Smart pebbles and the logic or rationization

In "Black Saturday" we have returned to what the group was designed to
discuss! I feel we need to put in another thread. LISA to me is all
about smart/brilliant pebbles. Why do we need pebbles? Some time ago I
saw an advertisement for the Vauxhall Astra in which it said that the
car has cost £750 million to develop. This at the then exchange rate
was over a billion dollars. Of course the individual cars are cheap.
The costs of constructing (and launching) spacecraft follows a similar
curve. If you can rationalize rockets and spacecraft so that there are
only a small number of basic types you can reduce costs.

LISA can be viewed in two ways. It is a gravitational wave detector,
but it is also a template for ultra stable navigation. When I was a
Physics student I did interference experiments over a comparatively
small range. The idea of coherence over 5 million km is both mind-
blowing and indeed points to a standard pebble, a pebble out of which
we can build large optical telescopes. LISA itself requires more
pebbles to achieve a really effective gravitational telescope. General
Relativity tells us that there are 5 planes of polarization and 3
pebbles are insufficient to resolve this ambiguity. If you want to
know the direction of a gravitational wave you will need large numbers
of pebbles. LISA in itself will help to confirm GTR. Despite what
certain individuals say there is no reason to doubt GTR, although it
would be gratifying to directly detect a gravitational wave.

How can we use pebbles? Well if you have a wavelength navigational
system you are able to :-

1) Construct large telescopes. If you have a ring 10km (say) in
diameter that ring can consist of identical mass produced mirrors. Of
course constructing a ring inside will mean having mirrors of slightly
different radii of curvature. Spectroscopy can be performed by moving
some mirrors an integral number of wavelengths out of sync. with the
others.

2) To realize SSP you need a large number of identical units.

In general costs are reduced by rationalisation. This is so
independently of your technology. This is another point. NASA is at
the moment going for Ares. How many Ares launches will there be. The
SSME is an expensive engine, but could be the cheapest solution if you
do not have that many launches. Cheaper still, of course, is to do
away with heavy indivisible loads and assemble in space.

As far as gravitational wells are concerned. The Moon is NOT a
stepping stone to Mars. You set off for Mars (if you are having a
manned mission at all) from LEO. This has been argued before. Phobos
is interesting. On a strict gravitational well basis you want a normal
planetary asteroid. But the well is not too large, you can use ion
drive (that is something else that needs discussion). However suppose
you mine it with robots. Astronauts could at some point pressurize a
gallery and live there.


- Ian Parker

Ian Parker wrote:

:In "Black Saturday" we have returned to what the group was designed to
:discuss! I feel we need to put in another thread. LISA to me is all
:about smart/brilliant pebbles. Why do we need pebbles?
:

We don't, regardless of all your continuous gibbering about LISA, any
more than we need 'AI', regardless of all your gibbering about that.

:
:Some time ago I
:saw an advertisement for the Vauxhall Astra in which it said that the
:car has cost £750 million to develop. This at the then exchange rate
:was over a billion dollars.
:

And your bull**** detector didn't go off? Mine just did.

:
:Of course the individual cars are cheap.
:

Let's look at your number above and assume the (preposterously large)
profit per vehicle of £4000 or so. How many vehicles do you need to
sell to recover the development costs?

:
:The costs of constructing (and launching) spacecraft follows a similar
:curve. If you can rationalize rockets and spacecraft so that there are
nly a small number of basic types you can reduce costs.
:

Somewhat true (assuming the 'rationalization costs' don't eat your
lunch), but this is just another way of saying that launch costs scale
with launch rates.

usual LISA gibbering elided as meaningless

:
:2) To realize SSP you need a large number of identical units.
:

Well, no, because you have to start somewhere. To realize SSP you
just need a few large units.

:
:As far as gravitational wells are concerned. The Moon is NOT a
:stepping stone to Mars. You set off for Mars (if you are having a
:manned mission at all) from LEO.
:

Ignoring the costs of getting everything to LEO in the first place.

:
:This has been argued before. Phobos
:is interesting. On a strict gravitational well basis you want a normal
lanetary asteroid. But the well is not too large, you can use ion
:drive (that is something else that needs discussion). However suppose
:you mine it with robots. Astronauts could at some point pressurize a
:gallery and live there.
:

But "a strict gravitational well basis" is a magnificently stupid way
to decide where you go.


--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn

All I am saying is that a large number of cars are cheap because
development costs are amortized. Nothing surprising in this. I am not
accusing the car companies of excessive profits cheating or anything
else. I am also claiming that amortization principles are generally
applicable.

What is needed is a smaller range of standard rockets + spaceraft
momponents.

You know what. I think there is a classified phase coherence project
lurking somewhere. I don't know and I can't prove anything. Why else
are you so dismissive. I think a spy telescope is going to be built at
GEO? At present the Middle East, for example, is glimpsed only hald
daily at LEO. At GEO an unfolding battle could be monitored
continuously.

Such a system would replace (partially) Predator drones. It would
totally replace Global Hawk. It would be possible to watch the
Pakistani/Afghan border constantly (assuming, of course, there is no
clould). No doubt your obervations would be mostly 3-5 microns.

For myself. I want to see extrasolar Earths and dark matter.


- Ian Parker

"Ian Parker" wrote in message
...
You know what. I think there is a classified phase coherence project
lurking somewhere. I don't know and I can't prove anything. Why else
are you so dismissive. I think a spy telescope is going to be built at
GEO? At present the Middle East, for example, is glimpsed only hald
daily at LEO. At GEO an unfolding battle could be monitored
continuously.

Such a system would replace (partially) Predator drones. It would
totally replace Global Hawk. It would be possible to watch the
Pakistani/Afghan border constantly (assuming, of course, there is no
clould). No doubt your obervations would be mostly 3-5 microns.

For myself. I want to see extrasolar Earths and dark matter.

Wow. Just wow. Do you believe in the tooth fairy too?

Jeff
--
"Many things that were acceptable in 1958 are no longer acceptable today.
My own standards have changed too." -- Freeman Dyson

On 6 Jan, 17:59, "Jeff Findley" wrote:
Such a system would replace *(partially) Predator drones. It would
totally replace Global Hawk. It would be possible to watch the
Pakistani/Afghan border constantly (assuming, of course, there is no
clould). No doubt your obervations would be mostly 3-5 microns.

For myself. I want to see extrasolar Earths and dark matter.

Wow. *Just wow. *Do you believe in the tooth fairy too?

I think that there are rocky planets orbiting stars. I have
consistenly stated that the search for ET, or should I put it more
precisely - the search for evolutionary probabilities depends on the
general improvement of observational technique. About 2 billlion years
ago Oxygen started to be produced by cyanobacteria. In fact what I
would propose to search for is Oxygen worlds. Worlds where there are
cyanobacteria at the very least.

Such a task is beyond our present observational techniques, but not
that far beyond. The next generation of telescopes could find Oxygen.

As far as a secret project is concerned, if it is being worked on it
is one of DARPA's stupider moves. Nobody would oppose astronomical
research wheras you have to think of countermeasures in a military
project. It would be a simple matter to fire a laser at such a spy
telescope. If this were at a viewing wavelength the laser need to
even be that powerful. Things like the Predator or even LEO satellites
are difficult moving targets.

There is one thing to remember about classified projects though. Even
when they are abandoned they remain classified. I am pretty sure (as a
fortune teller!) that there is a classified project but what its
status is I don't know.

BTW - I say "fortune teller". Fortune tellers do not foretel the
future, what they do is make a series of suggestions and they then
make their guesstimates based on the reactions they get. This was
explained in a TV documentary on spiritualism, where skeptics
investigated the whole thing. With Fred's reaction any half decent
spiritualist/clairvoyant would draw the obvious conclusion.


- Ian Parker