[ExI] extropy-chat Digest, Vol 90, Issue 29

Adrian Tymes atymes at gmail.com
Sat Mar 26 17:54:47 UTC 2011

2011/3/26 Stefano Vaj <stefano.vaj at gmail.com>:
> "Develop"? In my understanding, the technology was already more or less
> there in the sixties.

Proof of concept, sure.  Blueprints for a system that could be built today?
More importantly, how much of it does any private venture - or even NASA -
have ready access to today?  (Remember, it's been discovered that the
Saturn rockets could not be rebuilt today, due to loss of knowledge and
parts; you'd have to redevelop those entirely.  Same thing applies here.)

> The fuel is already stocked in strategic arsenals, and
> has already been paid for.

By agencies with no intention of using them for this venture, in forms that
are not well suited for this venture.  You'd have to buy it and reprocess it.

> And by no means you are easily taking thousands
> of tons out of the earth gravity wells with chemical rockets...

Irrelevant.  There's plenty of mass inside Earth's gravity well.  (BTW,
that's "well", singular, since you're talking about one planet.)

What's relevant is the cost of doing so.  You're far (far far *FAR*) more
constrained financially than in availability of sheer mass, so between
those two, you need to optimize for the financial angle to get best
results.  (I.e., highest chance of getting this package into space in
such a way that it can do what you want it to do there.)

If you have $100 million, and spend $40 million of that developing a
payload that's no more than 4,540 kg to geosynchronous transfer
orbit (with common rockets, that's about 2,270 kg to GEO, or a bit
more to Earth escape), the remaining $60 million can purchase a
single Falcon 9 launch.  Building, testing, and launching a nuclear
rocket would take more than $60 million, even if you got the payload
down to 1 milligram (mainly, the cost to get access to enough
nuclear fuel and the equipment to reprocess it).  Most packages of
interest would take more than $40 million to develop anyway.

There are efforts underway to drop a few 0s from the end of that -
both in cost per kg and in minimum size.  Just assuming one order
of magnitude on both sides - say you got your payload to under 200
kg, it'd cost $400,000.  One example: NASA has a Centennial
Challenge out to pay $2 million to someone who can get a 1 kg
package into orbit twice (and that's for the entire R&D program, not
just the two launches) - see

So, it simply costs more than it's worth to go nuclear if you're only
ever going to use it once.

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