Jones Beene wrote:
I would like to know how much mass of propellant a rocket would
require to launch from earth to orbit, and from earth to Mars.
Not all that much - if you do not carry the propellant into orbit !
- but instead adapt the power source to Bussard's nuclear ram-jet
idea.... where you collect the propellant in the ionosphere.
Okay, that takes care of earth to orbit. How about orbit to Mars?
A similar approach would be a conventional jet engine lifter to bring
the vehicle high into the atmosphere before rockets alone carry it to
orbit. In other words, a gigantic version of the Rutan SpaceShipOne design.
Of course I would prefer a space elevator, but for oversized packages
one might want a large earth-to-orbit vehicle.
I do not see much point to a large vehicle that can go from the
ground on earth all the way to Mars. Maybe earth to moon would be
practical (especially with 1 G constant acceleration), but the 20,000
DWT freighters I have in mind would transfer freight and passengers
at an orbital station or on the moon.
Getting back to earth is another problem. One of the biggest problems
with the Space Shuttle is the excessive wear and tear on reentry.
That is to say, using atmospheric friction to slow down. It would be
better to slow down in space with retro rockets and then land more
like a VTOL, more or less straight down, with rocket engines to break
the fall, as it were. The big space-bourne 20,000 DWT earth-to-Mars
vehicles would never re-enter. They would be disposed of on the Moon
or Mars. I suppose they would never take off in the first place; they
would be assembled in orbit or on the Moon.
But then again - why not use the dollar resources (if they were
available) to perfect Bussard's boron/proton small ICF Fusor design . . .
I do not know how close that is to practicality. Some of the high
temperature CF reactions such as glow discharge may become practical
sooner. But in any case, I meant cold fusion in the broadest sense;
i.e., fusion-colder-than-conventional- plasma-fusion, which would
include Bussard's work.
. . . what would be the comparative advantages of LENR in this
application over warm fusion (the ICF Fusor) ?
None. But suppose only CF is made practical, and the temperature is
limited to, say, 1000 deg C. I suppose that would call for a two- or
three-stage approach, starting with heat to electricity.
- Jed
