[extropy-chat] MARS: Because it is hard

[Eugen Leitl]

On Thu, Apr 15, 2004 at 09:01:55AM -0400, Dan Clemmensen wrote:

> Sorry, I assumed everybody would get the joke. I was too subtle. Next time I
> will add a smiley :-)

I'm kinda swamped, so I'm processing my backlong in a nonlinear sequence.
Bound to miss subtleties that way.
 
> Same problem:-) Yes, "ELLO"is surface-skimming, ignoring the odd mountain.

The Moon is anything but a featureless ball, unfolding and starting climbing
up with some ~N push takes forever, some packages will be duds and will fail,
so some insert randomization will be required, there are safety margins which
are several km with current LEO sats, etc.

> As I said, at these accelerations and distances, surface maglev and 
> launch/land
> systems are effectively identical. By adding minor inductive steering 
> systems
> at the fast end, you can safely hit any spot on a fairly wide belt from 
> any other spot
> in the belt. On the other hand, since each "station" is 150km long, we 
> don't really
> save much over a continuous track.

This strikes me as too long. It shouldn't take 150 km of rail accelerate some
few 10 kg to LLO.
 
> In another post you mentioned tall ramps for long launchers. I don't 
> think this
> is correct. The launcher simply follows the surface curvature of a 
> sphere to put
> a payload into ELLO. Of course. we want to pick a spot where that 

A little ramp will be required on the tail end; because it's not ELLO but LLO
(ELLO+X).

> perfect theoretical
> sphere terminates at the edge of a tall plateau overlooking a vast 
> lowland to give the
> payload a chance to raise its ELLO before it intersects the 

No time for that: you'll pass overhead again before you've unfolded fully,
and fired up the thruster. It might make sense to track the packet with
phased-array microwave initially to provide it with enough power on the
beginning so that it can start climbing rapidly.

I don't know of a good way to get rid of duds. Let the orbit decay? Vaporize
them? Intercept them with taxis?

> non-theoretical lunar
> surface. and of course you would add a small vertical component near the 
> end of the
> launch.

I didn't mean a tanget to Luna surface when talking ramp.
 
> Reminder: for any launch speed below lunar escape velocity, the payload 
> must be accelerated
> again after it leaves the surface. Otherwise, it will intersect the 

Hmm, sounds like it might make sense to use a pretty high ramp at the end
after all.

> surface before it completes
> one lunar orbit. I'm assuming an ion drive can provide sufficient 
> acceleration. If not,we will

Processing lunar materials will generate plenty of oxygen as waste product.
You could use pressurized oxygen to provide initial push. I'm not sure how
fast you can unfold solar/rectenna panels, or a sail (microwave pushed from
below).

> need to arrange for a space-based "catcher," or expend payload mass. 
> (Yes ions are technically
> mass, but you know what I mean.)

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