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Comment by yawz | Hacker News Reader

> If we would create a spacecraft right now, we could only reach about 200 km/s, which translates into 6300 years of travel. Of course technology is getting better with time and by the time a real interstellar project will be created, we can expect to have improved the duration by one order of magnitude, i.e. 630 years. This is speculative as technology as yet to be invented.

This is the dilemma that should make us really consider and possibly wait for the right technology. Otherwise it is quite possible to arrive to destination and find it populated for millennia.

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There have been at least a few SF stories built on that premise. It's driving me nuts that I can't recall which they were.

In Homesick by Lyn Venables the first interstellar crew arrive home and find that people have been lapping them for 30 years.

That’s 1952. Probably it was already a trope by then...

Alistair Reynold's Revelation Space universe explores this, often times with sub-light travelers arriving at what they thought would be one of the largest cities in known space only to find it devastated by a plague. More relevantly, the book Chasm City, set in this universe, explores a set of generation ships competing to arrive first at an uninhabited planet.

I think Allen Steele's Coyote series features this, but I can't seem to find any reference to it. (And I no longer have the books).

Kim Stanley Robinson's Aurora comes to mind, as it explores similar ideas to the study. The featured generational starship suffers from a deteriorating biome due to inbreeding and loss of nutrients, and the book also explores the effects of disasters and politics on the viability of such a journey,

I think Samuel R. Delany's "I was the first to find you" dealt with that, but it had the twist that the newer explorers knew about the previous ship that was still on the way and went looking for them.

... or not. It's been at least 15 years since I read it.

In addition to the already-mentioned Chasm City... Into the Sea of Stars by William R. Forstchen comes to mind. Generational ships take off from a dying Earth. The Earth recovers and faster-than-light technology is eventually developed. The FTL ships are tasked with tracking down the generational ships.

The problem there is that if you wait for the right technology to appear, it may never happen, because all of the effort and resources that would’ve been put into researching and manufacturing engines for interstellar ships would’ve instead been put into something else. There’s still a chance that we stumble upon the right tech anyway, but the chances are greatly reduced and even if we do, it’ll likely be far later (centuries even) than it would’ve been had we been had we actively been developing said technology.

From my perspective, it makes more sense to risk obsoleting previous missions and send ships as soon as it’s possible to do so because it’s a far better outcome than waiting for tech that never came and never sending a mission at all.

> This is the dilemma that should make us really consider and possibly wait for the right technology

If one is thinking from a species planning perspective, the question is an interplay between the (a) development of propulsion technology and (b) propensity for our species to annihilate itself. Given (a) and (b) are intrinsically related, there is likely an elegant solution.

I wonder what would happen if people launching later decided to pick up the people who launched earlier. Like they’re headed towards the same destination anyway, following the same general intergalactic line. Sure finding a ship in space is like finding a needle in a vast vacuum but maybe their ships would emit enough radiation for their “scent” to be traceable. And if picking up other traveler isn’t important enough to warrant a pit stop, maybe the ships that left earlier would have valuable information for the ships who leave later on.

Doesn't this assume you can slow down and start back up/get back up to speed arbitrarily?

I can't understand why 200km/s would be the cutoff. Couldn't we build a spaceship around nuclear reactors and accelerate far beyond that?

200 km/s seems an order of magnitude high to me for "today's technology". The Voyagers and New Horizons have an escape velocity of around 20 km/s. Isn't reaching escape velocity the metric you want here? You want to leave the solar system after all.

Parker Solar Probe his 200 km/s in orbit around the sun.

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