Wanted! Your Views On America's Space Program Goals

>FYI,
>
>"Wanted! Your Views On America's Space Program Goals"
>Space.com
>casspaceprogramgoals

snip

(my contribution)

Power satellites fail on the economics of lifting millions of tons of
hardware per year to GEO. (Or the long delay it would take to build
up space industry to use extraterrestrial resources.)

Surprisingly rockets in a power satellite context are good at energy
payback, a remarkably short 40
days. http://htyp.org/Hundred_dollars_a_kg/Note_1

Unfortunately, due to the high cost of rocket hardware, even fully
reusable rockets make the economics marginal. Not to mention the
traffic model has 6000 tonne rockets lifting off every hour. (More
than twice the size of a Saturn V!)

Last year two methods that use rockets for the first stage and either
a shortened space elevator or a laser propulsion system
emerged. Rough analysis indicates either will transport a million
ton/year to GEO in the $100/kg range. The laser capital budget is
fairly well understood; 4GW laser output will cost about
$10/watt. Including a few hundred 300 ton reusable rockets, the
transport system might cost $100 billion. The rockets would lift off
four times an hour, each with 25 tons of payload. Including
propellant, such a rocket weighs less than the smallest fully loaded Boeing 747

At this transport cost, it may be possible to install generating
capacity at $800/kW. That leads to bus bar power at a penny a
kWh. Power at the low a cost can be used to capture CO2 from the
atmosphere, reduce it with electrolytic hydrogen and sell liquid
fuels, gasoline, diesel and jet fuel, for a dollar a gallon. Making
gasoline, the need for penny a kWh power, low cost space transport
methods and a way to finance the whole project without government
money are discussed in some detail at the web sites linked
here: http://htyp.org/design_to_cost

Keith Henson