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Subject: SPACE Digest V11 #18

SPACE Digest                                      Volume 11 : Issue 18

Today's Topics:
             Re: More Info On SSX
              Galileo Update - 02/07/90
                   Re: SSX
          Re: Spacecraft drives and fuel efficiency
          Re: Galileo Update - 02/06/90 (Forwarded)
               MOS 1-B Launched
               Gravity Assist Mechanism
             Re: More Info On SSX
----------------------------------------------------------------------

Date: 7 Feb 90 12:24:32 GMT
From: ispi![e-mail]  (Jonathan Bayer)
Subject: Re: More Info On SSX

[e-mail] writes:


>/* Written  6:14 pm  Feb  5, 1990 by [e-mail] in m.cs.uiuc.edu:sci.space */
>/* ---------- "More Info On SSX" ---------- */

[ deleted ]

>The anticipated cost of
>each vehicle is around $30 million, yielding launch costs
>of about $50 per pound of payload in Low Earth Orbit.
>/* End of text from m.cs.uiuc.edu:sci.space */
>Forgive my math, but I get
>$30,000,000 / 20,000 lb = $1500/lb, not $50.
>For a 9,000 lb payload, it's $3333/lb. Where did you get $50/lb from?
>For a 20,000 lb payload, and $50/lb, the vehicle must cost only $1million.


Well, if you only use it once then your numbers are correct.  On the other
hand, if you assume that it will be used 100 times then the cost works out
as follows:

$30,000,000 / 20,000 lb / 100 trips = $ 15/lb

This is for the cost of the vehicle alone.  The rest of the cost is now fuel
and labor costs.


JB
--
Jonathan Bayer        Intelligent Software Products, Inc.
[phone]        500 Oakwood Ave.
[e-mail]        Roselle Park, NJ   07204

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

Date: 7 Feb 90 20:21:47 GMT
From: zaphod.mps.ohio-state.edu!usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Galileo Update - 02/07/90


                      GALILEO MISSION STATUS
                        February 7, 1990

     Today the Galileo spacecraft is 29.4 million miles from
Earth; round-trip light time is 5 minutes 16 seconds.  It has
rolled up almost 181 million of the 185 million miles around its
orbit from launch last October to the Venus flyby, which occurs
Friday night (a minute before 10 p.m. PST, or about 1 a.m. EST).
Heliocentric velocity has now reached about 83,000 mph.

     The Venus gravity-assist flyby will bring the spacecraft
about 10,000 miles above the cloud-tops, 41 degrees south of the
planet's equator.  Galileo will cross behind Venus, increase its
velocity by about 5,000 mph, and take up a different, slightly
larger solar orbit which comes within 65 million miles of the Sun
on February 25 and then curves out to fly by Earth in December
for its second gravity assist at a 600-mile altitude.

     During the Venus flyby, the spacecraft will record about 80
images and many other scientific observations for playback in
late October when the telecommunications link can support the
7.68-kilobit science data rate.

     The spacecraft continues in excellent health; the
power margin and spacecraft temperatures are as expected.
Galileo is in normal cruise mode, with part of the spacecraft
despun and the rest spinning at 3.15 rpm.  The telemetry rate
is 1200 bits per second, radiating from low-gain antenna No.
2. The spacecraft attitude sun point angle is at 2.6 degrees.
The first part of the Venus flyby operational sequence
was transmitted up yesterday (and is now active aboard
Galileo); the rest is to be sent up tomorrow.


 Ron Baalke                       |    [e-mail]
 Jet Propulsion Lab  M/S 301-355  |    [e-mail]
 4800 Oak Grove Dr.               |
 Pasadena, CA 91109               |

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

Date: Wed, 7 Feb 90 21:10:47 EST
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: Re: SSX


I have a 33-page paper entitled
                                 THE SSX
                          SPACESHIP, EXPERIMENTAL
                          -    -      -

                           by Maxwell W. Hunter
                              15 March 1988
                          Updated 11 March 1989

There's also a mailing address. I suspect Mr. Hunter would not appreciate
suddenly getting hundreds of requests for free copies, so I'm not posting it.
If anyone's really interested, I could send the address, and that person
could serve as a liaison. There are many figures and tables in the paper,
but perhaps at least the text part could be put in the archives.

The paper presents at least three concepts:
 - The philosophy of rocket design and launch services.
 - A specific proposal for an experimental design project.
 - Flames about current design approaches, policies, and organizations.

This paper is amazing in that it is almost a complete rewrite of the current
school of though on rocket design. Many ideas are presented that go strongly
against current thinking. Among the concepts presented:
 - Rockets are highly efficient because almost all of the chemical energy
   of the fuel and oxidizer goes into kinetic energy of the rocket.
 - Airbreathing rockets are not much good because too much of the energy
   goes into working against drag (no math to support this).
 - In a "properly designed" rocket, most of the cost of a launch is the
   cost of the fuel, and oxygen, being cheaper than hydrogen, adds little
   to the cost of the launch.
 - Vehicle weight (other than payload) is mostly a function of fuel tank
   weight, which is (linearly?) proportional to the energy density of the
   fuel. Therefore, propellant density times Isp squared is a much better
   index of desirability of a fuel than is Isp alone. This makes heavy
   hydrocarbons + oxygen a better choice than hydrogen + oxygen.
 - Launch costs (fuel cost multiplied by 3) should eventually drop to
   ~$10 per pound of payload.
 - Components should be built with plenty of design margin, for high reliability
   (the ALS approach). Rockets should be reusable. They should not require
   thorough checking between launches.
 - Vehicles should be built purely for test purposes (the NASP philosophy).
 - SSX should use technology developed for NASP.
 - SSX should be made with many engines (aerospike design) so that the
   failure of a few engines does not prevent safe landing.
 - Being reusable, SSX can be put through progressively higher test flights,
   until orbit is achieved.
 - SSX can be flown with or without humans aboard.
 - An effort should be made to minimize the number of people participating
   in a mission, to save labor costs.
 - Design programs should be fast.

Comments:
It seems to be the general custom in research that when an assertion is made
which closely matches the existing consensus, the research community is
generally willing to accept it based on simple arguments. When a strongly
contradictory assertion is made, however, much more rigorous proof is required
before it is accepted. This paper makes several claims that go very much against
current thinking in rocket design. I feel that the arguments to support some
of these views are not correspondingly rigorous. I would like to see a more
rigid mathematical analysis of these points. I also find some of the graphs
hard to interpret, such as the one which plots empty weight/payload weight
as a function of propellant cost/payload weight.

This is not to say that I have any specific doubts about the ultimate
viability of SSX. Many of the ideas presented seem very sensible. I just don't
think that this particular paper ties everything together in such a way that
it presents a truly convincing argument that SSX is the best way to go. Of
course, I may have misunderstood some of the paper, and there may be more
comprehensive papers that I have not seen.

If (as someone posted) the government has indeed decided to fund SSX research,
I hope that the first part of the money will go toward making a more complete
analysis, and a more specific presentation of the design proposal. This would
be consistent with the usual approach for government-funded research.

(As usual, these are my own opinions.)
                          John Roberts
                          [e-mail]

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

Date: 7 Feb 90 16:55:19 GMT
From: pacific.mps.ohio-state.edu!zaphod.mps.ohio-state.edu!uwm.edu!cs.utexas.edu!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Spacecraft drives and fuel efficiency

In article <[e-mail]> [e-mail] (Paul Dietz) writes:
>>>... anti-matter sounds as if it involves technical
>>>problems that make fusion engines look like tinker toys...
>
>>The fun part is, it may actually be the other way around!
>
>Really?  But we already have a proven method of releasing unlimited
>amounts of fusion energy -- hydrogen bombs.  Dyson designed an H-bomb
>propelled interstellar spacecraft years ago.  It had low acceleration,
>but it could reach .01 c.  I believe it used hydrogen bombs pushing
>against a copper plate, which was cooled by radiation.  A magnetic
>nozzle scheme might have better performance.

If we want to propel something with about the size and mass of Chicago,
Dyson's scheme works pretty nicely (although 0.01c is only marginally
viable as an interstellar velocity).  Unfortunately, it does not scale
down too well.  Dyson was figuring on 100MT bombs, as I recall.  Smaller
nuclear bombs are an expensive source of energy; very small ones are very
expensive.  When you get down into the range of interest for current
in-space propulsion, bombs basically aren't practical at all unless
you have a better way of igniting the reaction.  Which gets you back to
the problems of fusion, complicated by severe weight constraints.  A
spacecraft probably cannot use laser-ignited fusion unless lasers improve
vastly -- they are too heavy.  That's why Daedalus used electron beams,
which solves that problem at the expense of creating others.

Actually, a little bit of antimatter makes a dandy igniter for a fusion
reaction...!
--
SVR4:  every feature you ever |     Henry Spencer at U of Toronto Zoology
wanted, and plenty you didn't.| uunet!attcan!utzoo!henry [e-mail]

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

Date: 7 Feb 90 21:22:12 GMT
From: [e-mail]  (Jon Binkley)
Subject: Re: Galileo Update - 02/06/90 (Forwarded)

In article <[e-mail]> [e-mail] (Loren Petrich)
writes:
>[Galileo's main antenna] was not
>designed to get too close to the Sun; they had to install some
>insulation, and they have to keep the main antenna closed, or else it
>would disintegrate.

When the craft makes its second Earth flyby, will it come close
enough to the sun that they have to cover up the antenna again,
or will it remain unfurlled for the rest of its journey?

-Jon

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

Date: 7 Feb 90 22:44:09 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: MOS 1-B Launched

[This message is posted for Yoshiro Yamada of the Yokohama Science Center. -PEY]


* MOS-1b Launched *

 Marine Observation Satellite 1-b (MOS-1b) was successfully launched from
Tanegashima Space Center at 10:33:00 JST (UT+9h) on February 7, by the
H-1 rocket. All separation phases for MOS-1b, DEBUT (Deployable Boom
and Umbrella Test) and JAS-1b (Japan Amateur Satellite-1b) were confirmed.
 After the launch, the three payloads were nicknamed as follows:

      MOS-1B    MOMO-1b    (MOMO means peach in Japanese)

      DEBUT    ORIZURU (ORIZURU means crane shaped by folding paper in Japanese)

      JAS-1b   FUJI-2 (FUJI has two meanings in Japanese: Mt. Fuji and wisteria)


Missions:

MOS-1b

o Continue overall earth observations by Multi-spectrum Electronic Self-
a scanning Radio-meter, Visible and Thermal Infrared Radiometer, Microwave
Scanning Radiometer and Data Collection System.

o Establish earth observation satellite operation technology including two
satellite parallel operation.

o Establish sun-synchronous orbit injection technology by H-1 launch vehicle.

Piggy Back Payloads

DEBUT

o Deployable Boom and Umbrella Test (DEBUT) Satellite is the payload which
performs function verification experiments in a space environment on a
boom mechanism capable of being extended/retracted and an aerodynamic umbrella
capable of being opened/closed.

JAS-1b

o JAS-1b (Japan Amateur Satellite-1b) is a satellite which facilitates
worldwide satellite communications by amateur radio.
 The launch of JAS-1b enables amateur radio operators to learn about space
 science and satellites, also to understand space communication. JAS-1b will
 become the successor of JAS-1/Fuji-OSCAR 12, the Japan's first amateur
 satellite launched in 1986.


 Orbit

 MOS-1b        Altitude approx. 909km
            Inclination approx. 99deg
            Configuration Box type attached with cantilever
            type solar paddle: main body 1.26x1.48x2.40(m)
            solar paddle 2.00x5.28(m)
            Weight approx. 740kg (at launch)
            Mission life 2 years

DEBUT            Altitude elliptical approx. 900x1600(km)
            Inclination approx. 99deg
            Configuration stored: 400mm in diameter(26-side
            polyhedron) 470mm in length (structure+boom+
            aerodynamic umbrella)
            Weight 50+/-1 kg
            Power Subsystem Battery: Lithium battery (capacity
            95 Ah)
            Design Service Life approx. 10 days (due to life
            of the internal primary battery)

JAS-1b        Altitude elliptical approx. 900x1600(km)
            Inclination approx. 99deg
            Configuration 440mm in diameter. 470mm in length
            Weight approx. 50kg


(Sources: NASDA Information for Press and personal communication)

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

Date: 7 Feb 90 13:38:25 GMT
From: mcsun!ukc!axion!axion.bt.co.uk![e-mail]  (alan pengelly)
Subject: Gravity Assist Mechanism


 Here in the UK we recently had a couple of TV programs summarise the VOYAGER
missions. Firstly we would like to say to all those at NASA 'well done'. The
whole thing has been quite awe inspiring. But it also gave a couple of
computer scientists a problem. We thought we knew all about gravity assist
unitl we actually sat down and tried to work out the mechanism involved. We
have been arguing ever since. We have two schools of thought.

1) Angular momentum is transferred from the planet too the spacecraft. The
    increased velocity of the spacecraft after the encounter is at the
      expense of the planets angular momentum, so it rotates more slowly.

2) It is the kinetic energy of the planet that it transferred. Thus the
    planets orbital period increases ( but then surely the planet would
     adopt an orbit closer to the sun?)

Is there anybody out there that has a detailed understanding of gravity
assist? We would greatly appreciate some enlightenment of this subject.

Thanks in advance

Alan Pengelly

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

Date: 7 Feb 90 16:43:46 GMT
From: zaphod.mps.ohio-state.edu!samsung!umich!ox.com!itivax!vax3![e-mail]  (Allen W. Sherzer)
Subject: Re: More Info On SSX

In article <[e-mail]> [e-mail] (Walt Leipold) writes:
>>The anticipated cost of each vehicle is around $30 million,...

>Do you seriously believe that you can build a reusable space vehicle
>for less than a quarter of the cost of a 747?

Why not? On the other hand, suppose they are off by a factor or four.
In that case, it costs just as much as a 747. Still a good deal.

>If the gov't is going to
>be a customer, you probably won't even be able to meet the payroll of
>your QA dept for $30M/vehicle...

Not if HR2674 passes.

Another interesting thing about SSX is the funding source: SDIO. This
is a good sign IMHO because they more than anybody else in the government
needs low cost to LEO.

Interesting side note: a congressional aid I spoke with recently said
that SDIO is so pleased with their first commercial launch that they
plan to use commercial launch services from now on.

   Allen
----------------------------------------------------------------------------
| Allen W. Sherzer     | Cthulhu for President -                           |
|  [e-mail]         | If you're tired of choosing the LESSER of 2 evils |
----------------------------------------------------------------------------

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

End of SPACE Digest V11 #18
*******************