[ExI] Breakthrough Starshot - To The Stars!

[Anders Sandberg]

I first thought an Oberth maneuver would not work on a sail, but it does 
- very neat.

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.

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).


On 2016-04-24 01:08, Rafal Smigrodzki wrote:
>
>
> On Mon, Apr 18, 2016 at 12:10 PM, Giulio Prisco <giulio at gmail.com 
> <mailto:giulio at gmail.com>> wrote:
>
>     Paul Gilster will post a series of reports from the Breakthrough
>     Initiative conference "Breakthrough Discuss" on Centauri Dreams:
>
>     http://www.centauri-dreams.org/?p=35426
>
>
> ### 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.
>
>
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-- 
Dr Anders Sandberg
Future of Humanity Institute
Oxford Martin School
Oxford University

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