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Questions about "The High Frontier"



 
 
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  #521  
Old November 9th 07, 05:18 AM posted to rec.arts.sf.science,sci.space.history
Troy
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Default Questions about "The High Frontier"

or the technology that's going to be somehow developed that makes that
happen, despite the fact that rocket efficiency has been fairly constant
since the mid 1960's...


It might all well happen within the limits of chemical rockets.


Give me an explanation of how that's done from a technical point of view.
Show me a concept of making a chemical rocket that has a isp of around
1,000.
I'm not asking for a working drawing, I just want the basic concept.


Ask and ye shall receive:

Boron / lithium / boron spiked H2/LOX: Isp 530s (theoretical max 700s
- toxic as hell)

H2 + Fl: Isp 446s

H2 + O3: Isp 580s

Air-augmented kerosene: effective Isp 550s (researched for Soviet
mobile ICBM stages)

Monatomic H: Isp 650s (produced in lab but tends to blow up easily)

Metastable He-IVa: Isp 2200s (produced in lab - storable as a solid,
no dodgy magnetic storage)

Metastable He-IV*: Isp 3100s (cute, but HIGHLY unstable and has half-
life of 2.3 hours anyway)

H2 + tetroxygen: Unknown performance, thought to be superior to H2/O3

Metallic hydrogen / tetrahydrogen: Isp 1200-3000 (produced by rapid
shock compression, can be metastable and storable if surrounding
pressure rapidly quenched to ambient: storage density 10x that of liq.
H2 so very nice if achievable)

And I didn't even have to go to Nyrath's website. Of course, a 1000
sec chemical rocket won't bring space travel under the $200/kg mark.
It could be done with air-launched rockets burning hydrogen peroxide
and kerosene with a linear aerospike. Something like the USAF Dark
Horse spaceplane study. Possibly even getting to orbit in a single
stage because the fuel density is so high. No cryogenic handling
issues, no pad issues, just load up and go.

http://physci.llnl.gov/Organization/.../ComQuest.html
http://www.dcr.net/~stickmak/JOHT/joht13rocketprop.htm
http://www.strangehorizons.com/2004/...talodd-a.shtml
isdc2.xisp.net/~kmiller/isdc_archive/fileDownload.php/?
link=fileSelect&file_id=361 -

Bet you didn't picture a CPU that had a multi-gigahertz processing
capability twenty-five years ago, or a hard drive that could store 500
megs... and have those both sitting inside of something of around two
cubic feet in size in your living room either.
So much for the foreseeable future. :-D


5 years ago I was expecting 5GHz processors to be coming out "sometime
soon." Now, we have computers that cause hearing damage with their
cooling systems. I think it worth pointing out that a decent gaming
rig puts out more waste heat than a sweaty human in an EVA suit.

At least it's giving me a chance to realize that I was right all along,
and that Robert Zubrin really does sound like Bruce Dern out of "Silent
Running". ;-)


Hmmm... better keep him away from shovels, then.


And nuclear detonators.

Pat


Note to future spacecrew recruiters: do not hire wild-eyed biologists
with long curly hair.

  #522  
Old November 9th 07, 08:00 AM posted to rec.arts.sf.science,sci.space.history
Pat Flannery
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Default Questions about "The High Frontier"



bealoid wrote:

How much human supervision is a robot-machine allowed until it reaches the
point where it becomes a non-robot-machine?

Does it make any difference if that supervision is provided at a console
next to the machine down the mine, or at a console at the surface, or at a
console some miles away?


That could be a really tough question to answer, because the two could
fade into each other.
Many years ago, someone pointed out that a Sidewinder missile is a robot
that certainly doesn't obey Asimov's three laws of robotics, in that its
aim is to cause harm to come to people...the pilot of the enemy aircraft
it's homing on.
Once launched, it homes on the enemy all on its own, so it is a pure, if
very simple, robot.
A Sparrow III missile on the other hand requires that the target be
illuminated by the attacking aircraft's radar as it homes on the
reflected signals of that, so it probably isn't a pure robot.
A Phoenix missile is even more confusing...during the early phase of the
flight, the F-14 gives it commands to change its course to close on its
target, but once it gets close enough it begins to home on it all on
its own.
So sometimes it's a robot and other times not.
Let's see what Wikipedia says: http://en.wikipedia.org/wiki/Robot
Their definitions are all over the place also. :-)
When a robot becomes a android is kind of iffy also.
If it looks human, but you can easily tell it's a robot, is that a
android or not?
The full-sized Asimo prototype could be confused with a person wearing a
spacesuit.
Even the production small one looks more like person in a spacesuit than
what I'd expect a robot to look like.
Its proportions are very human...I always pictured something like Robby
from Forbidden Planet, or the Pol-Robs out of Magnus, Robot Fighter.
Asimo could be C3PO's great-grandfather.
On the other hand, that could be a very logical approach to things;
Robby would have a hard time going up stairs (his feet are too large) or
fitting in a conventional automobile.
At least he made up for the scary robot/android in Metropolis, and
helped give robots their good name back after the scary robots from the
movie serials.

Pat


  #523  
Old November 9th 07, 08:18 AM posted to rec.arts.sf.science,sci.space.history
Pat Flannery
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Default Questions about "The High Frontier"



IsaacKuo wrote:

Maybe the lunar material is collected using
a hexagonal formation of inverted funnels.
A puff of oxygen gas throws up a bunch of
lunar dust/regolith. Around the "impact" is
a formation of six upward pointed funnels,
so dust/regolith collects at the center.

Since there's no atmosphere to worry about,
even fine dust particles will quickly fall down
back into the collection funnels. At the base
of each funnel are heating elements to
begin processing the ore; as the ore near the
bottom is melted it flows into heated pipes
for the rest of the processing.

This mechanism may be less efficient than
scoops, but the reduced maintenance issues
may be worth it. The only moving parts are
valves for the gas puffers and wheels for moving
from one place to another.


A powerful magnet could pick up ferrous materials in a even simpler
technique as it's pulled across the surface.
One problem nobody's mentioned yet is the lunar night. Unless you limit
your mining activities to the lunar poles, and haul the materials up to
the top of a "eternal light" mountain for processing, you are going to
have two weeks gathering and processing and two weeks sitting around and
waiting for the sun to come back up.
If you are going to start running ore refineries and mass drivers with
nuclear power during the night period, you are going to need some
walloping big reactors, as the total BTU released by the reactor is
going to be the limiting factor for how much heat you have to refine
things with.

Pat
  #524  
Old November 9th 07, 08:49 AM posted to rec.arts.sf.science,sci.space.history
Pat Flannery
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Default Questions about "The High Frontier"



Mike Combs wrote:
Give me an explanation of how that's done from a technical point of view.
Show me a concept of making a chemical rocket that has a isp of around
1,000.


You seem to assume that the cost/lb is primarily a function of ISP. That
may not be the case.

We aren't sure about that. although the big dumb cheap booster is a very
fond dream of everyones, the infrastructure to move it around and launch
it may be more trouble that the lower cost of the vehicle justifies.
There's a rough middle ground...you don't need engines with the isp and
complexity of the SSME, but you don't want things as simple and low cost
as V-2 engines either, because you end up with a fairly small payload
riding on something the size of WvB's Cargo Rocket.
If you are going to try and make the vehicle completely reusable, either
in one piece or in stages. you are going to have to use very high isp
engines just to have any usable payload left due to the TPS and recovery
systems.
The Russians may have hit fairly near the mark with their R-7 series of
rocket derivatives which are pretty bulky for what they do, but are also
fairly cheap and very reliable.
One thing that the space tourism crowd hasn't ever seemed to recognize
is that if they are going for orbital flight, then after 50 years of
work, we still haven't been able to get past around a 95-97%
reliability rate with our orbital rockets.
That's okay for satellites put start extrapolation it into some sort of
passenger carrying service that has a fairly high launch volume, and you
had better have one mighty effective and reliable LES and abort
capabilities, or the fatalities are going to start piling up.
Bet you didn't picture a CPU that had a multi-gigahertz processing
capability twenty-five years ago, or a hard drive that could store 500
megs... and have those both sitting inside of something of around two
cubic feet in size in your living room either.


Yes, but has any of that lead to a robot that you can tell to go upstairs
and get your glasses? That's the kind of thing we were anticipating we'd
have by the 21st Century.



Thought we'd have fusion...and personal autogyros and flying cars for
that matter also.
We are probably around 50 years off from Asimov's world, but on the
other hand we do have some robots being integrated into things, and we
still haven't put a person on Mars, built even a small prototype SPS, or
put up even a small manned Moon base. Even our ISS is a long shot from
WvB's 1950's space station, regarding crew size in particular.
We were supposed to have Gemini spacecraft on Mars by now:
http://www.ninfinger.org/~sven/model...inggemini.html
Despite possible landing problems:
http://membres.lycos.fr/marsetsf/rc2/snap01034.jpg ;-)

Pat

  #525  
Old November 9th 07, 09:04 AM posted to rec.arts.sf.science,sci.space.history
Eivind Kjorstad
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Default Questions about "The High Frontier"

Hop David skreiv:

# can sense its environment, and manipulate or interact with things in it
# has some degree of intelligence or ability to make choices based on
the environment, or automatic control / preprogrammed sequence


That doesn't help much. Every object "interacts with things", even an
inert rock "interacts" with every other thing in the universe by way of
gravity.

"sense" is one of those words that are hard to define again. In any
case, by the WikiPedia-definition my car is certainly a robot.

It interacts with the environment, plenty even, and it has automatic
control and preprogrammed sequences. For example, if it senses that it
starts to rain, it independently starts the windshield-wipers. If it
senses that it will crash it goes trough a checklist and inside of 50ms
does on the order of 20 things to increase survival-chance (ranging from
increasing the pressure in the brake-assist to tensioning safety-belts
to inflating airbags, shutting off fuel-supply, cutting main power etc
etc etc) and the car is neither brand-new nor fancy, infact it's the
smallest Skoda you can buy.

Most people don't think of their cars as robots.

I think my point stands: there is no clear separation. Certainly no
universally agreed upon separation.

But whatever name you give to a machine, John's point still stands:
Where are the working mines with no people in it because they've all
been replaced by machines?


There are neither. No mines operated -solely- by machines. And no
asteroid-mines operated by humans. We're talking science fiction, so
this should hardly surprise anyone.



Eivind Kjørstad
  #526  
Old November 9th 07, 09:08 AM posted to rec.arts.sf.science,sci.space.history
Pat Flannery
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Default Questions about "The High Frontier"



Troy wrote:
On Nov 8, 9:38 pm, Pat Flannery wrote:

Hop David wrote:

Hop David wrote:

Pat Flannery wrote:

(snip)

Do you honestly believe miners are a bunch of clumsy morons? You
arrogant, ignorant, little prick.

I DID NOT WRITE THAT.


No, you didn't and I believe Hop was expressing regret at what he
wrote:

Quote from Hop:

"I've always regarded you as a gentle soul and a wonderful story
teller.
It distresses me to read some of my replies to you in this thread. "


So first he lies about what I wrote, then he says that he's sorry he
wrote what he did, then he killfiles me...all in one posting?
Is there any logic in that?

Pat
  #527  
Old November 9th 07, 09:11 AM posted to rec.arts.sf.science,sci.space.history
Eivind Kjorstad
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Default Questions about "The High Frontier"

John Schilling skreiv:

Classically, it's a robot if it has the ability to sense and respond to
the external environment.

Pragmatically, it only counts if the "sense and respond to the external
environment" bit applies to the normal exercise of the primary function
of the device; safety overrides and/or feedback control of secondary
functions need not apply. A car does not become a robot when you add
anti-lock brakes; it becomes a robot when it steers itself down the
road.


But my electric heater is a robot. It senses the external environment
(namely the temperature) and responds to it (by turning on or off the
heating). This is it's primary function, indeed it does its thing
unsupervised for weeks at a time, it is clever enough to know when I'm
at work and when I'm sleeping, so allows temperature to drop further at
those occcasions.

I've got a robot heating my bathroom-floor too. I give it orders twice a
year. The rest of the time it senses and responds to the environment
independently.


Eivind Kjørstad
  #528  
Old November 9th 07, 09:24 AM posted to sci.space.history
Pat Flannery
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Posts: 18,465
Default Questions about "The High Frontier"



OM wrote:
...As long as this thread has progressed, I'm starting to see more of
this happening. Apparently some of you guys aren't watching your
attribs while trying to trim your quotes. Keep a cooler head about
yourselves, and watch those attribs before you flame each other for
the wrong reasons!


Note how it was posted; with only a single quotation bar in front of it.
That had to be intentional.
I made a unintentional slip like that with the comment about the draft,
but it wasn't anything insulting, and I did leave both quotation bars
intact.
I also immediately apologized for it once it was brought to my
attention, and removed the message from all the newsgroups it was posted to.

Pat
  #529  
Old November 9th 07, 09:30 AM posted to rec.arts.sf.science,sci.space.history
Pat Flannery
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Default Questions about "The High Frontier"



Troy wrote:

These are interesting combos, but I never liked the concept of the
super-powerful monopropellants, because if something goes a little funny
in the storage tank, there is a very big explosion.

And I didn't even have to go to Nyrath's website. Of course, a 1000
sec chemical rocket won't bring space travel under the $200/kg mark.
It could be done with air-launched rockets burning hydrogen peroxide
and kerosene with a linear aerospike. Something like the USAF Dark
Horse spaceplane study. Possibly even getting to orbit in a single
stage because the fuel density is so high. No cryogenic handling
issues, no pad issues, just load up and go.


Henry Spencer took a couple of years to do it, but he talked me into
trusting H2O2 as a oxidizer (bad memories of the Me-163 and hydrogen
peroxide powered submarines kept crossing my mind).
It's fairly easy to work with if you treat it right (certainly a lot
safer than hydrazine or RFNA)
as is cheap and easy to produce in volume.

http://physci.llnl.gov/Organization/.../ComQuest.html


I like these two statements from that webpage:

"Metastable metallic hydrogen would have a very high density of stored
energy because it would have a density about ten times that of liquid H2
at 1 bar. Thus, the stored energy released by reversion to the diatomic
insulating fluid would also be very large and metastable metallic
hydrogen would have widespread applications as fuels. If this energy
were released relatively slowly or quickly, metallic hydrogen would be
either a clean propellant, as gasoline, or an explosive, respectively."

and

"If solid metallic hydrogen has sufficient strength, it might be useful
as a light-weight structural material. For example, automobiles made of
metallic hydrogen would be ~10 times lighter than current ones made of
steel, enhancing fuel efficiency and reducing conventional fuel
emissions. The ideal would be to synthesize metallic hydrogen to be
either extremely metastable, as diamond, for use as a structural
material or readily reactive, as gasoline."

Me, I'm not keen on driving around in something made of explosives. ;-)
"Introducing...the new 2025 Honda Hindenburg!"
Anyway, it's pretty early to be speculating on its properties without
even a fraction of a gram of it to study.

Pat
  #530  
Old November 9th 07, 09:50 AM posted to sci.space.history
OM[_6_]
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Default Questions about "The High Frontier"

On Fri, 09 Nov 2007 01:00:26 -0600, Pat Flannery
wrote:

When a robot becomes a android is kind of iffy also.


....The difference has pretty much been acknowledged as follows: If it
looks like a human, behaves like a human, and can perform basic tasks
exactly like a human, it's an android. On the other hand, if it can
perform bodily functions just like a human, but using mechanical
processes using parts that are designed to function *AND* look like
human parts, then it's a synthezoid.

Of course, if it's just a box on wheels with two armatures and claws,
it's a goddamn robot...:-P

OM
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