Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V13_0/V13_057.TXT

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Subject: SPACE Digest V13 #057

SPACE Digest                                      Volume 13 : Issue 57

Today's Topics:
              Re: some questions
             CRRES release from Columbus
             space news from Dec 17 AW&ST
          Re: What is cosmological constant?
           Re: Cameras in 0G, was: Re: MIR Vacation
              Voyager Update - 01/16/91
              Galileo Update - 01/16/91
               The Plains of Abraham II
           Re: Cameras in 0G, was: Re: MIR Vacation

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Date: 16 Jan 91 16:04:55 GMT
From: agate!bionet!uwm.edu!cs.utexas.edu!swrinde!elroy.jpl.nasa.gov!jato!mars![e-mail]  (Ron Baalke)
Subject: Re: some questions

In article <[e-mail]> [e-mail] (Earl W Phillips) writes:
>
>2) What is the meaning of the terms DESATS, SITURNS, STARCALS, etc
>on the satellite reports, and what do they do (why are they
>necessary)?
>

DESATS and STARCALS are terms used with Magellan.  A DESAT is where the
thrusters are fired briefly twice a day to bleed off excessive spin on
the reaction wheels.  When the wheels are spinning too fast, they are
saturated, thus the term DESAT (desaturation).  A STARCAL is done every
orbit (every 3.26 hours), and is used by the spacecraft to fine tune its
orientation.  The spacecraft turns towards the stars for a calibration, and
by using its star scanner and gyroscopes determines it current orientation.
If the orientation is more than a preset amount (usually 0.01 degree), the
appropriate reaction wheels are commanded to speed up or slow down until the
orientation is back within bounds.

A SITURN is a small maneuver done by Galileo to make sure that the High
Gain Antenna is pointed at the Sun to ensure that the instruments
underneath the spacecraft are shaded.

>3) Which are the Pioneers/Voyagers that have left the Solar
>Syatem?
>

Pioneer 10 & 11, and Voyager 1 & 2.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|
     | | | |  __ \ /| | | |      Ron Baalke         | [e-mail]
  ___| | | | |__) |/  | | |___   Jet Propulsion Lab | [e-mail]
 /___| | | |  ___/    | |/__ /|  M/S 301-355        |
 |_____|/  |_|/       |_____|/   Pasadena, CA 91109 |

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

Date: 15 Jan 91 23:01:36 GMT
From: snorkelwacker.mit.edu!usc!zaphod.mps.ohio-state.edu!magnus.ircc.ohio-state.edu![e-mail]  (Earl W Phillips)
Subject: CRRES release from Columbus


My hat's off to the 2 who say they spotted the CRRES release
from Columbus, Oh. I was ready and waiting, and saw nothing!
Perhaps the 2 who saw it could email me at the addres below,
and wew could coordinate a watcg/photo saeesion. My site was
Otterbein College, Westerville. Light polluted, yes, but I
routinely get nice astrophotos of OC's from there.

*****************************************************************
*                                    | ====@====      ///////// *
* [e-mail]|     ``________//         *
*                                    |       `------'           *
*                 -JR-               | Space;........the final  *
*                                    | frontier...............  *
*****************************************************************

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

Date: 16 Jan 91 04:35:00 GMT
From: usc!cs.utexas.edu!news-server.csri.toronto.edu!utzoo![e-mail]  (Henry Spencer)
Subject: space news from Dec 17 AW&ST

Soviets running pad tests on a smaller variant of Energia, with a smaller
core and only two strap-ons, giving a payload to orbit of 40 tons rather
than 100.

Toyohiro Akiyama returns from being the first journalist in space [probably
much to his relief -- he was spacesick and hadn't really kicked his tobacco
habit].  TBS has no complaints about in-flight support, although they are
still unhappy about financial haggling with the Soviets.

McDonnell Douglas contracts for three Delta launches, with options for 12
more, for NASA science payloads.  Also included are pad modifications at
Vandenberg.

Administration endorses Augustine Committee report, asking NASA to respond
in about a month with an initial plan to implement its recommendations.
The committee will reconvene later this year to assess progress.  NASA has
no quarrel with most of the report, but is concerned about the committee's
recommendation to terminate orbiter production.  [And rightly so -- it's a
thoroughly dumb idea, if the shuttle fleet is to continue to be a significant
part of NASA planning.]  There is also doubt on how to proceed on the
recommendation that NASA pursue a heavy expendable booster.

Columbia and Astro land at Edwards, after a threat of bad weather cut the
mission short by one day.  135 out of 200 planned observation targets
actually got looked at, with extensive use of on-board control and ground
control to work around failing electronics.  The astronomers are pleased
with the results despite the difficulties.

NASA is playing down the calls for a massive shakeup of the space station,
perhaps partly because it is not sure how to proceed.  One problem is that
the Augustine Committee said that Fred's primary mission should be life
sciences, while Congress tends to back microgravity materials work more
strongly, and NASA has been trying to avoid assigning priorities.  There
have been no serious design changes in recent weeks other than a decision
to split the US lab module and the living quarters into two smaller modules
each.  No decision has yet been made on the fate of the truss, which most
everyone except McDonnell Douglas has recommended killing.  Lenoir warns
contractors that it's going to hurt.

One contentious area of Fred is the perennial lifeboat question.  The
Augustine committee strongly recommended doing it, but NASA so far has
failed to convince Congress to fund it.

Another hot spot is that the committee recommended putting a single NASA
center in charge of each major project, and taken literally this would
mean scrapping the station's paperwork HQ in Reston.

A further touchy point is a strong recommendation that NASA separate
development from operations, under separate associate administrators.
Lenoir currently runs both.

Battle brewing over radio spectrum:  the space between 1435 and 1530 MHz
is currently allocated entirely to aircraft/missile flight-test telemetry,
but several groups proposing CD-quality audio broadcasting from satellites
would like pieces of it.  The aviation people are violently opposed, saying
the band is intensively used and should not be sacrificed to "yet another
entertainment and advertising vehicle".  The FCC has already shot down the
broadcasters' contention that the two groups could share the frequencies,
saying this shows "fundamental misconceptions regarding the way in which
flight test operations are conducted".

More Magellan pictures.  The planetary scientists are also starting to
analyze the data Galileo got during its Venus encounter, which finally
got sent to Earth in the last few weeks.  There are strong hints that
Venus is still volcanically active.  Magellan is still experiencing
occasional minor upsets, but on the whole, mapping is going well.

NASA medical researchers report that injections of promethazine appear
to be very effective against spacesickness.  Astronauts injected with
it after the onset of symptoms on their first day are generally free of
severe symptoms very quickly and completely well by the end of the
second day.  Previous orally-administered drugs, notably scopolamine,
have not worked well; it is now thought that absorption of oral drugs
is unpredictable and generally poor.

Energia NPO, the organization that designs and develops most of the
Soviet Union's major space hardware, has assumed management responsibility
for commercial sales of manned spaceflight.  Glavcosmos formerly did this.
--
If the Space Shuttle was the answer,   | Henry Spencer at U of Toronto Zoology
what was the question?                 |  [e-mail]   utzoo!henry

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

Date: 16 Jan 91 16:47:45 GMT
From: bywater!scifi!ndla![e-mail]  (Daniel E. Platt)
Subject: Re: What is cosmological constant?

In article <[e-mail]>, [e-mail] writes:
> Can someone give me a brief explanation of "cosmological constant"?
> I have the understanding that this is a base energy density for
> "empty" space; as opposed to a base energy level (vacuum energy level)
> for "empty" space.  Is this correct?  To what would this base energy
> level be due?  Uncertainty leading to a background cloud of paired
> virtual particles?
>

In deriving the field equations for gravity, Einstein assumed that curvature
of space could account for the dynamics of gravity by arguing that observers
cannot tell the difference between an accelerating frame and an inertial frame    in a curved space (including bending light, red shift, &c).  One of the
curvature tensors satisfy the same kind of conservation (divergence = 0) as
the stress energy tensor.  Einstein assumed these were proportional.  This is
physically nice because it associates the energy due to space bending with
energy, but it "hides" it in the curvature term itself (sort of like
"div D = 4 pi rho" hides the induced dielectric charges).  The proportionality
constant comes out to involve 'G' from Newton's gravity law in the
non-relativistic limit.

When issues of cosmology were considered, it was noted that the field equations
didn't admit a closed steady state solution.  It either expanded from a point
(big bang) continuously and divergently, or it opened and closed (oscillated)
again from a point (big bang).  I understand that Einstein felt very
uncomfortable with this, and looked for other rank 2 tensors that satisfy the
same conservation law (0 divergence).  The metric tensor does, so he added this
to the stress-energy tensor.  It would correspond to a sort of background
energy just because space was there, and with it, the field equations would
now admit a stable solution.  The constant in front of the metric tensor was
called the "Cosmological constant."

The discussion above is grossly over-simplified.  It does (I think) capture
some of the flavor of the arguments... particularly those surrounding the
cosmological constant.  The constant was introduced to preserve the steady-state
picture.  I've heard it suggested by Big-Bang supporters in the '70's (before
things seemed so strongly in their favor) that Einstein ended up regretting
that he suggested it at all... that he had intended to submit it as a conjecture
as one possible way that the universe could be steady state.  The idea seemed
to take off with a life of its own, and he regretted the choice.  However,
the person I heard it from had also said that E/M fields don't contribute to
the curvature since its stress-energy tensor is traceless.... (if you remember
that faux pas that I made when I asserted it so strongly).

Dan

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

Date: 16 Jan 91 16:26:09 GMT
From: agate!bionet!uwm.edu!zaphod.mps.ohio-state.edu!lavaca.uh.edu!menudo.uh.edu!nuchat![e-mail]  (Steve Nuchia)
Subject: Re: Cameras in 0G, was: Re: MIR Vacation

In article <[e-mail]> [e-mail] (Head UNIX Hacquer) writes:
>has a nasty habit of evaporating lubricants.  There is also the problem
>of 'cold welding', which is metal getting so cold that it freezes to the
>adjoining metal. These days vacuum survival might not be so important.

Nope.  Cold welding (also called vacuum welding) has nothing to do
with being cold.  When two pieces of metal are in intimate contact
you get diffusion across the boundary.  Once the boundary is "blurred"
enough, the parts are welded together.  This can be done in the laboratory
but it is difficult to get the surfaces clean and keep them clean
enough under an inert gas blanket, and very difficult in air.  In
vacuum a wiping action can polish the surfaces locally, allowing the
diffusion to start.

At human-compatible temperatures the diffusion is so slow that it
would be real surprising to find that vacuum welding was a factor,
At least for missions of normal duration.
Vacuum welding was observed on LDEF though.

--
Steve Nuchia          South Coast Computing Services      [phone]
    "Could we find tools that would teach their own use,
     we should have discovered something truly beyond price."
        Socrates, in Plato's Republic

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

Date: 16 Jan 91 19:52:22 GMT
From: agate!bionet!uwm.edu!zaphod.mps.ohio-state.edu!usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Voyager Update - 01/16/91


                         VOYAGER STATUS REPORT
                            January 16, 1991

                              Voyager 1

     The Voyager 1 spacecraft collected routine UVS (Ultraviolet Spectrometer)
data on source HR 1350.  On January 8 a frame of PWS (Plasma Wave) data was
recorded on the DTR (Digital Tape Recorder) for future playback.  Also on
January 8, a TLC (Tracking Loop Capacitor) test was uplinked from the 70 meter
station in Spain and completed over to the 34 meter station in Australia.
Round trip light time is 12 hours, 16 minutes.

     DTR Maintenance and science calibrations for the PLS/MAG/LECP
(Plasma/Magnetometer/Low Energy Charged Particles) instruments were executed
by the spacecraft on January 9.  Only the beginning and end of the DTR
maintenance were observed in spacecraft telemetry and only the first hour and
one-half of the science calibartion was observed due to the lack of available
DSN (Deep Space Network) support.

     A Dummy CC command was transmitted to the spacecraft on January 9 to
reset the Command Loss Timer and avoid entry into the CMDLOS routine.  It was
transmitted 20 minutes later than scheduled due to transmitter problems at the
34 meter station in Goldstone.


                              Voyager 2

     The Voyager 2 spacecraft collected routine UVS on source 53 PER.  On
January 8, one frame of high-rate UVS data was recorded.  Round trip light
time is 9 hours, 36 minutes.

     A Dummy CC command was transmitted to the spacecraft on January 7 using
the bracketed command procedure, 3 db command suppression and the high-power
transmitter at the 70 meter station in Australia.  There was no downlink
station available to monitor spacecraft telemetry a RTLT (Round Trip Light
Time)later; however, when telemetry was received the CCS (Computer Command
Subsystem) hours telemetry indicated three of the seven commands transmitted
were received by the spacecraft.  This special conservative DSS (Deep Space
Station) uplink configuration was used because the previous Dummy CC was not
acknowledged by the spacecraft.

     On January 10, the AACS (Attitude and Articulation Control Subsystem)
B and C gyroscopes were turned on to perform routine Gyro Conditioning.
Following the Gyro Fault Test 10 minutes later the AACS GYRO status indicated
gyroscopes AB rather than BC were on and other telemetry including temperature
and CCS indicated that a gyro swap occurred when the Gyro Fault Test was
enabled.  A mini-sequence is being planned to condition the C gyroscope and
investigate the cause of the switch and to determine why the automated fault
test failed.


                CONSUMABLE STATUS AS OF 01/16/91

     P R O P E L L A N T    S T A T U S           P O W E R

               Consumption
                 One Week  Propellant Remaining Output Margin
     Spacecraft     (Gm)               (Kg)      Watts  Watts
      Voyager 1      5             36.2 + 2.0     366   53
      Voyager 2      5             39.2 + 2.0     370   47

      ___    _____     ___
     /_ /|  /____/ \  /_ /|
     | | | |  __ \ /| | | |      Ron Baalke         | [e-mail]
  ___| | | | |__) |/  | | |___   Jet Propulsion Lab | [e-mail]
 /___| | | |  ___/    | |/__ /|  M/S 301-355        |
 |_____|/  |_|/       |_____|/   Pasadena, CA 91109 |

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

Date: 16 Jan 91 22:22:55 GMT
From: usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Galileo Update - 01/16/91


                         GALILEO STATUS REPORT
                           January 16, 1991

     Today, the Galileo spacecraft will be commanded to all-spin mode
operation due to the lack of valid star sets at required flight attitudes
until February 25.  While in the all-spin mode, the spacecraft will perform
sun acquisitions to maintain sun point for thermal control reasons.

     Tomorrow, the CDS (Command Data Subsystem) "B" memory copy activity is
planned.  This activity will copy the contents of the CDS "B" prime memory
into the extended memory using the same process successfully performed last
week for the CDS "A" copy activity.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|
     | | | |  __ \ /| | | |      Ron Baalke         | [e-mail]
  ___| | | | |__) |/  | | |___   Jet Propulsion Lab | [e-mail]
 /___| | | |  ___/    | |/__ /|  M/S 301-355        |
 |_____|/  |_|/       |_____|/   Pasadena, CA 91109 |

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

Date: 15 Jan 91 18:25:02 GMT
From: timbuk!cs.umn.edu!sialis!orbit!pnet51![e-mail]  (S Schaper)
Subject: The Plains of Abraham II

Well, Henry, this is your big chance to invade the U.S. Liberate the Northwest
third of the country...
**************************************************************************
Zeitgeist Busters!
UUCP: {amdahl!bungia, uunet!rosevax, chinet, killer}!orbit!pnet51!schaper
ARPA: crash!orbit!pnet51![e-mail]
INET: [e-mail]

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

Date: 15 Jan 91 21:11:58 GMT
From: voder!dtg.nsc.com![e-mail]  (Alan Hepburn)
Subject: Re: Cameras in 0G, was: Re: MIR Vacation

In article <[e-mail]> [e-mail] (H.A.Shaw) writes:
>
>    Whats all this about modifications for 0G?  I have a reasonably cheap East
>German camera, a mid range Japanesse 35mm compact, and before them a Kodak
>Instamatic which I got for my 7th birthday and worked perfectly for over 15
>years.  I use them the right way up, on their side, facing down for flat
>coping and even upside down or pointing straight up for buildings and trees
>from odd angles.  I have used them from sea level to 14,000 feet and out of the
>windows of aircraft, speedboats and rally cars.  I even changed the film in a
>rally car, doing 80 mph across the ploughed fields of France at 1am.  I have
>lens, both automatic and manual from 28mm to 1000mm, motor winds, flashguns
>etc.  I have around 20,000 slides in my current collection and I've never
>knowingly lost a shot because of gravity.  What difference does gravity make?
>
>Maybe it makes using a tripod a little more tricky :-)
>
>This sounds like the $483 space rated hammer again to me!
>

I can't recall what the criteria were, but I do recall that during the
early days of the US space program, a lot was made of the selection of
the Hasselblad as the camera of choice.  I recall several different times
seeing reports that it was the only camera that needed no modifications
for 0G use.  Maybe, as someone else pointed out, it was due to the use
of removeable film backs, which removed the necessity of the astronauts
changing film in 0G, I don't know.  I do know that they left several
Hasselblad bodies on the moon (if anyone wants to pick them up!).

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

End of SPACE Digest V13 #057
*******************