nuclear space engine - would it work ??

"Pat Flannery" wrote in message
...

Yes it has risen... but it is all equipment that has to interface with the
human explorer- in short you are sort of turning him into a cyborg with
detachable cybernetic parts; at some point you are going to end up with
equipment so sophisticated that the explorer merely has to point it where
he wants and it does all the rest.

But you'll still benefit from having a human close enough that the RF time
lag to earth and back doesn't get in a way. Be that in a suit, rover, or
base. Only when the robots can operate autonomously, including doing
routine maintenance on themselves, and each other, without *any* human
intervention, will you do away for the need to have a "man on the spot".

I think we're hundreds of years away from that, but that's an uneducated
guess on my part based on what current robots can do. Today, the DOD can
barely get them to drive a motor vehicle autonomously, let alone design an
automated tow truck or automated vehicle repair center. :-)

At that point you might want to leave out all the display screens for the
operator, and just do it all roboticly.
Our "future warrior" soldiers are already dragging several pounds of night
vision gear, thermal sights, computer interfaces and television cameras.
Soon, the poor guy is going to have no carrying capability for ammo or
food because of all the the electronic crap he has strapped on him...so
the Army is looking into powersuits to increase the soldier's carrying
capability.

And yet we don't see Humvees driving themselves in Iraq yet, do we?

And where it's going is obvious: http://www.msnbc.msn.com/id/6852832/
First the recon drones replace the recon planes, then the robot fighters
and bombers replace the manned fighters and bombers, then the war robots
replace the infantry.

But in the ase of recon drones and planes, there is usually a pilot sitting
in a virtual cockpit somewhere on the planet. Trying to do the same thing
with a Mars/Earth time delay makes that task orders of magnitude more
difficult.

And it will go the same way in space.

Things that are different, just aren't the same. You might eliminate a lot
of EVA with virtual control of Martain robots, but it's still far easier to
stick the controls for that robot on Mars than on Earth.

The most effective approach is to send *both*, and use them together.



I seriously doubt that we can afford a manned Mars flight.
It'd be extremely expensive to do, and I doubt it gives results anywhere
worth the financial outlay to do it.
The same might be said for the return to the Moon mission; it'd be
interesting to do, but it simply isn't that critically important to
justify the cost of it.
On he other hand we can give Mars a pretty good going over in a unmanned
manner at a comparatively low cost compared to a manned mission,
particularly if we come up with some good designs for fairly simple
lander/rovers and then make quite a few of them rather than our current
process of making one or two of a particular design and then moving on to
something new.
By the time we find out that we do have a great design...like our present
two rovers...we simply move on rather than exploiting it.
Although our present rovers can only land and operate on around 5-10% of
the Martian surface we should build some more to the same design and put
them down around the planet's equator where possible. This is something we
could do on the cheap for a fairly low cost with a good chance of success.

If we'd done Apollo in a more modular way, we'd have the skills necessary to
launch a Mars mission without resorting to super huge mega launchers to put
nearly everything necessary up in one launch.

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.


Again... this is today...what about around 2036? Remember what computers
were like in 1976?

Computers are only as good as their programs. As the program complexity
rises, so do your software development costs. It's not clear to me that
autonomous robots will be a real cost winner until they are already deployed
in terrestrial uses, like truck driving, before they'll be cost effective to
replace an astronaut in an EVA suit or sitting behind a computer screen in a
lander, directing semi-autonomous robots without a significant time lag.

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.


I'd bet within 50 years tops, probably sooner.
Dyna-Soar died when the ICBM's arrived, because they could do the job of
getting a H-bomb from point "A" to point "B" at a lower cost than a manned
system could.

This works for an expendable vehicle that has one function, flip the switch
that causes the bomb to explode. That's not the same as exploring Mars.

Our communications satellites are unmanned yet do sterling service.

Relaying communications is something these things are hard wired to do as
long as there aren't any hardware failures. And when there is
troubleshooting to do, the time delay to GEO isn't much compared to the time
delay to Mars. And this ignores all of the satellites that could have been
saved or had extended missions with manned servicing and refueling.

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.


I can guarantee if the aim was to get people on the Moon, and Moon rocks
back to Earth ASAP and at the lowest cost, Saturn V beat the hell out of
assembling a moonship at a space station von Braun style.
God knows how much all that would have all ended up costing once you start
figuring out all the things that would have had to be developed to make
the concept work.

But what you have is far more. You have the beginnings of a manned space
station in LEO. You have the technology to do in orbit refueling making LEO
to GEO space tugs and servicing missions possible. How many comsats have
died due to fuel exhaustion or other simple failures? How many expensive
satellites have been stranded in useless orbits because their expendable,
one shot upper stages didn't work properly?

What you have is the basis of sustainable manned spaceflight coupled with
the ability to assemble, deploy, and maintain unmanned earth orbiting
satellites.

Jeff
--
"They that can give up essential liberty to obtain a
little temporary safety deserve neither liberty nor
safety"
- B. Franklin, Bartlett's Familiar Quotations (1919)

On Mon, 09 Oct 2006 12:07:06 -0700, Steve Hix
wrote:

snip

Machines that could be used to cover terrain where wheels can't go might
be pretty useful. Especially in applications where speed isn't critical,
and long-term observation might be.

Not that I expect to see them in the near future.

http://www.youtube.com/watch?v=y3W8dm5JxFc

David Spain wrote:


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.


After Apollo, NASA's greatest "accomplishment" has been alpha ****-can I
aka ISS. If you want something ****ed up royally, get the government to
do it. It has been downhill at NASA ever since 1986. It has been over 30
years since anyone has ever set foot on the Moon.

Bob Kolker

David Spain wrote:



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.*


I seriously doubt this... you re probably going to have tourist flights
into orbit in around a decade, but the amount of money required for a
Mars mission is way beyond anyone outside of the income level of Bill Gates.
Governments are the only entities who have the money to engage in
something of this magnitude, and they will want control over the program
in exchange for that funding.


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?


The FAA hinted that the laissez-faire attitude toward privately funded
spaceflight would change in a big hurry as soon as fatalities occurred.

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?


Something like SpaceShipOne doesn't pose much of a threat to people
under its ascent flightpath.
That's not the case with something that has the energy onboard to reach
orbit.
Something with half-full propellant tanks slamming into a city at a few
thousand mph is going to do private spaceflight no good at all in the
public's eyes.


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.


The big thing that will keep private enterprise from doing that will be
the huge capital investment needed versus the very iffy prospect of
making a reasonable profit on their investment in a reasonable period of
time.
On of the few real money-making ideas that probably would work in space
is the SPS system; and no private entity has the money to come anywhere
near funding a project of that scale and its needed infrastructure.
Even major nations would have a hard time footing the bill for something
of that magnitude, and if it does come about, it might well be a U.N.
program as a way of fighting global warming with everyone kicking in the
bucks.

Pat

Hans Moravec's robot company, SEEGRIDhas just sold the first handful
of commercial autonomous mobile robots. See SEEGRID.com. They truly
are autonomous, using vision to map their surroundings and navigating
from the learned map. They do not depend at all on GPS or other
external signals or tricks of site preparation. I hear that the
purchasers are very happy with their performance. Hans current timeline
for a robot capable of operating essentially unsupervised in a setting
like an asteroid mine is about fifteen years.(H.P.M. Personal comm.)

Scott Hedrick wrote:

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

They brought their water with them.

The longest Lunar mission lasted about three days.

Bob Kolker

"Robert Kolker" wrote in message
. ..
Scott Hedrick wrote:

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

They brought their water with them.

*Exactly*. So a visit, or even a colony, *isn't* impossible if there is no
local source of water. That *really* smashes the economics, but doesn't make
it impossible if something of sufficient value is obtained.

Even here on Earth, there are plenty of people who have to haul in water to
where they live. Doesn't stop them from living there.

The longest Lunar mission lasted about three days.

With solar cells and a sunshade, they might have made it another day or two.

In article .com,
wrote:
purchasers are very happy with their performance. Hans current timeline
for a robot capable of operating essentially unsupervised in a setting
like an asteroid mine is about fifteen years.(H.P.M. Personal comm.)


For very large values of fifteen.

--bks

Scott Hedrick wrote:

"Robert Kolker" wrote in message
. ..

Scott Hedrick wrote:

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

They brought their water with them.


*Exactly*. So a visit, or even a colony, *isn't* impossible if there is no
local source of water. That *really* smashes the economics, but doesn't make
it impossible if something of sufficient value is obtained.

Even here on Earth, there are plenty of people who have to haul in water to

There is a difference between piping water or walking to a well, and
hauling water from earth to else where out of our gravity well. Think
about it.

where they live. Doesn't stop them from living there.

For a self sustaining habitat to exist on another planet there must be
free water (or water that can be made free) on -that- planet. Water is
too dense to hault in large amounts from earth.

That is why the most likely place to build habitats is on Europa. That
moon is a water world.

Bob Kolker

Steve Hix wrote:

In article ,
Pat Flannery wrote:


Steve Hix wrote:



Actually, as long as you don't require high speed, leg-based machines
would be able to go places that tracked and wheeled vehicles can't go at
all, or only with great difficulty.

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.


The Army's been playing around with this idea since the 1960's, but the
Humvee's don't have legs on them yet.



Nor are they ever likely to have them. That's not at issue.



Yes, it is.
You want to cover rough terrain in a wheeled vehicle?
Let me introduce you to the Mace missile Teracruzer of the
late1950's-early 1960's: http://www.mace-b.com/38TMW/Missiles/MM-1.htm
This SOB could go through swamps, up mountainsides, over slushy snow,
deep mud, sheer ice, small boulders, or tree trunks.
Unless you intend to set down in some sort of Chesley Bonestell lunar
terrain, this concept will do just fine in getting you around in around
95% of the alien ground you are going to run into.



The legged vehicle is slow, it's complex, and it's not very energy
efficient at all - compared to wheels in particular.



Did you bother at all to read what you quoted above your comment?

Where you *can* use wheels, there's not much that can compete with them.

Most places where you can't use wheels, wings are a better solution.



Not on the Moon or Mars- you are going to need some mighty big wings to
keep anything airborne in a vacuum..or even in the low atmospheric
density of Mars.
A dirigible might have some chance on Mars, but I'd love to see what
happens to it the first time it runs into a 10,000 foot high Martian
dust devil.

There may well be some niches where leggy gadgets might be better than
either; perhaps severe broken terrain in an area where any small flying
device used for intelligence collection is going to either get shot
down, or would compromise data collection.

In fact, we do use leg-mobile data collection equipment, it's just that
so far, it's been men hauling the gear and setting up and doing the data
collection.

Machines that could be used to cover terrain where wheels can't go might
be pretty useful. Especially in applications where speed isn't critical,
and long-term observation might be.



The problem is distance covered; a slow-moving legged machine can't
cover that much in any given timeframe...the autonomously controlled
wheeled vehicle can. Moving from interesting point to interesting point
requires something that can move faster than a thousand feet in a day at
top speed.

Not that I expect to see them in the near future.



I wouldn't expect to see them at all.

Pat