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They don't need to keep exact position; they just need to know their relative distance offsets from Earth to synchronize pulses.

They can do some work to keep station; the idea is that by adjusting attitude, they can adjust the magnitude and direction of their drag vector.

https://arxiv.org/abs/2309.07061

It's absolutely infeasible with current technology, but it doesn't look like it's total unobtanium.

I agree. Sounds like the plan is to have the signals from each probe add up coherently, which means the laser pulses need to be coherent with each other. The wavelength of optical light is 100s of nanometers, so that is the level of precision required spatially, relative to the much much larger probe spacing that they quote. This (plus the required temporal coherence) is probably not possible without the probes actively locking their lasers to each other, but now each probe needs the optics to send and detect the optical signal from at least its nearest neighbors. I can't say if this is impossible given the weight restrictions, but it sounds rough.

Can you say relativistic corrections hell? "Over lightyears" means it takes literally years for these things to coordinate moves with each other, to say nothing of post-launch coordination messages from Earth.

> "Over lightyears" means it takes literally years for these things to coordinate moves with each other

The swarm ends up around 100,000km wide. Initial distances are longer, but never on the order of light years.

Yeah, I think he missed the part where it discussed the swarm would have to be mostly autonomous since communicating back to earth for any sort of management commands is completely out of the question.

It's amazing they can still do it with voyager which is roughly 24 hours for one way traffic, 48 for round trip.

I'm not sure "swarm over interstellar distances" makes any sense here, then. How many stars are within 100,000 km of each other and what percentage of stars does that represent?

The idea is, you launch a large number of probes, accelerated one by one, working so that they'll arrive at the same time to the same star (Proxima Centauri). If you lose a bunch, no problem.

They'll be spread out over a big distance, but team up to do imaging and to return data from that star.

> They'll be spread out over a big distance

Compared to the distance that you'd go to get a coffee, yes. Compared to the distance to Proxima Centauri, oh hell no. Compared to that distance, they travel as a pack.

There's about a "402 million to 1" ratio between the two distances, 100 000km size of the swarm vs the 40,208,000,000,000 km distance to Proxima Centauri.

https://imagine.gsfc.nasa.gov/features/cosmic/nearest_star_i...

A swarm 100 000km wide could in its entirety pass between the Earth and the Moon with room to spare.

https://www.nasa.gov/wp-content/uploads/2009/07/180561main_E...

Yes, of course. We all know these numbers. I teach a space engineering class where students chirp out in recitation "400km to LEO, 40,000 km to GEO, 400,000 km to the moon". The degree of "well acktually" trying to be pedantic here is unnecessary.

If a swarm of bees goes a couple of miles away, they don't spread out over a couple of mile distance. They are a relatively tight pack that then goes to the new place and then converges to be quite small. That's the same as what this mission is.

100,000 km is quite small as far as interstellar distances are concerned, but quite big as far as an aperture for distributed imaging or beamforming (and for avoiding hazards that are hard to see beforehand). The latter, of course, is what actually matters.

My apologies, I was not trying to be pedantic or to correct you. It's for other readers too and does not contradict, really.

FWIW, I looked up those numbers because I do not have them memorised. The typical reader here seems even less informed than that, and they would benefit - I don't think that "we all know these numbers".

Seems like I should be the one apologizing; it's hard to know tone online, and I thought you were trying to assert it wasn't a swarm like the other people. Sorry about that.

(P.S. they're not the right numbers; just the right orders of magnitude).

> How many stars are within 100,000 km of each other and what percentage of stars does that represent

That's less than half the distance from the Earth to the Moon, so leaving binary star systems to one side, the answer is none and zero.

A large asteroid passing 100,000 km from the Earth is a considered a near miss in my book, since it's easily cislunar.

But you're missing the point entirely; parent is saying that individual craft in the swarm are within that distance of each other - that's the diameter of the swarm; the line "The swarm ends up around 100,000km wide" gives that away.

The distance between stars is orders of magnitude larger. "the swarm" crosses interstellar distances and communicates back as a whole. But communications between elements of the swarm do not and cannot cross that distance, they have to stay quite close to each other, e.g. within 100,000 km as they cross the void together.

You're missing the point entirely: framing the swarm as "covering interstellar distances" is misleading and betrays a certain naivete in thinking about space travel that compromises the reporting on this plan.

> You're missing the point entirely

I think not.

> "covering interstellar distances" is misleading

It can be read in 2 ways yes (is the interstellar distance crossed by the swarm who do that together, or does the radius of the swarm encompass interstellar distance) but it's clear which one is intended. Again, "The swarm ends up around 100,000km wide" tells you which one it is. Non-naïve people know or look up that 100,000km is not even an interplanetary distance, let alone an interstellar one. It's relatively tightly bunched when crossing the 40,208,000,000,000 km to Proxima Centauri. Yes I look this kind of thing up.

> a certain naivete in thinking about space travel that compromises

Don't be absurd.

Is this the same argument you proffer every time clickbait language is used?

Bees swarm over distances of miles. But the swarm doesn't stretch out miles. They form a dense group that moves somewhere miles away.

Ships _spread out_ over 100,000km will literally cover interstellar distances as a swarm by _traveling to another star_. That's the whole point. A bunch of insects can swarm a thousand km from the time it forms to when it breaks up, even if the swarm itself is never more than a couple of km in diameter.

station keeping is definitely possible. each craft could use its comms laser for impulse