"Keith Willshaw" wrote in message
...

"Earl Colby Pottinger" wrote in message
news
"Keith Willshaw" :

"Earl Colby Pottinger" wrote in message

How did you get from solid chunks of Uranium or Uraninuim Oxide to
dust,
High speed impact does that nicely

No, it does not, metals deforms under impact, ceramics break up, Neither
converts much of the mass to lots of dust particles just the right size
to
stay inside the lungs.


I suggest you do some reading on how metallic Uranium
behaves on impact, here's a hint - its pyrophoric

Second how do you get them to the right size.
See above

That was not an answer and you know it.

As the old bet goes, I take a tablespoon of uranunium and you take a
talbespoon of something common like nicotine and whoever lives the
longest
keeps the money
But then nicotine is an alkaloid poison and nobody is launching large
quantities into space

Yes, but you are acting like uranium is some sort of super poison, but if
you
took the bet I would be able to walk out alive and you would be dead. So
start treating uranium for what it really is a radioactive heavy metal
toxic
subtance that must be handle with care and sealed away the best way
possible.


Actually I'm behaving as if Uranium is a heavy metal that
needs handling with care and respect

But it is not a super posion where the little's leak will wipe half the
country and it is death to even see it. The fact is tons of uranium has
been
released into the air already and we are still here. A reactor failure
is
not going to wipe us out.


I dont recall claiming it would.

Considering the problems of intergrating a 'hot' reactor, it seems very
unlikely even without any cites.
In other words your guessing.

And you are doing elsewise? I don't think so.


I am not the one making the claim that its launched cold,
frankly I dont know but given the poor safety record
of Soviet designed reactors I'd need to know before
making that assumption.


Efficent is not the first order of bussiness, and the plan is to use
reactors so that we do have short trips. For early designs one
way only, or only one return trip may be all we want out of a unit.
Trouble is these reactors put out LESS power than triple
junction solar arrays.

Not in the outer solar system they don't.


Yes they do, these reactors had an operational life of less
than a year

Explain again why we should pay more and accept a higher risk
for lower power - I dont see it.

You are the one claiming higher risks. So far everyone injuried by
falling
space hardware has been hit by none nuclear parts

The cost of cleaning up the mess left by Kosmos 954 was in excess
of 14 million dollars (in 1977) and that was in a remote area

Nuclear power gives us more speed and operates further from the sun than
solar panels.


No nuclear propelled spacecraft has ever flown, there are spacecraft
propelled by solar electric drive in service. This claim fails
the reality check.

If it had ever been done for anything more complex
than the Soviet Bouk you might have a point but
thus far it hasnt.
You do realize that is the oppisite of what you said earlier in this
messages about pre-testing reactors?
I'm conceding the POSSIBILTY the Soviets MIGHT
have done this and pointing out that even IF they
dis its largely irrelevant to high power designs.

Thanks for being flexible. But why do you say it is irrelevant?


Because the Soviet designs werent suitable for
high levels of power generation or extended service.
Essentialy they were simply higher powered RTG's

They put out only 2 kw and weighed around 1200kg
Thats less than 2 watts per kg, the latest generation of
solar cells out out 100 wats per kg in near earth orbit
and 10 watts per kg at Jupiter.

The present generation of nuclear generators designed
for use in space just dont output the levels of power
that would justify their use.

Hmm, what would be this "present generation" of nuclear reactors? Old
Soviet designs dating from the 70s, never designed for high power output?

More reasonably the SP-100 technology would be the baseline for a new
"present generation", for which detailed design work was done in the early
90s. This gives about 80 watts/kg for the megawatt power system under
consideration, about par with the present generation of solar cells near
Earth, and an 8-1 advantage over solar cells near Jupiter. Using the
proposed thin film cells you have cited with 400 W/kg output, they have a
5-1 advantage near Earth, but a 2-1 disadvantage near Jupiter.

80 watts/kg gives a mass of 12.5 tonnes for a 1 MW power system. A manned
mission to Mars is going to weigh much more than the ISS, which is 100
tonnes at present, so this power ratio is high enough that the mass doesn't
look like a major issue.

The cost of a nuclear power system is going to be higher, both in
development costs and to produce the actual article; and the solar system
can be built and tested in smaller systems before scaling up which is not
feasible with the reactor design. On the other hand, large light weight
structures make aerobraking difficult.

The two technologies seem generally competitive in performance, but space
nuclear reactors do have a high hurdle to cross before a program will be
funded which is not true for solar cells. On the other hand, a manned
mission to Mars will be extravagantly expensive anyway so the cost factor
probably will not be critical, practical considerations of mission benefit
would be the deciding factor.