Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V13_2/V13_259.TXT

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Subject: SPACE Digest V13 #259

SPACE Digest                                     Volume 13 : Issue 259

Today's Topics:
             Pioneer 11 Update - 03/08/91
              Pegasus and Taurus
Re: German conference highlights doubts about ESA's manned space plans
               * SpaceNews  11-Mar-91 *
Re: German conference highlights doubts about ESA's manned space plans
        Re: Value per pound vs. cost per pound
               Re: Reliability

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

Date: 12 Mar 91 00:42:58 GMT
From: usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Pioneer 11 Update - 03/08/91


                            PIONEER 11 STATUS REPORT
                                  March 8, 1991

     Additional scans of Canopus were made by the Pioneer 11 spacecraft at
lower gain settings on March 2, but again produced multiple locks. The data
is being compared with previous data to see if one of the contacts could
be Canopus.  The 36-hour receiver switch timer was re-enabled on March 2, in
an attempt to cause a receiver switch during long tracking gaps.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|      Ron Baalke         | [e-mail]
     | | | |  __ \ /| | | |      Jet Propulsion Lab |
  ___| | | | |__) |/  | | |___   M/S 301-355        | Change is constant.
 /___| | | |  ___/    | |/__ /|  Pasadena, CA 91109 |
 |_____|/  |_|/       |_____|/                      |

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

Date: 12 Mar 91 00:18:44 GMT
From: news-server.csri.toronto.edu!utzoo![e-mail]  (Henry Spencer)
Subject: Pegasus and Taurus

In article <[e-mail]> [e-mail] (Fraering Philip) writes:
>... It also seems that Pegasus
>is meant to be military than commercial in that commercial payloads
>don't need to be launchable from anywhere. At the expense (additional,
>it may seem, for with Taurus OSC seems to be abandoning the approach)
>of having to pay for a carrier aircraft, Pegasus can launch anywhere
>the plane can take off...

Actually, Taurus is also being sold initially to the military, and one
of the conditions of the initial purchase is that Taurus demonstrate the
ability to launch from (nearly) bare concrete on a few days' notice.

Commercial payloads don't need to be launchable from anywhere, but that's
not the only thing the air launch buys you.  For one, you can get an
equatorial launch without an equatorial launch site, which is non-trivial
because current equatorial sites are not readily available except to their
owners.  In general, air launch bypasses a lot of launch-site hassles.

> But if
>Pegasus is so good, why are they developing Taurus?

I think the answer is basically "larger payload".
--
"But this *is* the simplified version   | Henry Spencer @ U of Toronto Zoology
for the general public."     -S. Harris |  [e-mail]  utzoo!henry

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

Date: 11 Mar 91 02:36:00 GMT
From: zephyr.ens.tek.com!tektronix!sequent!crg5![e-mail]  (Nick Szabo)
Subject: Re: German conference highlights doubts about ESA's manned space plans

In article <[e-mail]> [e-mail] (Andreas G. Nowatzyk) writes:

>True, but I read the original argument slightly differently: It is possible
>to design Solar Max, etc. for in-orbit repair by robots, which was not done.

I didn't mean this, but this is a good point.  Incidentally, Solar Max
did need special design changes to allow repair (as opposed to retrieval
and relaunch) by astronauts.  It would be interesting to compare the cost
of redesign for robotic vs. the cost of redesign for human repair, and
then factor in the costs of human EVA time vs. telerobotic repiar time.


>....For example, a lot of consumer equipment (VCRs & such) and
>some computer gear (Mac's, printers, etc.) are now routinely designed for
>robotic assembly. Lots of tiny details reqire attention: aviod screws,
>avoid round screw-in connectors, provide guide-paths for modules,
>snap-into-place things are king, locking mechanisms that require tools to
>push in several places are fine, but ones that require rotary action are not,
>avoid ill shaped objects like cable harnesses, ... nothing really fancy, but
>it is quite a departure from the way current space probes are designed.
>
>Furthermore, in-orbit repairs are limited to module swaps. It's hard to
>imagine someone replacing a 300+ pin surface mounted chip during EVA.

Good point.  Are there any large differences between design for robotic
and astronautic EVA repair?


--
Nick Szabo            [e-mail]
"What are the _facts_, and to how many decimal places?"  -- RAH

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

Date: 11 Mar 91 03:56:19 GMT
From: ka2qhd![e-mail]  (John Magliacane)
Subject: * SpaceNews  11-Mar-91 *


SB SPACE @ AMSAT < KD2BD $SPC0311
* SpaceNews  11-Mar-91 *

Bulletin ID: $SPC0311


                              =========
                              SpaceNews
                              =========

                         MONDAY MARCH 11, 1991

SpaceNews originates at KD2BD in Wall Township, New Jersey, USA.  It
is published every week and is made available for unlimited distribution.



* VOICES FROM SPACE *
=====================
This past week radio amateurs around the world heard the voice of the recently
launched AO-21.  The voice message, coming from the AO-21 downlink frequency
of 145.983 MHz spoke the following words: "I'm completely operational and my
ciruits are functioning perfectly."  This voice mode is referred to as Mode 8
among the AMSAT-DL and AMSAT-U-ORBITA groups responsible for AO-21's design
and assembly.  At this time it is not known how often Mode 8 will be in
operation on AO-21.  Also, engineering checkout is still ongoing and it could
be some time before the operational schedule for AO-21 is known.  Users
should monitor the downlink of 145.983 MHz to see which mode AO-21 is
currently operating.  As soon as a schedule is available from AMSAT-DL,
it will be published immediately and made available to all amateurs.

OSCAR-21 Frequency Allocations and Modes of Operation:

Linear Transponder Uplink:    435.030 - 435.120 MHz (90 KHz)
Linear Transponder Downlink:  145.880 - 145.970 MHz (inverted)
O/P Power: 12 watts max.
Beacon  : 145.810 MHz, CW telemetry.

Gain of satellite RX/TX antennas: 2.3 dBi each (dipoles)
Input sensitivity:  -125 dBm (435 MHz) for a C/No of 45 dB/Hz

SAT-RX-1:  435.016 MHz +-10 KHz  1200 bps, FSK, NRZIC/Biphase-M (JAS, PACSAT)
SAT-RX-2:  435.155 MHz +-10 KHz  (AFC) 2400 bps, BPSK, Biphase-S
SAT-RX-3a: 435.193 MHz +-10 KHz  (AFC) 4800 bps, RSM, NRZIC/Biphase-M
SAT-RX-3b: 435.193 MHz +-10 KHz  (AFC) 9600 bps, RSM, NRZI (NRZ-S) +Scrambler
SAT-RX-4:  435.041 MHz +-10 KHz  (digital AFC) RX for RTX-DSP experiments

The downlink can be switched to the following operating modes:
Transmit frequency:  145.983 MHz

Mode 1: 1200 bps, BPSK, NRZI (NRZ-S) (like FO-20)
Mode 2:  400 bps, BPSK, Biphase-S (AMSAT mode for OSCAR-13 beacon)
Mode 3: 2400 bps, BPSK, Biphase-S (planned for OSCAR-13)
Mode 4: 4800 bps,  RSM, NRZIC (Biphase-M) (like 4800 bps uplink)
Mode 5: 9600 bps,  RSM, NRZI (NRZ-S) + Scrambler (like 9600 bps uplink)
Mode 6: CW keying (only for special events)
Mode 7: FSK (F1 or F2B), e.g. RTTY, SSTV, FAX, etc. (only for special events)
Mode 8: FM modulated by D/A signals from DSP-RISC processor (e.g. speech)


* U2MIR NEWS *
==============
By: John Shalamskas, KJ9U -- 02 March 1991

A probable first in Amateur Radio was achieved today when 16 two way
FM voice contacts were conducted with the MIR spacecraft by Hawaii "hams"
in a single pass.  Ham operators on Oahu and Maui exchanged greetings
with Musa Maranov, U2MIR, in the orbiting Soviet space station.
From approxinately 7:54 AM to 8:05 AM HST, excited Amateurs passed
their callsigns and names to their counterparts who were streaking by
400 km overhead.  The relatively small number of Amateur Radio
stations in Hawaii and a great deal of pre-pass planning allowed
many participants to make contact in a limited time, using only
modest equipment.

After difficulty had been encountered during early packet contacts,
Joe Weite (KH6GDR) suggested emulating the military/commercial process
of parcelling out time slots in a manner that would make best use of
the geographical location of each ground station.  The first attempt at
using this method for voice contacts has proven to be extremely beneficial.

The [tentative] list of happy operators follows:

WA6EMV +  NH6XW     NH6VT     AH6HU     K6WR      WH6CJO    NH6RY     KA6NEI
KH6GDR    WY0H      KZ0A +    KJ9U      AH6GR +   NH6UY     KH6GPI +  KH6QR

A '+' denotes contacts that I did not hear directly, but were confirmed
by others immediately after the pass. Congratulations!

Musa did not use the expected "list" format, but everyone adjusted quickly.
Even though Musa was waiting for calls instead of calling us,
everyone did their best to remain in sequence.  It worked exceedingly well!
Musa kept up a good rate all through the pass, even contacting a couple of
stations on Maui and Hawaii that weren't aware of the list.  These Amateurs
were also quite courteous, even using remote-controlled stations at
high elevations to monitor Oahu in order to prevent interfering with others.

A discussion was held on the 146.88 MHz repeater after the pass.
The general consensus was that this was a very special event!
The mutual cooperation made it easy to hear and work Musa.
There were also a number of requests for an "official" list of
contacts from U2MIR.  We'll have to wait and see if that will happen.
It's quite likely that it will, if we ask Musa to make it available
on his packet radio Personal Message System (PMS.)

The Soviet cosmonauts aboard MIR have been active on 145.550 MHz,
using either packet radio (a digital communications mode) or
narrow-band FM voice.  Scanner enthusiasts should hear the signals
from MIR easily.  Some hams heard Musa using only handheld radios!

I learned a lot of things from this experiment.  The strongest impression
I am left with, however, was that the people here in Hawaii are among
the nicest in the world!  When the operation could easily have become
a "pileup", everyone restrained the urge to talk, waiting their turn in
a civilized fashion.  Hats off to all who helped make this event so
successful!


* SAREX NEWS *
==============
The Shuttle hardware problems that are forcing a delay of this month's
shuttle mission will NOT delay next month's SAREX mission.  Therefore,
a joint ham-radio contact between the Shuttle and Soviet space station
Mir appears possible.


* TNX RPT! *
============
A special thanks to all those who sent e-mail messages to SpaceNews:

WB3JFS, KB5NFN, KC6HEW, N6WDV, N7PDE

73, de John, KD2BD


/EX
--
John A. Magliacane                 FAX  : [phone]
Electronics Technology Department  AMPR : KD2BD @ NN2Z.NJ.USA.NA
Brookdale Community College        UUCP : ...!rutgers!ka2qhd!kd2bd
Lincroft, NJ  07738  USA           VOICE: [phone] ext 607

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

Date: 11 Mar 91 16:56:26 GMT
From: news-server.csri.toronto.edu!utzoo![e-mail]  (Kieran A. Carroll)
Subject: Re: German conference highlights doubts about ESA's manned space plans

Nick Szabo [e-mail] write:
Subject: Re: German conference highlights doubts about ESA's manned space plans
Date: 8 Mar 91 01:53:56 GMT

> In article <[e-mail]>
> [e-mail] (Henry Spencer) writes:
>
> >Experience so far says very strongly that if you plan to do in-space repairs,
> >you had better plan to have humans (or the imaginary just-as-flexible
> >teleoperated robots which will be available almost right away now for sure,
> >really, trust us) on hand.
>
> Or, if you prefer not to pay the $1,000,000++/hour cost of an EVA, you
> could make sure it works before you launch it.

Nick, to ``make sure'' that a satellite ``works'' before you launch it,
you might have to spend anywhere from millions to tens of millions of
dollars, depending on the complexity of the spacecraft. What level of
reliability do you want to design into the satellite, and verify via
ground testing? 99%? Or three nines? Or four? Do you want dual-string
redundancy? Or are you going to make your designers hate you forever,
and insist on triple-string?

All those satellites that we've seen fail on orbit, including the ones that
the Shuttle was sent up to repair, were designed by people who tried
to ``make sure that it works'' befoire launch. Many of the people involved
in design of these are very smart, and very conscientious, probably more so
than you and I. Satellites don't typically fail because of sloppy design or
construction. They fail because >nobody< can imagine beforehand >all< the things
that might go wrong with a complicated, custom-built device.

My view is the cost of using spacecraft could be made cheaper if moderately-priced
on-orbit check-out and servicing facilities were available to be rented out.
That way, a great deal of the expense in designing spacecraft could be eliminated
(``the NASA way'' of design wouldn't have toof the expenses of ground-testing the beasts. However, this assumes that
you have >people< in orbit to do the testing and repair --- because the things that
will go wrong with your satellite will be exactly those that you didn't anticipate,
and so you won't have built your teleoperated robot to handle that
unexpected contingency, and so the robot won't be able to effect the repair.


--

     Kieran A. Carroll @ U of Toronto Aerospace Institute
     uunet!attcan!utzoo!kcarroll [e-mail]

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

Date: 11 Mar 91 18:34:41 GMT
From: news-server.csri.toronto.edu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Value per pound vs. cost per pound

In article <[e-mail]> [e-mail] (Glenn A. Serre) writes:
>Henry says:
>>...There may be a slight constraint to avoid major releases
>>into sensitive regions of the upper atmosphere, but I can't imagine this
>>having much impact, given that launchers climb through those regions
>>very quickly for other reasons already.
>
>Nick:
>This "coasting phase to protect the ozone" is yet another constraint that
>must be imposed on a system already strained to its technical limits.
>
>Me:
>Who mentioned a "coasting phase"?  Just don't use solid fuel boosters that
>produce Chlorine compounds, use rp1-lox, lh2-lox, or NO4-N2H2.

Actually, the possibility of a coasting phase came up in private mail, so
it's not *quite* out of left field.  There may be some concern about release
of even water vapor into sensitive regions.

Nick's problem here is that he doesn't know much about launcher design,
or he wouldn't make ridiculous statements like "already strained to its
technical limits".  Launcher designers commonly trade off performance for
reliability, ease of handling, use of existing hardware, etc.; you would
not find such tradeoffs in systems that were stretched to their limits.
As a case in point, almost every launcher designer uses 3 or even 4 stages
to get to orbit, when Atlas did it with 1.5 over thirty years ago.  There
are large margins of performance available if environmental constraints
become serious enough to justify major redesign.
--
"But this *is* the simplified version   | Henry Spencer @ U of Toronto Zoology
for the general public."     -S. Harris |  [e-mail]  utzoo!henry

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

Date: 11 Mar 91 22:59:56 GMT
From: news-server.csri.toronto.edu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Reliability

In article <[e-mail]> [e-mail] (John Roberts) writes:
>>peculiar myth within NASA that all possible problems can be anticipated,
>>and you really can be certain that the thing will work before you launch it.
>>The universe keeps trying to tell NASA that this is wrong...
>
>That last statement sounds a little too broad. Just about everything they
>launch is chock full of backup systems, and the unmanned devices have both
>on-board recovery systems and provision for ground-based reconfiguration.

All of which can handle only expected classes of failures, by and large.

On-board recovery systems and provision for reconfiguration are of limited
help if your thrusters explode when fired continuously... and we very nearly
sent Galileo up with thrusters that did exactly that.  (The thruster problem
was discovered only because TVSat 1 used the same thrusters, and it fired
them long and hard in attempts to shake its stuck solar array loose.  Had
Galileo been launched on schedule, it would have been very lucky to reach
Jupiter.  TVSat 1 went up during the post-Challenger hiatus.)

On-board recovery systems and provision for reconfiguration are of limited
use if your solar arrays flap every time you cross from sunlight into
darkness... last I heard the HST people had given up on ever being able
to get full compensation for this, as the onboard systems just don't have
enough crunch.  It would be unfair to also mention the mirror-distortion
actuators that don't have enough muscle to take the spherical aberration
out, so I won't :-).

On-board recovery systems and provision for reconfiguration didn't save
Seasat, or the Viking 1 lander, or the attitude-control system on Solar Max
either.  All of these things deal only with expected classes of problems.
They can still be blind-sided by something unexpected.

>If you're thinking of simpler multiple probes, I think that has both good
>and bad points, and has to be evaluated on the merits of each case...

Simplicity vs. multiple missions is a complex tradeoff.  But putting all
your eggs in one basket is foolish whether that basket is simple *or*
complex, because *failures do happen*.  Complex systems, while often
better equipped to cope with failures, also are more prone to them.
--
"But this *is* the simplified version   | Henry Spencer @ U of Toronto Zoology
for the general public."     -S. Harris |  [e-mail]  utzoo!henry

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

End of SPACE Digest V13 #259
*******************