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Date: Wed,  1 Nov 89 01:27:35 -0500 (EST)
Subject: SPACE Digest V10 #181

SPACE Digest                                     Volume 10 : Issue 181

Today's Topics:
               Re: Magellan Temperature
             Re: Galileo Schedule
             Uplink schedule (Forwarded)
         NASA Headline News for 10/25/89 (Forwarded)
      STS-34 flight crew press conference scheduled (Forwarded)
           Mach - what does it really mean?
    Re: Balloon Launch attempt of a High Power Rocket (40 Miles).
           Magellan Status for 10/25/89 (Forwarded)
----------------------------------------------------------------------

Date: 26 Oct 89 03:23:15 GMT
From: [e-mail]  (Peter G. Ford)
Subject: Re: Magellan Temperature

In article <[e-mail]> [e-mail] (Cesar Quiroz) writes:
>What happened to the temperature problem?  I seem to have missed the
>resolution.

Magellan has experienced several temperature problems, each with a specific
solution or work-around:

[1] High temperature at nozzle of Venus orbit injection motor. Solved by
    pointing the spacecraft so that the sun never shines directly up the
    nozzle.  Once in orbit, the motor is tossed away, the problem with it.

[2] High temperatures at the nozzles of attitude control motors that have
    been exposed to direct sunlight for extensive periods.  Ground tests
    with spare motors show that the temperatures won't harm the motors but
    they will cause the hydrazine fuel to pre-ignite before it hits its
    catalyst and make the performance erratic. The work-around is to "purge"
    a hot motor with a very small burst of fuel immediately before using it.

[3] High temperatures in the equipment bay containing the attitude control
    electronics when that bay is illuminated by direct sunlight. The
    workaround is two-fold: 1) slowly rotate the spacecraft so that no one
    side remains in sunlight for too long, and 2) tilt the solar panel
    arrays so that they receive less than their maximum exposure to sunlight
    (the panels were producing more electrical power than the spacecraft
    could use, the excess being shunted into a large resistor which was,
    in turn, heating the spacecraft itself.)

The bottom line is that the thermal problems don't look particularly
serious. There is more worry about the effect of the very active Sun on
the attitude control system -- solar protons hitting the star-sensing
telescope produce intense flashes of light that interfere with the
pointing accuracy. This problem is still being worked on -- the current
thinking is that the on-board computers can be programmed to analyze
the star-sensor signals and reject the spurious ones. I'm sure you'll
be hearing more about this in the regular Magellan bulletins.

Peter Ford
MIT & Magellan Project

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

Date: 25 Oct 89 19:04:35 GMT
From: uhccux![e-mail]  (Jeff Goldader)
Subject: Re: Galileo Schedule

In article <[e-mail]> [e-mail] (George Kyriazis) writes:
>
>My question is:  How much memory does Galileo have?  If it plays back
>the pictures from Venus after it gets rid of its influence, it must
>be some time, and assuming that it takes several pictures, where does
>it store all this information?
>
>That brings the question of the resolution of the pictures, and how
>many primary colors (if any) are there for each picture.  Can anybody
>answer that?
>

Galileo will store the Venus data on its tape recorder, which has a capacity
of 900 Mbytes.  The amount of data it can gather at Venus is limited by this
capacity.

Here are some numbers for the imaging system I pulled out of the latest
Aviation Week:

The wide-field camera uses a 1.5m f/8.5 Richey-Chretien telescope, just
like Voyager's.  The narrow-angle telescope also has the same specs as
Voyager, but Av Week didn't list those.  The detector is an 800x800
charge-coupled device (aka CCD) which is sensitive to wavelengths of
4000-11000 Angstroms.  There are seven filters.  All images are black-
and-white, but color images can be put together from several different
filters.  The field of view is 0.47 degrees, and the pixel resolution
is 10 microradians.

Jeff Goldader                        University of Hawaii
[e-mail]      Institute for Astronomy

"So, Lonestar, now you see that Evil will always win- because Good is stupid."
-The Dark Lord Dark Helmet, _SPACEBALLS_

Disclaimer: The University of Hawaii and the Institute for Astronomy neither
support nor are in *any way* responsible for these opinions.

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

Date: 25 Oct 89 20:32:35 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: Uplink schedule (Forwarded)

LMD                                             October 25, 1989



              ATTENTION SATELLITE NEWS COORDINATORS


SATELLITE FEED DATE:    WEDNESDAY, NOVEMBER 1, 1989
UPLINK TIMES:           1:00 PM EST - KU BAND "G" STAR 2
                        2:30 PM EST - SATCOM F-2R
RUNNING TIME:           14:30

                      SATELLITE COORDINATES

KU Band "G" Star 2 - Orbital Position 105 degrees west longitude,
transponder 7.  Uplink frequency 14396 Vertical - Downlink
frequency 12096 Horizontal.  Audio 6.2 and 6.8 MHZ.  Two
Playbacks, both audio tracks each feed.

Satcom F-2R - frequency "C" band - orbital position:  72 degrees
west longitude - Transponder 13, frequency 3960.0 MHZ vertical
polarization.  Audio 6.8 MHZ.  Due to single track audio playback
capability, program will be uplinked twice.  The first playback,
channel 1 is a fully mixed track with narration, actualities,
music and effects.  The second playback immediately after the
first, channel 2, is effects and actualities only.

THE FOLLOWING 4 NEWS FEATURES WILL BE UPLINKED:

"Combating Malaria" - NASA scientists  are experimenting with
remote sensing techniques which could make it possible to
determine where the highest concentration of malaria transmitting
mosquitoes are likely to occur.

"Voyager's Last Encounter" - This feature will focus on what the
spacecraft revealed about the planet now that scientists have had
a few weeks to analyze the data.

"Better Airplane Wings" - A Lear Jet and an F-106 are being used
by researchers to investigate ways of improving the performance
of airplane wings.

"Sights and Sounds of Space" - Jane Ira Bloom, a saxophonist and
composer wrote and composed music commemorating the return to
flight of the space shuttle.  She joined a team of artists
commissioned to document the U.S. space program.

NASA CONTACT IS:    J.L. HEADLEE    (XXX)YYY-ZZZZ

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

Date: 25 Oct 89 20:25:18 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: NASA Headline News for 10/25/89 (Forwarded)

-----------------------------------------------------------------
Wednesday, Oct. 25, 1989                     Audio:  202/755-1788
-----------------------------------------------------------------

This is NASA Headline News for Wednesday, October 25th......

Technicians at Dryden Flight Research Facility report that the
orbiter Atlantis sustained minimal tile damage during its just
completed flight.  An initial inspection shows that no tiles are
missing, and overall about 25 dings were reported on the
orbiter's lower surface.  The reinforced carbon-carbon chin panel
also was reported in good shape and will not have to be removed
prior to Atlantis' next flight in February.  The tires and brakes
have been removed.  Normal scuffing was observed on the tires and
no damage was reported on the brakes.  The current processing
schedule calls for Atlantis to return to Kennedy Space Center
aboard the 747 shuttle carrier on Saturday.

At KSC...wind and rain this morning forced the postponment of
rollout of the orbiter Discovery to the launch pad.  The move is
now scheduled to begin tomorrow morning at 12:01 Eastern time.
Discovery's crew is scheduled to fly into KSC on Saturday, to
participate in a two-day launch countdown rehearsal which begins
Sunday morning.  They will fly a classified DoD mission later
next month.

Aerospace Daily reports the compromise $12.4 billion NASA budget
for FY '90 goes to the Senate floor today.  The House has not yet
scheduled debate on the measure.

And the Daily reports...the House Space, science and Technology
Committee has scheduled two days of hearings next week on NASA's
rephasing program for Space Station Freedom.  The committee wants
to review the affect of rephasing on commitments to international
partners.









                         ***********










-----------------------------------------------------------------
Here's the broadcast schedule for public affairs events on NASA
Select television.  All times are Eastern.

Thursday, Oct. 26......

     7:00 A.M.         Roll out of the orbiter Discovery to
                       launch pad 39-B.

    11:30 A.M.         NASA Update will be transmitted.

All events and times are subject to change without notice.
-----------------------------------------------------------------
These reports are filed daily, Monday through Friday, at 12 noon,
Eastern time.
-----------------------------------------------------------------
A service of the Internal Communications Branch (LPC), NASA
Headquarters, Washington, D.C.

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

Date: 25 Oct 89 20:27:00 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: STS-34 flight crew press conference scheduled (Forwarded)

Sarah Keegan
Headquarters, Washington, D.C.                   October 25, 1989

Jeff Carr
Johnson Space Center, Houston,


EDITORS NOTE N89-71

STS-34 FLIGHT CREW PRESS CONFERENCE SCHEDULED

     The STS-34 astronaut crew will meet with news media at the
Johnson Space Center, Houston, on Wednesday, Nov. 1, to discuss
the recent mission to deploy the Jupiter probe, Galileo.  The
event will begin at 2 p.m. EST, and consist of a slide and video
presentation by the astronauts, followed by questions.

     News media are invited to participate at JSC in Building 2,
room 135, or via two-way audio from NASA Headquarters,
Washington, D.C., the Kennedy Space Center, Fla., the Marshall
Space Flight Center, Huntsville, Ala., or the Jet Propulsion
Laboratory, Pasadena, Calif.

     Live NASA Select television coverage will be carried on
Satcom F2R, transponder 13, C-band, at 72 degrees W. longitude,
3960.0 MHz, 6.8 MHz.

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

Date: 25 Oct 89 19:49:22 GMT
From: ksr![e-mail]  (Chris Jones)
Subject: Mach - what does it really mean?

One of my pet peeves is the use of Mach numbers in space flight contexts.  As I
understand it, Mach 1 is the speed of sound (under ambient conditions, I would
guess).  I understand the usefulness of saying that something is going more or
less than the speed of sound, since aerodynamic characteristics change passing
through that speed, but hearing that the shuttle enters the atmosphere at, say,
Mach 24 is so much hooey in my opinion.  What does it mean when I hear some
NASA spokesperson say that?  Since the speed of sound depends on temperature,
pressure, and composition of medium, what does it mean when I read in AW&ST
(October 9, 1989, p. 109) that the Titan probe released from the Cassini
mission will end its entry phase at a velocity of about 1.5 Mach?  What's wrong
with m/sec or some similar "real" unit?

(Yes, I've read one answer to the question posed in my subject.  I'm not really
sure messages are crufty hacks...)

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

Date: 25 Oct 89 17:02:53 GMT
From: mailrus!jarvis.csri.toronto.edu!db.toronto.edu![e-mail]  (John Hogg)
Subject: Re: Balloon Launch attempt of a High Power Rocket (40 Miles).

In article <[e-mail]> [e-mail] (Brad Templeton) writes:
>But what good is a baloon rocket launch?  When it comes to getting into
>orbit, 90% of the problem is gaining horizontal velocity, not going through
>the atmosphere or gaining altitude.

Yes, but the launch described was sub-orbital, and the balloon seems to
have roughly doubled its altitude.  From the description given, the
project is hobby rocketry on an enthusiastic scale, so maximum altitude
is a goal in itself.  However, the performance boost could also be very
welcome if the rocket were used simply as a vehicle.  Atmospheric
studies can gain by looking at more atmosphere, and a lofted launch
would be a real boon to microgravity work.  Once the vehicle falls back
into ``substantial'' atmosphere, the micro-g ride is over.  For
vehicles with marginal performance, a balloon launch may be necessary
to get any clean microgravity at all.

Not all rockets go into orbit.  (Not even all peaceful rockets.)
There's a real market out there for up-and-down trips.  The American
start-ups are using this fact to climb into the market incrementally,
and old hands (such as Bristol Aerospace in Winnipeg) have been selling
rockets like the Black Brant for many years.
--
John Hogg            [e-mail]
Department of Computer Science, University of Toronto

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

Date: 25 Oct 89 20:22:40 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: Magellan Status for 10/25/89 (Forwarded)


                     MAGELLAN WEEKLY STATUS
                          Oct. 25, 1989


     This is the weekly Magellan status report. Magellan on
Tuesday, Oct. 24, reached the point in Venus' orbit where the
planet will be next Aug. 10. So it has one more orbit around the
sun before orbit insertion. The spacecraft is 75,911,294 miles
from Earth. Having passed through perihelion on Oct. 7, Magellan
is slowing as it begins its return to the orbit of Earth and is
now traveling at a speed of 84,455 mph relative to the sun. The
one-way light time is 6 minutes and 48 seconds.

     Magellan is operating without major problems as it begins
the second third of its cruise, moving away from the sun.

     Only two of the scheduled seven star calibrations performed
last week were fully successful. All others had only a partial
attitude update from one star due to spurious interrupts from
increased solar activity. Another major solar flare on Oct. 19
does not bode well for the coming week's starcals. The good news
is that the flight software patch to alleviate the problem with a
filter passed its first test in the System Verification
Laboratory.

     In conference with Kearfott, the gyro manufacturer, it was
determined the most likely cause of the erratic behavior of both
current and temperature on gyro B2 is vibration of the main
bearing retaining ring at low temperatures. The analysis is
preliminary, and is continuing. Kearfott believes that since all
excursions of the telemetry values are well within specification
limits, there would be no attitude problem if mission operations
is forced to return to it. A backup gyro is currently being used.


     SPACECRAFT
     Distance from Earth (mi)             75,911,294

     Velocity Geocentric                  64,036 mph
              Heliocentric                84,455 mph

     One-way light time                   6 mins, 48 secs

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

End of SPACE Digest V10 #181
*******************