Re: Space funding (was Re: Hillary needs to quit)

"A.G.McDowell" <mcdowella@[EMAIL PROTECTED]
> wrote:

>In article <4807a928.604678765@[EMAIL PROTECTED]
>, Derek Lyons
><fairwater@[EMAIL PROTECTED]
> writes
>>"A.G.McDowell" <mcdowella@[EMAIL PROTECTED]
> wrote:
>>
>>>If the lack of progress in chemical rockets is
>>>excused by fundamental limits, then why are we planning to throw money
>>>at it? Couldn't we throw money at technologies that haven't yet
>>>approached their fundamental limits?
>>
>>If you know of one that isn't a) a hideous environmental disaster or
>>b) doesn't require unobtanium plating for the handwavium reaction
>>chamber, a wealth of riches and a possible Noble Prize awaits you.
>
>I suspect that the wealth of riches and the Nobel Prize will require
>conclusive proof. I have heard of plausible ideas for research:
>
>1) Ion drive once you are in vacuum and in orbit - this pays off at
>launch time in satellites if you can use it for station-keeping instead
>of chemical thrusters and reduce the total mass that you need to lift to
>orbit.

That's fine for station keeping - but the main beef against chemical
rockets is their use in boosters.

>2) Skyhook/Space elevator/fountains of paradise, OK - this needs
>something that is currently unobtanium, but there seems to be more
>distance between what we can do now and what we think is theoretically
>possible than there is with chemical rockets.

So long as the materials required remain unobtanium, the amount of
headroom theoretically available once the unobtanium is available is
pretty much meaningless.

>3) Alternate first stages. This is a whole spectrum from current
>research (SCRAMJET and various launch-from-aircraft/balloon schemes) to
>the SF (rail gun on the Andes/ launch from the top of Everest).

The problem is - all of the proposals for alternate first stages
actually require a light usage of unobtanium alloys, but this usually
escapes casual scrutiny and the proponents thereof rarely engage in
serious scrutiny.  (And indulge in some amazing mental gymnastics when
they do so they can ignore two very im****tant points.)

Lets take, for example, the often bandied about high speed horizontal
launch - either from a catapult or from some form of aircraft.  This
is very good for getting a modest amount of horizontal velocity, but
gives you very little vertical velocity...  And orbital velocity is a
vector quantity that needs velocity in both planes.  This means you
need a significant additional chemical stage to avoid ending up in a
lithocapture orbit.  (Guns have the same problem, only they give
velocity in the vertical while lacking velocity in the horizontal.)

Proponents of these schemes avoid thinking about this by comparing
'cost of kg launched' - and don't think too hard about the fact that
in their scheme the 'kg launched' includes the massive weight and cost
of this additional stage while traditional rockets properly charge
this cost to the booster.

The second point they avoid (mightily!) thinking about - is that if
you have a world where there is enough demand to justify the billions
of dollars of research, development, and infrastructure investment in
alternate schemes... then chemical rockets also get a hell of a lot
cheaper because it now makes sense to invest a fractional amount of
what the alternate scheme would cost in mass producing chemical
rockets.  

Ultimately this, what alt.spacers call the "chicken and egg effect",
the utter lack of demand, is the _real_ problem.  Engaging in mental
masturbation over kewl tech is much easier and more entertaining than
thinking about Hard Problems, so few bother to think about the Hard
Problems.

>I suspect that if you set up the problem of launching a large number (to
>amortise costs) of small (10kg) payloads to orbit, and that if those
>payloads were as tough as artillery shell proximity fuses, and that if
>you threw this problem at a super-intelligent optimisation program, so
>as to make absolutely the best possible use of current technology, the
>launch system that you got out wouldn't look much like Apollo.

No matter what technology you chose - a 10kg payload program is going
to look much different from Apollo.  The problem is that such a
program is pretty pointless as there isn't (and is unlikely to ever
be) much demand for 10kg payloads, and it's unlikely the resulting
launch system will scale gracefully.

>4) Pure unobtanium - in other words, do thirty years of pure materials
>science before returning to launch systems design.

With the exception of space elevators, materials science isn't the
limit on performance of pretty much any launch system.

>>>I applaud, for instance, the idea of "cheap access to space", but I
>>>would like to point out that (very loosely) there are two ways of
>>>getting cheap access to space - you can reduce the cost, per kilogram,
>>>of putting hardware in earth orbit, or you can reduce the kilogram
>>>weight of hardware necessary to achieve any required function.
>>
>>The first is easy and uses nothing but well understood industrial,
>>engineering, financial, and management techniques.  The main barrier
>>is the massive up front investment.
>>
>>The second is very hard and involves working at the bleeding edge of
>>virtually every field involved.  The main barrier - working at the
>>bleeding edge is never cheap.
>>
>>D.
>It's not cheap and never will be, but if our goal is to achieve the best
>possible space technology in 50 years time, or to produce a large
>improvement in capability, and not a series of publicity stunts, then it
>is more efficient to pay for the research before building vehicles in
>quantity, and not during or after.

Except you don't gain the experience needed to design the vehicles to
be launched in quantity... without launching vehicles in quantity.
Real Life isn't like the movies where all the problems can be sorted
out in the lab.

D.
-- 
Touch-twice life. Eat. Drink. Laugh.

http://derekl1963.livejournal.com/

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL