[ExI] Spacecraft (was MM)

[Eugen Leitl]

On Sun, Jan 02, 2011 at 06:19:32PM -0800, spike wrote:
> 
> ... On Behalf Of Samantha Atkins
> ...
> 
> >...One nice thing about these big laser beams to orbit is they could
> accidentally or on purpose de-orbit a lot of space junk that has accumulated
> there.  :)
> 
> I don't follow you there.  Suppose you hit a dead satellite with a laser.
> Now you may cause some pieces to break off, but that doesn't actually
> deorbit anything.

Presumably, the laser would make the target hot enough to cause
asymmetric ablation, which can be used to lower the orbit until
it decays spontaneously.

It's admittedly far more likely to break the thing up into multiple
debris, and thus exacerbate subsequent cleanup (IIRC there are
plans to use a carbon mesh on a tug to collect debris). Wonder who's
going to pony up the cleanup costs?
 
> >...  Hmmm.  Perhaps a decent feasibility test is to do some such target
> shooting...
> 
> We have the control systems adequate to do this now.  But it isn't clear to
> me what would be accomplished, other than create a huge mess of orbiting
> debris.

It'd be better using a maglev launch to ~Mach 1 or higher at 6 km
height and subsequent tracking by a battery of multiple 1 MW
lasers. If that doesn't work, you can still use a conventional
rocket, or a scramjet/rocket hybrid.
 
> >... Of course there would me a major international uproar over such...
> 
> Ja I can imagine that.  We currently have a big problem with our LEO
> satellites gradually losing power from solar panels getting pitted by 10 to
> 100 micron class debris.  Shooting dead satellites with a laser would make
> that problem waaay worse I fear, and the US has more to lose than anyone.

The amount of debris out there is getting out of hand. IIRC the
recent space plane got hit by at least 9. If this continues, this
will impact manned spaceflight and extravehicular activities
especially. You'd also need armoring, which will increase weight.
Some orbits, or whole orbit ranges would become off-limits.
And people could start salting orbits with tungsten or uranium
balls as celestial terrain denial.

-- 
Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
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