Subject:
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Re: Where's all that gravity coming from?
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Newsgroups:
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lugnet.space
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Date:
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Thu, 8 Mar 2001 22:42:31 GMT
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Viewed:
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494 times
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>
> Ouch.
>
> And yes, this is all ignoring Officer Einstein's interstellar speed limit.
>
> Steve
My figures (hasn't this been done in off-topic already?)
note: 3e8 is 3 * 10^8 or 300,000,000
Proxima Centauri - about 9 ly away
1 year = 31557600 seconds, or 3e7 s
c = 3e8 m/s (speed of light)
1 ly = 3e7 s * c
d = Proxima Centauri = about 1e17 m
Simple acceleration:
a = 10 m/s/s (about 1g)
d = 0.5 a t^2
1e17 m = 0.5 * 10 m/s/s * t^2
Solve for 1/2 the distance (half trip)
t = sqrt( 1e16 ) = 3e8
So time in seconds gives about 10 years to reach halfway at acceleration 1g
At that point you'd have picked up velocity of 10c, clearly impossible; but
having
reached the halfway point in 10 years you could zoom through Centauri in
just one
more year! You'd be arrested in Centauri for violating galactic speed
limits, or worse.
But suppose you limited your velocity to 0.01c or 3e6 m/s you need only 3e5
seconds of
acceleration or about 3 days.
During that time you'd travel 5e11 m or about 3 AU's
1 AU = about 1.5e11 m = radius of Earth's orbit around Sol
If you could get 1g of acceleration for a breath-taking 3 full days you
could visit
anywhere in the inner planets in a week or so. However your spacecraft can't
carry that
fuel mass... take the local, not the express.
Anyway, at that speed it's about 1000 years to Proxima Centauri.
I think the typical Bussard interstellar hydrogen scoop becomes effective at
that speed
(0.01c) so you would continue to accelerate, picking up fuel as you go.
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Message has 1 Reply:
 | | Re: Where's all that gravity coming from?
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| (...) We talked about a similar trip to Mars awhile ago (it was 40 hours, I think). (...) Actually, Proxima is 4.22. But we'd be more interested in Alpha Centauri A and B, which are 4.35 ly distant. (...) d(A&B) = 4.35 ly = 4e16 m (...) sqrt(4e16 / (...) (23 years ago, 9-Mar-01, to lugnet.space)
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Message is in Reply To:
| | Re: Where's all that gravity coming from?
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| In lugnet.space, Damraska wrote: [snip] (...) [snip] Here's another problem: with the conventional approach of acceleration via some propulsion, artificial gravity is not your problem. The real problem is shedding the excessive G's. My numbers could (...) (23 years ago, 8-Mar-01, to lugnet.space)
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