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Subject: SPACE Digest V10 #420

SPACE Digest                                     Volume 10 : Issue 420

Today's Topics:
          COBE Update - 01/12/90 (Forwarded)
             Re: Giotto Update - 01/12/90
           Payload Status for 01/12/90 (Forwarded)
               Giotto Update - 01/12/90
   Re: Electromagnetic Braking (was Re: Nuclear Reactors in Space)
   Re: Electromagnetic Braking (was Re: Nuclear Reactors in Space)
       Re: Scientific value of Apollo (was Re: Motives)
             Re: KSC tours (long)
----------------------------------------------------------------------

Date: 13 Jan 90 00:56:08 GMT
From: zaphod.mps.ohio-state.edu!usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: COBE Update - 01/12/90 (Forwarded)

EARLY COBE RESULTS IN ACCORD WITH BIG BANG THEORY

     A major advance in cosmology was revealed today as early
results from NASA's Cosmic Background Explorer (COBE), launched
last fall, were presented at the American Astronomical Society
meetings held at Crystal City, Va.

     Preliminary results are in accord with the predictions of
the Big Bang theory, which traces the origin of the universe to a
primordial explosion some 15 billion years ago.  The universe
today shows that sometime after the Big Bang additional
release(s) of energy must have occurred.  COBE's new results
severely limit the magnitude and character of such a release.

     Limited COBE data now indicate a smooth, uniform Big Bang.
However, small deviations from a blackbody spectrum -- the
characteristic signature of radiation from an opaque object of
uniform temperature -- would reveal energetic processes in the
early universe.

     COBE scientists reported that the instruments onboard the
spacecraft are performing exquisitely with precision never before
achieved.  Such precision puts new constraints on theories to
explain the present universe.

     Over the 2-year mission, COBE will continue to collect much
more data.  Scientists expect the final data to be ten times more
sensitive than these early results.

     These early results were reported to the American
Astronomical Society by the principal investigators for the three
instruments:  the Far Infrared Absolute Spectrophotometer
(FIRAS), the Differential Microwave Radiometer (DMR) and the
Diffuse Infrared Background Experiment (DIRBE).

     Dr. John Mather, Principal Investigator for FIRAS and
Project Scientist, reported that the spectrum measurement of the
cosmic microwave background (a relic of the Big Bang) is highly
accurate and heralds a major advance in observational
cosmology.  Based on a small sample of data, FIRAS measurements
show no deviation from a blackbody spectrum as large as one
percent of the peak brightness of the cosmic microwave background
over the wavelength range 500 microns to 5 millimeters.

     When FIRAS captured these data, it was pointed toward the
North Galactic Pole, where emissions from our own galaxy, the
Milky Way, are expected to be low.  Using only 9 minutes of sky
observations, FIRAS already has produced the most precise cosmic
microwave background spectrum measurement ever made.  Much more
exposure time will be obtained during the mission.

     Dr. George Smoot, Principal Investigator for the DMR,
presented the first COBE maps of the variation in brightness of
the cosmic background radiation over the sky.  The maps, taken at
frequencies of 31, 53 and 90 GHz, indicate that the cosmic
background radiation is equally bright in all directions.  The
question of what and where are the progenitors of galaxies and
large clusters of galaxies is still open.

     The preliminary results from DMR are based on only about 20
days of data and also indicate the extraordinary smoothness of
the universe.  This instrument will continue to take data for two
years, which will improve its sensitivity to search for
anisotropies, or "lumpiness," in the early universe well beyond
the present limits.

     Dr. Michael Hauser, Principal Investigator for DIRBE, showed
maps of half the sky taken at wavelengths of 1.2, 12, and 240
microns (never before achieved for the 1.2 and 240 micron
wavelengths).  Final maps from this experiment will enable COBE
scientists to search for radiation from the first stars and
galaxies.

     These initial maps, taken over a one-week period, clearly
reveal bright foreground radiation from stars, dust in our own
Solar System, and interstellar dust.  DIRBE maps half the entire
sky every day at 10 different wavelengths and it covers the
entire sky in 6 months.

     At the AAS meeting, Dr. Nancy W. Boggess, Deputy Project
Scientist, gave an overview of the mission, reporting that COBE
has met or exceeded all design goals.  At launch, all systems
deployed as planned.  The RF/Thermal Shield, which protects all
three instruments from solar and terrestrial radiation, is more
spectacular than hoped.

     This efficient shield results in a lower than anticipated
temperature of the dewar, the giant thermos bottle that maintains
the FIRAS and DIRBE at operating temperatures below 2 degrees K.
The dewar now operates at 1.4 degrees K, though designed for 1.6
degrees K less. The lower temperature will enable the detectors
of the COBE instruments to be more sensitive.  It also makes the
lifetime of the liquid helium, which keeps the dewar
cryogenically cooled, longer than the original 12 to 14 months.
It is now expected to last 430 days.

     COBE was launched Nov. 18, 1989, aboard the last NASA-owned
Delta rocket, from the Vandenberg Air Force Base, Calif.  COBE is
managed by NASA's Goddard Space Flight Center, Greenbelt, Md.,
for the Office of Space Science and Applications.  GSFC is
responsible for the design, development and flight operations, as
well as for the development of the analysis software and for the
production of the final mission data sets.

 Ron Baalke                       |    [e-mail]
 Jet Propulsion Lab  M/S 301-355  |    [e-mail]
 4800 Oak Grove Dr.               |
 Pasadena, CA 91109               |

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

Date: 12 Jan 90 21:27:34 GMT
From: bfmny0![e-mail]  (Tom Neff)
Subject: Re: Giotto Update - 01/12/90

It's exciting to think of a platform like Giotto already out there
and ready to use.

This raises an issue.  I know it's not simple to reprogram a craft for a
new mission.  But what if 'general purpose' probes were launched into
Earth or Solar orbit AS budget and schedules permitted, and
'assigned' to 'hot events' later on?
--
 1955-1975: 36 Elvis movies.  |  Tom Neff
 1975-1989: nothing.          |  [e-mail]

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

Date: 12 Jan 90 23:53:49 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: Payload Status for 01/12/90 (Forwarded)

Daily Status/KSC Payload Management and Operations 01-12-90


- STS-31R HST (at VPF) -

Cite PR to correct a problem with IPCU/UDM cable connect to
SIP panel is complete.  HST bay 4 door opening and door angle
measurement ops are complete.  Yesterday cite was powered up
and the IPCU/UDM latch test was completed.  HST has a lost
single point ground in the area of bay 4.  Suspect a short in
the cable bundle.  This is under engineering evaluation and
troubleshoot is being performed.

- STS-32R SYNCOM (at Pad A) -

Final planning for download of LDEF and SYNCOM ASE continues.

- STS-35 ASTRO-1/BBXRT (at O&C) -

Spacelab activation and system activation were completed.
The closed loop testing was accomplished.  Successfully
completed checkout of the experiment 2 UIT commanding and
checkout of the thermal recorder.  Have started the
experiment 3, WUPPE, commanding.

- STS-40 SLS-1 (at O&C) -

Installation of MVAC mock-ups continues.  Weighing rack 5
was accomplished.  Rack 11 mating to subfloor elements is
complete.  Pyrell foam replacement was active yesterday.

- STS-42 IML (at O&C) -

No activity.

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

Date: 12 Jan 90 18:32:19 GMT
From: zaphod.mps.ohio-state.edu!usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Giotto Update - 01/12/90


                     Giotto Mission Readiness Test
                          January 12, 1990

     Reactivation tests of Giotto continue. Yesterday's overall test
was successful. Test objectives were to flow 46,080 bits/sec of
prerecorded Giotto data from the Mission Control
and Computing Center (MCCC) in JPL to the European Space Operations
Center (ESOC), exercise the command interface, and to exercise the
DSS/NOCC/ESOC telemetry interface. These test objectives were
accomplished. MCCC playback from the was at 46,080 bits/sec only.
An "all ones" data pattern and an "all zeroes" pattern were transmitted
and received successfully by ESOC. The command system worked well
throughout the test. Network Operation Control Center (NOCC) was able
to receive and validate S/X band tracking, S/X band ranging, and monitor
data. ESOC and NOCC were also able to frame sync uncoded telemetry data.

 Ron Baalke                       |    [e-mail]
 Jet Propulsion Lab  M/S 301-355  |    [e-mail]
 4800 Oak Grove Dr.               |
 Pasadena, CA 91109               |

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

Date: 12 Jan 90 05:56:28 GMT
From: zephyr.ens.tek.com!tektronix!psueea!parsely!bucket![e-mail]  (Leonard Erickson)
Subject: Re: Electromagnetic Braking (was Re: Nuclear Reactors in Space)


Electromagnetic braking of a spacecraft isn't practical for a very simople
reason. What are you going to do with all the energy?

On earth some electric vehicles use regenerative braking. This uses the
electric motors as generators, and thus slows the vehicle. This was once
tried with some sort of diesel-electric bus. Since it lacked batteries
to store the power they placed a cast-iron grid on the bottom of the bus
to act as a *large* resistor and dissipate the power as heat. After they
dug a few grids out of the street (and bus out of buildings at the foot
of the hill) they gave up on the idea.

Figure the how many megawatts you will be generating by trying to slow
a medium sized probe at a reasonable rate. Now figure the heat equivalent.
Remember, kinetic energy is equal to 1/2  the mass times the velocity
*squared*! One kilogram at 1 kn/sec is 50 kilowatt-seconds. At 10 km/sec
( a rather slow speed for an interplanetary probe) it's 5 Megawatt-seconds
of energy per kilogram.

So let's say the probe masses 1 metric tonne. And you have an hour to chop
the velocity from 20 km/sec to 10 km/sec. We start with 4e11 joules. At
the end we'll have 1e11. The difference is 3e11 joules. So we need to
dump 8.3333e7 joules/sec. That's over 83 Megawatts!!! Unless you have a
good way of using (or at least getting rid of) that much power, your
probe will be a rapidly expanding cloud of plasma.

Y'know, until I did these calculations I hadn't realized just *how much*
power we were talking about...
--
Leonard Erickson        ...!tektronix!reed!percival!bucket!leonard
CIS: [70465,203]
"I'm all in favor of keeping dangerous weapons out of the hands of fools.
Let's start with typewriters." -- Solomon Short

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

Date: 13 Jan 90 04:33:52 GMT
From: rochester![e-mail]  (Paul Dietz)
Subject: Re: Electromagnetic Braking (was Re: Nuclear Reactors in Space)

In article <[e-mail]> [e-mail] (Leonard Erickson) writes:
>
>Electromagnetic braking of a spacecraft isn't practical for a very simople
>reason. What are you going to do with all the energy?

You have two choices.  You can turn it to heat and radiate it,
or you can use it to accelerate some reaction mass.

The first is actually a well understood technology.  I am sure you
have in your home some objects that radiate many watts of power from
tiny resistive elements -- incandescent light bulbs.  For resistive
braking, I imagine we'd use a grid of fine tungsten or carbon wires,
operated at very high temperature.  If the grid operates at 2000 K
(what is the operating temperature of a light bulb?) it would radiate
.9 MW per square meter of surface.  If you can run your radiator at
3000 K, this goes up to 4.5 MW/m^2.

If we can use the energy to expel reaction mass, additional
braking could be obtained by directing the reaction mass in
the forward direction.  The engine would have to be very
efficient, though, or it would have to operate at high temperature
so the waste heat could be easily radiated.

    Paul F. Dietz
    [e-mail]

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

Date: 11 Jan 90 14:20:41 GMT
From: mcsun!ukc!icdoc!syma![e-mail]  (Nick Watkins)
Subject: Re: Scientific value of Apollo (was Re: Motives)

In article <[e-mail]> [e-mail] (Henry Spencer)
writes:

>The primary launcher for the more sizable unmanned missions these days
>is Titan-Centaur.  Name one commercial mission that has used it.  (Hint:
>there aren't any, and none are planned last I heard -- the Commercial
>Titan configurations currently on offer don't use Centaur, as I
>recall.)
 "[Martin Marietta] ... said the Commercial Titan would be compatible
with the Centaur, IUS, PAM, and Minuteman third stage for upper stage
applications. "We could use it with most any stage; that's why we
didn't develop commercial Titan with a specific stage"".  (AW&ST, 8th
Jan., p.43). I agree that nobody has actually bought one with a Centaur.
 Anybody know anything about the TOS upper stage for Mars Observer? Is
it the Minuteman 3rd stage referred to above?

>It was developed specifically for Viking, at considerable expense (which,
>of course, is seldom charged against Viking).  (I'll post more on the
>Voyager/Viking launcher history when I have a bit more time.)  Its primary
>use is planetary missions, with a recent small sideline in heavy military
>payloads.
Please do post, I for one would be interested to know when the Helios
and Voyager launches were added to the manifest. Presumably Titan
Centaur began when the original Saturn V based mars project was
cancelled ? The heavy military launcher is of course the Centaur version
of the Titan IV.

>Furthermore, the planetary people clearly would very much like a still
>heavier launcher, with still less commercial potential.  They are very
>badly cramped by the limitations of Titan-Centaur, especially when the
>bigger missions like Mars sample return are considered.
Exactly how much can a Titan IV with Centaur send to Mars, then?




--
Nick Watkins, Space & Plasma Physics Group, School of Mathematical
& Physical Sciences, Univ. of Sussex, Brighton, E.Sussex, BN1 9QH, ENGLAND
JANET: [e-mail]   BITNET: [e-mail]

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

Date: 12 Jan 90 21:20:18 GMT
From: snorkelwacker!usc!zaphod.mps.ohio-state.edu!wuarchive!rex!uflorida!mephisto!prism![e-mail]  (Shaun Heath)
Subject: Re: KSC tours (long)


I don't think the tours are anywhere near as rushed as has been indicated
here.  Both tours, Canaveral and Kennedy, are 2 hours and ten minutes long.
I was not rushed on any of the tours when I took them, and never had a
complaint about being rushed (I worked there for a while).

As far as getting close to the pads when a shuttle is being readied, I can
imagine that they were keeping the busses pretty far away when there was
the protest trouble.  But there are other reasons for temporarily not letting
tourists get close to the pad.  Whenever they would fill the ET, tours
weren't allowed anywhere near the pad (I think at least 1.5 miles away).

If you are going to the Spaceport, go straight to the ticket booth when you
get there.  Especially in the summer.  Get both tour tickets and IMAX film
tickets (the IMAX is great).  If you get there late, you might be looking at
a wait of several hours before your first tour(again,especially in summer!).
In July and August they put over 10,000 people on the bus tours every day.

Tours are only $4 for adults, $1.75 for kids. That surprised a lot of people.
I think that it is a bargain.

hope someone found this useful....

(BTW  I don't plug the place because I worked there- the work sucked.)

Shaun Heath

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

End of SPACE Digest V10 #420
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