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Comment by drorco | Hacker News Reader

Pretty cool exercise.

I wonder why governments are concerned over military use with this technology. If anyone wanted to bring a satellite down, wouldn't it be easier to just blow it up with a projectile/hack it/jam it/laser it? The military option of developing a complicated satellite robot to push satellites off orbit sounds stupid.

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The military implications are likely less about de-orbiting & more about in-orbit docking and manipulation expertise.

IMHO, space is big + satellites are hard to track, if they're highly-maneuverable or designed to be stealthy = possibility of launching untracked microsatellites that couple with space assets and wait for activation

Critically, add in the fact that most space-based assets are likely several years, or even decades old, and designed to minimize mass, and I'd hazard almost no satellites have on-board sensors designed to detect approaching objects.

Consequently, the first signal you get is when your satellite goes dead or tracking telemetry shows it moving without command.

Which is vastly sneakier than a huge IR bloom from a known missile site for an anti-satellite missile launch (that also happens to look like an ICBM launch).

Edit: For precedent, Red Storm Rising (1986, Tom Clancy & Larry Bond, back when Clancy wrote more hard military thrillers and wasn't yet a name brand) discusses a then-current conflict between NATO and the USSR that features Soviet grappling satellites quietly taking out NATO space assets as part of a surprise first strike.

> IMHO, space is big + satellites are hard to track, if they're highly-maneuverable or designed to be stealthy = possibility of launching untracked microsatellites that couple with space assets and wait for activation

From what I've read, I understand it to be more of the opposite: there's nothing to hide behind in space, and NORAD and NASA track nearly every piece of debris in orbit, not to mention satellites. So it would be hard for an adversary to do anything like that sneakily, even if there might not be any countermeasures (unclassified ones, anyway). I'm no expert, of course.

Everything that reflects radar... most space junk isn't trying to hide, nor manuevering under power.

The security model for satellites has historically been one of assuming physical access was effectively impossible. With technology like this that assumption is going to evolve into needing to consider protections against tampering where physical access is possible.

The primary issue with space weapons is space is big and stuff is moving in insanely quickly. Current anti satellite weapons don’t need to enter orbit they basically stand in front of one and get run over. That works for a single satellite, but the side effect is debris from such collisions may end up taking out your own satellites.

Yanking a satellite out of orbit avoids such collateral damage. Any practical weapon would need a lot of deltaV but Ion drives plus solar panels could be enough.

You could, but the missiles would generate debris on impact. They could also be intercepted in some circumstances.

Instead if you position a bunch of "service" and "maintenance" satellites that are conveniently in orbits near enemy satellites (in terms of delta-V) then basically get to prestage the entire event before war actually breaks out.

There are plenty of satellites that basically spend time "near" unfriendly nations satellites. This is mostly for counter-intelligence as far as I can tell.

To disable an enemy satellite quietly one theory I heard was to simply carry a can of black spray paint aboard, then use it to coat the enemy satellite when you want to disable it. Anything optical would be disabled immediately. The satellite would probably overheat because the reflective coating would be gone.

That spray paint idea is very interesting.

I imagine you could get some very extreme temperature differentials with a good paintball shot in the right location.

Good point. A paintball is simpler and easier than a spray can anyways. As a bonus, if it hits something weak it will probably destroy or damage that component in the process.

Probably too energetically intense, but what if it pushed a junk satellite into one of their military satellites?

Also, there have been rumors that a number of ‘dead’ satellites are actually spy satellites using the ‘dead’ status as cover, which maybe this could make no longer tenable with some plausible deniability?

If you're a country with your own satellites, most ASAT weapons are a problem because they create debris that hinders your own operations. Countries like the US also have their own satellites that can immediately detect terrestrial missile launches, so you don't have much in the way of plausible deniability. While the launch of your space-tug would still be tracked, it's a little bit more obfuscated since you can launch months or years before you maneuver into position.

Once you're close enough to interact with a satellite, you can also visually inspect or even retrieve it, which might yield useful information.

You can’t shoot down very many satellites until you poison the orbits with debris that knocks out all satellites.

If you can grab and deorbit a satellite, you can also grab it and steal it to learn its secrets.

Plus they're loaded with really good materials. I know little, but one example is gold in the welds--for satellites, and only for satellites, some contact or weld is done with 80% gold, 20% tin, which is the best for corrosion, some special qualities. Also heat foil is solid gold.

But only on satellites.

You’re right about some of the contacts, but the foil on the outside is similar to mylar, a plastic-based aluminised film.

https://www.nesdis.noaa.gov/news/good-gold-are-satellites-co...

Well a McLaren talked about using gold foil on the inside in its cars, because it was efficient according to some metric and was used in aerospace.

I highly doubt all satellites since 1957 used the same material, and further that it's that easy to find out what it is.

But I believe you, I bet that's a common foil they typically or even uniformly use for a lot of things.

I think you're referring to McLaren lining their engine bay with a thin layer of gold? The use case here was very good heat transfer with low weight, since you only need a very thin layer to do it. "Aerospace" is unfortunately a word that is overused by PR departments because it sounds flash. "Aircraft-grade aluminum" is the main one. It's a meaningless word because it just means some particular alloy of the metal.

The difference is that here McClaren wants to transfer heat via condution very efficiently. In space you can't do that because everything is in vacuum - condution is very inefficient. So the way you get heat in or out is via radiation, and that means the Sun is a problem. The films around satellites are designed to reflect sunlight. The gold in there is probably kapton, or something very similar. Polyimides were developed by DuPont in the 1950s and in the 60s they came up with Kapton which is now ubiquitous in electronics (flexible PCBs for example). Kapton was used on the Lunar Module (and other bits):

https://apollo11space.com/apollo-11-kapton-foil/

Some of the best-in-class films today are manufactured by a company called Dunmore. They made insulation layers for Hubble, Curiosity, JWST and some other high profile missions. All these companies do defense contracting so they probably make films for spy satellites as well.

https://www.dunmore.com/industries/insulation.html

Thank you very much, that is the knowledge I wanted to communicate.

Astronaut's helmet visor is another one.

The debris could pose a danger to their own satellites.

Plausible deniability.

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