nuclear space engine - would it work ??

In article ,
Robert Kolker wrote:
...Recycling buys some time but the moment of truth comes. Either the
population stops growing or we mine metal from the oceans...

Even a relatively cautious prediction concludes that Earth's population
will peak and then start falling late in this century, as the poorer
countries industrialize and go through the "demographic transition" of
falling birth rates. The trends are already visible -- half the planet's
population already lives in countries with fertility below replacement
level, whereas virtually nobody did fifty years ago. This has been coming
for a long time -- the idea that the population would just keep growing
and growing and growing was always based on a very simplistic analysis.

The tough part will be getting through the next century. The population
at peak will be a lot higher than it is today. As will energy demand --
China is already about to pass the US as the planet's #1 CO2 producer.

Earth is really quite well supplied with most resources. (For example,
there is no way we are ever going to run out of aluminum -- a significant
fraction of the total mass of Earth's crust is aluminum -- although it may
get somewhat more expensive to produce.) The handful of elements that we
really are a bit short of are likely to be hard to find in space. The one
resource that's a really good candidate for import from space is energy.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

Scott Hedrick wrote:

"Robert Kolker" wrote in message
. ..

I think the soundest approach is population limitation.


You first.

Right there is the problem. Heavy taxes will have to be levied on having
more than two children.

Bob Kolker

bombardmentforce wrote:

The dinosaurs had no asteroid survival plans, our only plan is to plan
to plan on warning.

And neither do we. If a big asteroid or comet hits 99.999 percent of the
human race will perish whether we have space wessels or not. There is no
way of getting more than a few off the planet regardless of how much we
spend on space wessels.

And if a few do get off, where shall they live? The Solar System is a
very bad neighborhood. The only place that is fit for humans is planet
earth hidden in a magnetosphere envelope.

Bob Kolker

David Spain wrote:


I image only a fraction of the energy released by the bomb is actually
providing
propulsion. IIRC you need some kind of super shock absorber that
resonates with the
explosive pulses connecting the plate to the spacecraft if you want to
provide
a comfortable experience for the occupants. Also IIRC the bomb
detonates at a
goodly distance (many, many, many miles) from the spacecraft.


There is lot of downloadable Orion material here, including the now
declassified official reports on Project Orion:
http://www.lepp.cornell.edu/~seb/cel...ion/index.html

Pat

I haven't read all the responses so this may have been said.

The point of using nukes was the high specific impulse. That allows a high
final velocity like ion engines. Unlike ion engines they would not be calibrated
in milimouse-farts so the acceleration time is not an issue.

As a design concept it was of interest and maybe still is. But the first
practical test of an ion engine was only a two years ago after decades of easy,
safe ground based lab research. That sent a European package to the moon.
Consider the engineering time required to solve the nuke propulsion details
given the ground based tests of the shock absorbing system and the like in the
New Mexico desert.

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That means he is a traitor to America.
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Henry Spencer wrote:

Earth is really quite well supplied with most resources. (For example,
there is no way we are ever going to run out of aluminum -- a significant
fraction of the total mass of Earth's crust is aluminum -- although it may
get somewhat more expensive to produce.) The handful of elements that we
really are a bit short of are likely to be hard to find in space. The one
resource that's a really good candidate for import from space is energy.

There is the Sun. We should use it.

Bob Kolker

On Thu, 05 Oct 2006 10:12:16 GMT, Matt Giwer
wrote:
snip

But the first practical test of an ion engine was only a two years ago after decades
of easy, safe ground based lab research. That sent a European package to the moon.

NASA's Deep Space 1 launched in 1998, with an ion engine. It was pretty successful.

Dale

"Henry Spencer" wrote in message
...
China is already about to pass the US as the planet's #1 CO2 producer.

Gee, didn't they sign the Kyoto treaty?

Matt Giwer wrote:

But the first practical test of an ion engine was only a two years ago
after decades of easy, safe ground based lab research.


No, there was Deep Space 1, and decades before that SERT II (although
the NASA PAO seems to have oddly forgotten that mission when it was
talking about Deep Space 1):
http://www.grc.nasa.gov/WWW/ion/past/70s/sert2.htm

Pat

Pat Flannery writes:

Matt Giwer wrote:

But the first practical test of an ion engine was only a two years ago
after decades of easy, safe ground based lab research.

No, there was Deep Space 1, and decades before that SERT II (although
the NASA PAO seems to have oddly forgotten that mission when it was
talking about Deep Space 1):
http://www.grc.nasa.gov/WWW/ion/past/70s/sert2.htm

And I even dimly remember some russian, err, soviet mission with an
(experimental?) ion engine much earlier... can't find it right now. It
was some interplanetary probe, I think.


Jochem

--
"A designer knows he has arrived at perfection not when there is no
longer anything to add, but when there is no longer anything to take away."
- Antoine de Saint-Exupery