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The Universe Within 12.5 Light Years

(www.atlasoftheuniverse.com)
266 points algorithmista | 4 comments | 05 Sep 25 22:20 UTC | HN request time: 0.001s | source
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ghssds ◴[05 Sep 25 23:54 UTC] No.45145093[source]▶
It should be a goal for Earth to send a probe to one of those stars. As the probe will be unmaned, a mission taking a hundred years or more is not out of question.
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asdff ◴[06 Sep 25 00:26 UTC] No.45145325[source]▶
There are already plans to reach alpha centauri in about 20 years with unmanned probes (1). There still remain some technical hurdles in terms of the laser design to propel these probes afaik but it seems like this could be solved with more funding.

Too bad we are in the current era of eschewing scientific research in favor of crony politics.

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

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1. pavel_lishin ◴[06 Sep 25 01:18 UTC] No.45145670[source]▶
Something like Starshot seems like it could benefit from future developments without holding back a launch today. Something with a sail can always have a laser aimed at it; maybe we launch it today with a tiny laser we fire from orbit, and in 50 years, we accelerate them to a significantly better cruising speed by firing from a laser array on the moon.
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2. sfink ◴[06 Sep 25 18:22 UTC] No.45151637[source]▶
No, you have to zap them early. Lasers still spread out (see "beam divergence"), so you have to impart most of the momentum while they're still close enough for your lasers to hit with enough power.

Sadly, that also means you have to accelerate them hard if you want to get to a decent fraction of c before they're effectively out of range. Which means your solar sail has to be really, really tough while being really, really light.

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3. pavel_lishin ◴[07 Sep 25 18:32 UTC] No.45160912[source]▶
I haven't done the math, but if we had significantly powerful lasers, shooting from the vacuum, isn't it very possible that we could actually deliver more acceleration to a far-away probe in 20 years than we could from Earth-based (or even orbit-based) lasers right now?

I have no idea what the best-case scenario for laser acceleration is.

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4. sfink ◴[09 Sep 25 18:50 UTC] No.45186782{3}[source]▶
No.

Let's say our initial boost got it up to 0.1c. After 20 years, it's gone 2 light years. If we make our space-based laser aperture really big, let's say 1km, then the light reaching our probe is something like a 25000km wide radius. That's not going to power anything.

If you slow down the initial 0.1c, then pretty quickly you're better off not sending it out at all and getting a bigger boost from your giant space laser being close for the initial acceleration.

The diffraction limit is annoying.