Re: Space travel with lasers

From: Dave (noemail_at_hell.gov)
Date: 12/30/04 

Date: Thu, 30 Dec 2004 15:36:22 GMT

Slowing down at the other end never occurred to me. OTOH, star fly-bys
would seem a good place to start. You could send up a dozen probes and find
a star with a interesting planetary system, like one that has liquid water.
At that time you could figure out a way to slow down for the next trip.
Then send something more substantial there.

If looping around the sun gets you there ok. My laser or maser propulsion
now is refined. You set up a nuclear or solar powered master laser which
powers a series of mass produced slave repeaters spaced out. The slaves
have large arrays that gather the diverged beam, concentrate it, and resend
it to the next slave. In between missions, the slaves are powered in series
from the master to "recharge" them for boosting signal and maneuvering for
next mission and placing new slaves, but they are mostly passive in
retransmitting hopefully with low loss. During mission they aim beam at the
passing space probe in turn. Slaves can also serve as high powered future
space stations or data relays. Dream on thanks for cool wikipedia link and
all replies.
davef

"George Dishman" <george@briar.demon.co.uk> wrote in message
news:cqvk44$u63$1@news.freedom2surf.net...
>
> "Jonathan Silverlight" <jsilverlight@spam.merseia.fsnet.co.uk.invalid>
wrote
> in message news:YeLSWRMEyz0BFws7@merseia.fsnet.co.uk...
> > In message <cqva8u$rag$1@news.freedom2surf.net>, George Dishman
> > <george@briar.demon.co.uk> writes
> >>
> >>"Dave" <noemail@hell.gov> wrote in message
> >>news:yLFAd.4005$s66.733@newssvr31.news.prodigy.com...
> >>> Yep a series of stations is also what I dreamed up after my initial
> >>> question.
> >>>
> >>> You're right sunlight is free and gravity sucks so better yet, we fly
a
> >>> unmanned solar sail powered space station to the heliopause. It then
> >>> launches a separate interstellar space ship (equipped with several
> >>> nuclear
> >>> powered lasers to drop off as needed in interstellar space, sort of
like
> >>> boosters). The lasers themselves, lagging behind, can be accelerated
> >>> from
> >>> preceding lasers to increase their usefulness, e.g. a train of lasers,
> >>> with
> >>> each laser relatively slowly moving apart, providing cumulative
energy,
> >>> with
> >>> the lead space ship moving the fastest. Gravity noise should be much
> >>> less
> >>> a
> >>> problem out there for aiming purposes so might not need many lasers.
> >>> Eventually lasers will be lost, but massive long term acceleration
> >>> first.
> >>> Avoid Oort cloud. Counter thrust may be needed? ok?
> >>
> >>If you are thinking interstellar then the limitation
> >>is stopping at the other end. If you use the sail to
> >>stop, there are no lasers waiting for you, just the
> >>light from the destination star. By symmetry, you can
> >>get all the speed you can use by looping close to our
> >>Sun and getting as much speed as you can without lasers.
> >>You might lose a little to drag on the way but close
> >>the sail on the voyage will take care of most of that.
> >>
> > Robert Forward wrote a novel (Flight of the Dragonfly) in which the
> > laser-propelled spacecraft decelerates by dropping a ring-shaped outer
> > section which reflects light back to the inner part.
> > The novel describes a manned ship with a 1000km diameter sail,
>
> I've seen the idea as an illustration but I think
> only for interplanetary work. The problem is trying
> to get most of the power into such a small region
> when the target is light years away. The Rayleigh
> limit applies to lasers too.
>
> The only workable alternative I've seen would use
> tether cables to create magneic drag, but that assumes
> good knowledge of the magnetic field of the target star.
>
> > but he also proposed a tiny version called Starwisp. There's a Wikipedia
> > article at <http://en.wikipedia.org/wiki/Starwisp>.
>
> From that page:
>
> "At such extreme long range the maser would be unable
> to provide any propulsion, .... Starwisp would not
> slow down at the target star, performing a high-speed
> flyby mission instead."
>
> In fact with nanotech manufacture, a mesh could be made
> with the cell size less than the wavelength of light so
> it is possible we could get a significant density
> improvement over current materials though conductivity
> may be an issue.
>
> George
>
>

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