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A Visionary Project Aims for Alpha Centauri, a Star 4.37 Light-Years Away

nytimes.com

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Re: A Visionary Project Aims for Alpha Centauri, a Star 4.37 Light-Years Away

#132

Post by david-given »

rm_-rf_slash wrote: post #83

Why don't we focus and reflect the sun's rays instead? Or even combine this and the traditional rocket method by putting the emitters in space to catch the sun and push these tiny craft after they've been shot from the Earth by the zillions in a single satellite. That way we deal with two big problems at once: generating laser energy sufficient for escape velocity, and focusing lasers through an atmosphere layer. Bet…

Apparently you can't collimate sunlight because it's not a point source.

But I've been unable to find an explanation as to exactly why which I can understand, because this aspect of optics is deeply unintuitive, but the magic phrase to search for is 'conservation of éntendue'. If you find one, let me know.

Re: A Visionary Project Aims for Alpha Centauri, a Star 4.37 Light-Years Away

#134

Post by david-given »

rm_-rf_slash wrote: post #85
comboy wrote: post #76

How is such thing able to communicate back with earth? Doesn't it require a lot of energy to create signal that we will be able to receive on earth (or satelite)?

Not a scientist but I first read this on The Economist and they summed it up pretty well: "At its destination it would beam back pictures of the star’s planets with its on-board laser. No current observatory could possibly pick up such a signal—but the kilometre-wide launch array should be able to. The optical systems used to meld the output of the lasers could be used in reverse as a vast and sensitive telescope." h…

I'd be kinda hesitant about relying on a ground-based receiving station. How stupid would you feel if after 40 years flight, you missed the return signal because your receiving station happened to be on the wrong side of the Earth?

Re: A Visionary Project Aims for Alpha Centauri, a Star 4.37 Light-Years Away

#135

Post by tuyguntn »

yongjik wrote: post #23

So the whole thing should weigh in the order of several grams, yet it should be able to deflect 100GW of incoming radiation near perfectly (otherwise it will instantly vaporize) while maintaining structural integrity under the acceleration of 60,000g for two minutes? And whatever laser sources we're using must track this smartphone-sized object during these two minutes across several million kilometers. Perfectly. (I…

Its not about result, its about intention.

Intention leads to results (even small)

Small results lead to bigger results (bigger resources, like more knowledge)

Bigger resource leads to greater intentions

And here is why humans are still better than DeepMind, while (true) { learn, invent }

Re: A Visionary Project Aims for Alpha Centauri, a Star 4.37 Light-Years Away

#136

Post by cb18 »

slg wrote: post #116
Carrok wrote: post #111

Earlier quoted context omitted.

Because while all we can see is the blinking light, the probe can see the things close to it far more clearly. As the above quote says the probe will "beam back pictures of the star’s planets." We can receive these pictures through the data received from that blinking light, but we can't see the planets in question. Now we can.

But why would we be unable to see the star's planets if we are able to see a probe that small?

'Seeing' the probe is like being connected to the internet.

Your friend in Japan can take a picture of an apple and email it to you in the US. Your friend's camera is like the camera on the probe.

You can't see the apple from where you are, but your computer can 'see' the internet.

Your friend uses the internet to send you a digital code that your computer turns into a picture of an apple.

The optical systems used to meld the output of the lasers could be used in reverse as a vast and sensitive telescope.

But why would we be unable to see the star's planets if we are able to see a probe that small?

The laser receiver might be able to see the planets in question, but a probe with an interstellar worthy camera in the direct vicinity of the planets would obviously be able to capture a much higher resolution image.

Re: A Visionary Project Aims for Alpha Centauri, a Star 4.37 Light-Years Away

#137

Post by civilian »

LockandByte wrote: post #69

I am a self-proclaimed 'newbie' when it comes to understanding energy, astronomy, and physics in general, but I have a few questions and any answers or opinions would be appreciated: 1.) Why in the world does the 'Light / Laser Beamer' need to be physically located on earth? Why not in space? 2.) Is building 'check-points' for both data and power atop the planets not a possibility? (Solar, chemical, etc).

For #2: What do you mean by check points? Which planets would you build the checkpoints at? When you say "atop", do you mean on the planet's surface, or in a polar orbit, or in orbit generally?
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