Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v13_0/v13_097.txt

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Subject: SPACE Digest V13 #097

SPACE Digest                                      Volume 13 : Issue 97

Today's Topics:
         MAJOR SOLAR FLARE ALERT - 27 JANUARY
              Re: More on space cameras
               Voyager CD-ROMs
      Re: Metrics (was Re: Rotating Joints for Habitat)
            SALUT altitudes as f(t) needed
                 Tenth Planet
         Comparing reliability [Part 2 of 2]

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Date:    Sun, 27 Jan 91 13:07:24 MST
From: [e-mail] (Cary Oler)
Subject: MAJOR SOLAR FLARE ALERT - 27 JANUARY
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                        --  MAJOR SOLAR FLARE ALERT  --

                               JANUARY 27, 1991

                              Flare Event Summary
                           Potential Impact Forecast

                                    --------


MAJOR ENERGETIC EVENT SUMMARY

     Another major energetic Tenflare exploded from Region 6471 today.  The
flare began at 14:39 UT, peaked at 15:50 UT and ended near 16:04 UT on
27 January.  The flare, located at S14E59, attained a class X1.9/1B rating
and was associated with a Type IV sweep frequency event.  There are strong
suspicions that this flare was a proton flare.  Although no solar protons
have been observed yet, a proton shock is expected to occur near 04:00 UT
on 28 January.  The proton event is expected to be relatively weak, near
20 pfu at greater than 10 MeV.

     Region 6471 is expected to continue to produce major flaring possibly
throughout it's transit on the solar disk (possibly for the next 13 days).
Terrestrial impacts could become high as this region traverses the disk and
crosses into the western hemisphere within the next 5 days.

     Regions 6462 and 6466 are magnetically and optically complex, but are
not producing any significant flaring.  They do, however, have the capability
of spawning major flares and could do so at any time.

     The solar flux achieved a level of 301 today, the highest it has been
since August 22 of 1990.  It has jumped a whopping 57 points in the last
three days alone (98 points in the last 6 days)!  Active regions are
continuing to rotate around the east limb in more active configurations than
expected.  The solar flux is expected to remain above 300 for at least the
next several days (barring any significant decay in any of the regions
currently visible).

     There is a significant possibility for extended 6 meter openings due to
the greatly enhanced solar radiational output.  Please also note that a polar
cap disturbance could commence near 04:00 UT if the proton shock presently
predicted manifests itself on 28 January.


POTENTIAL TERRESTRIAL IMPACT FORECAST

     This latest flare is expected to produce mostly active conditions.
Active geomagnetic conditions are expected to begin late on 27 January or
sometime early on 28 January due to the X10.8/SF major flare of 25 January.
Impacts from this latest flare are expected to keep geomagnetic activity at
active levels through to 29/30 January.  There is a risk of high latitude
minor to major storming (most likely remaining confined to minor storming).
Middle latitudes should remain mostly active to very active with possible
brief periods of minor storming.  The predicted planetary A-index values
for the next three days hover near 25, so periods of minor storming are
quite possible over middle latitudes.  High latitudes will be affected most
strongly, with very active to minor storm conditions and risks of brief
major storming.

     Auroral activity will pick up on 28 January (UT time).  High latitudes
will witness moderate to high auroral activity.  Middle latitudes will
witness predominantly low to moderate activity.  Radio communications near
the auroral zones will be poor to very poor.  Conditions will improve with
distance away from the auroral zones. However, increased noise, absorption
and flutter fading are possible over middle and low latitudes as the
increased corpuscular radiation reaches the earth.

     There is a chance of some isolated VHF auroral backscatter
communications on the evening of 28 January and most likely also 29 January.
The quality, duration and extent of the conditions suitable for such
communications will depend to a large extent on the intensity of the flare
impact.  Presently, only isolated instances of backscatter are expected.
If activity surpasses levels predicted, more widespread backscatter may
become possible on the VHF bands.

     Barring any further major flaring, conditions should improve by 30
January (possibly earlier).  Major flaring is likely, however, so there is
a chance that the activity could be extended into early February.

     Reports of degraded radio propagation over the next 3 days would be
appreciated.  Please send any reports of degraded conditions along with a
description of the conditions experienced, to: [e-mail]. Thanks.


**  End of Report **

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

Date: 25 Jan 91 04:29:52 GMT
From: bbn.com!nic!kira!emily![e-mail]  (Garrett Wollman)
Subject: Re: More on space cameras

Maybe the guy from IMAX Systems (is that still their name?) can talk a
bit about the "Large Format Camera" (which *is* one of theirs,
right?)... I remember seeing a feature on them on "Venture" about
three or four years ago, when they were just starting to make waves...


Does NASA pay to have the LFC up there (as a supply), or does IMAX--or
a file producer--pay to put it there, so that they can make a movie of
it later?

-GAWollman

Garrett A. Wollman - [e-mail]

Disclaimer:  I'm not even sure this represents *my* opinion, never
mind UVM's, EMBA's, EMBA-CF's, or indeed anyone else's.

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

Date: 28 Jan 91 05:57:22 GMT
From: pacific.mps.ohio-state.edu!zaphod.mps.ohio-state.edu!usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Voyager CD-ROMs


     I've received a number of inquiries about the Voyager images available
on CD-ROMs.  There are eight CD-ROMs that contain about 16,000 images taken
by Voyager 1 and Voyager 2 on their encounters with Jupiter, Saturn and
Uranus.  The CD-ROMs are available to the general public at the NSSDC
(National Space Science Data Center) at the Goddard Space Flight Center.
There is a charge of about $75 for the 8 CD-ROM set, and NASA employees
get a discount.  You can contact the NSSDC at:

        National Space Science Data Center
        Request Coordination Office
        Goddard Space Flight Center
        Code 633
        Greenbelt, MD  20771

        Telephone: [phone]

        Email address:   [e-mail]

     The images are stored in compressed format on the CD-ROM with each
image being about 220K.  A decompression program, called PCDCOMP, and an
image display program that runs on an IBM PC computer, call IMDISP, are
included with the CD-ROMs.  The most recent versions of the PCDCOMP
(version 2.0) and IMDISP (version 5.6) programs can also be obtained via
anonymous ftp at ames.arc.nasa.gov site under the filename imdisp56.zip in the
pub/SPACE/IMDISP directory.  When the images are uncompressed, they will be
about 670K in size, so a large hard disk is recommended.  For each compressed
image there is a corresponding "browse" image, which is a scaled down version
of the original image (1/16 size) which can be viewed directly off the CD-ROM.
All of the images are the raw, unprocessed images taken by the Voyager
spacecraft.  All of the images are monochrome images since Voyager carried a
black-and-white camera.  All of the color images you've might of seen on
the news and in magazines were images created by the Image Processing
Lab at JPL; there are no color images on the CD-ROMs.  However, the IMDISP
program mentioned before gives you the capability to perform some image
processing functions on the images, as well as applying color palettes
to the images.

     A set of four CD-ROMs containing the Neptune images taken by Voyager 2
is due to be released at the end of February 1991, and these CD-ROMs will also
be available at NSSDC.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|      Ron Baalke         | [e-mail]
     | | | |  __ \ /| | | |      Jet Propulsion Lab |
  ___| | | | |__) |/  | | |___   M/S 301-355        | It's 10PM, do you know
 /___| | | |  ___/    | |/__ /|  Pasadena, CA 91109 | where your spacecraft is?
 |_____|/  |_|/       |_____|/                      | We do!

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

Date: 27 Jan 91 08:26:13 GMT
From: zaphod.mps.ohio-state.edu!sdd.hp.com!cs.utexas.edu!news-server.csri.toronto.edu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Metrics (was Re: Rotating Joints for Habitat)

In article <[e-mail]> [e-mail] (Garrett Wollman) writes:
>[I say metric rather than specifically SI because kilograms are an awfully
>inconvenient unit for weighing paperclips, thumbtacks, and all those
>other things that the government buys in quantity...

If you buy in quantity, kilograms of paperclips are not unreasonable.
The Pentagon alone probably uses megagrams a year. :-)

In any case, SI certainly permits use of prefixes whenever appropriate.
(And the removal of the "kilo" prefix from "kilogram" when using another
prefix or none.)

>... Besides, you will never get Americans to
>write "metre" or accent "kilometer" on the first syllable :-).

"Meter" is an acceptable alternate spelling of "metre" in the English-
speaking countries, and in the US :-).  And lots of us don't pronounce
"kilometer" in that strange way.
--
If the Space Shuttle was the answer,   | Henry Spencer at U of Toronto Zoology
what was the question?                 |  [e-mail]   utzoo!henry

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

Date: Mon, 28 Jan 91 15:51:15 +0100
From: [e-mail] (Daniel Fischer)
Subject: SALUT altitudes as f(t) needed

Is there a kind soul who has collected the orbital height of SALUT 7 since
it was raised to a 'secure' 500km orbit in 1986 and could mail me such a
list (or fax a graph). Would be used in a review article, full credits to
supplier given!

Daniel Fischer = [e-mail] = fax. FRG-228-525-229

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

Date:         Mon, 28 Jan 91 15:14:48 EST
From: Leonard Abbey <[e-mail]>
Subject:      Tenth Planet

I have forwarded Rich Schroeppel's comments on the Tenth planet to
Tom Van Flandern via CompuServe's ASTROFORUM.  Dr. Van Flandern,
formerly of the U.S. Naval Observatory, and a leading participant in
the search for Planet Ten, is a regular habitue of ASTROFORUM.  Here
is his reply:


#: 78027 S4/The Solar System
    28-Jan-91  12:45:54
Sb: #78015-Tenth Planet, et al.
Fm: Tom VanFlandern/DC 71107,2320
To: Lenny Abbey 72277,566

Lenny,
       Thanks for posting the interesting Bitnet messages.  Please feel free to
post any or all of the following information.

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

       An up-to-date summary of the Planet X debate and search status may be
found in "Planets Beyond" by Mark Littmann, Wiley Science Editions, 1988.

       For the orbits of both Uranus and Neptune, the situation is as follows:
If one fits only the 20th century data, the fit is reasonably good.  If 19th
century data is included, the 20th century fit becomes distinctly poorer.
Deviations of both planets from their best-fit computed trajectories is small
in the 20th century, somewhat greater in the 19th century, and greater yet in
the 18th century.  Statistically significant deviations are also seen in the
orbits of Jupiter and Saturn; but these are small enough that systematic errors
of observation cannot be excluded as the cause.

       Two opposite conclusions have been drawn from the above facts.  One
school, with proponents at JPL (which processes only the 20th century data),
believes that the pattern of deviations simply reflects the improving accuracy
of the observations.  They maintain that the problems are likely to be
undetected systematic errors in the older observations.  The other school, with
proponents at USNO (where I used to work), suspects that the deviations are
caused by a "Planet X" on a long-period elliptical orbit, which has been
increasing its distance from the Sun over the past 200 years, causing the
deviations to become smaller.  I am in the latter school; and my new
organization, Meta Research, is working on this problem now.

       The rebuttal case against systematic errors and favoring the Planet X
interpretation is approximately as follows:

       (1) If only the 20th century data is fit, the fit is reasonably good.
But if that "good" orbit, which has ignored the 19th century data, is
extrapolated backwards to the 19th century, it veers rapidly away from the
observed trajectory; and the deviations are so large that it is inconceivable
that the old observations could have been so poor.  But if any consideration at
all is taken of the 19th century data, it puts "kinks" into the 20th century
fits, which are no longer so good.

       (2) The only other objects which we can observe accurately enough, and
which are sensitive to Planet X perturbations, are comets whose orbits go out
beyond Neptune.  Six such comets have appeared more than once, so that we can
check for orbital changes.  Short-period comets have a well-known
non-gravitational force acting on them from solar radiation pressure; but it
acts only in-plane.  But the six comets which go out beyond Neptune, and only
those six, also show unmodelled deviations perpendicular to their orbital
planes.

       (3) Work done by Harrington and myself suggests that a Planet X with a
mass in the range from 2-5 Earth masses and a Neptune-crossing orbit could have
been responsible for the apparent chaos among Neptune's major moons, such as
reversing the direction of Triton and causing Nereid to nearly escape the
planet.  Such a hypothetical planet could in fact have caused the escape of
other former Neptunian moons, thereby also explaining the origin of Pluto and
Charon (which have many characteristics of Neptunian moons, and are in a
Neptune-crossing solar orbit).

       -|Tom|-


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

Leonard Abbey
Georgia Tech
Research Institute
[e-mail]

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

Date: Tue, 29 Jan 91 00:21:13 EST
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: Comparing reliability [Part 2 of 2]


>From: [e-mail] ("Allen W. Sherzer")
>Newsgroups: sci.space
>Subject: Why man rate? (was: space news from Dec 17 AW&ST)
>Date: 25 Jan 91 00:25:59 GMT
[Part 2 of 2]
>>>This calls into question the entire 'man rating' process. Why add all that
>>>expense when it doesn't add to safety?
>>Because it does.
>Not from what I can see. The Shuttle is at best no safer than the non-man
>rated alternatives and at worse a little less safe.

I don't think two entirely different design approaches can be used to
evaluate the value of 'man rating'. My perception is that Delta is
reliable because it is fairly simple, and has a more mature technology and
better safety margins. The Shuttle is more of a collection of newfangled
devices that are being driven hard with very little safety margin, so that
one might think it almost certain to fly apart. The extraordinary efforts
to increase reliability and 'man rate' the vehicle are largely an effort to
make up for these problems inherent in the basic approach. The result is
a launcher with a reliability that is on par with other launchers, or
perhaps better. I think this is an interesting result - it shows what can
be done if you throw enough money at a problem. Note the other side of this
view - with the amount of care that went into its design, the Shuttle
could have been made much more reliable - vastly better than the other
launchers on the market - if the design margins had not been so tight.
The Shuttle was caught in a tradeoff between safety, performance, cost,
and a number of other factors such as mission requirements. It would be hard
for me to say in retrospect whether the best tradeoffs were chosen, and
if not, what should have been done. As matters stand now, riding the Shuttle
once or twice won't do too much to your life expectancy, but riding it
every week would definitely be a very bad idea. :-)

Yet another problem with comparing reliability ratings for one-shot uses -
the payloads may be different, as is the case for the Shuttle and the
current Delta. To avoid a controversy over specific numbers, consider
a single payload you have, which can be placed in orbit in one launch
by launcher A (rated as 98% reliable), or which can be divided into four
pieces and lifted by four launches of launcher B (rated as 99% reliable).
The overall chance of complete success using launcher A is then 98%, and
for the multiple B launches it is now about 96%, so you actually lower
your chance of success by using the more reliable but smaller launcher.
In another application, it may be possible to replace components of the
payload lost by launch failure, so a business using the service would
have to factor in cost of replacement versus cost of launch services,
possible loss of future services from a reusable vehicle, and so on.
I think it's clear that the comparison of reliability ratings in a
practical situation can be a very complex undertaking, and there are
few really useful rules of thumb. Unfortunately, high-level policy
makers are sometimes prone to using emotion and political considerations
more than mathematics in making their decisions.

For  the particular effort that launched this debate long ago, namely
calculating the odds of launch without mishap of Freedom (early 1990 version)
on the Shuttle versus the LLNL station on a near descendent of Delta, the
answer seems obvious - the LLNL station would be more likely to get up
safely. This is not from an argument that the Delta would be more reliable
than the Shuttle, but because the LLNL station is so much lighter than
Freedom that it requires a lot fewer launches. Even if (as I believe) the
Shuttle is more reliable on a per-launch basis than the Delta, a couple
of Delta launches (I'm not yet sure of the exact number) are more likely to
all be successful than 20 or 30 Shuttle launches. The mathematics are such
that the Freedom mission planners *must* make provision for the possibility
of a launch failure.

>BTW, on January third Norm Augustine made the exact same point in a
>Congressional hearing. As you know his committee advocates building
>a heavy lift vehicle. One member asked him about man-rating this new
>launcher. He pointed out that may not be needed because of the
>safety of the hardware. It turns out that the system MUST be safe
>enough for people because the payloads are worth far far more
>than the crew. If it wasn't safe, nobody would fly their payloads
>on it.

Conversely, NASA *currently* prefers to launch its most expensive payloads
on the Shuttle, based partly on the judgement that the presumably greater
reliability justifies the greater cost and risk of crew and (expensive)
Shuttle. ("Reliability" here means that it will *eventually* launch,
though not necessarily on a tight schedule, and that the payload will
either be placed successfully or returned to Earth safely in the event
of an abort. The presumption is that the payload must have at least a
significant fraction of the value of the orbiter.) As newer high-reliability
ELVs come on line, this will presumably change. In the meantime, there are
plenty of payloads which are not particularly expensive or unique, for
which some less expensive launch method is fully satisfactory.
      John Roberts
      [e-mail]

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

End of SPACE Digest V13 #097
*******************