Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V11_1/V11_127.TXT

Internet Message Format | 1991-07-08 | 18KB

Return-path: <[e-mail]>
X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson
Received: from beak.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/[e-mail] (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests)
          ID </afs/andrew.cmu.edu/usr1/ota/Mailbox/gZxp0wu00VcJ81TU5n>;
          Fri,  9 Mar 90 01:42:06 -0500 (EST)
Message-ID: <[e-mail]>
Reply-To: [e-mail]
From: [e-mail]
To: [e-mail]
Date: Fri,  9 Mar 90 01:41:37 -0500 (EST)
Subject: SPACE Digest V11 #127

SPACE Digest                                     Volume 11 : Issue 127

Today's Topics:
    Reliability, Bureaucracy, and Spaceflight Costs (long)
            Re: Ulysses Update - 03/06/90
             Re: SR-71:  LA to DC
                   RE: EMP
        Ejection seats (was Re: Challenger's Last...)
             Re: Challenger's Last Words
              Re: hubble telescope power
       Re: Americanisms (was: Ulysses Update - 03/06/90 {sic})
              Galileo Update - 03/06/90
----------------------------------------------------------------------

Date: 8 Mar 90 15:09:00 PDT
From: "SSD::COBBHS" <[e-mail]>
Subject: Reliability, Bureaucracy, and Spaceflight Costs (long)
To: "space+" <[e-mail]>


                  I N T E R O F F I C E   M E M O R A N D U M

                                        Date:     08-Mar-1990 14:22 PST
                                        From:     Cobb, Henry S.
                                                  COBBHS
                                        Dept:     CLFP
                                        Tel No:   32504

TO:  _MAILER!                             ( _DDN[[e-mail]] )


Subject: Reliability, Bureaucracy, and Spaceflight Costs (long)

(This is a loooong message.  And I apologize for the @#$%&* All-In-One
mail header, but I can't figure out how to turn it off.)

Summary:  the costs of spaceflight are driven largely by desired mission
reliability.  Bureaucracies tend to desire reliability as high as
possible, without regard to cost.  Corporations may _or_may_not_ do
"better," depending on their internal structures.

Longwinded flame begins here:

Civil servants are classical bureaucrats.  A bureaucrat does not get rich
in a hurry; he slowly improves his fortunes through career progression.
Bureaucrats are self-selected for this trait: people who want more action
don't become (or remain) bureaucrats.  Bureacrats do not seek the Big Win.

Instead, they seek to avoid the Big Loss.  Moderate success is all
that is needed to keep a career on track, but any failure can end it.
This makes bureaucrats extremely risk-averse.  In the space program, this
tends to drive reliability requirements to the very top of the practical
range.

Stipulate, for the moment, that half the cost of the NASA/Air Force way
of building spacecraft is due to nontechnical factors: Congressional
micromanagement, Federal Acquisition Regulations, MIL-SPECs,
pork-barrelling, big-company sloth, etc.  The other half, then, is due to
technical factors.  IMHO, the most significant of these is the desired
mission reliability.

Once upon a time (pre-1965), the space program was controlled by
scientists and engineers.  These folks were chasing the Big Win.  First
pictures of the Lunar farside, first probe in Mars orbit, first manned
rendezvous, etc.

In those days, it was an accepted fact that some 10-20 percent of our
rockets would blow up.  To get a reasonable chance of mission success,
you _had_ to build at least two probes.  If you were trying something
really new, you might build three or four or five.  It didn't make sense
to try to make the probe much more reliable than the rocket, so the
probes were pretty cheap.  If you put men on a rocket, you gave them a
way to punch out, and crossed your fingers.

Well, the folks messing around in those early days discovered a whole lot
of techniques which could be used to improve reliability.  Techniques like
change control systems, and redundancy, and extensive environmental
testing, and detailed computer simulation, and comprehensive quality
control.  They applied a few of them, and the reliability of spacecraft
and launchers went up.  They refined their techniques, and reliability
increased again.  Eventually, failures became comparatively rare.

Until the moon landing, the space program was run by goal-oriented people.
They wanted whatever reliability it took to reach the moon.  If
reliability conflicted with mission requirements, the mission won.  After
the moon landing, most of those people left in search of other goals.  The
ones who stayed were bureaucrats, and bureaucrats see reliability as the
supreme objective.

Reliability techniques have a price.  Management oversight is expensive.
Design changes become slow and cumbersome.  Taken to extremes, you get the
situation I've seen in the Orbiter Processing Facility at KSC: one tech
turning a wrench, with two QC guys, three engineers, and four managers
watching him turn it.  Reliability does not come cheap.  But if you're
willing to pay for it, you get it.

The STS has a booster success record of some 97% at this point.  This
stands up pretty well against any other booster, historical or current,
free world or Russian (especially if you look at the first thirty-odd
launches of that booster).  On-orbit and recovery success rates are 100%
to date.

(Side note:  the general public is innumerate.  20 successes out of 20
tries does not mean that the expected system reliability is 100%.  It
means only that system reliability is _probably_ better than about 95%.
We all found out the difference after a few more launches.)

NASA spends a _lot_ of money to achieve that level of reliability.
This is the tradeoff that bureaucrats will always make.  There isn't
really any Big Win to be had in the Shuttle program (or any airline),
only a Big Loss.

There is, of course, another way.  If you're willing to accept, say, 85%
mission reliability, you can build things a lot cheaper.  Use good design
tools, but don't over-analyze everything.  Don't test every incoming part
to death.  Assume that your workers know what they're doing, and don't
pay QC people to hawk their every move.  In short, wait for something to
break before you try to fix it.

This approach, too, has a price.  You'll go back to building two of
everything you care about (it may still be cheaper).  You'll have to
accept the occasional failure as a routine cost of doing business.  Most
of all, you'll have to set up your organization so that individuals are
not blamed for failures.  If you can't do that, they'll all turn into
bureaucrats, and your costs will follow NASA's into the ionosphere.

I'm not defending the Shuttle, or NASA, or the current way of doing
business in aerospace.  I'm not saying that any of these is the "right"
way to do spaceflight.  I'm merely pointing out that different
philosophies exist, and that they have a major impact on such things as
cost and risk.  Anyone who says that spaceflight could be done "better"
or "cheaper" is obliged to identify his assumptions about reliability
and risk.

It is possible to have an expensive organization with a high success rate.
NASA is proof of this.  It is possible to have a cheap organization with a low
success rate: see AMROC, SSI, etc.  It may be possible to have a cheap
organization with a high success rate, but there is no proof to date.

================
Stu Cobb
COBBHS @ AFSC-SSD.AF.MIL  [26.30.0.65]

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

Date: 8 Mar 90 22:00:58 GMT
From: vax8530![e-mail]  (T. Joseph Lazio, Cornell University)
Subject: Re: Ulysses Update - 03/06/90

In article <[e-mail]>, [e-mail] (Ron Baalke) writes:
>
> 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.
>
>
>              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
>

    End of mission?  Does this mean that during the last pass,
    in attempt to gather some particular datum, that the craft
    will be flown close enough to the Sun to fry it, or
    end of the scheduled mission and contact with the
    craft will continue as it heads toward interstellar space
    away from the ecliptic?


>
>  Ron Baalke                       |    [e-mail]
>  Jet Propulsion Lab  M/S 301-355  |    [e-mail]
>  4800 Oak Grove Dr.               |
>  Pasadena, CA 91109               |
--
      T. Joseph Lazio
      Astronomy Department, Cornell University  [phone]
      [e-mail]
      [e-mail]

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

Date: 7 Mar 90 15:59:06 GMT
From: amdahl!drivax![e-mail]  (Kral)
Subject: Re: SR-71:  LA to DC

In article <[e-mail]> [e-mail] (John H. Kim) writes:
>The SR-71 for the
>Smithsonian made the trip from Los Angeles to Washington DC
>in 68 min, 15 sec.  The target time was 64 minutes.  Does anyone
>have any more info like exact distance travelled, altitude, etc?

Their flight path was such that they watched the sun rise and set 3 times (this
from an interview with the pilot).  A truley awsome experience.

--
kral     408/647-6112            ...amdahl!drivax!braun
"To surrender is to remain in the hands of barbarians for the rest of my life;
 To fight is to leave my bones exposed in the desert waste"
        - ancient chinese poem

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

Date: Thu, 8 Mar 90 08:45:48 EST
From: [e-mail] (Ken Ellis)
Subject: RE: EMP

In article <[e-mail]> [e-mail] (Tim Maroney) writes:

}How so?  A friend who is a well-known hard SF author with a degree in
}physics told me (and put in one of his books) that any sufficiently
}powerful explosion will cause a shower of Compton electrons from the
}upper atmosphere, which is what fries electrical circuits and is what
}we call EMP.

This statement seems to imply that EMP is made up of particle
radiation (electrons) that bombard electrical circuits and cause them
to fail. While a high altitude burst will produce a shower of ions, it
is unlikely that they will ever reach the ground due to their
interaction with the Earth's magnetic field. Note that EMP stands for
Electro-Magnetic Pulse. It is a pulse of electromagnetic radiation
radiated by the ions that are created and then accelerated through the
Earth's magnetic field by a large explosion. The EM radiation then
propagates to the Earth's surface and induces very large electrical
currents in conductors that will heat up and fry any connected
electronic components.

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

Date: 6 Mar 90 19:07:18 GMT
From: [e-mail]  (Jon C. R. Bennett)
Subject: Ejection seats (was Re: Challenger's Last...)




[e-mail] (Daniel Fischer) writes:
> Chris Jones and Scott Brown write:

> 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?

I belive that the incedent in question refered to the second XB-70 which
was struck by one of its chase planes during flight testing. The XB-70
suffered damage to its wing and rudders, causing it to enter a high g
dive. The crew of the XB-70 had an ejection capsule (a cross between a
seat and a pod) which was designed to protect the crew in the event of a
ejection at high mach numbers. It was belived that the high g's
encountered durring the dive prevented the capsule from deploying. The
entire XB-70 program, including footage of the collision between the XB-70
and it's chase plane, is very well documented in "Wings" a very good (bbc
I think) series on aircraft. All in all it seems that ejections seats are
prefereble to pods or capsules if only on the KISS principle. Also the
weight of the equipment required to implement an escape pod is probably
better spent making the rest of the craft more robust.

Also if anyone happens to have copies of episodes on video tape I would
like to hear from you.

jon bennett

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

Date: 8 Mar 90 18:47:31 GMT
From: linus!chance![e-mail]  (Dave Davis)
Subject: Re: Challenger's Last Words

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>In article <[e-mail]> [e-mail] (Daniel Fischer) writes:
>
>>I've never heard anyone mentioning whether it would have been possible to add
>>a parachute system that would have allowed a survivable landing?
>
>Marginally possible, *if* you assume that the cabin separates cleanly from
>the rest of the orbiter *without* separating from or damaging the parachute

(Stuff deleted...)

The basic difficulty in designing such a system is predicting the
forces involved and handling them.  An arbitrary explosion may eject
the capsule in a sideways direction, potentially damagin your
parachute system or making it impossible to deploy.  So, the result
might be just better preserved, but dead, crew members.

=================================================================
Dave Davis
MITRE Corp.
McLean VA

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

Date: 8 Mar 90 18:30:43 GMT
From: cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!aplcen!haven!uvaarpa!hudson!astsun9.astro.Virginia.EDU![e-mail]  (Greg S. Hennessy)
Subject: Re: hubble telescope power

In article <[e-mail]> [e-mail] (Nick
Kline) writes:

#The reason why I am bothering you all with this information is that in
#a discussion on the 'scopes, an astronomy graduate student (speaking
#on his own, I assume) said that ground based 'scopes, especially the
#new variety to be manufactured by the U. of Az. are, much better than
#the space based variety, and in fact are "10 to 20 times more powerful"
#than the Hubble Space Telescope.

One problem with HST is that it is rather small, only 2.5 meters in
diameter. There are many 4 meter telescopes now, with a 10 meter in
Hawaii, and many 8 meter designs being either constructed or planned.
These telescopes can collect many more photons than HST, since the
collecting area is much bigger, but HST still will have better
resolution than these telescopes, especially for extended objects.
There are observations that only HST can do. There are also
observations that ground based observatories can do better than HST.


-Greg Hennessy, University of Virginia
 USPS Mail:     Astronomy Department, Charlottesville, VA 22903-2475 USA
 Internet:      [e-mail]
 UUCP:        ...!uunet!virginia!gsh7w

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

Date: 8 Mar 90 14:35:37 GMT
From: bfmny0![e-mail]  (Tom Neff)
Subject: Re: Americanisms (was: Ulysses Update - 03/06/90 {sic})

In article <[e-mail]> [e-mail] (C.E. Thompson) writes:
>>             08/24/91 - First Conjunction
>
>It can be quite confusing for us to read dates in your weird local format :-)

Yeah, I mean after all, 08/24/91 could mean ANYTHING.   :-)

--
"The country couldn't run without Prohibition.       ][  Tom Neff
 That is the industrial fact." -- Henry Ford, 1929   ][  [e-mail]

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

Date: 7 Mar 90 19:57:25 GMT
From: elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Galileo Update - 03/06/90



                     GALILEO MISSION STATUS
                          MARCH 6, 1990

     Today the Galileo spacecraft is 54.3 million miles from
Earth, 65.6 million from the Sun, going almost 90,000 mph in its
solar orbit.  It has rolled up 239 million miles in space since
launch last October 18.

     The spacecraft health continues to be excellent, and the
program of activities continues to be rather quiet.  Galileo is
doing a sun-point maneuver every other day.  These maneuvers are
part of the current operational sequence.  After each one,
Galileo's star scanner looks at a slightly different circle of
stars to verify its pointing and spin rate.  The flight team has
checked and updated the star maps carried in spacecraft memory,
to be sure the onboard computers (which estimate attitude and
spin rate) have good inputs.  They also completed a calibration
of the spin detector, a centrifugal sensor providing redundant
spin-rate data, backing up the star scanner, gyros, and
acquisition sun sensor for this purpose.

     The spacecraft is also performing selected "cruise science"
measurements of certain fields and particles, at a low level of
activity (compared to a planetary flyby).  Galileo's telemetry
rate is limited by the distance and angle of the Earth to 10
bits per second (the lowest) from today through March 25. Galileo
will switch Low Gain Antennas on March 12.

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

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

End of SPACE Digest V11 #127
*******************