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teehuis t1_jd6hnt6 wrote

Isn’t that like hundreds of thousands of years away from us at our current space travel rate?

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The_Solar_Oracle t1_jd6jkq0 wrote

Excluding the fact that we can certainly make faster probes, the study of habitable exoplanets is not and never has been contingent on the ability of people to visit them. We can still gather data and that data is still useful.

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danielravennest t1_jd90e6s wrote

In particular, the Sun is a gravitational lens. If you travel about 800 AU in the opposite direction from Alpha Centauri, you can look back and see what is there in great detail, because the lens is 2 million km in diameter. One reason to be that far out is to make it easy to block out the Sun itself, including prominances and the solar corona.

Centauri is 276,000 AU, so using the Sun is a lot easier mission.

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imapassenger1 t1_jd6nnmh wrote

A mere four light years, our nearest neighbour. So at least messages will only take 8 years round trip. There was some recent speculation about a type of probe potentially capable of velocities up to 1/4c as I recall but I can't recall the details.

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shreddor t1_jd6nvys wrote

Dude I had no idea that radio waves etc would travel at the speed of light in a vacuum. Very cool.

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skydivingdutch t1_jd6xuxd wrote

Radio waves and light are both the same electromagnetic radiation, just different energy levels.

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rocketsocks t1_jd6vwz2 wrote

Nobody will ever be able to visit ancient egypt, time machines would break the laws of physics, but that doesn't mean there's no value in studying it.

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danielravennest t1_jd8zgzp wrote

Current technology is nuclear reactors and electric propulsion. We can feasibly get to 300 km/s with multiple stages. That makes Alpha Centauri 4250 years away.

But due to the "arrival paradox", a trip that long doesn't make sense to try. Assuming technology will keep improving, a later ship with better technology will be faster, and pass the older, slower ship before it arrives. Consider what our technology was like in 2,200 B.C. (4250 years ago).

Only if technology reaches a dead end, or the trips are short enough to not be passed before arrival (perhaps 50-100 years) does it make sense to try.

Our tech is already good enough to travel about 3 times the speed of the Voyagers, and catch up with them about the time their power gets so low we lose contact. If we really wanted to we could do that. We won't, since there are better and closer missions we can do instead.

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teehuis t1_jdakp4w wrote

But how do we control these at such great distances since it takes Looooooong to get a signal back and forth. Like a couple minutes delay is a bit different from a couple months delay

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danielravennest t1_jddsu44 wrote

You don't. You program them ahead of time. We rarely send commands to the Voyagers any more. They are a light-day away. Mostly we just point a Deep Space Network dish at them at the expected time, and collect the data.

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