia.org/wiki/Space_Liability_Convention

So, for example, when AST SpaceMobile goes bankrupt; if its satellite hits something belonging to someone from the United States, it is not obvious that they would be able to sue anyone.

Space Liability Convention - Wikipedia

Σ(i³) = (Σi)² Oct 15, 2023

@michael_w_busch @Wikisteff @jknodlseder @sundogplanets I'd like to note that this is all a bit untested: law is rarely created and refined before it's needed.
So they *will* be able to sue if some court will hear the case; and whatever the outcome, someone *will* be able to appeal if some other court will hear THAT. And while it is all happening, legislative bodies will argue endlessly and possibly pass laws that possibly (but not likely) address the case at hand and after a couple of these shows have played out precedents will have been established that some future litigation may or may not consider binding. 🤷
As the law always seems to go...

Dagnabbit, Pascaline! 💥Oct 14, 2023

@sundogplanets No no no I am worried, for sure!

JP Oct 14, 2023

@sundogplanets b-b-b-b-but their hockey-stick growth! won't we please think of the GROWTH!

(no, fuck them, deorbit their shit and burn it all. gah.)

Steffen Christensen Oct 14, 2023

@sundogplanets Of course, it depends on the orbits. You could put a million satellites in MEO orbits without a Kessler, but NEO?
Hah, no.

Steffen Christensen Oct 14, 2023

@sundogplanets Apparently Rwanda wants to Kessler LEO: https://africanews.space/rwanda-has-submitted-itu-filing-for-27-orbital-shells-of-327320-satellites/

Biggles Oct 14, 2023

We'd be fine on the interplanetary exploration - higher chance of launch fails, but after the few minutes in the danger zone the probe should be free of danger from Kessler syndrome shenanigans. But yes, anything that depends on an extended presence in orbit - especially LEO - would be messed up for a long time.

Σ(i³) = (Σi)² Oct 15, 2023

@sundogplanets a single LEO is ~40000 km in length, i.e. 40 million m. One million satellites in a single orbit around the earth would be spaced 40m apart. Spread them over, say, 50 orbit s and you have ~2km between them - that's entirely feasible without super interesting collisions between them (anything with a low enough delta vee not to create debris I shall consider a nuisance, not a problem).

I'd say there's room for several million objects in LEO 🤷 (and many, many more in MEO)

Moved to @[email protected]Oct 15, 2023

@SvenGeier @sundogplanets I think you're assuming that nothing goes wrong, which is a classic engineering mistake.
https://youtu.be/7LUUk6wVNrY?si=WUDHm_BeCEVtfCvM

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Jonathan Hendry Oct 15, 2023

@SvenGeier @sundogplanets

Maybe if everything works exactly correctly.

But everything does not work exactly correctly.

Morten Oct 15, 2023

@SvenGeier @sundogplanets But they travel about 3 km per second. I feel like your buffers are very narrow.

Allan Chow Oct 15, 2023

@sundogplanets Planetes is too prescient 😭

Allan Chow Oct 15, 2023

hanscees Oct 15, 2023

@sundogplanets learned something today

The Kessler syndrome (also called the Kessler effect,[1][2] collisional cascading, or ablation cascade), proposed by NASA scientist Donald J. Kessler in 1978, is a scenario in which the density of objects in low Earth orbit (LEO) due to space pollution is numerous enough that collisions between objects could cause a cascade

https://en.wikipedia.org/wiki/Kessler_syndrome

Kessler syndrome - Wikipedia

Incognitim Oct 15, 2023

@hanscees @sundogplanets
It's also a slightly terrifying hashtag you can follow #KesslerSyndrome

Steve Easterbrook Oct 15, 2023

@hanscees @sundogplanets
Now go watch the movie “Gravity”. It will sear the Kessler effect into your brain.

hanscees Oct 15, 2023

@steve @sundogplanets thanks, seems like a nerve wrekking movie.

CelloMom On Cars Oct 15, 2023

@steve @hanscees @sundogplanets

Also Neal Stephenson's SF novel, "Seveneves". A compelling tale.

Steve Easterbrook Oct 15, 2023

@CelloMomOnCars @hanscees @sundogplanets
Yes! I loved Seveneves!

Virginicus Oct 15, 2023

@hanscees @sundogplanets one of our physics-department colloquium speakers back in the 1980s told us that one day Earth would have rings like Saturn. Didn’t think it would happen in my lifetime.

Full Metal Accountant Oct 15, 2023

@sundogplanets
We're just making a loose Dyson sphere of the earth.

Catherine Berry Oct 15, 2023

After how many cycles of disaster do we rebrand "The Tragedy of the Commons" to "The Utterly Predictable Consequences of Wrecking the Commons, You Morons"?

Demi Marie Obenour Oct 15, 2023

@sundogplanets Is the problem a lack of Space Traffic Control?

This is a serious question. Obviously even 1 million satellites is still a tiny fraction of the volume available in Earth orbit, so collisions should not be a problem provided that all of the satellites are functional and perform active collision-avoidance maneuvers when needed. That last part is the hard one, of course.

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