Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_4/V15NO474.TXT

Internet Message Format | 1993-07-13 | 18KB

Date: Mon, 30 Nov 92 05:02:38
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #474
To: Space Digest Readers
Precedence: bulk


Space Digest                Mon, 30 Nov 92       Volume 15 : Issue 474

Today's Topics:
                  Comparative Launcher Reliabilities
                         Dante on "Nightline"
                  Evil wicked flying bombs! (2 msgs)
                         HST black hole pix?
                     Shuttle replacement (4 msgs)

    Welcome to the Space Digest!!  Please send your messages to
    "[e-mail]", and (un)subscription requests of the form
    "Subscribe Space <your name>" to one of these addresses: listserv@uga
    (BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle
    (THENET), or [e-mail] (Internet).
----------------------------------------------------------------------

Date: 30 Nov 92 04:29:45 GMT
From: Josh 'K' Hopkins <[e-mail]>
Subject: Comparative Launcher Reliabilities
Newsgroups: sci.space

[e-mail] writes:

>Josh 'K' Hopkins writes:
>
>>There are ELVs with worse records that shuttle's, but I think there
>>are also a few with better records.
>
>  I can't find any.

As we've discussed before, reliability statistics are very tricky things, given
issues as to what counts as a failure and whether all data is available in
the case of foriegn launches, however I did find a few good ones.  The data I'm
using comes from Isakowitz and includes launches up to Dec 31 1990.

    Tsyklon - 199/201 = 99%
    Cosmos - 371/377 = 98.4%
    N-1/N-2/H-1 - 22/22 = 100%

There are of course other systems whose launch record is short enough that
they've achieved 100%, but I think the Japanese record is long enough to be
worth including.  Of course, much of the work is straight out of Delta programs
so they had some unfair advantages.  The Soviet data is questionable but worth
considering.  As you said before, timing is important.  The shuttle has a
respectable record for a system's first launches.  On the other hand, depending
on when you choose the time constraints, Soyuz family vehicles have approached
reliabilities of 99.9% over very large numbers of launches now that they have
several decades of development under their belt.
--
Josh Hopkins                                          [e-mail]

    "Why put off 'til tomorrow what you're never going to do anyway?"

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

Date: 30 Nov 92 03:43:12 GMT
From: Kurt Schwehr <[e-mail]>
Subject: Dante on "Nightline"
Newsgroups: sci.space

[e-mail] (John Roberts) writes:

>-From: [e-mail] (John Thompson Reynolds)

<bunch deleted>

>The main objective from NASA's viewpoint is to test rover design and
>techniques used in teleoperation, under conditions that in some ways
>approximate those of other planetary bodies and conditions in space.

>The science obtained is a bonus - apparently sufficiently valuable that they
>didn't just cook up big refrigerated chambers in the US (though artificial
>environments are not as effective for finding unforeseen problems). Also,

<bunch deleted>

>John Roberts
>[e-mail]

I can't really comment on the CMU Dante project but I can give a bit of
info about Carol Stoker's telepresence ROV project.  There are three
primary objectives of her program in Antartica:

     1) Solar Power - They are trying a new solar array developed by NASA
         to get a cleaner source of energy for Anarctica exploration.  Up
         now the primary energy source has been diesel generators.

     2) Communications - They (both groups) are the first to set up live
         video from the Antarctic.  The idea is to have a telepresence
         operator trying to drive the vehicles in Antarctic from the
         continental USA.

     3) Human Factors - How to best use telepresence.  How to get groups
         sciencetists and engineers to work better in remote and harsh
         conditions.

These three goals are sponcered by NOA/NSF (?) along with NASA so they
get their name in the publicity along with NASA and CMU.  This is joint
project between a whole bunch of groups to this stuff going.

    The ROV project's focus at NASA is prep work for a trip to Mars.  This
is Carol Stoker's primary interest in the project.  They are working to
figure out how to get the most out of future Mars exploration.  One of the
things they are look at besides how to use telepresence to control vehicles
is the comparative biology program.  The bacteria in perenially ice covered
lakes may be similiar to what might possibly have lived on Mars is life
was ever present there.  This kind of work is going on in NASA's exobiology
program by people like C.P. McKay, C. Stoker, and D. Andersen.  The work
on the lake biology is valid science.  The ROV will allow extended bottom
time over human divers.

    Stoker took the ROV to Florida last year.  That trip was to test the
ROV surveying coral diseases.

   Note: the ROV is NOT currently capable of stereo video.  That is something
planed to be add next year.  The project is also using a new fiber optic
HMD just developed.

Also, all opinions and mistakes are mine and not NASA's.  I'm not a NASA
employee... just a summer intern for C. Stoker.

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

Date: Mon, 30 Nov 1992 01:49:42 GMT
From: Toni Kotinurmi <[e-mail]>
Subject: Evil wicked flying bombs!
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (James Davis Nicoll) writes:
>In article <[e-mail]> [e-mail] (Charles R. Martin) writes:
>>In article <[e-mail]> [e-mail] (Simon E. Booth) writes:

>>Just a quibble, but it's real damned hard to get a n-weapon to go off in

>be next to impossible to crack. I think most of the older devices with
>mechanical security devices have been retired.

>    If someone acquired a nuclear device illicitly, to use it would
>require  access to  the  proper PAL code  as well.
>                            James Nicoll

  Yes, but the point is, if someone acquired nuclear device, would they try to
use is "lawfully" or would they just take good use of the radioactive material.
  I have little knowledge, but at least to US N-weapons it is true (as far as
I know) that they are minimized on the use of radioactive material. That is,
you'd still have to have considerable knowledge if you want to detonate
this 'little' amount of fission-capable material.
  On the other hand, you know the (old) Soviet weapons, which were not supposed
to be so accurate but so powerful that they destroyed the target, a

interested party could gain more fission material by stealing one or two
of those--Not to say it would be too easy to detonate a bomb,
but they could certainly put enough radioactive dirt on any city to make it
uninhabitable by (even mis-) detonating this device...

Toni Kotinurmi

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

Date: Mon, 30 Nov 92 09:55:35 MET
From: [e-mail]
Subject: Evil wicked flying bombs!

Charles R. Martin writes (28 Nov 92 18:32:33 GMT):

>Just a quibble, but it's real damned hard to get a n-weapon to go off in
>a crash.  This  is a direct correlary of the fact that it's hard to get
>one to go off at all.

Not entirely true (see below).                               J. Pharabod
---------------------------------------------------------------------
From "International Herald Tribune", Thursday, May 24, 1990:
COMPUTER POINTED TO FLAW IN SHELL
By R. Jeffrey Smith, Washington Post Service
WASHINGTON - The 1988 discovery that a U.S. nuclear artillery shell
could be exploded accidentally stemmed from dramatic improvements
in computer programs that simulate the complex workings of nuclear
weapons, according to U.S. officials and weapons scientists.
  The W79 warhead was designed in the mid-1970s, so it would explode
only after receiving deliberate electronic instructions triggered
as it nears an enemy target, not while it is still in its howitzer
launch tube.
  But in early 1988, U.S. scientists modeling the high temperatures,
intense pressures and movement of particles that could result from
an accidental, partial detonation of the explosive material around
the nuclear core of the warhead found an unacceptable risk of a
significant nuclear yield, several U.S. officials said.
  They said that they had come to this conclusion by studying the
first simulations of the workings of the bomb in "three dimensions",
a feat made possible by powerful new computers.
  The Defense Department safety standard, adopted more than 15 years
ago, requires that "there shall be positive measures to prevent
nuclear weapons involved in accidents or incidents, or jettisoned
weapons, from producing a nuclear yield".
  U.S. officials say that none of the dozens of nuclear weapons
involved in fires or accidental explosions has breached this
standard.
  They add, however, that the design of nuclear artillery shells
make them particularly susceptible to accidental detonation.
  Its designers chose not to use a special volatile material in the
warhead considered "insensitive" - relatively nonexplosive - to such
mishaps as being hit by a stray bullet.
  Driven by the military demand for an extremely small lightweight
weapon, they instead used a lighter explosive material that detonates
more readily.
  The shell's designers also packed extra plutonium into the core
of the weapon, giving it more energy and bringing it closer to a
"critical mass" of material needed for nuclear fission to begin.
  One scientist said that the W79 and a slightly smaller version,
W82, "are right on the edge of safety by virtue of their design
alone."
-------------------------------------------------------------------------

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

Date: 30 Nov 92 07:07:55 GMT
From: Craig Fifer <[e-mail]>
Subject: HST black hole pix?
Newsgroups: sci.space

Just out of curioisity, how was it that I saw pictures of the
black hole on my local evening news if they are not being
released?  The images were some sort of animation that samcked
of computer enhanced graphics.

-Craig Fifer
[e-mail]
--
_____________________________________________________________________________
|   Never play leapfrog with              |   Craig Fifer                   |
|   a unicorn!   -Murphy                  |   3736 Heritage Road, S.W.      |
|                                         |   Roanoke, Virginia  24015-4518 |

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

Date: 30 Nov 92 03:19:09 GMT
From: Pat <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>>a crash of a vehicle containing *rocket* fuel, perhaps miles from
>>intended touchdown, like main street in Disney World for example.
>
Please dont confuse LH2/LOX for something as dangerous as Nitric Acid or Kerosene.   Granted LH2  is flammable, it is probably the best of rocket fuels
in terms of relative dangers to the public.  it deflagrates in a reasonably
slow time in uncontrolled conditions...  look at the challenger loss.
tank fails.  big puff of steam.  if they hadnt been doing mach 10, they have been in much better shape.
>
>Note that a DC coming down will have not much more fuel in its tanks
>than a typical light aircraft.  Almost all the fuel gets burned on
>the way *up*.
>--

Now if DC-1 is going to run like an airliner it should be landing with a fuel
reserve.  have they made plans for this?  i think airliners no longer use
the 1/3 tanks rule, now they use  something like this.  estimated flight time
plus time to divert to secondary airport plus 20 minutes.  will
DC-1  have something like this?  could be interesting.  tower to DC:
were socked in, you'll have to divert to miami.  DC:  Roger keneedy descent
clear us to angels 100.....

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

Date: 30 Nov 92 03:29:13 GMT
From: Pat <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Brian Stuart Thorn) writes:
>
>
>Oh, now stop harping on the SRBs. It wasn't the Solid Rocket Booster which
>led to the loss of Challenger, it was those ninnies in NASA and Thiokol
>management. They're the ones that said "37 degrees? Sure, let's go ahead
>and launch it..."
>

You forget that the SRB field joints showed significant burn through
even in warmer operating weather.  in fact one of the flights in 60 degree
weather had worse burn through then some of the colder flights.

>On a related topic, why on Earth didn't NASA just put those joint heaters
>on the SRB back in '86 and start flying again, fixing the other problems
>one at a time through a reduced flight rate? Ah... politics.
>
I believe that once they lost one shuttle they suddenly discovered that the
shuttle had a significantly high risk of loss due to any of a number of
problems many of which were fixed at the same time.  i am sure henry can
detail them,  but i believe they fixed some flaws in the engine
turbopumps which  could have led to total loss of the craft.

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

Date: 30 Nov 92 03:36:25 GMT
From: Josh 'K' Hopkins <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

[e-mail] (Allen W. Sherzer) writes:

>>    Oh, PLEASE! Do you HONESTLY believe a crew would have survived the
>>    April, 1986 Titan 34-D launch failure?

>Yes I think they would have had a 50/50 chance. When they take off one
>guy always has his finger on the abort button. Less than 1/5 a second would
>have been enough.

I have trouble believing someone can make the very significant decision of
seperating the hypothetical capsule (and thus canceling the mission) with 1/5
of a second reaction time.  I recall at least one case (Apollo? Gemini?) where
one of the astronauts was faced with data suggesting this decision might be
required - it's not an easy one.  However, I do not debate that rockets with
capsules are generally safer than side mounted configurations.  When a shuttle
engine fails, the explosion is right next to the vehicle.  When a standard
configuration fails, the explosion is well aft of the crew and standard escape
methods are proven to be effective.

--
Josh Hopkins                                          [e-mail]

    "Why put off 'til tomorrow what you're never going to do anyway?"

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

Date: 30 Nov 92 03:49:36 GMT
From: Pat <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:
>>In article <[e-mail]> [e-mail] (Brian Stuart Thorn) writes:
>>
>>>However, my argument was that the RL-10, which will power the DCX, has
>>>failed twice in flight in the past 18 months.
>>
>>If the same failures happen to DCX then all they need do is shut down the
>>engines which did start, find and fix the problem, and fly again. This will
>>result in RL-10's with one less malfunction and a more reliable system.
>
>They're at 10,000 feet, closing fast with the ground, and half their
>engines don't start (that's what happened in the recent failures). So
>they just stop the others, get out and fix the problem, and proceed
>to land? I don't think so. I think they'll smear all over the landscape
>before they even have time to realize they have a problem. A failure
>on the pad is one thing. A failure coming down is something altogether
>different. Yeah I know they're lighter coming down, but asymetric
>thrust still sounds bad when you're close to the ground and have to
>make a perfect 4 point touchdown. Can you gimbel the remaining engines
>enough to still stay perfectly upright as you descend? Can you do
>it quickly enough if the failure is close to touchdown?
>
>Actually I suspect they'll static test the engines a bunch of times
>before trying to light them in flight. But let's consider a different
>scenario. DC-1 is supposed to receive airliner grade servicing. We
>know that airliners receiving that grade of service have engines *fall
>off* in flight. Suppose a fuel feed line fatigues from multiple flights.
>It wasn't X-rayed before flight because this is airliner grade servicing.
>So the thing lets go as they pass through 10,000 feet on their way to
>a landing at O'Hare. A couple of tons of rocket fuel starts streaming
>down among the firing engines as they pass over the Loop. What's their
>abort mode? Or assume it's at takeoff and they have a full fuel load.
>Airliner servicing isn't zero defects because that costs too much and
>stresses are fairly low and an engine falling off or a fuel line rupture
>is generally survivable due to the presence of wings and a fire bottle.
>Spacecraft stresses are much higher and DC-1 will glide like a flaming
>rock. This is high risk stuff, not airliner grade hazard at all. It
>costs a lot more to do zero defects, recall that standing army at the
>Cape? And things still sometimes go boom. DC-1 better stay away from
>populated areas until it's been crash tested a few times.
>
>Gary

I imagine they will do what most airliners can do.  close a valve
feeding that engine from the fuel pump or the tank.  then abort
to another site.  there was an incident where a DC-9 dropped an engine
mid flight.  they closed the fuel feed valves and aborted to a convenient
strip.  no big flaming rock.  gary, i think you have this flaming
stuff on your mind too much.

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

End of Space Digest Volume 15 : Issue 474
------------------------------