[ExI] Rocket rant

[Keith Henson]

(Tagged on a discussion of spending less than NASA for space craft)

Unfortunately, I don't think any chemical only rocket can get the cost
to GEO down to where power satellites make sense.  Only 1.3% of a
Falcon Heavy makes it to GEO (19 tons out of 1440).  Skylon, because
it burns air a quarter of the way to orbit, gets 6 tons out of 300 to
GEO (2%)

At high traffic rates, Falcon Heavy might get down to $1000/kg and
Skylon to $350/kg.  I can imagine 3 Skylon takeoffs per hour.  I
cannot imagine launching 3 Falcon Heavy per hour.  If power sats must
have $100/kg to make economic sense, then neither one of them will do
it.

However, using laser-heated hydrogen, a 125-ton Skylon variation can
deliver 25-30 tons to LEO and 18 tons to GEO.  That's 15%.  Cost is
less than doubled by the investment in lasers while payload fraction
goes up by 7-8 times.

The front-end investment is over $100 B; it makes power plants cheap
enough to sell the power at 1-2 cents per kWh.  The demand is
certainly there at $1.6 B/GW, 1/5th the cost of a GW nuclear plant.
Demand at such a low cost would permit very rapid growth, to one or
two TW/year.  At that rate, power sats would end human dependence on
oil and coal within two decades from the start.

Keith