Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_5/V15NO568.TXT

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Date: Sat, 19 Dec 92 05:00:09
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #568
To: Space Digest Readers
Precedence: bulk


Space Digest                Sat, 19 Dec 92       Volume 15 : Issue 568

Today's Topics:
                      : Relay to Follow Galileo?
                     Aerospike engines/SSTO/DC-?
                                Aurora
             Chicken Guns (was Re: "trivial engineering")
                           DoD launcher use
                              EVA costs
               Galileo Update - 12/08/92 (Earth Flyby)
                      Galileo Update - 12/18/92
                 Justification for the Space Program
                       Mach 8+ Space/Spy Plane?
    MOL (was Re: Terminal Velocity of DCX? (was Re: Shuttle ...))
                  Relay to follow Galileo? (3 msgs)
                            Space Tourism
                                 SPAN
                      SSTO Concepts FAQ (2 msgs)
           Terminal Velocity of DCX? (was Re: Shuttle ...)

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

Date: 18 Dec 92 16:17:24 GMT
From: Curtis Roelle <roelle@uars_mag.jhuapl.edu>
Subject: : Relay to Follow Galileo?
Newsgroups: sci.space

[e-mail] (Brian Stuart Thorn) writes:

>The folding, umbrella-type antennae have been used at least ten times
>in space (that is, two each on TDRS-A, TDRS-C, TDRS-D, and TDRS-E, one
>on ATS-6 (late-70s pathfinder comsat) and one on Galileo.
>
>Only the one on Galileo failed to open on command, and there is still
>hope it will be coaxed open. (They haven't tried brute force yet.)

>Lesson:  OPEN THE DAMNED ANTENNA IMMEDIATELY AFTER LAUNCH!!!

And again writes,

>  Ryan...
>
>  Galileo's umbrella-type High Gain Antenna was left in the folded
>  position because it was thought that the high temperatures it would
>  encounter during the Venus flyby portion of the mission could warp
>  the antenna. They attempted to open the antenna only after the Venus
>  flyby, when Galileo flew farther from the Sun. It was jammed.

>  Cassini, I think, will have a standard hard HGA, similar to the
>  Voyager and Magellan antennae. I hope the Galileo problem does not
>  prevent future spacecraft from using the folding antenna design. It
>  worked quite well on the TDRS satellites.
>
>  -Brian

Is there a possiblity that, despite Galileo's HGA parasol, solar heat
could have still been a factor in its failure to deploy?  Especially
when one considers that for the nine successful deployments out of
ten, cited above, every corresponding spacecraft never left earth
orbit, while Galileo got as close to the sun as the planet Venus.

Curt

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

Date: Fri, 18 Dec 1992 16:01:32 GMT
From: Edmund Hack <arabia!hack>
Subject: Aerospike engines/SSTO/DC-?
Newsgroups: sci.space

There has been a lot of speculation as to the reasons why the SDIO SSRT
program  is not using the aerospike engine for propulsion as originally
envisioned by the SSTO proponents in the 60s and later.

I saw a summary of the report done by The Aerospace Co. for the Air Force on
the SSX proposal that was made by Max Hunter, et.al.  This proposal was
the one that lead to the SSRT program being started by SDIO.

A couple of caveats emerged concerning the SSX design that were felt to be
potential show stoppers in meeting the SSX goals, all related to the
use of aerospike engines.  First, the "engine first" reentry profile
required active cooling of the heat shield/engine plug assembly.  It was
felt that this complicated plumbing could be a nightmare to repair if
a leak developed and hindered access to part of the structure.  Since
low maintenance was a goal of SSX, this was considered a risk.  Second,
no aerospike engine of the size  proposed had ever been built, much
less tested.  This was also a risk, as "simple scaling" of rocket engines
is an oxymoron.  Third, the exact performance characteristics of
aerospike engines at high thrust and multiple altitudes are somewhat
unknown.  The aerospike work NASA had funded had limited data from
vacuum tests, concentrated on lower thrust engines (since the test
stands at Lewis? in the vacuum chambers can only evacuate a limited
amount of exhaust products).  Given the uncertainty about large aerospikes,
I'd agree that they are a risky choice with multiple points of failure.
My opinion is that Marshall or Lewis ought to be working on them (as well
as ion engines, arcjets (although DOD may fly some soon), solar sails,
and nuclear thermal engines) right now, rather than only trying to tweak an
additional 3 Isp out of H2O2 engines.

The study was cautiously favorable to SSX, recommending use of conventional
engines if possible, and watching weight margins carefully.  (The major
warning was that if the mass of the vehicle rose only slightly from
projections, the useful payload would be wiped out.  From what I have
seen, the DC-X team is very aware of this.)

I would also like to second Bill Higgins' call for the SSTO
"discussion" to be calmed down a bit. There has been more heat than
light generated recently.  It is pointless to argue about what the
DC-? can or can't do at this point.  Let's watch the DC-X flight this
spring and lobby, lobby, lobby for more money.

--
Edmund Hack - Lockheed Engineering & Sciences Co. - Houston, TX
[e-mail] - I speak only for myself, unless blah, blah..
"You know, I think we're all Bozos on this bus."
"Detail Dress Circuits" "Belt: Above A, Below B" "Close B ClothesMode"

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

Date: 18 Dec 92 13:05:56 GMT
From: Del Cotter <[e-mail]>
Subject: Aurora
Newsgroups: sci.space

In article <[e-mail]> Steinn Sigurdsson writes:
>In article <[e-mail]> [e-mail] (Nick Haines) writes:
>
>   Assuming that it's launching from the continental USA. Seems much more
>   likely to me (given the sightings over the Netherlands as well) that
>   one of the long-runway US bases in the UK or Germany is `home' to an
>   Aurora.
>
>Nah, not isolated enough, rumour seems to be that the forward
>base is a US NATO base in Scotland.

Yes, Scotland's still in the UK at time of writing...

(What's a US NATO base?)

--
 ',' ' ',','  |                                                  |  ',' ' ',','
   ', ,','    |       Del Cotter       [e-mail]      |    ', ,','
     ','      |                                                  |      ','

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

Date: 18 Dec 92 18:15:34 GMT
From: Pat <[e-mail]>
Subject: Chicken Guns (was Re: "trivial engineering")
Newsgroups: sci.space

The F-16 in the early 80's was having a real problem with bird strikes
fracturing the canopies, so i heard for a while the air force
was launching Frozen turkeys and chickens at the aircraft
to test canopies.  i guess the frozen bit was to make the birds
harder.

it was a tidbit in the paper.

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

Date: 18 Dec 1992 00:16:37 GMT
From: steve hix <[e-mail]>
Subject: DoD launcher use
Newsgroups: sci.space

>In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:
>
>>I don't think much if any recon was flown [ in Iraq].
>>The Air Force had better things to do with its aircraft.

What do you call a military force in combat who doesn't conduct recon
(having better things to do)?

The loser.

--
-------------------------------------------------------
| Some things are too important not to give away      |
| to everybody else and have none left for yourself.  |
|------------------------ Dieter the car salesman-----|

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

Date: 18 Dec 92 14:48:17 GMT
From: [e-mail]
Subject: EVA costs
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (John Roberts)
writes:
>While it wouldn't be fair to divide the cost of an entire Shuttle mission
>by maximum EVA time to get US EVA costs, I expect a more reasonable
>accounting method would still get a figure up in the millions of dollars
>per hour. Don't the EVA suits have a certain maximum number of hours they
>can be used per flight?
>John Roberts
>[e-mail]
>
   The suits have about 7 hours of oxygen in their primary O2 tanks,
and about the same amount in their secondary tanks under normal use
conditions.  But since the secondary tanks are meant to serve as
a supplement should the suit get a leak or the primary system fail,
this does not give the astronaut 14 hours of oxygen.  The real limiting
consumable is battery life, about 8 hours.  But this limit is for each
EVA.  Once the suits are hooked up to the orbiter, the oxygen, water, and
batteries are filled and recharged.  (The secondary O2 tanks are not
rechargable because they have 3 times the pressure as the primary tanks.)

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

Date: 18 Dec 1992 14:57:53 +1100
From: Mike Robson <[e-mail]>
Subject: Galileo Update - 12/08/92 (Earth Flyby)
Newsgroups: sci.space

[e-mail] (Ron Baalke) writes:

>Forwarded from Bill O'Neil, Galileo Project Manager

>                            GALILEO STATUS REPORT
>                                Earth Flyby
>                              December 8, 1992

>     The Galileo Spacecraft is operating normally in the dual-spin mode and
>is transmitting coded telemetry at 115.2 Kbps (115,200 bits/second).

>     Yesterday, part 2 of the EE-11 Earth encounter memory load sequence
>was uplinked.  Moon closest approach occurred at approximately 7:58 PM PST.

[...]

>     Today, December 8, 1992, Earth closest approach occurred at approximately
>7:09 AM PST.  Real-time commands are being sent to enable the Sun algorithms,
[...]

11 hours and 11 minutes from the moon to the earth! Is this a record?

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

Date: Sat, 19 Dec 1992 01:12:13 GMT
From: Ron Baalke <[e-mail]>
Subject: Galileo Update - 12/18/92
Newsgroups: sci.space,sci.astro,alt.sci.planetary

Forwarded from Neal Ausman, Galileo Mission Director

                                   GALILEO
                      MISSION DIRECTOR STATUS REPORT
                                POST-LAUNCH
                          December 11 - 17, 1992
         *************************************************************
                   Merry Christmas and Happy New Year!!

         Because of the Christmas Holiday, the Mission Director Report
         will not be published next week.  The next report will be on
         January 7, 1992.

         *************************************************************

SPACECRAFT

1.  On December 11, real-time commands were sent to turn ranging off in order
to maximize the downlink telemetry performance for the science instrument
calibration activities scheduled later in the day.

2.  On December 12, real-time commands were sent to zero out the Bright Body
Avoidance (BBA) vector onboard the spacecraft.  This vector was causing the
star scanner shutter to close sooner than expected resulting in infrequent
dropouts of the first star in a two star set.  This action was taken to
eliminate the possibility of the star dropouts increasing and causing SEQID
to fail which in turn would have caused the gyros to be selected as the
primary attitude source and would have adversely effected scan platform
priority and the possibility of tripping gyro fault protection.

3.  On December 12, real-time commands were sent to turn Two-Way Noncoherent
(TWNC) on prior to the sequence controlled Extreme Ultraviolet Spectrometer
(EUV)/Ultraviolet Spectrometer (UVS) cross calibration activity.

4.  On December 13, the spacecraft went through perihelion at a solar distance
of .982 AU.  All spacecraft temperatures were near predicted levels.

5.  On December 14, a NO-OP command was sent to reset the command loss timer
to 264 hours, its planned value during this mission phase.

6.  On December 14, a routine sun vector update was performed.  This sun
vector is valid until December 31, 1992.

7.  On December 15, real-time commands were sent to disable the attitude
control bright body avoidance fault protection after the completion of the
Earth 2 flyby.

8.  On December 15, real-time commands were sent to turn the TWNC off prior
to the SITURN on December 16 in order to receive two-way doppler data for
navigation purposes.

9.  On December 16, the spacecraft executed a 14-degree SITURN which brought
the cone angle down from approximately 95 degrees to 83 degrees.  Subsequently,
the telecommunication performance improved prior to the Earth/Moon conjunction
movie playback beginning on December 17 and continuing into December 19.

10. On December 16, the Galileo Optical Communications Experiment from an
Earth-based Xmitter (GOPEX) experiment was completed.  This experiment
consisted of pulsing a laser at the Galileo spacecraft from the Table Mountain
Observatory (TMO) and the Starfire Optical Range (SOR).  The Solid State
Imaging (SSI) camera was shuttered while slewing across the Earth resulting
in a series of illuminated pixels in the image.  Initial results indicate that
laser transmissions were successfully detected from both TMO and SOR.  Data
analysis is continuing.

11. On December 17, real-time commands were sent at the direction of the PI
(Principal Investigator) to turn the Plasma Detector (PLS) instrument off
approximately 31 hours before the stored sequence onboard the spacecraft
would have turned the instrument off.  The instrument temperature at turn off
was approximately 43.7 degrees C which was less than one degree below the
maximum waived temperature limit of 44.4 degrees C.

12. During the reporting period, numerous science instrument
calibrations/characterization activities were performed to take advantage of
the high telemetry data rates while close to the Earth.  Activities included
Near Infrared Mapping Spectrometer (NIMS) partial Photometric Calibration
Target (PCT) calibration, NIMS partial Radiometric Calibration Target (RCT)
calibration, Extreme Ultraviolet Spectrometer (EUV)/Ultraviolet Spectrometer
(UVS) cross calibration, EUV star calibration, UVS syscan, NIMS mirror scan
calibration, Plasma Wave (PWS) calibration, and Solid State Imaging (SSI)
partial PCT.  All calibration/characterization activities were performed
nominally and data analysis is in progress.

13. The AC/DC bus imbalance measurements exhibited some change. The AC
measurement has ranged from 13DN to 17DN and now reads 17DN (3.9 volts).
The DC measurement has ranged from 44DN (4.7 volts) to 157DN (18.5 volts) and
now reads 157DN (18.5 volts).  These measurement variations are consistent
with the model developed by the AC/DC special anomaly team.

14. The Spacecraft status as of December 17, 1992, is as follows:

       a)  System Power Margin -  79 watts
       b)  Spin Configuration - Dual-Spin
       c)  Spin Rate/Sensor - 3.15 rpm/Star Scanner
       d)  Spacecraft Attitude is approximately 6 degree
           off-sun (leading) and 83 degrees off-earth (leading)
       e)  Downlink telemetry rate/antenna- 1200bps(coded)/LGA-1
       f)  General Thermal Control - all temperatures within
           acceptable range
       g)  RPM Tank Pressures - all within acceptable range
       h)  Orbiter Science- all instruments are powered on
           except the PPR, NIMS, and PLS
       i)  Probe/RRH - powered off, temperatures within
           acceptable range
       j)  CMD Loss Timer Setting - 264 hours
           Time To Initiation - 240 hours


UPLINK GENERATION/COMMAND REVIEW AND APPROVAL:

1.  The EE-12 (Earth-Earth 12) Preliminary Sequence and Command Generation
products were approved by the Project on December 16, 1992.  This sequence
covers spacecraft activities from January 20, 1993 to January 23, 1993 and
from February 8, 1993 to April 12, 1993.

2.  The Dual Drive Actuator (DDA-5) Part A sequence memory load was approved
for transmission by the Project on December 17, 1992.  This sequence covers
High Gain Antenna (HGA) motor hammering activities from December 28, 1992
through January 4, 1993.  Part B of this sequence will be reviewed for
approval on December 30, 1992, subsequent parts of the overall DDA-5 sequence
will be reviewed and approved as needed after January 4, 1993.  The commands
for windup/hammering activities on December 29 and 30 were also reviewed.
Individual sets of hammering/windup commands will be approved as required
immediately prior to being uplinked to the spacecraft.


TRAJECTORY

     As of noon Thursday, December 17, 1992, the Galileo Spacecraft trajectory
status was as follows:

    Distance from Earth         6,928,300 km (.05 AU)
    Distance from Sun           147,267,200 km (0.99 AU)
    Heliocentric Speed          140,300 km per hour
    Distance from Jupiter       836,434,500 km
    Round Trip Light Time       0 minutes, 48 seconds

SPECIAL TOPIC

1.  As of December 17, 1992, a total of 8815 real-time commands have been
transmitted to Galileo since Launch.  Of these, 3768  were initiated in the
sequence design process and 5047 initiated in the real-time command
process.  In the past week, 29 real time commands were transmitted: 15 were
initiated in the sequence design process and 14 initiated in the real time
command process.  Major command activities this week included commands to
turn ranging off, zero out the bright body vector, turn the TWNC on, reset
the command loss timer, turn the TWNC off, disable the bright body avoidance
fault protection, and turn the PLS instrument off.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Choose a job you love, and
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | you'll never have to work
|_____|/  |_|/       |_____|/                     | a day in you life.

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

Date: Fri, 18 Dec 92 07:37:31 GMT
From: Felix Gorney Mfg 4-6983 <[e-mail]>
Subject: Justification for the Space Program
Newsgroups: alt.rush-limbaugh,talk.politics.space,sci.space

: |>      Can any of you think of any moral or philosophical justification
: |>     for using huge amounts of taxpayer money to fund the "space
: |>     program" at all?  Not counting, of course, it provides high-
: |>     pay, high-tech jobs for a bunch of us.
:


This country does not do enough basic research as it is. The space
program, and the defense department have done a great deal of this.
Their research has led to such things as the computers we are using.
The first electronic computers were developed by the military. I
beleive they were using them to crack codes.

Felix Gorney



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

Date: Fri, 18 Dec 1992 05:39:17 GMT
From: Robin Kenny <[e-mail]>
Subject: Mach 8+ Space/Spy Plane?
Newsgroups: sci.aeronautics,sci.space

[e-mail] () writes:
: In article <[e-mail]>, [e-mail] (Rich (the Wiz)
: Silva) says:
: >
: >    Apparently reported in some English Aeronautic Journal was
: >    a story claiming that the US has a new spy plane capable of
: >    Mach 8+ (at least) in test.  Apparently said plane has a
:      [ ... ]
: I was in Joshua Tree national forest last May when I saw a plane in the upper
: atmosphere fly across the sky about as fast as metors do I didn't here any
: sonic booms but I't couldn't have been a jet airliner it was moving too fast
: I did notice it's contrail was lumpy like -+-+-+-+-+-+ like a pulse.
                                            ^^^^^^^^^^^^
Popular Science magazine had a photograph of a "mysterious" contrail that
looks like -+-+-+-+-+-+, and very thin compared to other trans-sonics.
This was ?September 1992 (this year anyway)
:
: >--
: >Rich Silva
: >Locus Computing Corporation                [e-mail]
: >                  {uunet,ucivax,trwrb}!lcc!rich
: >       {randvax,ucbvax,trwspp}!ucla-se!lcc!rich

Robin Kenny - nope; nothing to do with where I work and completely my own
              opinions (not my employer's)  Couldn't you tell by the content?
              --------------------------------------------------------------

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

Date: Fri, 18 Dec 1992 10:44:41 GMT
From: Hartmut Frommert <[e-mail]>
Subject: MOL (was Re: Terminal Velocity of DCX? (was Re: Shuttle ...))
Newsgroups: sci.space

[e-mail] (Edward V. Wright) writes:

>You heard wrong.  One MOL flew (unmanned).

Could somebody provide data ?
-
 Hartmut Frommert                 <[e-mail]>
 Dept of Physics, Univ of Constance, P.O.Box 55 60, D-W-7750 Konstanz, Germany
                                           -- Eat whale killers, not whales --

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

Date: Fri, 18 Dec 92 08:33:48 EST
From: John Roberts <[e-mail]>
Subject: Relay to follow Galileo?

-From: [e-mail]
-Subject: Re: Relay to Follow Galileo?
-Date: 17 Dec 92 18:25:13 GMT
-Organization: The MITRE Corporation, McLean VA 22102

-     I would like to see the math that shows that TDRS could not be sent to
-Jupiter, remember that a TDRS has relatively large fuel tanks, in addition to
-fuel in the IUS.

I expect that the TDRS satellites have only very small rocket engines,
intended for slow maneuvering and stationkeeping. It might take a stronger
thrust over a shorter period of time to insert it into Jupiter orbit.

John Roberts
[e-mail]

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

Date: Fri, 18 Dec 1992 14:32:01 GMT
From: [e-mail]
Subject: Relay to follow Galileo?
Newsgroups: sci.space

It seems to me that there is a lot of stuff that people have not thought of
regarding sending a TDRSS after Galileo.  For example, I'm not sure you can
just splice in an RTG in place of solar panels.  Are they the right voltage?
Power?  How about mass distribution and other dynamic considerations?  Are the
thrusters placed correctly now?

How about the thermal environment during the cruise and Jovian orbit?  TDRSS
was designed for the environment of Earth orbit (in particular, Clarke (geo-
synchronous) Earth orbit.

Someone already pointed out the Jupiter insertion burn may need to be higher
thrust/shorter duration than the station keeping engines can provide.  I
suppose
it is conceivable that the Apogee kick motor might be better suited, but I
doubt it given the relative gravity (and thus the incoming probe velocity) at
Jupiter.

Burns

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

Date: 18 Dec 92 23:44:07 GMT
From: Ron Baalke <[e-mail]>
Subject: Relay to follow Galileo?
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] () writes...
>
>It seems to me that there is a lot of stuff that people have not thought of
>regarding sending a TDRSS after Galileo.  For example, I'm not sure you can
>just splice in an RTG in place of solar panels.  Are they the right voltage?
>Power?  How about mass distribution and other dynamic considerations?  Are the
>thrusters placed correctly now?

One other consideration is that the satellite would have to be radiation
hardened to survive in the strong radiation belts surrounding Jupiter.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Choose a job you love, and
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | you'll never have to work
|_____|/  |_|/       |_____|/                     | a day in you life.

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

Date: 17 Dec 92 14:27:01 GMT
From: [e-mail]
Subject: Space Tourism
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Del Cotter) writes:
>
> It wasn't Duncan (though he was there) but Patrick Collins, of the
> School of Management, Imperial College.  He wrote an article on the
> subject in Analog about the same time.  He now works in Japan and has
> an email address, but I haven't got it yet.


More of interest, Pat is working on *Space Tourism* in Japan.

Guess who'll have the furst space hotel?

>    ', ,','    |       Del Cotter       [e-mail]      |    ', ,','
--
================================================================================
Dave Clements, Oxford University Astrophysics Department
================================================================================
clements @ uk.ac.ox.vax            |  Umberto Eco is the *real* Comte de
dlc      @ uk.ac.ox.astro        |           Saint Germain...
================================================================================

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

Date: Fri, 18 Dec 1992 01:18:49 GMT
From: Bruce Shetler <[e-mail]>
Subject: SPAN
Newsgroups: sci.space

Apparently there is something called the Space Physics Analysis
Network.  Does anyone out there have knowledge of this net, how to
access it, etc.?  Feel free to reply here or via e-mail.

Thank you,
Bruce

--

========================================================================
  Bruce Shetler
  Photon Research Associates          Living in Southern California...
  San Diego, CA   92121               The ultimate oxymoron?
  [e-mail]
========================================================================

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

Date: 17 Dec 92 18:37:40
From: Steinn Sigurdsson <[e-mail]>
Subject: SSTO Concepts FAQ
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Paul Dietz) writes:


   In article <[e-mail]> [e-mail] (Steinn Sigurdsson) writes:

   >to handle the fuelling. Consensus was LOX/LH2 trucks carried
   >about 3 tons, we need 300 tons total - that's 100 trips


   That's wrong -- the figure was that LH2 tankers carry 3 to 5
   tons, but we said nothing about LOX tankers.  LOX is much more dense
   than LH2, and most of the mass of the propellant is LOX.

Ok, I can believe that - factor about 15 in fact from CRC,
so we're looking at 3 ton LH2 trucks and 30 ton LOX trucks?
 - I presume if you go much over 30 tons weight you're looking
at new more expensive trucks (what does KSC use?).

Now, DC-1 wants something like 300 tons total, so 75 tons LH2
and 225 tons LOX? That's still 30 fuel trips, maybe doable with
three shifts in 24 hours, but I don't think you can do it in 8 hours?
Not with one crew.

What mass flow rates do LOX and LH2 pumps use? eg the KSC ones?

|  Steinn Sigurdsson    |I saw two shooting stars last night        |
|  Lick Observatory    |I wished on them but they were only satellites    |
| [e-mail] |Is it wrong to wish on space hardware?        |
| "standard disclaimer"    |I wish, I wish, I wish you'd care - B.B. 1983    |

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

Date: Fri, 18 Dec 1992 02:59:23 GMT
From: Paul Dietz <[e-mail]>
Subject: SSTO Concepts FAQ
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Steinn Sigurdsson) writes:

 >Now, DC-1 wants something like 300 tons total, so 75 tons LH2
 >and 225 tons LOX? That's still 30 fuel trips, maybe doable with
 >three shifts in 24 hours, but I don't think you can do it in 8 hours?
 >Not with one crew.

You mixture ratios are off.  The oxygen/hydrogen mixture ratio
in the SSME is 6; in the Saturn J-2, 5.5.  At a ratio of 6
this would be about 43 tons of hydrogen and 257 of oxygen.
About 20 trips.

However, the launcher would almost certainly have fuels piped to it
directly from remote storage tanks, as NASA currently does at the
shuttle pads.

    Paul

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

Date: 18 Dec 92 17:53:17 GMT
From: Pat <[e-mail]>
Subject: Terminal Velocity of DCX? (was Re: Shuttle ...)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Brian Stuart Thorn) writes:
>>>In the history of spaceflight, that has seldom been the case.
>>
>>True, but that has far more to do with the design process we use for
>>spacecraft. Shuttle is the most complex vehicle ever built according
>>to NASA PR (I have no idea just why NASA thinks that is worth boasting
>>about). There is no reason to think that building for simplicity won't
>>work. That is why everybody who has studied the problem believes that
>>a SSTO can be built either now or in the near future. Even NASA internal
>>assessments say it can be done.
>>
>>  Allen
>
> That it can be done, I am more or less with you. (But I fully expect
> a design problem or two to slow things down...) That it can be done
> at the price you quote, that's another story. Say I'm from Missouri.
> Show me.
>
> -Brian
>



I believe in point of fact, that is the whole point of the DC-Y.
DC-X will prove the operations and technology.  DC-Y will push the
envelope to LEO, and test the new engines.  DC-1 is then production.

Given the low cost of the DC-X,Y test program, we should be advocating
the completion of the test program.  If it succeeds,  then we should
all feel good.  if it costs too much,  we should head back to the
drawing boards.  God knows,  maybe HTHL is the way to go for cheap
space flight and gary gets to say "I told you so"  1x10(6) times.




My gut feel, is that SSTO will always be cheaper then Stacked rockets.
Now if there is some way to get useful payload to orbit in an SSTO,
we will see.

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End of Space Digest Volume 15 : Issue 568
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