Nuclear justification for manned spaceflight

Given the desire to use nuclear propulsion for deep space exploration
(i.e. VASIMR, Mars 1986, Mars 1994, etc.), but the danger of
uncontrolled re-entry of radioactive materials ( see Cosmos 954),
maybe all nuclear reactors in LEO should be put there by manned
vehicles, reside on manned platforms, and be manually controllable.
Always having a "man-in-the-loop" provides the same type of additional
safety margin that pilots give to commercial planes.

On May 4, 9:55*am, wrote:
Given the desire to use nuclear propulsion for deep space exploration
(i.e. VASIMR, Mars 1986, Mars 1994, etc.), but the danger of
uncontrolled re-entry of radioactive materials ( see Cosmos 954),
maybe all nuclear reactors in LEO should be put there by manned
vehicles, reside on manned platforms, and be manually controllable.
Always having a "man-in-the-loop" provides the same type of additional
safety margin that pilots give to commercial planes.

A thorium reactor is failsafe, unless it lands directly on your office
or home.

However, within the Earth-moon L1 (Selene L1) it's 97% of the time
getting 100% solar illumination, plus half the time a healthy amount
of lunar IR to work with (combined we're talking 100+ TW), not to
mention dipole energy with that moon connected at one end. So, who
who the hell needs an orbiting reactor?

~ BG

wrote in message
...
Given the desire to use nuclear propulsion for deep space exploration
(i.e. VASIMR, Mars 1986, Mars 1994, etc.), but the danger of
uncontrolled re-entry of radioactive materials ( see Cosmos 954),

That was not a terribly good design because the radioactive materials
weren't contained in such a way that they could remain intact during reentry
(which is done with all US RTGs and the like).

maybe all nuclear reactors in LEO should be put there by manned
vehicles, reside on manned platforms, and be manually controllable.
Always having a "man-in-the-loop" provides the same type of additional
safety margin that pilots give to commercial planes.

Given all of the manned space accidents (fatal and non-fatal) what makes you
think that requiring a "man in the loop" is going to make much of a
difference in safety?

Jeff
--
"Take heart amid the deepening gloom
that your dog is finally getting enough cheese" - Deteriorata - National
Lampoon

Given all of the manned space accidents (fatal and non-fatal) what makes you
think that requiring a "man in the loop" is going to make much of a
difference in safety?

Jeff

It's true that plane crashes still happen despite pilots in the
cockpit. However, pilots are ulimately responsible for the safety of
passengers and usually pay with their own lives if they screw-up.
This gives many passengers the confidence necessary to board planes.

In the case of nuclear reactors in space, the concern with an
uncontrolled re-entry is causing an international incident and an
environmental disaster costing billions to clean-up. Having people
with hands-on control at all times would go a long way toward giving
governments the confidence to allow spaceborne reactors in spite of
the risks.

wrote in message
...
Given all of the manned space accidents (fatal and non-fatal) what makes
you
think that requiring a "man in the loop" is going to make much of a
difference in safety?

It's true that plane crashes still happen despite pilots in the
cockpit. However, pilots are ulimately responsible for the safety of
passengers and usually pay with their own lives if they screw-up.
This gives many passengers the confidence necessary to board planes.

Irrelevant. We're talking about spacecraft, not aircraft.

In the case of nuclear reactors in space, the concern with an
uncontrolled re-entry is causing an international incident and an
environmental disaster costing billions to clean-up. Having people
with hands-on control at all times would go a long way toward giving
governments the confidence to allow spaceborne reactors in spite of
the risks.

So you're ducking the current safety record of manned spacecraft and
changing your argument that having a man in the loop would somehow inspire
confidence in other governments. I find this argument weak. NASA has
launched plenty of unmanned (and manned) spacecraft with nuclear RTG's on
board and despite the protests of a few nutjobs that don't understand the
engineering behind the nuclear RTG's, there really aren't problems with
convincing other governments that the US knows what it's doing.

One final thing you're ignoring. No one would launch a space based nuclear
reactor "hot" because of the problem of cooling it, among other things.
Prior to that the nuclear fuel could reside in similar reentry/impact proof
containers used by existing RTG's (scaled up of course). You'd only
activate the reactor in space where it would be safe to do so. for
something like a reactor for a Mars mission, this wouldn't be until the
reactor was on the surface of Mars (again due to cooling issues).

Jeff
--
"Take heart amid the deepening gloom
that your dog is finally getting enough cheese" - Deteriorata - National
Lampoon

On 5/4/2010 8:55 AM, wrote:
Given the desire to use nuclear propulsion for deep space exploration
(i.e. VASIMR, Mars 1986, Mars 1994, etc.), but the danger of
uncontrolled re-entry of radioactive materials ( see Cosmos 954),
maybe all nuclear reactors in LEO should be put there by manned
vehicles, reside on manned platforms, and be manually controllable.
Always having a "man-in-the-loop" provides the same type of additional
safety margin that pilots give to commercial planes.

Then you run into the problem of protecting the crew associated with it
from the radiation of the reactor.
You may already know about it, but there's a lot of detail on the Soviet
space reactor such as was used on Cosmos 954 he
http://www.svengrahn.pp.se/trackind/RORSAT/RORSAT.html

Pat

"Jeff Findley" wrote in message
...


there really aren't problems with convincing other governments that the
US knows what it's doing.



It looks like Pres Obama intends to keep the current NASA budget
even after the shuttle. Maybe more pure research with propulsions
systems will take place in the next few years. I think that quick trip
to Mars might become a reality faster now.





Jeff
--
"Take heart amid the deepening gloom
that your dog is finally getting enough cheese" - Deteriorata - National
Lampoon

Nuclear propelled manned spacecraft will be much less expensive if
they can be assembled, operated, and maintained in LEO rather than HEO
when they are not traveling to some destination in the solar system.
However, in HEO, a nuclear propelled spacecraft can be left unattended
or even abandoned without danger to people or places on Earth. In
LEO, this is not an option. Any loss of control of the spacecraft
would result in the ejection of the reactors into a higher orbit and
the loss of many billions of dollars.

Modern automation can make loss of control of a spacecraft highly
unlikely. Backup manual control can make it even less likely.
Perhaps the risk could be made small enough that governments and the
public would be willing to accept it.

On May 5, 3:48*am, "Jeff Findley" wrote:
wrote in message

...

Given the desire to use nuclear propulsion for deep space exploration
(i.e. VASIMR, Mars 1986, Mars 1994, etc.), but the danger of
uncontrolled re-entry of radioactive materials ( see Cosmos 954),

That was not a terribly good design because the radioactive materials
weren't contained in such a way that they could remain intact during reentry
(which is done with all US RTGs and the like).

Apples and Oranges. RTG's are not reactors. The last time the US had a
space reactor was SNAP circa 1965 I believe, which subsequently
disintegrated in orbit spilling its radioactive contents.

SNAP like the russian reactors launched with the fuel already inserted
since they werent manned flights. When you say "not a terribly good
design" what would be your solution given no manned presence to insert
the fuel.

Additionally, in the 80's/90's when the US was again interested in
Space reactors they intended to use a Topaz and satisified themselves
after minor modifications that it was safe, although US
environmentalists eventually caused that launch to be cancelled.

For the sake of this argument it doesnt matter though. If you want
Nuclear power in space, Russia will sell and launch reactors for you
and is willing to develop larger power ones if required. They also
have some designs (though only preliminary) for manned reactors whose
fuels is shipped in caskets like US RTG's and inserted in space
alleviating any issues there.

On May 4, 9:55*am, wrote:
Given the desire to use nuclear propulsion for deep space exploration
(i.e. VASIMR, Mars 1986, Mars 1994, etc.), but the danger of
uncontrolled re-entry of radioactive materials ( see Cosmos 954),
maybe all nuclear reactors in LEO should be put there by manned
vehicles, reside on manned platforms, and be manually controllable.
Always having a "man-in-the-loop" provides the same type of additional
safety margin that pilots give to commercial planes.

I noticed that that all the following posting assume
some form of fission nuclear power. I'll suggest
that fusion might be the 'ultimate' power source
for a grand interplanetary drive. Though it might
need a fission reactor for jump start power. The
ideal would be a deuterium/boron fusion reactor though
that needs much work. Then again aneutronic fusion
maybe too 'Star Trekie' to be practical anytime in
the next century or two.

But since fission is a nearer term solution, I'll suggest
LEO parking is better than HEO during the working life of the machine.
At the end of life, a gravity well like the moon or even Venus
might serve as a good dumping ground. If there was a
fleet of ships, landing one one in shallow gravity well
might be ideal as in time when the radioactivity waned
in the distant future the old ships might become a
resource.

For 'space' to fly much beyond Earth orbit, it will take
a better way up, a better way out, a good way down
and up at the goal, and then finding some resource to exploit
out in the great beyond. So what is valuable enough for
the effort? A rare earth element perhaps? Moreover,
processing in such a situation would serve to keep off-world
toxic chemical byproduct wastes.

Trig