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Subject: SPACE Digest V11 #121

SPACE Digest                                     Volume 11 : Issue 121

Today's Topics:
              SR-71 on CNN Headline News
    Re: Magellan Update - 03/02/90 -- now reprogramming spacecraft
                 EMP
       Challenger's Last Words & Galileo Camera 'Blemishes' #2
              Ulysses Update - 03/06/90
               Re: More info on Pegasus
----------------------------------------------------------------------

Date: 6 Mar 90 14:34:26 GMT
From: bbn.com![e-mail]  (David Waitzman)
Subject: SR-71 on CNN Headline News

Last night I saw a short piece on the SR-71 retirement on CNN Headline
News.  While it didn't really offer any new news, the in-flight videos
were really cool.

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

Date: 6 Mar 90 12:46:00 GMT
From: unmvax!nmtsun![e-mail]  (Daniel Briggs)
Subject: Re: Magellan Update - 03/02/90 -- now reprogramming spacecraft

In article <[e-mail]> [e-mail] (Anita Cochran) writes:
>
>As an example, I am involved with the Comet Rendezvous/Asteroid Flyby (CRAF)
>mission.  If we decided one day that we want to point to a particular
>feature on the comet and cycle through 5 filters, it will be a minimum
>of 4 weeks from the time we request it until the time it is uplinked
>and executed.  Obviously, this takes away sponteneity!  First and
>foremost is spacecraft safety.  We scientists are trying to shorten
>the time but we are not winning the battle.

Wow, that is a long time.  Is that number longer than some of the previous
missions?  In particular, I am certain that during Voyager II's encounter
with Neptune, mission scientists were able to target particular features of
Neptune in under a few days.  At least some of these (eg. the scooter), were
not visible until the spacecraft was very close to the planet, and several
frames were centered right on it.  Indeed, there was a good deal of anxiety
in predicting its position, since they had only a few previous frames to work
with, and they weren't completely certain that they could hit it.  At the
time, I had the vague impression that this was all coming from some sort of
discretionary imaging time budget.  Is there some means whereby you can
declare an "unspecified" image on CRAF, perhaps within some other mission
constraints.  (Say, that you can't move the filter wheel, and that the
instrument must point within epsilon of some point.)

I think that most of the earth orbiting observatories have some mechanism
similar to what I describe.  (I'm pretty sure that IUE does, and I think that
Hubble does too.)  If memory serves regarding Hubble, there is a mode where
you can send _very limited_ real time commands to it.  (Basically to select
one of several prepared branches in your observing schedule.)  This in
principle would let you select between different instruments or between
several very closely spaced targets based on the feedback you get from the
real time monitoring of your program.  I grant you that this flexibility is
pretty hard to reconcile with a scheduling program that can _barely_ run
faster than real time, but I think it's true.  Any STSI people want to
correct me?

-----
This is a shared guest account, please send replies to
[e-mail] (Internet)
Dan Briggs / NRAO / P.O. Box O / Socorro, NM / 87801  (U.S. Snail)

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

Date: 6 Mar 90 17:58:49 GMT
From: zaphod.mps.ohio-state.edu!samsung!aplcen!stda.jhuapl.edu![e-mail]  (Jim Meritt)
Subject: EMP

In article <[e-mail]> [e-mail] (Tim Maroney) writes:
}It would also take a pretty large hydrocarbon explosion to create EMP.

accidently.

If you are trying, it doesn't.  You do have to doctor the charge a bit, though.


"In these matters the only certainty is that nothing is certain"
                    - Pliny the Elder
These were the opinions of :
[e-mail]  - or - [e-mail]  - or - meritt%aplvm.BITNET

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

Date: Tue, 6 Mar 90 14:55:09 +0100
From: mpirbn![e-mail] (Daniel Fischer)
Subject: Challenger's Last Words & Galileo Camera 'Blemishes' #2

Chris Jones and Scott Brown write:
>...I don't feel a need to know all the lurid details of the tragedy.
>...There is no need to know this ...too personnal to be open for public
>observation. Just my opinion...
Right when it comes to discuss what happened in the crew compartment prior to
impact on the Atlantic. But there's also the technical side of this drama:
I still recall how shocked I was when I first realized on the video footage
of the accident that the front part of the orbiter emerged from the explosion
in *one* part. And months later I heard that it most likely survived airtight!
I've never heard anyone mentioning whether it would have been possible to add
a parachute system that would have allowed a survivable landing? Why does it
seem to be so difficult to build such a system, that even the designers of the
Hermes space shuttle finally decided to abandon the idea to save the crew cabin
as a whole, in favor of simple(?) ejection seats? Is it correct that such a
system was once installed in a U.S. bomber but failed completely in the first
*real* accident? Can somebody give me details about this incident?

--- The following item was to appear in SPACE Digest Vol.11 Issue 76, but
several subscribers received this issue in a scrambled form. Here it's again ---

The Venus shot by the Galileo spacecraft in Av.Week 19 Feb. p.25 shows
"several ring-shaped shadows" - who knows what precisely has caused them?
I recall the same phenomenon from Viking Orbiter pictures and from Voyager 2's
camera. In the latter case the rings were seen only in highly enhanced images
(like of Uranus' disk), but the defective Galileo frame doesn't look much
processed.
  Will it be possible to suppress these "blemishes" (AW&ST) by use of a
suitable flatfield or will they spoil every Galileo picture ? I was always a
bit scared by the fact that there's just   o n e   camera going on this big
journey, compared to the 4 cameras on the two Voyagers.

   Daniel Fischer, Max Pl. Inst. Radioastron., FRG   [[e-mail]]

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

Date: 6 Mar 90 17:16:55 GMT
From: elroy.jpl.nasa.gov!forsight!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Ulysses Update - 03/06/90



                              Ulysses
                       Mission Readiness Test
                           March 6, 1990

     Ulysses is a joint mission carried out by NASA and the European Space
Agency (ESA). The primary objectives of the Ulysses mission are to
investigate, as a function of solar latitude, the properties of the solar
wind, the solar corona, the sun-wind interface, the heliospheric magnetic
field, solar radio bursts and plasma waves, and interstellar/interplanetary
neutral gas and dust. The secondary objectives of Ulysses includes the
measurements of the Jovian magnetosphere during the Jupiter flyby phase,
and detection of cosmic gamma ray bursts and gravitational wave measurements.

     Ulysses is to be launched by the Space Shuttle in October 1990. Using
a two-stage IUS solid-rocket motor in combination with a Payload Assist
Module (PAM-S) kick stage, Ulyssses will be injected into a direct
Earth-Jupiter transfer orbit. Ulysses will arrive at Jupiter in March 1992.
It is interesting to point out that Ulysses will arrive at Jupiter before
Galileo. At this point, the Jovian gravitational field will deflect the Ulysses
spacecraft into a high-inclination orbit south of the ecliptic plane.  The
out-of-ecliptic orbit has an aphelion of 5 AU and a perihelion of 1.5 AU.
About 46 months after launch, Ulysses will pass under the southern pole of
the Sun at a distance of 2.3 AU. Ulysses will then proceed to pass over
the northern pole a year later. The Ulysses mission will end in September
1995.

     The Ulysses's Mission Readiness Test (MRT) so far has been successful.
All objectives for telemetry, tracking, command and monitor data types
were met. Command data transfers were accomplished by JPL's Network
Operations Control Center (NOCC) and Mission Control and Computing Center
(MCCC). S and X bank tracking data was validated by NOCC displays.A S band
uplink sweep was performed followed by S and X band ranging exercises. The
Telemetry Simulation Assembly (TSA) was configured standalone and all bit
rates for both S and X band were validated with no problems.

                    Key Dates for Ulysses

             10/05/90 - Launch from Space Shuttle
             12/30/90 - First Opposition
             08/24/91 - First Conjunction
             02/01/92 - Second Opposition
             03/11/92 - Jupiter Closest Approach
             09/07/92 - Second Conjuction
             03/03/93 - Third Opposition
             05/29/94 - Beginning of First Solar Pass
             08/28/94 - End of First Solar Pass
             02/05/95 - Perihelion
             05/29/95 - Beginning of Second Solar Pass
             09/11/95 - End of Second Solar Pass
             09/30/95 - End of Mission


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

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

Date: 6 Mar 90 15:10:59 GMT
From: samsung!umich!sharkey!amara![e-mail]  (S. Khai Mong)
Subject: Re: More info on Pegasus

In article <[e-mail]>
    [e-mail] (George William Herbert) writes:
#>   on the rocket], at about 950 lbs/ft^2 force.  After 81 seconds, the
#>first stage burns out and seperates.  At this point, the rocket is at
#>208,000 feet and moving at mach 8.7.
#>   The second stage is controled by a cold-gas reaction control system
#>which takes over immediately after the first stage seperates.  At 87 seconds
#>into the flight, the third stage ignites, thrusting at an angle of 26
#>degrees above the horizon.  At this point the craft is at 231,000 feet
#>altitude.  At the 120 second mark the payload fairing seperates from
#>the craft.  At 159 seconds the second stage burns out, with the craft
#>at 552,000 feet and 17,800fps velocity.  It is oriented 18.4 degrees
#>above the horizon.
#>. . .
#>   an angle of 1.9 degrees to the horizon.  At this point the third
#>stage ignites, and burns until 533 seconds, at which point the
#>spacecraft is at 250 miles and 25,000fps velocity [orbital velocity].

Is something wrong with the description of the stage firing timing
descriptions?



--
Sao Khai Mong:   Applied Dynamics, 3800 Stone School Road, Ann Arbor, Mi48108
[phone] (uunet|sharkey)!amara!khai  [e-mail]

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

End of SPACE Digest V11 #121
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