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<div class="moz-cite-prefix">I first thought an Oberth maneuver
would not work on a sail, but it does - very neat. <br>
<br>
The effective delta_v is the impulse multiplied by sqrt(1+2V_esc /
delta_v). This shows why this strategy may not be effective for
the final burn: if you want to have a delta_v much larger than
solar escape velocity (a measly 50 km/s) then the factor will be
close to one. <br>
<br>
Accelerating the sails to a high initial velocity and then turning
on the main burn laser still saves you some energy, but since you
want to feed in many orders of magnitude more velocity all of this
is a minor improvement at the cost of extra complexity (=more
things can go wrong) and distance (=laser dispersion losing you
power). <br>
<br>
<br>
On 2016-04-24 01:08, Rafal Smigrodzki wrote:<br>
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<blockquote
cite="mid:CAAc1gFj-JwdPHmiGNTwoq+J071kedtXOEPpizXAAgoUQDX4umA@mail.gmail.com"
type="cite">
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<div class="gmail_quote">On Mon, Apr 18, 2016 at 12:10 PM,
Giulio Prisco <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:giulio@gmail.com" target="_blank">giulio@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">Paul
Gilster will post a series of reports from the
Breakthrough<br>
Initiative conference "Breakthrough Discuss" on Centauri
Dreams:<br>
<br>
<a moz-do-not-send="true"
href="http://www.centauri-dreams.org/?p=35426"
rel="noreferrer" target="_blank">http://www.centauri-dreams.org/?p=35426</a></blockquote>
<div><br>
</div>
<div>### I am wondering if it makes sense to do the
following: Have a number of space lasers positioned
throughout the solar system. Build the spaceship somewhere
far out, like the asteroid belt or in the rings of Saturn
(lots of free-floating mass to eat there). Start boosting
towards the Sun, using increasingly more powerful lasers
(because closer to Sun means more energy to feed them),
let the spaceships skim the Sun for a bit more
acceleration, and then continue boosting on the way out of
the Solar system. You could move stuff pretty fast this
way. </div>
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<br>
<br>
<pre class="moz-signature" cols="72">--
Dr Anders Sandberg
Future of Humanity Institute
Oxford Martin School
Oxford University
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