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RE: More nuclear propulsion...
Years ago,
Robert Heinlein, an author of speculative fiction with a surprising record of
foresight/prediction, opined that the first practical application of fusion
would be spacecraft. In his analysis, he included transit times for
continuous boost spacecraft, and Mars was about a week's travel
time.
If I recall
correctly, the analysis can be found in the book "Universe" and its updated
re-release "Expanded Universe"
Dave
Neil
Hmmmmm,
This is
from: jpreisig@aol.com
.
Howdy Radsafe people... Hope all
is well in your neck of the woods.
So, I
guess we (the USA) are down to 3 (???) space
shuttles.
I guess it is time to build 3 to 5
new space shuttles, or whatever
spacecraft
NASA is proposing to build next. I suppose we (the USA)
can
build these spacecraft over the next 5
or 10 years. Let's use existing
technology to improve the next set of spacecraft. Existing shuttles
are
10 to 20 years old??? How many
flights should a shuttle make, before it
is
retired from the fleet???
Dr. Cohen is
pretty correct. Nuclear propelled spacecraft need never
get
close to Earth again, after they are
launched the first time. We could have
spacecraft that bring materials up to the space station (or the
moon???)
and then have nuclear-powered
spacecraft that go out into space
from the
space-station or moon. Maybe someday we'll even do
nuclear
refueling at the space
station.
I'd prefer a nuclear propelled spacecraft based on fusion, but
fission
propelled spacecraft may have to do
for now. The US fusion community
has
just jumped back into the ITER fusion program, funding-wise, with
a schedule lasting another 10-15
years. I may be quite old before we
see
any commercial fusion energy. The
US is also continuing to fund
existing
fusion programs (NSTX at Princeton's Plasma Lab, etc.
---
see their
web-site).
I guess some of my crude calculations (described on radsafe)
resulted in nuclear propulsion-based
one-way trip times to Mars of about
one or
two weeks. So, in a total time of one month (trip to Mars), how
much Cesium, Strontium (fission fragments,
etc.) does one create by
fissioning U-235 or
Plutonium??? Not very much, I'll bet. So much
for
any big hazard, if one doesn't run the
reactor all that often, and if one
refuels
periodically.
One big aspect of nuclear propulsion that is being somewhat
ignored,
is that nuclear propulsion gives
one available energy (and power) to
give
improved (and more-controlled) flight (dynamics)
performance.
A spacecraft (with nuclear
propulsion) re-entering the Earth atmosphere
and experiencing difficulties might (with some warning) be able to go
back
into space, and perhaps wait for a
rescue
shuttle.
Clearly, one might not get 1000 times more energy from
nuclear
propulsion (over chemical systems)
but a factor of 5 to 100 might be nice.
Maybe that is too much available energy, but nuclear
propulsion
systems will have energy
(inefficiency) losses also. I am very sorry
to
to hear of the recent lost
shuttle.
In other news, Brookhaven National Laboratory has a new director
---
see their web-site for details. A
chemist (Ray Davis), formerly at
Brookhaven, won
the Nobel Prize (in Physics --- with several other
people)
for his work in cosmic ray research.
The people at RHIC (the Relativistic
Heavy Ion
Collider at Brookhaven) are now colliding deuterons with
Gold.
There is a link on BNL's Main Web-page to
see how AGS/RHIC is
running. Some of the
experiments at RHIC are PHENIX, STAR, BRAHMS,
PHOBOS, etc. The BNL web-pages have links to the web-sites of
these experiments. Browse at
will???
Have a good
weekend....
Regards,
J.R. Preisig,
Ph.D.