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Subject: SPACE Digest V9 #357

SPACE Digest                                      Volume 9 : Issue 357

Today's Topics:
          Metric-is-UNAMERICAN Myers to head NASA !?
             Re: Fusion newgroup proposal
        Re: Room Temperature fusion, expert skepticism
        Power Requirements for Constant-Thrust Rockets
             Re: Asteroids and Pd fusion
               NSS Space Hotline Update
         Re: Solid State Fusion for Launchers
         Re: Solid State Fusion for Launchers
----------------------------------------------------------------------

Date: 8 Apr 89 05:15:19 GMT
From: steinmetz!sunspot![e-mail]  (Emmett Black)
Subject: Metric-is-UNAMERICAN Myers to head NASA !?


> Deputy Administrator Dale Myers to head NASA !

don't forget who was responsible for adopting non-Metric
units of measurement on the space station!
does this look like a good sign to you?

And guess where Fletcher went?

The story I've heard is that he's off to the University of Utah;
to head up the Room-temperature Fusion project ... the one for which the
Utah Legislature was having a special session to appropriate a budget!




--Emmett
    J.E.Black; GE Research/K1-3C26; Schenectady, NY 12345
    [e-mail];   ...!uunet!steinmetz!crd!blackje

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

Date: 8 Apr 89 05:01:22 GMT
From: steinmetz!sunspot![e-mail]  (Emmett Black)
Subject: Re: Fusion newgroup proposal

In article <[e-mail]> Scott Jensen writes:
>Steve Fischer writes:
>|I suggest an alternative name:  sci.physics.fusion
>|No mistaking the topic there!
>
>Alot  of the discussion started by this cold fusion topic has been along
>the lines of 'utopia here I come' and 'oh no, megadeath', and these
> ...
>have a more general fusion group as a sci group.
>--
>..............................................................................
>Scott C. Jensen
>[e-mail]

 ... and the way the drivel has been turned up on this topic
     it would appear that we need SEVERAL new news groups:

    talk.fusion, soc.fusion, alt.fusion, AND sci.physics.fusion

So let's PLEASE try to show some restraint - there are several good
books in the library - please look there before posting any more
questions on the order of "where does heavy water come from?" ...

This is why "real scientists" don't read news.
Thanks for your support. (flame-off)

--Emmett
    J.E.Black; GE Research/K1-3C26; Schenectady, NY 12345
    [e-mail];   ...!uunet!steinmetz!crd!blackje

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

Date: 8 Apr 89 19:23:16 GMT
From: steinmetz!sunspot![e-mail]  (Emmett Black)
Subject: Re: Room Temperature fusion, expert skepticism

> another contributor writes: "I'm inclined not to..."

after getting more detailed information, I have become considerably
more skeptical -- original statement of "inclined to believe" was
based purely on reputation and recommendation of colleagues who know
both F&P personally.

now, after having read the F&P paper and two BYU papers [Jones, et.al],
i tend to be skeptical of the F&P results (the BYU claims are more
reasonable, more modest, [and have been tentatively confirmed at
Brookhaven]) --- even my colleague who has know F&P for 25 years
now shakes his head in disbelief.

 ... i may be skeptical, but i'd really LOVE to see them turn
     out to be right after all!



--Emmett
    J.E.Black; GE Research/K1-3C26; Schenectady, NY 12345
    [e-mail];   ...!uunet!steinmetz!crd!blackje

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

Date: 8 Apr 89 19:20:04 GMT
From: jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Kieran A. Carroll)
Subject: Power Requirements for Constant-Thrust Rockets

[e-mail] (Mark A. Sobolewski) writes:
>
> ><Because the power requirements are not merely high, but staggering, if
> ><the fuel consumption is to be kept sane.  . . . way up in the terawatts . . .
> ><. . . 1% inefficiency means you have to dissipate gigawatts of heat.
>
>     For the record... I get 1 gigawatt for a 20 kilo-ton (metric) mass
> accelerating at 1g.  (P=E/t, delta(v)=g*delta(t) (1 second),E=0.5mv^2,
> 20,000,000kg)  (minimum power consumption of course).
>

What you seem to be trying to calculate here is the power associated with
the change in the kinetic energy of the spacecraft, as measured in some
appropriate frame of reference. If so, you've done your calculation wrong.
Consider this:

E = 0.5 * m* v**2

P = dE/dt = d(0.5 * m* v**2)/dt
          = 0.5 * m * d(v**2)/dt (assuming dm/dt to be zero)
          = 0.5 * m * 2 * v * dv/dt (chain rule)
          = mvg

where v is the velocity measured with respect to the reference frame used,
and dv/dt is assumed to have the value of g. Thus, the power required
is a function of velocity of the spacecraft.

Now, what reference frame shall we use? If we use a frame attached to the
spacecraft, then v is always zero, and so P=0. Not a very useful result...
Let's use a frame such that v=0 just at the moment that the rocket starts up
(ie. a frame at rest with respect to the starting point of the spacecraft).
Then, v increases linearly with time, and so P increases linearly with time.
E then measures the kinetic energy of the spacecraft, as measured in the
reference frame that we have chosen.

This is all not very useful. If we chose a >>different<< reference frame, we
could easily have P being >>negative<< (for at least part of the time). When
considering a rocket engine's power, what we really want to look at is
the rate of kinetic energy being imparted to the >>reaction mass<<
being expelled by the spacecraft, measured in the spacecraft's frame of
reference. Consider an infinitesimally small particle of reaction mass, dM,
which is initially at rest in the spacecraft, but is then expelled at a
velocity of V. The change in kinetic energy of this particle is then

dE = 0.5 * dM * V**2

Therefore,

P = dE/dt = 0.5 * V**2 * dM/dt

That is, power consumption of the engine (assuming perfect efficiency) depends
on exhaust velocity V, and mass flow rate dM/dt. In order to accelerate at a
constant thrust, while conserving reaction mass, high exhaust velocities are
required; this tends to require a very high-powered engine. Current rocket
vehicles achieve a high acceleration by using a high value of dM/dt; of course,
this depletes their reaction mass rapidly. Constant-thrust ion-powered engines
use an extremely low value of dM/dt, and a very high value of V; ecen so, they
require a lot of electrical power to drive them (this is why they are not common
on current satellites -- what you save in reaction mass due to the high V,
you lose in the mass of the solar array that you need to power the ion engine).

I hope this clears things up a bit.
(I also hope that I've avoided any errors here!)

--

     Kieran A. Carroll @ U of Toronto Aerospace Institute
     {allegra,ihnp4,decvax,utai}!utzoo!kcarroll

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

Date: 8 Apr 89 21:29:05 GMT
From: mailrus!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Asteroids and Pd fusion

In article <[e-mail]> [e-mail] (andrew) writes:
>... The existence of a heatsink at 3 degK should be a great help for
>the engine design...

Not as much as you think.  Getting the heat out to that heatsink is
*not* a trivial problem.  The shuttle uses the entire inner surface of
its payload-bay doors as a heat radiator.  If you look at pictures of
the space station, you'll see two sets of big flat panels sticking
out -- solar panels, and radiators.  Fusion rockets are likely to have
quite serious cooling problems, at least in high-performance versions.
(Chemical rockets dump heat into their fuel, but a high-performance
fusion rocket doesn't use fuel quickly enough for that approach to work.)
--
Welcome to Mars!  Your         |     Henry Spencer at U of Toronto Zoology
passport and visa, comrade?    | uunet!attcan!utzoo!henry [e-mail]

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

Date: 8 Apr 89 03:44:00 GMT
From: arisia!cdp![e-mail]
Subject: NSS Space Hotline Update


This is the National Space Society's Space Hotline for the week
ending April 7th, 1989.

At the Kennedy Space Center.......

On Friday Astronauts completed running through the final hours of
a practice countdown exercise on the shuttle Atlantis.  The
Atlantis will launch the Magellan Venus Radar Mapper to map the
cloud shrouded surface of Venus with a Synthetic Aperture Radar
instrument.  This high priority payload must be launched during
the April 28 through the end of May launch window.  The launch is
scheduled for April 28 at 2:24pm EDT.  Launch technicians have run
into some minor problems in the past week, but so far April 28 is
still viable.  The formal launch date will be set at the flight
readiness review, which will take place on April 13 and 14.

It is expected that the White House will soon formally nominate
Rear Adm. Richard Truly, currently deputy administrator for Space
Flight, to be the NASA Administrator.  In addition current Marshall
Space Flight Center director J.R. Thompson is expected to be
nominated for the NASA deputy Administrator position.  The White
House is expected to get a waiver from congress to allow Truly to
keep his active status as a Naval officer so he will not loose his
military pension.

At the Fifth National Space Symposium resigning NASA administrator
James Fletcher declared that the civil space program has recovered
from the Challenger disaster, but struggles to keep its budget in
tact.  In his farewell speech Fletcher warned that America's future
in space will be in jeopardy if Congress cuts its $13 billion
dollar budget.

Rep Bill Nelson (D-Fla.) stated during a hearing of his Space
Sciences and Applications Subcommittee that, he personally favors
a manned, multi-national mission to Mars.  But that's the sort of
goal that President Bush must set.  Dr. Thomas O. Paine stated
during the hearing that, strong Presidential leadership in
advocating long range goals so that the NASA/Industry/University
environment will be motivated by the sense of a common direction
and purpose, thereby maximizing the research dollar.

    The President of the National Space Society, Charles Walker
testified to the same committee, "that the National Space Society's
members wish delivered to the members of this subcommittee and your
colleagues throughout Congress is not one laden with technological
arguments or of budgetary wizardry. It is a message, plain and
simple, in the tradition of the American dream and the American
spirit - we believe that United States must be a leader on the
space frontier, or it will cease to be the great hope for human
liberty and freedom."

Eight more chicken eggs that rode on the Space Shuttle Discovery
that were scheduled to hatch this last weekend have died.  32
fertilized chicken eggs were sent up, 16 fertilized 9 days in
advance and 16 fertilized 2 days in advance.  All the younger eggs
died, and the older ones all survived.  The results of the
experiment has raised concern that some species of plants and
animal need gravity to reproduce.

Astronaut Franklin Chang-Diaz has developed a coffee maker for the
Space Shuttle program so that the Astronauts could get a decent cup
of joe during the missions.  The coffee maker brews a cup of coffee
in 45 seconds, no mess, and uses less coffee beans.  Called the
Elan Galileo, it will fly on the Atlantis Orbiter during its
Galileo mission in October.  It's due out in stores sometime this
summer for about $100.00.

In a 12th successful launch in a row, Arianespace launched an
Ariane-2 rocket carrying a Nordic tv satellite into low earth
orbit.  The launched occurred last Sat. night, 24 hours late due
to technical problems.  19 minuets into the flight the satellite
was ejected into an egg-shaped transfer orbit so that it can
achieve geo-stationary orbit.

The Soviet Union has revealed the details of the lose of their
Mars/Phobos Moon probe at an international press conference last
Monday.  They stated that spacecraft's radio transmitter which was
under program to remain silent during a photography session, was
expected to switch back on, but never did.  Ground control was able
to re-establish a link for about 13 minuets till the transmitter
went silent and has been ever since.

Stefania Follini who's been living in a 10' by 10' room in a cave
in Carlsbad New Mexico is after 81 days of isolation, lost in time.
When scientists asked her (on March 31, 1989) what the date was,
she responded Feb. 22.  As an experiment that the Pioneer Frontier
Explorations and Researchers of Anocana, Italy is sponsoring, Ms.
Follini has been sealed off from the outside world except by
computer, for 81 days and will be for another four to five months,
to study the physical and psychological effects of insolation
experienced during long duration space travel. Scientist monitor
her with hidden cameras and microphones.  Ms. Follini now stays
awake for 30 hour stretches, and considers it a normal working day.

This has been Jordan Katz reporting for the National Space
Society's Space Hotline.

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

Date: 8 Apr 89 15:38:30 GMT
From: haven!uvaarpa!virginia!uvacs![e-mail]  (Ray Lubinsky)
Subject: Re: Solid State Fusion for Launchers

In article <[e-mail]>, [e-mail] (Jorge Stolfi) writes:
>
> On the other hand, cheap energy on the Earth means there won't be any
> need for solar power satellites (SPS).  Now, SPSes are the only
> large-scale space operation that is not obviously an economical
> nonsense.  Without SPSes, space colonies would lose their main raison
> d'etre; and without space colonies, there is hardly any reason to
> consider lunar and asteroid mining.  (By the way, cheaper energy would
> make possible to exploit many low-grade ore bodies that now are
> uneconomial, so mining the asteroids for the Earth market would make
> even less sense that it does now.)

I hate to break the news to you, but SPS never had a chance anyway.  For
starters, it requires a huge infrastructure, massive startup costs, and
potential biohazard (at least, I'll pass on living anywhere near the microwave
collectors, thank you).  What reason is there to believe that states and
businesses would not turn to some more mundane sources of energy with lower
initial costs as opposed to something that might turn a profit twenty or
thirty years after beginning development?  I'll admit that SPS is a rational
plan in the long run, but (especially in the Reagan Era of quick profits and
leveraged buyouts) that kind of rationality is not likely to make it on to
anyone's agenda.

There will be plenty of reasons for people to inhabit space when the time
comes.  But they will be evolutionary reasons not revolutionary initiatives.
Personally, I imagine that after some substantial (on orbit) research of 0 G
materials processing, there will be hundreds of reasons for the development and
habitation of LEO and the Moon.

--
| Ray Lubinsky                         [e-mail] (Internet) |
|                                      rwl@virginia                  (BITnet) |
| Department of Computer Science,      ...!uunet!virginia!uvacs!rwl    (UUCP) |
| University of Virginia               [phone]                 (voice) |

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

Date: 8 Apr 89 23:43:06 GMT
From: jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Solid State Fusion for Launchers

In article <[e-mail]> [e-mail] (Ray Lubinsky) writes:
>... What reason is there to believe that states and
>businesses would not turn to some more mundane sources of energy with lower
>initial costs as opposed to something that might turn a profit twenty or
>thirty years after beginning development?  ...

Most other *large-scale* energy sources also involve high capital costs
and very long payback times, these days.  Not to mention environmental
problems.  It is not immediately obvious that powersats are inferior in
these respects.  Where they do have a problem is that they're novel and
untried.  The power industry considers multi-billion-dollar investments
fairly routine -- yes, folks, there *are* non-government investors who
can put up capital on that scale -- but *only* for well-proven systems
where eventual profits are virtually certain.
--
Welcome to Mars!  Your         |     Henry Spencer at U of Toronto Zoology
passport and visa, comrade?    | uunet!attcan!utzoo!henry [e-mail]

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

End of SPACE Digest V9 #357
*******************