Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V13_5/V13_546.TXT

Internet Message Format | 1991-06-28 | 18KB

Return-path: <[e-mail]>
X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson
Received: from hogtown.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/[e-mail] (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests)
          ID </afs/andrew.cmu.edu/usr1/ota/Mailbox/Ec=s:jy00WBw84Gk4S>;
          Tue, 14 May 91 02:24:48 -0400 (EDT)
Message-ID: <Uc=[e-mail]>
Precedence: junk
Reply-To: [e-mail]
From: [e-mail]
To: [e-mail]
Date: Tue, 14 May 91 02:24:42 -0400 (EDT)
Subject: SPACE Digest V13 #546

SPACE Digest                                     Volume 13 : Issue 546

Today's Topics:
               Re: Saturn V and the ALS
               Shuttle launches
             Re: Laser launchers
              Re: Why the space station?
             Re: Laser launchers
            SPACE Digest V13 #518

Administrivia:

    Submissions to the SPACE Digest/sci.space should be mailed to
  [e-mail].  Other mail, esp. [un]subscription requests,
  should be sent to [e-mail], or, if urgent, to
             [e-mail]

----------------------------------------------------------------------

Date: Sun, 12 May 91 11:28:40 -0400
From: "Allen W. Sherzer" <[e-mail]>
Subject: Re: Saturn V and the ALS
Newsgroups: sci.space
Cc:


In article <[e-mail]> [e-mail] (Brad Mears) writes:

>|> First explain to me why it costs $10 billion and ten years to do what
>|> McDonnell and Martin say can be done for $500 million and four years.

>uh - less overhead? :)

No need for a smiley. That's a large part of the reason. An important
part of this contract was that it was outside the Federal Acquisition
Regulations (FAR). For this effort the government was buying only
launch services for a specified price. From their point of view there
was no vehicle to develop.

>Seriously, I haven't seen their proposals and can't comment on them.

Fair enough. But please do read the article in the September 90 issue of
Aerospace America. If for no other reason then you owe it to yourself to
be as informed as you can be.

>My "seat-of-the-pants" comment is that their low-bid could be a low-ball.

Why would they lowball for a fixed price contract? They would lose
a lot of money that way.

>The quotes I saw from Rockwell to build Shuttle-C were a great deal
>more $500M.  What will McDonnell and Martin do differently than Rockwell?

The only difference is acquisition outside the FARs. I think Shuttle-C
could be built for similar development costs outside the FAR. In fact,
the government estimate of the cost of Titan V development inside the
FAR is twice that of the estimate for outside the FAR [1].

>|> What did NASA learn from the Shuttle?

>They learned a LOT about what goes into performing routine space operations.
>This is the knowledge that they hope to use in construction of the next
>vehicle.

How much can they have learned? Since they will spend 20 times what they
need to, it can't be much.

>|> From what I see they think everything
>|> is fine (except that Congress should buy more orbiters). This is also not
>|> a flame but a serious question.

>I don't know how to address that.  It seems to be more a matter of perception than
>a matter of fact.

I don't understand what you mean here. My perception or NASA's?

>As far as asking for more orbiters, NASA asks for more because
>they think they need(?) a fleet with N orbiters.  Until they get N, they keep
>asking.

That's hard to understand. If NASA had learned anything they would have
said to themselves: "Holy shit, this sucker is expensive. We better not
buy any more and put the savings into cheaper approaches". Instead of being
upset at the Augustine recommendation that no more be build they would
have been glad they where pulled from the fire without needing to admit
a mistake.

[1] For the government quote see: "Launch options for the future: a buyers
    guide" by OTA. Quotes outside the FAR come from the Zenith Star proposal.

  Allen

--
+---------------------------------------------------------------------------+
|Allen W. Sherzer |        Allen's tactics are too tricky to deal with      |
|   [e-mail]   |             -- Harel Barzilai                           |
+---------------------------------------------------------------------------+

------------------------------

Date: 12 May 91 03:41:46 GMT
From: taco!eos.ncsu.edu![e-mail]  (DAVID F ROBINSON)
Subject: Shuttle launches

Was there ever any consideration for launching the shuttle off of the carrier
aircraft.  It could have been carried to 40-50 kft and after it cleared the
aircraft it could ignite its engines.  Wouldn't this have greatly reduced
the fuel mass required?  With this scenario the shuttle also could have glided
back in case of any engine problems.




***********************************
* David F. Robinson
* [e-mail]
* Aerospace Engineering - NCSU
***********************************

------------------------------

Date: 13 May 91 02:37:44 GMT
From: cis.ohio-state.edu!magnus.acs.ohio-state.edu!zaphod.mps.ohio-state.edu!wuarchive!rex!rouge![e-mail]  (Fraering Philip)
Subject: Re: Laser launchers

In article <[e-mail]> [e-mail] (Gary Coffman) writes:

>Well consider that for an electrically powered laser, conversion of
>primary fuel to electricity is, at best, 40% efficient. Transmission,
>control, and application of the electrical energy is, at best, 80%
>efficient. And laser conversion is, at best, 10% efficient. That's
>an overall efficiency of 3.2% right there. Then add in the fact that
>atmospheric blooming will reduce the delivered energy of the beam
>by a factor of 1000 to 1000000 at high altitudes, and you have a system
>with terrible efficiency. While for a rocket, the longer it runs, the
>faster it goes since it's mass ratio is continually improving right
>up until burnout.

No, the longer the rocket is supposed to run, the _worse_ its mass
ratio was when it started.  Usually much worse. You're using semantic
tricks to make the rocket look better than it is. "Since it has lower
fuel efficiency, it improves faster."

I also notice you pick the laser system _you_ would use and then go on
to show that it wouldn't work. Basically all you've proven with that
argument is that if it's going to be attempted, *you* should *NOT* be in
charge of the project.

>I wasn't arguing that R&D engineering problems need to be solved so
>much as I was arguing that fundamental physical laws prevent the
>system from being a practical, efficient, alternative to rockets. We
>could throw hundreds of billions into an R&D engineering program to
>develop anti-gravity too, but fundamental physical laws would have to
>be broken for it to pay off. At the power levels required to loft real
>payloads into orbit, atmospheric blooming is an intractable physical
>problem.  Once the air is ionized into a plasma, the plasma is
>optically opaque cutting off further power transfer. Talk to the guys
>who have actually fired high power lasers, the laser fusion folks, and
>see what they say about the absolute necessity of having a hard vacuum
>to fire the beam through.

What's that exchange from "The Princess Bride?"

"Inconceivable!" (for the 50th time)

"I don't think that means what you think that means."

I think I've seen this argument before, word for word. I even think that
this post gives me a strong sense of deja-vu. It probably got posted twice
due to some strange machination within the net. I've also heard the phrase
"Fundamental physical laws" before. It sounds _very_ familiar.

Specifically, Nick Szabo's arguments about chemical launchers and cost.

Anyway, the laser fusion people want to produce a plasma with a pressure
and heat product several magnitudes higher than the core of the sun.
The amount of energy concentration is much higher here than will be needed
in an operational laser launcher.

Granted, research does need to be done. But you seem to be implying
that NASA shouldn't do it. Then who? The size of a prototype laser launcher
is about $100 million, beyond the range of any universities. Private
Enterprise? Oh sure, the lead times in the research is 20 years too long
for the government to do it, so we'll have the people so capital-short
they're seeling their grandparent's internal organs put money into the
thing which won't pay off for a couple decades (as _you_ seem to believe).

SDI is investigating it and they have an urgent military need to fill.
They, as well as private industry, the military, et al, have vast pressures
against their doing {\em {\em {\em BASIC RESEARCH }}} (btw, {\em whatever} in
TeX puts the whatever in boldface) when they are compared to NASA. People
say we need NASA because there are things private industry is too short
sighted to look into. And it probably wouldn't make that much more sense
for private industry to put money into it now. But if NASA won't do basic
research, what do we have it for, and if NASA is to handle mainly operational
aspects, why have a private space industry? Why limit this to space?
If the governments going to do operations and all that, there certianly
isn't any need for the Gannett Technologies Group to exist, it can be
nationalized and taken over by something like the Dept. of Redundancy Dept...

Basically, if NASA can't do the basic research, who can? They're much
better suited to do it than anyone else.

>Tethers need to exceed the theoretical strength of materials limits by
>orders of magnitude to work. Again, a fundamental scientific breakthrough,
>not engineering R&D, needs to occur before tethers can become reality, if
>ever.

Not for smaller tethers. They could even reboost themselves by coupling
with the Earth's angular momentum via the Earth's magnetic field, to make
up for losses when something gets picked up from ye olde suborbital rocket.

--
Phil Fraering
[e-mail]
''It's a Flash Gordon/E.E. Smith war, with superior Tnuctip technology
battling tools and weapons worked up on the spot by a billion Dr.
Zarkovs.`` - Larry Niven, describing the end to _Down in Flames_.

------------------------------

Date: 13 May 91 05:42:37 GMT
From: sequent!muncher.sequent.com![e-mail]
Subject: Re: Why the space station?

In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>
>If you assume that you are never going to do large scale in space assembly

We won't need in in they _way_ you or NASA think we will need it.
Large scale assembly isn't very valuable unless there are a lot
of materials lying around with which to scale.  Fred does
nothing about the need for cheap building materials, which is the
real problem.  Rather, it sucks up money from missions of exploration
that would give us knowledge about solar system resources with which
to solve the problem.  Right _now_, Congress is deciding on Fred
vs. SIRTF, a powerful infrared telescope which would discover thousands
of new asteroids and comets.  Fred is incredibly destructivce of the
long-term potential for large scale space assembly.


>and that you are never going to need to launch really large probes into
>deep space or to the planets using exotic propulsion systems, or if you

The explorers want many more, smaller probes, and none of the exotic
systems require assembly.  Fred does not doing anything about this need,
instead it sucks up money from exploration.


>assume that large scale human presence in space is never going to occur

At 1,000,000 times the cost of a Winnebago for the same living quarters,
Fred does nothing but take us further away from this.


>and that you don't need life science data for long term zero G existence,

There is a small need for this, but it won't be met by putting
statistically insignificant sample sizes in an unrepresentative space
environment (underneath the Van Allen belts) at only one gravity level.
A mission with only 1% the cost of Fred would put statistically
valid samples of near-human biology into many different kinds of
radiation, shielding, and gravity environments, including micro, lunar,
Martian, and full gravities.  This would give us over 10 times the
knowledge on the subject for 1/100 the cost.

How's this for an argument: "if you assume we will never build a
starship, then we don't need to build a starship right now."
"If you assume we will never want a gazebo, then we don't need
to build the gazebo this summer." If we ever want to do these fun
things, the only alternative is to rush out do them right now?  Sheesh.



--
Nick Szabo                [e-mail]
"If you understand something the first time you see it, you probably
knew it already.  The more bewildered you are, the more successful
the mission was." -- Ed Stone, Voyager space explorer

------------------------------

Date: 13 May 91 05:16:14 GMT
From: sequent!muncher.sequent.com![e-mail]
Subject: Re: Laser launchers

In article <[e-mail]> [e-mail] (Fraering Philip) writes:

>I've also heard the phrase
>"Fundamental physical laws" before. It sounds _very_ familiar.
>
>Specifically, Nick Szabo's arguments about chemical launchers and cost.

Whoops, nope, BZZZT, I never said that.

I said "fundamental limits".   And that probably connotes something
harder than what I meant. The limits are those of technology learning
curves, not of the ultimate nature of the universe.

The chemical launch cost curve, and comparisons to other internal-chemical
transportation systems confirm that that the cost/learning curve is
approaching a limit at about $1,000/max lb LEO.  Meanwhile, over 100 times
as much funding has gone into chemical rocket research than all of the other
methods combined during the last 20 years, confirming that chemical
rocket research is well-trod ground, while the other technologies are a
freshly plowed field.  In AI terminology, this branch of the search tree
has been thoroughly scoured.  The laser-launch, tether, etc. branches
have barely been looked at.

A review of the whole thesis point by point:

* The cost/learning curve for chemical rocket vehicles is approaching a
  limit at about $1,000/max lb. LEO, well above what is needed for
  affordable space emigration (between $1-$10/max lb. to LEO, depending
  on whether it is affordable only to upper class, or to upper
  and middle class.  This stranslates to $4-$40/lb. to a Lagrange point
  space colony, or $5-$50/lb. to a lunar or asteroid colony.)
* A discovery significantly changing that curve will also change the
  cost curves of other internal-chemical vehicles, such as cars,
  airplanes, etc.  And vice versa.  An advance dropping chem rocket
  launch costs to $1/max lb LEO. will just as likely drop the cost of a new
  car to $3, or a round-trip ticket NY-Tokyo to $.75.
* The search space for this kind of technology is well-trod, making
  curve-changing advances highly unlikely.
* The search space for laser launch, tethers, EML is fresh territory,
  making it much more likely that R&D on these fronts will provide
  fundamental, curve-changing advances.
* Government lab's primary role is research on technologies
  with high potential for breakthroughs, which is too long-term
  for private industry to undertake.  In other words, government
  should be breaking new ground.
* Private industry's role is R&D, and operations, on technology
  demonstrably profitable in the current or near future.
* _Therefore_, government labs should be doing R&D on the advanced.
  new-field launch technologies.  Chemical rocket research should
  be the job of private industry.

In other words, looking for big chemical rocket cost reductions
is like going out today and looking for a big gold nugget at Sutter's
Mill.  It is like being the last in line at an Easter-egg hunt.
Chances are, somebody already found the good stuff.

If private industry can prove me wrong, I'm all in favor of that.



--
Nick Szabo                [e-mail]
"If you understand something the first time you see it, you probably
knew it already.  The more bewildered you are, the more successful
the mission was." -- Ed Stone, Voyager space explorer

------------------------------

ReSent-Message-ID: <Added.wc=[e-mail]>
Resent-Date:  Mon, 13 May 91 13:38:08 EDT
Resent-From: Tom <[e-mail]>
Resent-To: [e-mail]
Date:         Fri, 10 May 91 02:10:53 EDT
Reply-To: [e-mail]
From: [e-mail]
Subject:      SPACE Digest V13 #518
Comments: To: [e-mail]
To: david polito <[e-mail]>, Tom McWilliams <[e-mail]>

Subject: Re: Ethics of Terraforming (was Re: Terraforming Venus)

>[e-mail] (Henry Spencer) writes:
>>[e-mail] (Ken Sheppardson) writes:
>>>  Is there anyone else out there who questions the ethics of tampering
>>>  with other planets (with or without the presence of life) to make them
>>>  more 'earthlike'? ...
>>
>>How do you feel about the Hawaiian Islands, which were bare volcanic rock
>>until all those foreign plants and animals moved in and started tampering?
>>If what nature did there was right, how can it be wrong for nature (which
>>includes us) to do the same thing elsewhere?

>Anybody else out there getting this strange feeling of deja vu?   I even
>checked the dates to make sure these weren't ghost postings resurrected
>from the dead (as occasionally happens).

Yup.

>This point (Hawaiian Islands) is where I jumped into the conversation last
>time ... I'm not gonna bother again.  Didn't anybody out there save all the
>discussion of the ethics of terraforming from last time around?   Seems
>pointless to rehash all this when we just did it a few weeks ago .....

I don't rememeber where I came in.  All I can say (that I don't remeber
saying beofore) is that I think the orignal poster may be suffering from
an acute case of 'White Liberal Guilt'

What was/is being done to the cultures and ecologies of the planet are
are real tragedy and loss.
But avoiding frontiers in space because of the effects of frontiers on this
planet sort of misses the point of the guilt in the first place, huh?

Tommy Mac
Acknowledge-To: <18084TM@MSU>

------------------------------

End of SPACE Digest V13 #546
*******************