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nuclear space engine - would it work ??



 
 
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  #91  
Old October 8th 06, 06:24 PM posted to sci.space.history
Monte Davis Monte Davis is offline
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Default nuclear space engine - would it work ??

Robert Kolker wrote:

One really neat outcome of developing autnomous robots for space
exploration is that it would stimulate the development of AI at a
greater pace than AI has been enjoying.


I doubt it. Don't give in to tunnel vision: the aggregate markets here
on earth for AI, increasingly autononomous robotics, telepresence,
etc. are much bigger than anything space is likely to provide for a
long time to come.

Ultra-light-weight robotics, yes... possibly radiation-hardened
robotics... but those are niches.

Monte Davis
http://montedavis.livejournal.com
  #92  
Old October 8th 06, 11:41 PM posted to sci.physics.fusion,sci.space.history,soc.history.what-if,alt.history.what-if
Scott Hedrick
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Default nuclear space engine - would it work ??


"Robert Kolker" wrote in message
. ..
That is not the best use of robots. Robots can go into an environment that
would kill or disable a human.


Which ia *precisely* why it's not robots vs. people, and only fools discuss
which one is better for space exploration. The *correct* answer is that both
are necessary because they compliment each other. Robots are terrific for
cursory preliminary examinations, such as what the current Mars Rovers are
doing. Detailed investigation will take people. Because the expense for
people is more than the expense for machines, the use of machines will
provide the initial data needed to send people to the areas where they can
provide the greatest science, while machines continue the more routine
exploration. The results of use of people and machines together do not equal
people + machine, they are more like people * machine.

You don't need a person to provide routine weather information, like the
kind Viking provided. You don't need a person to take pictures. You do need
a person to direct the machine where to go to take pictures, and you need a
person to decide if something in the picture warrants closer investigation.
If you're short on time, people will outproduce machines by a far margin. I
believe Henry pointed out that the astronauts on Apollo 15 travelled as much
as the Mars Rovers have in three + years on their first day.

How much science did the Mars Polar Lander produce? If people had been
there, controlling the landing, would the engines have shut off early?
People are, and will be for the foreseeable future, better at thinking than
machines. However, because of that, they tend to suck at simple, boring,
routine things.


  #93  
Old October 8th 06, 11:45 PM posted to sci.physics.fusion,sci.space.history,soc.history.what-if,alt.history.what-if
Scott Hedrick
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Default nuclear space engine - would it work ??


"Robert Kolker" wrote in message
...
Forget perfection. How about sufficient in the practical sense? No water;
no colonies no habitats. We must find water or we are stopped in our
tracks.


That's fine, but your example doesn't support that. Pick a mission that was
specifically tasked to find water on the moon and failed.

I note that you failed to mention that nobody has found bourbon on the moon,
either. If *I* had gone to the moon with 1960s era gear, I'd need a good
slug of booze after landing.

What about sodium choride or free oxygen? Those weren't found, either, but
there's no habitat without air.

Robots don't need water. Humans do.


Clearly, the astronauts *did* find water on the moon. They couldn't have
survived without it.


  #94  
Old October 8th 06, 11:58 PM posted to sci.physics.fusion,sci.space.history,soc.history.what-if,alt.history.what-if
[email protected]
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Default nuclear space engine - would it work ??

Steve Hix wrote:

I recall seeing a writeup of a new-ish leg-thing in development
specifically to deal with terrain that isn't suited for wheel/track
vehicles. It wouldn't replace wheels, certainly, but it could supplement
them for some environments.


Let's launch hibernating, suited, robot-jockeyed mountain goats to
mars...

  #96  
Old October 9th 06, 12:33 AM posted to sci.space.history
Jochem Huhmann
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Default nuclear space engine - would it work ??

Pat Flannery writes:

Jochem Huhmann wrote:

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.


At the time, some in the U.S. thought Voskhod 1 was equipped with ion
engines due to a somewhat garbled Soviet description of the spacecraft
which stated it had "ion plotters of the direction of the ship's
velocity vector". What these really were was a set of ion detectors that
allowed the spacecraft to determine its orientation in relation to its
orbital path.


Yeah, but ion (or better Hall Effect Thrusters) were flown since the
70ties by the Soviets. I still can't find more specific data, but some
sources count more than 100 missions.

And then there is also SNAPSHOT, an USAF satellite using a cesium ion
engine in 1965, SERT-2 using a mercury ion engine in 1970...
experimental, but still. Old stuff, actually.


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
  #97  
Old October 9th 06, 01:25 AM posted to sci.physics.fusion,sci.space.history,soc.history.what-if,alt.history.what-if
Henry Spencer
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Default water finding (was nuclear space engine - would it work ??)

In article ,
Steve Hix wrote:
Worse, on a short-term project that never did expect to be able to
explore areas that had much likelihood of containing usable amounts of
water; they didn't have enough delta-v to permit landing anywhere other
than close to the lunar equator.


The constraints on landing sites were actually a bit more complicated than
that. A polar Apollo landing *would* have been possible, although it
would have presented some difficulties. Harrison Schmitt's "do something
ambitious with the last few Apollos" proposal included a polar landing.

We'll ignore for now that strong evidence for water at the lunar poles
didn't show up until some time later.


Actual *evidence* didn't become available until quite recently... but
speculation about water deposits at the poles goes back to 1961. This was
one of the reasons why Schmitt wanted to try a polar landing.

Initially, humans're going going to have to bring it with them, and they
will continue to have to recycle stringently.


Alas, recycling of this level of stringency will not be easy. Notably,
there is currently no good substitute for water as an expendable coolant
for spacesuits, and you don't get to recycle that water -- it's gone. A
local source of "makeup" water, to cover losses and recycling limitations,
is highly desirable.

Happily, fuel cells generate water, and that will continue to be useful.


Fuel cells generate water only if you lug along LH2 to feed them, which is
no longer seen as a particularly useful approach for most applications.
Note that NASA's current Apollo remake is going to be solar-powered, with
nary a fuel cell in sight.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |
  #98  
Old October 9th 06, 01:45 AM posted to sci.physics.fusion,sci.space.history,soc.history.what-if,alt.history.what-if
Henry Spencer
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Default nuclear space engine - would it work ??

In article ,
Pat Flannery wrote:
For which we need men in space, for the same reason we generally use
hands-on machinery to build hydroelectric dams: because in the real
world, automation and remote control are not up to such complex jobs.


At the moment; but what around twenty or thirty years in the future?


Or forty, or fifty, or... Greg Benford once asked Hans Moravec how soon
we could build a robot that could climb down a geothermal vent on Mars.
The answer was "half a century"... and Moravec is a leading robotics
researcher and well known as an *optimist* about robot capabilities. But
he's actually *done* robotics work, and it shows in his time estimates.

...our two rovers are sending back lots of useful data, and the life
support that would have been required for two human explorers on Mars
for the period of time that the rovers have been operating would be
anything but trivial.


You get what you pay for. The advance estimate made by Steve Squyres,
science boss for the MERs -- "the rovers will be able to do in a day what
a skilled field geologist can do in 30 seconds" -- has held up pretty
well. With that kind of multiplier in effect, the extra resources needed
to support human explorers no longer look so wasteful.

The line of what humans can do stays fairly level, aided by equipping
the human explorer with more and more high technology equipment that
must be designed in such a way as to interface with him.


Make up your mind: does it stay fairly level, or does it rise with the
addition of that equipment? In fact, it has risen quite a bit.

The most effective approach is to send *both*, and use them together. In
particular, the capabilities of robotic systems expand dramatically if
humans are available for repair, refurbishment, and low-lag teleoperation.
They can be used to offload a lot of routine chores, freeing up human
hands and heads for things that robots can't do effectively.

and at some future point it first meets
it, then crosses it...and the machine has the advantage and is more
capable than a human explorer would be.


Someday, possibly. Not soon.

Remember how we first had to build a space station with many cargo
rocket launches, and then head for the Moon? Everyone thought that would
be the case back in the fifties, but we improved our rockets enough that
no space station was needed, and we could do the whole mission with a
single rocket launch.


Yes, but we can't any more. The one-big-rocket approach was driven by a
political imperative for haste, and the capability was lost once that
imperative was satisfied. Building a space station as an assembly base is
*still* the right approach for sustained spaceflight. We didn't bypass
the assembly station because that approach became obsolete; we bypassed it
because political expediency overruled technical merit.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |
  #99  
Old October 9th 06, 03:53 AM posted to sci.space.history,soc.history.what-if,alt.history.what-if
David Spain
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Default Can Democracies Open the Space Frontier?

Henry Spencer wrote:
In article TywVg.8$i84.2@trnddc01, David Spain wrote:

[snipped for brevity]

NASA will never, ever put men on Mars. Their target date for it i
receding more than a year per year. But the first footprints on Mars
almost certainly will be those of free men.


Maybe. I hope so. But I don't think history guarantees it.

Henry you and I are in complete agreement that private enterprise allowed
to work freely is likely to get us into space far ahead of what NASA and the
US gov. (working alone or jointly with other govs.) could do.*

The question is, in a time when everything under the Sun has a political
price in the US (I'll exclude Canada for now ;-), if a private enterprise
has a mishap that kills a number of people (either in Space or on the ground)
can the "democracy" keep from putting its big foot into the works? Every
politician loves a disaster. What better way to self-promote and in the process
get passed some crazed regulations or create a monster bureaucracy to regulate
(kill) space development?

Imagine this, a private enterprise embarks on a massive campaign to open
Space, but can't do so from a democracy because of the regulatory framework,
where insurance company actuaries hold the real reins of power.

So they go where? Hmm, how 'bout a beneficent ruler in the Mideast? Say
the Sultan of Brunei? Or closer to the Equator, maybe 50 years down the
road the Islamic Courts Of Sudan?

First footprint on Mars, brought to you by the Great Wall Space Development
Corp., sponsored by the Sultancy of Brunei, paid for with US/EU petrol-dollars
and dollars and euros flowing freely over decades of trade surpluses....

Dave

*Apollo 2.1 should be SHUT DOWN, NOW. NASA needs a DRASTIC overhaul, NOW.
The operational parts (Manned Spaceflight Center, Kennedy Space Center)
should be spun out into a quasi-public corp. like Amtrak, with *HEAVY* private
sector involvement**. The rest of NASA should be re-org'd and replaced with
...... NACA! YES NACA. Put NASA back on its original course. Advisory role
and laboratory expertise to the private sector. Do it NOW. While we have the
beginnings of a private sector space program that would BENEFIT from co-operation
with NACA rather than wasting taxpayer monies on doomed one-off manned missions
that long term have no chance of success w/o private sector involvement anyway.

FWIW ask the Apollo 2.1 crowd that if we take Apollo as our baseline example of
how to get to Mars, what good is a mission to Mars if you have to
wait 5 decades between flights?

**Maybe there's no real rationale for this either, other than feelings of
sympathy for those in the astronaut office. But face it, what do the
current crop of astronauts do when Space Shuttle is retired? Let's not bring
up another generation of dedicated, hard-working people stuck going down the
rat-hole of the wrong path. Note I'm focusing on the manned spaceflight programs.
The unmanned programs have been doing well at NASA and would continue to flourish
under NACA as well, since NACA better fits the role of academia/gov. co-operation
that is and has been essential for the success of the unmanned programs.

BTW, I've never felt Space Shuttle was the wrong path. Just the opposite.
The problem is that the program was never allowed to *evolve* with better
craft, newer designs etc. as it would have had it been in the competitive
private sector.

Gov. monopoly in Space must end, NOW. I do not wish my tax money going to
subsidize space monopolies like NASA in its current form.

Dave


  #100  
Old October 9th 06, 05:15 AM posted to sci.space.history
Pat Flannery
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Posts: 18,465
Default nuclear space engine - would it work ??



Neil Gerace wrote:

I doubt that a robot can solve differential equations in three dimensions
fast enough to catch a ball let alone drive a tank



The tank would be the robot; just as those robotic vehicles the army has
the test for every year would work.
Everyone keeps picturing something like this:
http://www.umich.edu/~umfandsf/film/...en-robby-1.jpg
dismounting from its vehicle and going around picking up rocks with its
metal hands, but it will probably look more like a larger and souped up
version of one of our present rovers...maybe with treads rather than
wheels now that we know it can get stuck in the dust, and has a hard
time going up hills.
It may not have arms, but simply a scoop that takes up rock samples at
the front end, runs them through its innards for analysis and dumps them
out the back end unless they are very interesting in which case it keeps
them for delivery to a central analyses point where they can be packaged
for return to Earth in a unmanned rocket.
People keep pointing out that robots can't do everything a human can,
and that's certainly the truth.
The Mars robot won't be able to sing and dance, write sonnets, or play a
mean game of poker (unless it's one of those drones from "Silent
Running"), but it won't have to to accomplish its exploration mission.
It will be entirely optimized for that mission and won't need to eat or
drink water either. It will almost certainly be powered by a RTG system
with possible help from a solar array, and the heat from the RTG will
keep its innards warm during the cold Martian night, extending its life
by preventing thermal shock to its internal mechanisms. Given the luck
our two resent rovers have had, one can picture this hypothetical rover
having a lifetime of several years and the ability to cover many, many,
miles in its exploration of the Martian environment.
It also won't get moody and homesick after a few months on Mars like
human explorers well might.
Assuming we make the Ares V, this would be a very good mission for it to
perform. Given we got our two rovers to Mars on Delta 2's, something
with Saturn V capabilities could put some pretty impressive things on
the surface of Mars with even a single flight. Two or three big rovers,
several Spirit sized rovers, and a return rocket for samples does not
seem out of the question, especially if a nuclear upper stage is used in
a direct ascent mission
Alternately, the booster could be used to land several smaller rovers at
various points on the Martian surface, while its main section stays in
Martian orbit acting as a high data transmission rate link between the
rovers and Earth.
Given the increasing capabilities of nanotechnology, and one can picture
a whole slew of solar powered minirovers (about the size of a shoebox)
being dropped onto the Martian surface in a single mission from polar
orbit. In that case one wouldn't have to be too careful about picking
safe landing spots, as in case the first one was destroyed, another
could be assigned to its target site.
They wouldn't do very much per rover; just take photos, check out the
weather, and do some rudimentary soil sampling via radioactive
backscatter bombardment of the rocks they encounter.... but having a
grid of around fifty of them on the surface of Mars crawling around
would be a great first step in figuring out which sites deserve a closer
look by more capable rovers.
Do all three of these missions, starting with the last and working up to
the first, over a period of years would take only three Ares V launches,
and that's fewer than a single manned mission to a single site would
require.
With luck you might be able to pull this all off at around the cost of
three Shuttle missions, minus the cost of developing the spacecraft and
landers themselves, and the scientific payoff would be exceptional for
the price paid.

Pat
 




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