Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V12_4/V12_436.TXT

Internet Message Format | 1991-06-28 | 18KB

Return-path: <[e-mail]>
X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson
Received: from beak.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/[e-mail] (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests)
          ID </afs/andrew.cmu.edu/usr1/ota/Mailbox/cb4fRXy00VcJMF0k4m>;
          Wed, 10 Oct 1990 01:53:40 -0400 (EDT)
Message-ID: <[e-mail]>
Precedence: junk
Reply-To: [e-mail]
From: [e-mail]
To: [e-mail]
Date: Wed, 10 Oct 1990 01:53:08 -0400 (EDT)
Subject: SPACE Digest V12 #436

SPACE Digest                                     Volume 12 : Issue 436

Today's Topics:
            Re: Ulysses Update - 10/06/90
              Re: Launch cost per pound
       Re: Reusable verses Expendable launch vehicles.
            Re: Manned/unmanned tradeoffs
            Re: Ulysses Update - 10/06/90
            Re: Manned/unmanned tradeoffs
         Element Sets for Solar System Orbits
     Re: Motorola Cellular phone Comsats and cheap space
            Re: Manned/unmanned tradeoffs
             Pioneer 11 Update - 10/09/90
             7's in Mercury flight names?
            Re: Magellan Update - 10/09/90

Administrivia:

    Submissions to the SPACE Digest/sci.space should be mailed to
  [e-mail].  Other mail, esp. [un]subscription notices,
  should be sent to [e-mail], or, if urgent, to
             [e-mail]

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

Date: 9 Oct 90 03:49:19 GMT
From: sdd.hp.com!elroy.jpl.nasa.gov!jato!mars![e-mail]  (Ron Baalke)
Subject: Re: Ulysses Update - 10/06/90

In article <[e-mail]> [e-mail] (Wayne Hayes) writes:
>In article <[e-mail]> [e-mail]
>(Ron Baalke) writes:
>>      Key Dates for the Ulysses Mission
>>      ---------------------------------
>>      02/08/92 - Jupiter Encounter
>>      05/30/94 - Beginning of First Solar Pass (South Pole)
>>      02/05/95 - Perihelion
>>      05/30/95 - Beginning of Second Solar Pass (North Pole)
>
>Am I reading this right?  Three years from Jupiter (aphehelion?) to
>perihelion, and only one year from South to North?  How far away from
>the Sun is Ulysses staying?  At
>this time scale, I estimate Ulysses' semi-major axis at about 3 AU;
>I understand that we don't really have to get close to the Sun to get
>good readings of things like the magnetic field, it just spoils the
>naive picture I had of Ulysses skimming majestically and bravely just
>above the Sun's photosphere.  :-)
>
After a gravity assist from Jupiter, the closest Ulysses will get to the sun
is 1.4 AU.  It will be 2.3 AU when it passes over the poles of the sun.
From a scientific standpoint, it really doesn't matter that much whether the
spacecraft is 1 AU or 2.3 AU when it passes over/under the poles of the sun;
it would still be traveling through unexplored regions of the solar system.
Of coursce, if Ulysses was to get closer than 1 AU to the sun, then you have
to add thermal protection to the spacecraft. The closest Ulysses will ever
get to the sun in its lifetime is when it was on Earth.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|
     | | | |  __ \ /| | | |      Ron Baalke         | [e-mail]
  ___| | | | |__) |/  | | |___   Jet Propulsion Lab | [e-mail]
 /___| | | |  ___/    | |/__ /|  M/S 301-355        |
 |_____|/  |_|/       |_____|/   Pasadena, CA 91109 |

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

Date: 9 Oct 90 09:45:58 GMT
From: agate!shelby!helens!hanauma![e-mail]  (Joe Dellinger)
Subject: Re: Launch cost per pound

In article <[e-mail]> [e-mail] ("Allen W. Sherzer") writes:
>No, the Soviet workers are not as productive as their western counterparts.
>On the other hand, they are (as you point out) paid a lot less. Maybe our
>workers, who are far more productive (and far better paid) can produce
>products just as cheap.

I just thought I should point out that there's a major (and all too common)
economic misconception lurking below the surface here. A country can still
compete successfully in a service even if they are lousy at it! All that
matters is that they are less lousy at that than they are at other things,
and that they are willing to have a standard of living to match their overall
lousy productivity.

For example, suppose that 10000 Soviet workers can either be employed to make
1000 washing machines or 1 rocket launch. Now suppose 10000 American workers
can either make 10000 washing machines or 2 rocket launches in the same time.
The Soviets are WORSE at making both washing machines AND rockets, right?
So why should the Americans want to bother trading with them?

Because we can trade them 1000 of our cheap washing machines and receive
in return one rocket launch. That's a lot cheaper than simply launching
a rocket of our _own_, which costs us _5000_ washing machines!

From the Soviet point of view, it is better to use their 10000 workers to
make one rocket launch, which they can then sell to the US in trade for 5000
of our washing machines. If they instead used their workers to make
washing machines directly they could only get 1000 of them for the same effort.

How is this possible? It works because the Soviets get lower pay:
a Soviet worker can earn .5 washing-machine-monetary-units (by making rockets
and selling them to the US), while an American earns 1
washing-machine-monetary-unit, for a standard of living 2 times higher in
America. (The same ratio holds when measured in terms of
rocket-launch-monetary-units, too.)

Got it? Nifty, eh?

[This example is stolen/modified from a recent issue of "The Economist".]
\    /\    /\    /\/\/\/\/\/\/\.-.-.-.-.......___________
 \  /  \  /  \  /Dept of Geophysics, Stanford University \/\/\.-.-....___
  \/    \/    \/Joe Dellinger [e-mail]  apple!hanauma!joe\/\.-._
** tick ****** tick **** tick! *** tick! ** tick! tick! tick! RING! **** WHAM **

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

Date: 8 Oct 90 17:30:31 GMT
From: sun-barr!newstop!texsun!convex!convex.convex.com![e-mail]  (Edward V. Wright)
Subject: Re: Reusable verses Expendable launch vehicles.

In <[e-mail]> [e-mail] writes:

>A failure in an expendable does not mean the loss
>of any future capability. The problem can usually be quickly fixed and put
>into the production line, whereas reusable vehicles would take much longer
>to repair since the fix would have to applied to your whole fleet of
>currently built vehicles.

To assume that a single vehicle, like the Shuttle, can meet all
our space transportation needs is as ridiculous as assuming that
a single aircraft can be designed to fill the various missions --
military, commercial, scientific, recreational -- carried out by
aircraft today.  We need a variety of commercial launch vehicles
to meet the needs of a variety of users.  This will also prevent
a failure in a single design from grounding the entire fleet.


Again, with todays failure rates of 1/50, this
>is an important factor.

>For reusable vehicles, failure rates similar to that
>of airlines would be required.

Exactly, but there is no reason to belive such rates should not be achievable.
Before a new commercial airliner or military aircraft goes into service,
it completes hundreds of test flights.  This is only possible with a
reuseable vehicle.  For expendable or partially reuseable (Shuttle-type)
vehicles, the costs of conducting this number of flight tests are
prohibitive, ans so the Shuttle was declared "operational" after
only four flights!  We must learn to design and operate spacecraft
the same way we design and operate aircraft.  (This does not mean
that they must *look* like aircraft, however.  Ballistic vehicles
may prove to be preferable to winged designs.)

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

Date: 8 Oct 90 22:42:23 GMT
From: celit![e-mail]  (Dave Smith)
Subject: Re: Manned/unmanned tradeoffs

In article <[e-mail]> [e-mail] (Marvin Minsky) writes:
>Planes have minimum speeds, hence each delay implies a
>minimum reaction-distance.  But that has little to do with spaceships,
>or earth-ships.  Tankers can be "flown" as slow as you want, hence
>have no problems with time delay, for well-trained pilots.

Certain processes have minimum time delays.  For example, soldering.  Leave
the soldering iron on the device for too long and you have a fried device.
I'm sure there will be plenty of on-orbit procedures that will have inherent
time limits.

Tankers are an excellent example of what can happen when something unexpected
occurs between the control input and the expected result.  The crew of the
Exxon Valdez knew they were going to crash into the reef several minutes
before they actually did but could do absolutely nothing about it.  Granted,
they should have known where they were and where the reef was but accidents
happen.

--
David L. Smith
FPS Computing, San Diego
ucsd!celerity!dave or [e-mail]

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

Date: 9 Oct 90 14:44:00 GMT
From: bionet!agate!darkstar!helios![e-mail]  (Steve Allen)
Subject: Re: Ulysses Update - 10/06/90

In article <[e-mail]> Ron Baalke writes:
>After a gravity assist from Jupiter, the closest Ulysses will get to the sun
>is 1.4 AU.  It will be 2.3 AU when it passes over the poles of the sun.

Here is an interesting question on behalf of all of us who can plot the
orbits of bodies in the solar system:

During most of their journeys, Galileo and Ulysses are both on effectively
Keplerian orbits around the sun.  Are the navigation groups able and ready
to publish those elements in these newsgroups?  A great many readers
have the ability to plot out these orbits and see for themselves where
the probes have been and should be going.

If anyone can dig up the nominal elements for each stage of the journey,
I for one would be really interested to see them posted.

Steve Allen
[e-mail]     ...!ucbvax!ucscc!helios!sla

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

Date: 9 Oct 90 09:33:34 GMT
From: usc!wuarchive!zaphod.mps.ohio-state.edu!rpi![e-mail]  (Jim Kasprzak)
Subject: Re: Manned/unmanned tradeoffs

In article <[e-mail]> [e-mail] (daniel mocsny) writes:
>While we are on the subject of dealing with time delays, I
>wonder if anyone has considered hiring whales to teleoperate
>bulldozers on the Moon.
>

  Ignoring about fifty zillion biotechnical problems, and assuming that such
a thing were indeed possible...

  Why would the whales have any interest in doing such a thing?
--
 Jim Kasprzak          [e-mail] (internet)
 RPI, Troy, NY         [e-mail]
 "A spirit with a vision is a dream with a mission."  -Rush

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

Date:       Tue, 09 Oct 90 16:23:26 EST
From: [e-mail]
Subject:    Element Sets for Solar System Orbits

    Does anyone have ready access to the element sets for
the orbits of the various spacecraft we discuss here, such
as Galileo, Ulysses, Voyagers, Giotto, and even future ones
such as CRAF.  Also, it would be interesting to have Magellan's
orbital element sets to keep track of its progress in
Venician orbit.  Is there sufficient interest to have such
data posted here semi-regularly, assuming someone has access
to the data?

[e-mail]

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

Date: 9 Oct 90 01:19:00 GMT
From: umigw!mthvax![e-mail]  (David Lesher)
Subject: Re: Motorola Cellular phone Comsats and cheap space

>> No matter what people may say about the C news patch system, putting
>> Henry on top of an Arianne 4 is not the answer :-)

>This was the funniest Usenet posting I've seen in weeks.  I'm still
>giggling...

>However, it might to fun to contemplate the Usenet Orbit Project...
>only, what would we put up there?

Well, there's LOTS of room for disk storage.....
The rings we saw from Voyager sure LOOK like platters....
We could archive the flame wars going on in this group and
talk.anything.........
But, how do we make winchester heads fly in a vacuum?


--
A host is a host from coast to [e-mail]
& no one will talk to a host that's close............(305) 255-RTFM
Unless the host (that isn't close)......................pob 570-335
is busy, hung or dead....................................33257-0335

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

Date: 9 Oct 90 04:08:17 GMT
From: media-lab![e-mail]  (Marvin Minsky)
Subject: Re: Manned/unmanned tradeoffs



In article <[e-mail]> [e-mail] (Dave Smith) writes:
>In article <[e-mail]> [e-mail] (Marvin Minsky) writes:
>>Planes have minimum speeds, hence each delay implies a
>>minimum reaction-distance.  But that has little to do with spaceships,
>>or earth-ships.  Tankers can be "flown" as slow as you want, hence
>>have no problems with time delay, for well-trained pilots.
>
>Certain processes have minimum time delays.  For example, soldering.  Leave
>the soldering iron on the device for too long and you have a fried device.
>I'm sure there will be plenty of on-orbit procedures that will have inherent
>time limits.
>
>Tankers are an excellent example of what can happen when something unexpected
>occurs between the control input and the expected result.  The crew of the
>Exxon Valdez knew they were going to crash into the reef several minutes
>before they actually did but could do absolutely nothing about it.  Granted,
>they should have known where they were and where the reef was but accidents
>happen.

I find examples like this very frustrating.  A human has a loop
time-delay of about 1/5 second.  People can solder large things but
not small things.  As you recognize, the Valdez disaster was poor
management.  They should have used an autopilot or two.  The
time-delay for LEO operation for a Space-station would increase the
delay to 1 second, using crude synchronous satellite relays, or to
about .35 second with low-orbit relays (more expensive).

We're talking about replacing a 30 Billion dollar station that may
very well never be completed and may be impractical to operate
(hundreds of shuttle flights, thousands of EVA hours, etc.) versus
something like a 1-2 billion dollar system that might wwell be more
productive.  The only objection is that operations might proceed 2-5
times slower, but can be remotely manned by perhaps 100
round-the-clock remote operators.

So let's quite talking about random time delays.  Find me an "inherent"
-- and important -- one that can by done in .2 seconds, but has no
replaceable equivalent that can't be done with a .4 second loop delay.

Hard, isn't it.

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

Date: 9 Oct 90 15:13:24 GMT
From: sdd.hp.com!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Pioneer 11 Update - 10/09/90


                           Pioneer 11 Update
                            October 9, 1990

     On October 6, the 70 meter antenna in Goldstone, California, was
unable to obtain lock on the downlink on the Pioneer 11 spacecraft.
The 70 meter antennas in Australia and Spain were also unable to obtain
lock the following day.  The stations are reporting that the AGC (Automatic
Gain Control) is fluctuating from -168 dbm to a threshold of -180 dbm for
a period of 3 to 4 seconds.  It is suspected that the spacecraft's antenna
is off Earth point.  Further uplink attempts will be made using the high
power transmitter at 100kw and performing continuous sweeps.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|
     | | | |  __ \ /| | | |      Ron Baalke         | [e-mail]
  ___| | | | |__) |/  | | |___   Jet Propulsion Lab | [e-mail]
 /___| | | |  ___/    | |/__ /|  M/S 301-355        |
 |_____|/  |_|/       |_____|/   Pasadena, CA 91109 |

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

Date: 3 Oct 90 04:13:12 GMT
From: unisoft!fai!sequent![e-mail]  (Jerry Gerue)
Subject: 7's in Mercury flight names?

I noticed that each of the Mercury flights had a "7-name" -
    Aurora 7
    Friendship 7
    Freedom 7
    etc
Does anyone know the reason for the 7's, or who chose the
names, or any other related folklore?  This is for a school
report; please answer by mail (sooner the better :-).

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

Date: 9 Oct 90 20:51:20 GMT
From: snorkelwacker!usc!elroy.jpl.nasa.gov!jato!mars![e-mail]  (Ron Baalke)
Subject: Re: Magellan Update - 10/09/90

In article <[e-mail]> [e-mail] (Sandi Piazza) writes:
>>
>>      The Magellan spacecraft has now completed 177 mapping orbits of Venus,
>> with good radar data recieved from at least 173 orbits.  Spacecraft systems
>
>  This is probably a dumb question, but I'll ask anyway.  What is going to
>  be done about getting the information missed in the 4 orbits for which
>  there was no good data received?

It will pick up the missing data during the extended mission.  The primary
mission is only going to last 243 days, which is the length of one Venus
rotation.  There will be some missing gaps during the primary mission;
the south pole because the spacecraft is transmitting data back when it is
over the pole,  a larger pole-to-pole gap will be missed during the
Superior Conjunction (Earth & Venus on opposite sides of the sun), and a
small region in the southern hemisphere when data transmission to Earth
will be blocked by Venus itself.  All of these missing gaps are expected to
be recovered during the extended mission.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|
     | | | |  __ \ /| | | |      Ron Baalke         | [e-mail]
  ___| | | | |__) |/  | | |___   Jet Propulsion Lab | [e-mail]
 /___| | | |  ___/    | |/__ /|  M/S 301-355        |
 |_____|/  |_|/       |_____|/   Pasadena, CA 91109 |

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

End of SPACE Digest V12 #436
*******************