Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V13_6/V13_610.TXT

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Subject: SPACE Digest V13 #610

SPACE Digest                                     Volume 13 : Issue 610

Today's Topics:
        Re: Dimensions of Shuttle bay wanted.
                Re: lifeboats
          Re: SPACE station or NOTHING!!!!!
             Calculating delta-V
              Re: Budget Numbers Wanted
         Re: New Subject--Solar Collectors (Dual Use)
           Re: Rational next station design process
       Re: Laser launchers (really microwave launchers)

Administrivia:

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

Date: 21 May 91 23:41:00 GMT
From: swrinde!zaphod.mps.ohio-state.edu!think.com!spool.mu.edu!cs.umn.edu!kksys!wd0gol!newave![e-mail]  (John A. Weeks III)
Subject: Re: Dimensions of Shuttle bay wanted.

In <[e-mail]> [e-mail] (Ralph Busch) writes:
> I'm in need for the dimensions of the space shuttle bay.  Actually, if anyone
> has figures on the size of canisters that the Space Station Freedom was going
> to be made of, that would be really handy!

I do not have the exact numbers.  Since I cannot visualize sizes based on
dimensions very well, I use a couple of ball-park analogies.  The orbitor
is about the size of a 727.  The cargo bay is about 45' long and about 15'
in diameter.  This is about the size of 2 semi truck trailers parked side
by side.  The payload weight is about the same as a fully loaded semi
truck.

> Also, if you have the figures for the soviet shuttle, that'd be nice, but not
> necessary.

If one were to say about the same as the NASA Shuttle, you would probably
not be too far off.

-john-

--
=============================================================================
John A. Weeks III               [phone]             [e-mail]
NeWave Communications, Ltd.                        ...uunet!tcnet!newave!john

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

Date: 22 May 91 15:41:08 GMT
From: sdd.hp.com!caen!ox.com!fmsrl7![e-mail]  (Ron Carter)
Subject: Re: lifeboats

In article <[e-mail]> [e-mail] (George William Herbert) writes:
>You're forgetting something... all the orbital maneuvering (reaction control
>system etc) was on the SM if I remember correctly.  I'm not sure how happy the
>astronauts would be about dropping hydrazine in their capsule for RCS
>purposes.

The CM had limited reaction control capabilities.  I've seen the
Apollo 9 CM a few times; there are most definitely RCS nozzles
built flush into the skin down near the heat shield.  The CM
most definitely carried fuel for these thrusters; the hydrazine
(or whatever) problem is old hat.

However, these jets won't work for orbital maneuvering for
several reasons.

1.)    They are designed to maintain spacecraft attitude
    during re-entry.  Thus, they can only roll, pitch
    and yaw the spacecraft.
2.)    Thrusters to translate the spacecraft in the X, Y
    and (important for docking) Z axes are absent.
3.)    The rotational thrusters aren't balanced.  (They
    didn't need to be.)  A little translational push
    from a rotation is of no consequence during re-entry,
    but it is a serious problem when docking.

This means that the CM cannot be used as a crew vehicle
or lifeboat without either modification or an SM-equivalent.
It can't dock without assistance, nor push away from a
space station either.  These capabilities are required
for either crew rotation or lifeboat operations.

Considering our progress in ultra-low-power electronics
(for avionics), high-strength materials (for oxygen tanks),
powerful batteries, and other technologies, it should not
be difficult to design a CM-equivalent which can be shipped
up to a space station, dock with it, and then either work
as a crew transport or lifeboat.  It might be possible to
build one into a CM-shell and omit the SM, but I believe
that it will be necessary to get somewhat fancy with the
thruster configuration to achieve the necessary capabilities.

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

Date: 23 May 91 18:46:56 GMT
From: aio!vf.jsc.nasa.gov![e-mail]
Subject: Re: SPACE station or NOTHING!!!!!

>
> Well, if we go ahead and build the station as currently conceived,
> it'll just be that much harder for me to convince my professors who

I guess they feel as if the the S.S. Freedom is competing for dollars with
them.  Do they remember all the data on the sun we got from skylab?


>
> With the astronomical pricetag for the shuttle, he doesn't believe
> cheap spaceflight is possible.
>

For the first shot a reuseable vehicle, the shuttle does quite well.  Its
launch cost is less than the Saturn V.

--

Mike Kent -      Lockheed Engineering and Sciences Company at NASA JSC
        2400 NASA Rd One, Houston, TX 77058 [phone]
        [e-mail]

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

Date: 23 May 91 23:06:32 GMT
From: agate!spool.mu.edu!samsung!munnari.oz.au!yoyo.aarnet.edu.au!sirius.ucs.adelaide.edu.au!levels![e-mail]
Subject: Calculating delta-V

In calculating the delta-V (change in velocity) that a rocket stage imparts
one needs to multiply the engines Specific Impulse (if it is given in seconds)
by the acceleration of gravity at Earth's surface. My question is what is the
standard (if there is one) that rocket scientists use for g? In the metric
system, the approximation for g that we used in high school is 9.81 m/s^2.
However, my little Casio calculator table gives the (Standard) g as
9.80665 m/s^2.

If your engine has a 450 s SI and the propellant mass to empty mass is equal to
3, you obtain from the rocket equation a delta-V of 6120 m/s for
g = 9.81 m/s^2, 6114 m/s for g = 9.80 m/s^2, or 6118 m/s for the Standard g.
A rocket engine already has errors in what the actual the value of SI is and
if one is uncertain as to what g to use this will add more errors into what the
actual delta-V will be. As can be seen, errors of between +2 m/s and -4 m/s
can occur simply because of the uncertainty of g. If there is a standard g
that rocket scientists use, this would remove this uncertainty.

A good solution is to give SI as the ratio of thrust (in Newtons) to
propellant consumption (in kg/s). This will give SI in m/s and there is no
need to multiply g in working out delta-V. In the imperial system thrust is
measured in pounds-force, i.e., one pound-force is the force required to
accelerate one pound by one g. We then get into the same problem of what g to
use. The metric system defines one Newton as the force required to accelerate
one kg by one one m/s^2. (Using g = 9.80665 m/s^2 and 1 lb = 0.453592 kg,
1 lbf = 4.44822 N).

--
Steven Pietrobon, Australian Space Centre for Signal Processing
School of Electronic Engineering, University of South Australia
The Levels, SA 5095, Australia.          [e-mail]

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

Date: 22 May 91 18:17:36 GMT
From: swrinde!zaphod.mps.ohio-state.edu!usc!nic.csu.net!csun.edu!corona![e-mail]  (Stephen Walton)
Subject: Re: Budget Numbers Wanted


[This is exactly as I received it via e-mail.  Some hard numbers
are clearly needed in this discussion.]

Statement of the Honorable Bob Traxler, Chairman, VA, HUD, and
Independent Agencies Subcommittee, House Appropriations Committee
-- May 15, 1991

"Today's action of the VA-HUD and Independent Agencies
Appropriations Subcommittee, in accepting my recommendations to
terminate funding for the development of NASA's Space Station
Freedom, reflects the fact that our Federal Government's budgeting
has hit a dead end.  We simply can no longer afford huge new
projects, with huge price tags, while trying to maintain services
that the American people expect to be provided.

The Fiscal Year 1993 scenario is also dismal. Under last year's
budget agreement, the Subcommittee does not expect any increase
beyond the percentages in this year's allocation: 5.4% in budget
authority and 5.6% in outlays.  Furthermore, prior-year
appropriations will produce increased outlays that will adversely
impact the Subcommittee's ability to fund the various agencies
within its jurisdiction.  In brief, if we cannot afford to fund
the space station this year, there is no way that we would be able
to fund it next year.

The budget crunch this year requires us to terminate development
of the space station; if we stay on the same budget course, we
will soon be faced with the prospect -- even the necessity -- of
making more awful decisions in the years ahead.

The VA-HUD Subcommittee funds a range of important human needs
programs: VA hospitals, housing for the poorest in our society,
environmental clean-up programs on which the health of ourselves
and our planet depend, education and basic research programs on
which our future depends, and, yes, our civilian space program
with which we address another basic human need -- the need to
explore.

In terminating funding for the space station, we have been able to
provide nearly full funding for other space science research
efforts and we have provided full funding for the research and
education programs of the National Science Foundation. We have
provided a much needed increase for the VA hospital system, which
I wish could have been more, in order to help keep our Nation's
medical services for veterans in operation. We have provided
generous funding for our nation's environmental programs. Finally,
we have maintained our nation's commitment to housing for the poor
and homeless."

Traxler budget WITHOUT / WITH SSF
===============================================
RESEARCH & DEVELOPMENT        Station -- Out        Station -- In
Space Station                 -1,928,900,000
Space Flight Capability Development
   New Launch Systems             ---                -175,000,000
   General Reduction             -10,000,000          -50,000,000
Space Science and Applications
   General Reduction              ---                  35,000,000
   SETI                           ---                  -7,000,000
   SIRTF & OSL's Phase B's        ---                 -25,000,000
   LIFESAT                       -10,000,000          -15,000,000
   Life Science (Space Station)  -25,000,000          -25,000,000
   AXAF                           ---                 -50,000,000
   EOS                            ---                 -75,000,000
   CRAF                           ---                 -45,000,000
   LANDSAT                        +5,000,000              ---
   Microgravity                  -11,500,000              ---
   Remotely Piloted Aircraft      -5,000,000           -5,000,000
   SAR                           +10,000,000              ---
   Classroom of the Future        +1,500,000              ---
Information Systems               -5,000,000           -5,000,000
COMMERCIAL PROGRAMS
   COMMERCIAL APPL/ENHANCEMENTS   -5,000,000           -5,000,000
   COMMERCIAL TRANSPORTATION      -5,000,000          -25,000,000
Aeronautics and Space Technology
   Aeronautics Res. Gen Reduction ---                 -10,000,000
   NASP                           ---                 -25,000,000
   Exploration Technology        -10,000,000          -52,000,000
   Space Automation and Robotics  ---                 -50,000,000
   Exploration Mission Studies    -5,000,000          -15,000,000
   General Reduction (Space Tech) ---                 -25,000,000
Academic Programs                 ---                  -9,000,000
General R&D Reduction             ---                 -25,000,000
Total NASA R&D                -2,003,900,000         -753,000,000

SPACE FLIGHT
Space Tranp.Prod.&Operations
   General Reduction              ---                -200,000,000
   Assured Shuttle Capability     ---                 -75,000,000
   Structral Spares               ---                 -75,000,000
   ASRM                         +175,000,000         +175,000,000
   Tracking                      -25,000,000          -50,000,000
Expendable Launch Vehicles
   TDRSS LAUNCH VEHICLE          -39,000,000          -39,000,000
   Titan IV Craf/Cassini         -35,000,000          -50,000,000
   Mobile Satellite              -24,000,000          -24,000,000
   General Reduction             -10,000,000          -10,000,000
      Total NASA Spaceflight     +42,000,000         -348,000,000

R&PM
   Gen.Reduct.Fund Source III    -13,000,000          -75,000,000
   Gen.Reduct.Fund Source I&II   -12,000,000          -25,000,000
      Total R&PM                 -25,000,000         -100,000,000

CONSTRUCTION
   ASRM (to Spaceflight Acct.)   -50,000,000          -50,000,000
   Space Station Proc. Facil.    -35,000,000             ---
   CEISIN Facility                +3,400,000             ---
      TOTAL NASA              -2,068,500,000       -1,251,000,000

--
Stephen Walton, Dept. of Physics & Astronomy, Cal State Univ. Northridge
    "Lately it occurs to me/What a long, strange trip it's been"

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

Date: 22 May 91 19:18:06 GMT
From: agate!spool.mu.edu!news.uu.net!igor!rutabaga![e-mail]  (Bill Baker)
Subject: Re: New Subject--Solar Collectors (Dual Use)

In article <[e-mail]> [e-mail] (Paul Blase) writes:
[...]
>There is a limit, but in general photovoltaic cells operate most efficiently
>at very high light levels.  This is why many new solar-cell designs use
>concentrators (mirrors) to increase the light flux at the cell.  The closer
>you are to the sun, obviously, the smaller a system you need for a given
>amount of light on your cell.

[...]

>Don't forget that there is another way of producing electricity from
>sunlight: dynamic power, aka a steam turbine.   I think that it is a
>toss up as to which would be cheaper right now.

Pardon me if this is a dumb question, but isn't the obvious
answer to combine the photovoltaic and thermal transfer
methadologies?  I've read that people using collectors with
photovoltaic cells cool them with water to keep them below the
critical temperature.  Isn't this wasting heat?  Can't you
capture the thermally transmitted energy from a PV cell just
like any other solar heating collector?

I guess the limiting factor is the upper temperature limit of
the photovoltaic cells vs. the most efficient operating
temperature of a thermal transfer medium.  I read that the
newest solar thermal plants were heating an oil-based fluid to
around 700 degrees F, which seems to be way over the limit for
PV cells.  Still, couldn't a combined system at least preheat
a transfer medium before passing it on to a final heating
stage (not necessarily thermal)?

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

Date: 23 May 91 04:57:00 GMT
From: agate!tornado.Berkeley.EDU![e-mail]  (George William Herbert)
Subject: Re: Rational next station design process

In article <[e-mail]> [e-mail] (Nick Janow) writes:
>> This isn't how space programs funding is done now...
>That's your argument?  We should decide to go ahead with a vague project,
>_then_ decide the details, like who can/will use it and who might be willing to
>pay for the services, just because "that's the way they do it now"?

No.  I'm doing a specific project with a specific set of missions.  The
life science/human biology people will use it, as well as a few others 'while
we're there'.  The government in its infinite (cough) wisdom already funds
similar missions/needs, so presumably that's where it will come from.

>> The President and VP seem to want Freedom, whatever the cost.
>Political advertising is a really poor excuse for an otherwise unrelated
>engineering project.
>> ) we've already decided how much one is worth.
>Really?  I thought the project was still undefined, so how could there be a
>firm cost to be accepted?  The cost projections seem more like tools used for
>the current round of budget fighting, with no real meaning beyond that.

'Worth' not 'Cost'.  The Executive branch feels it's 'worth' whatever they
think it will cost (presumably to some undefined limit above what NASA said
it would).  Congress has a 'cost' estimate that they think exceeds the
'worth' of the project.  Trading off cost and worth is sort of iffy in many
cases where the worth is scientific return or something less tangible.

-george william herbert
[e-mail]

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

Date: 15 May 91 16:32:03 GMT
From: elroy.jpl.nasa.gov!swrinde!zaphod.mps.ohio-state.edu!unix.cis.pitt.edu!pitt!nss![e-mail]  (Paul Blase)
Subject: Re: Laser launchers (really microwave launchers)

to: [e-mail] (Thomas Johnsson)

 TJ> I wonder if anyone has considered beaming the power to the
 TJ> launch vehicle using microwaves instead of a laser. Presumably
 TJ> power can be converted to microwaves with greater efficiency
 TJ> than laser light.  In the vehicle end, the beamed power could
 TJ> either heat up a medium direcly, or be converted to electricity
 TJ> (a lot!) with a rectenna to drive a mass driver.

The trouble is the size of the rectenna required.  NASA has already built a
microwave powered airplane, for long-duration upper atmospheric studies.
The thing (unmanned, of course) looks like a cross between a U-2 and
an AWACS, the big circular thing being the rectenna

--- via Silver Xpress V2.26 [NR]
--
Paul Blase - via FidoNet node 1:129/104
UUCP: ...!pitt!nss!Paul.Blase
INTERNET: [e-mail]

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

End of SPACE Digest V13 #610
*******************