One to Two Starlink Satellites Are Falling Back to Earth Each Day

Those findings are simulated, not observed. Hence "potential."

> it's a non-trivial change in chemical composition over the entire globe, and effecting a complex and poorly-understood part of the climate system. What could go wrong?

Perhaps a lot. Perhaps not much. It's a good question to study. But if this is an issue, it's solvable--carbon composite satellite structures could use a boost in demand and funding.

> "In situ measurements showed evidence of a 1,000% increase in stratospheric aluminum levels from 1976 to 1984 (Zolensky et al., 1989), which was associated with the emission of hundreds of tons of such particles from solid rocket motors (SRM) during atmospheric ascent (Brady et al., 1994)"

If you follow Brady et al. (1994)[0], you'll read that every Space Shuttle launch (Table 1) deposited 112 tons of Al2O3 into the stratosphere (>15 km).

[0] https://apps.dtic.mil/sti/pdfs/ADA289852.pdf

This isn't a new phenomenon at all; in fact the peak alumina pollution from in the past (112 tons per STS launch) exceeds the worst-case future estimates from academic research (360 tons per year from satellite reentries).

(/meta Coincidentally, I once linked that exact Brady paper on HN, three years ago[1]. Actually, long before the current social media fad for being concerned about satellites. At the time I wrote, and this has truly aged well, "No one ever gave a shit").

[1] https://news.ycombinator.com/item?id=34812863

Another 500 km won't affect latency much. It'll be around 3 more ms per round trip.

LEO maxes out ~ 1,200 miles radius, geostationary is at little over over 22,000 miles radius.

Kessler cascades are localised to specific orbits. In low-earth orbit, they're a problem for a few years.

They're going to be annoying. But not catastrophic.

> there is always one which is on the highest level

Highest level?

There are other factors, too - imagine you're trying to send a penny around the entire equator of the earth, and think of the largest possible explosion you could subject it to without vaporizing it. A stick of dynamite could launch a penny only around a half mile's distance around the equator, assuming ideal conditions, which is about .0025% of the circumference of the earth, which is 10% of the distance between the earth and the moon, and the moon is about 25% of the distance from which earth's gravity stops being a significant factor.

If you carefully deployed a large number of well timed series of dynamite sticks precisely located so that each blew up perfectly beneath the penny at its apex following each previous explosion - you'd need 150-300 sticks to get the penny out past the edge of the effective gravitational well, the point at which other factors in the solar system have the dominant influence - it'd effectively leave earth and start falling toward the sun. At any point closer to earth than that, it will slowly and inexorably return back to earth, reaching up to 25,000 mph before vaporizing itself in the atmosphere (if it fell from the outer edge). If you had no atmosphere, a clear shot, and the "ideal" penny cannon to launch it, you could hypothetically reach escape velocity with only a quarter stick of dynamite.

Incidental bursts of gas, or even outright exploding objects in space are not going to launch a bunch of stuff into much deeper orbit. There's a constant downward pull, and gas and dust creating drag and downward acceleration the closer in you get, and just vast, incomprehensible distances to travel under the influences of gravity. Getting things to go faster than 25,000mph, or reaching escape velocity, without vaporizing the thing you're trying to make go fast, requires as big a continuous explosion as you can make over as long a time period as possible.

I love that AI can whip up an xkcd style "What-If?" type scenario for these questions.

Humans are bad at intuiting exponents. There is roughly 200x more volume in LEO than there is between the ground and cruising altitude. Plane changes, moreover, take a lot of energy--you aren't going to get enough energy out of a collision to pollute nearby orbits.

Sure they can: Leading/trailing each other is quite common. Intersecting orbits are riskier, but also possible without inevitable collisions.

Obviously it requires a more scientific analysis but it does seem to me that burning a lot of shit on the atmosphere might be problematic.

SpaceX has loads of international launch and connectivity customers. China undercutting SpaceX would significantly compromise its prospects.

The first is that IIUC, CFCs release chlorine atoms which catalyze ozone, whereas aluminium oxide catalyzes the creation of chlorine atoms from chlorine reservoirs, which then go on to catalyze ozone. I loosely believe at this point after some sketchy research and maths that this makes it around two orders of magnitude more potent.

The second is that these particles are produced directly in the upper atmosphere. I couldn't give you a number for how much that changes things, but I assume it's nontrivial.

The final point I've noticed is that mass to orbit has been increasing at a rapid exponential rate recently, and it would not surprise me at all to soon see an extra order of magnitude on it.

Worst-case, that could change your 5,000 year figure to just a couple. I don't think it's that bad, I'm not overly concerned about this issue, but given ozone depletion is a legitimate existential threat and the numbers don't immediately make it seem impossible, I think it's worth paying attention to.

There are high-atmosphere effects we don't yet understand. RP-1 produces soot, particularly when burned fuel rich. And methalox still releases methane since again you're not burning your fuel perfectly.

But the simplicity of non-hypergolic non-kerosene rocket fuel chemistries like the ones SpaceX uses is they burn remarkably clean. You don't get a bunch of additives producing weird neurotoxins, or incomplete combustion inventing organic compounds in the high atmosphere.

(I'm ignoring cryogenic fuels, which literally produce water vapour as an exhaust because liquid hydrogen is a bastard.)

> As in, we could launch a million rockets per day with a negligible effect on the air and other environments?

No. Starship releases like 360 tons of CO2 per launch [1].

That said, nobody is launching a million rockets a day. We might get to like 3 or 4 a day in our lifetimes. Barring some novel economic opportunity in space, launch emissions are likely to remain negligble for the foreseeable future.

[1] https://www.theecoexperts.co.uk/news/elon-musk-rocket-emitte...

Has it?

Destroying the Amazon destroys information. Light pollution simply raises the cost of our accessing it. I suppose one could model this out to some effect on deep-space astronomy's productivity. But if that effect is real--and I've seen zero evidence it is--the solution is a tax on satellite launches to fund more observatories.

I strongly disagree.

If "Starship to Mars" is a possibility, then so is "Starship to the asteroid belt". It's very close to "Starship to the asteroid belt, capture asteroid, return to Earth orbit" - and that's very close to orbital mining of metals that are rare and valuable on Earth.

A single astronaut with a shovel could do more science in a couple days than all the probes combined in the last 54 years (Which have barely scratched the surface). For all we know there are literal fossils a few meters below the surface but none of our technology had the ability to even start looking.

It's something for humanity to be excited about and root for. What happened to wanting to achieve things? Having things to look forward to, build toward and be proud of is healthy for society. Must we aspire to and dream of nothing because there's suffering on earth, is that what it is? Why can't we take it as the objective good it is that we're trying to push technological boundaries that will unlock more advancements in science? In what world does HN not want that?

Apollo to the Moon was near useless by that metric. We wouldn't have Starship to orbit if we hadn't gone to the moon.

...Starlink and SpaceX are funded through investments and taxes. When they launch a non-profit's satellite I guess, indirectly, through donations, too.

Also, what? Why is the funding source a measure of value?

There is a reason these taxes are popular among rich countries and opposed by emerging ones.

Is this some AI answer or did you foobar this math by a factor of 100?

Running cables across out land is less impactful than lofting satellites?