Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_5/V15NO556.TXT

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Date: Thu, 17 Dec 92 05:00:11
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #556
To: Space Digest Readers
Precedence: bulk


Space Digest                Thu, 17 Dec 92       Volume 15 : Issue 556

Today's Topics:
                           Aurora (2 msgs)
                             Chase planes
                      DoD launcher use (2 msgs)
                     Galileo's atmospheric probe
      Galileo's Atmospheric Probe Passes Health Checks (2 msgs)
                          Micro-g in KC-135
             Need information on Infinite Universe Models
                    Re : Relay to Follow Galileo?
                           SSTO vs. 2 stage
           Terminal Velocity of DCX? (was Re: Shuttle ...)
                            What is DC ??
               what the little bird told Henry (2 msgs)

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

Date: Wed, 16 Dec 92 13:25:41 GMT
From: Dean Adams <[e-mail]>
Subject: Aurora
Newsgroups: sci.space

[e-mail] writes:
 >>The previous reports were based on "design concepts", these are much
 >>more direct reports.  There is no logical reason for simply "discarding"
 >>such information.
 > I still think that the sightings reported in this August 24 issue
 > are not better than UFO sightings:

I have to disagree, for one thing because AW&ST considered them
worthy of publication.

 > 1990 sightings: occurred during night or late evening (visibility?),
 > number of witnesses not reported, apparently no inquiry about the
 > witnesses (tired? drunk? ill?)

Why do you say "apparently no inquiry"?   This is AW&ST, not some ufo rag.
They operate with a great deal of journalistic integrity.  I'm quite sure
if their only source was a "drunk", it would not have been reported.

 > April 1991 sighting: daytime, but the craft was said "dwarfing an
 > F-16 chasing it". This casts a doubt on this sighting:
It does??

 >is it usual that US military planes chase US secret aircrafts?

Absolutely!  Ever hear the term "chase plane"?  There are a long list of
reasons they would be used during various times during a flight, in addition
to some potential program specific concerns such as RCS or sound masking.

 >(well, maybe it was an exercise).
No reason it had to be.

 >Same questions about the witnesses.
Same answer.  :->

 >No photos, no video films.
There were contral photos...  BUT, considering how there are only a
*handful* of these "sightings", not getting a direct photo is quite
understandable.  Were there any photos of the F-117A prior to the
official release?  I don't beleive so, even though it flew for almost
a decade.

 >>It did not sound like it was very highly substantiated...
 >It was no more substantiated than the above criticized sightings.
Doubtful.

 >However, since the object was hovering or flying at very low speed,
 >the sightings lasted for more than a few seconds, which was probably
 >not the case for the AW&ST sightings
AW apparently could not corroborate that particular story.  I have a feeling
that "Popular Mechanics" has considerably looser publication standards than
Aviation Week.  It did not sound overly credible to me either...

 >>>Popular Mechanics and AW&ST are no more serious than UFO reviews.
 >>Where is the logic there?  I can't speak for P.M., but have you
 >>ever read AW&ST?  It is VERY serious.
 >Yes, I have read it. It's generally serious... except when it reports
 >sightings.
Why would it "suddenly" no longer be serious?  Those reports are printed
when they corroborate information from other sources, and when they come
from credible origins.

 >In this last case, it seems no more serious than UFO reviews
 >(at least I think so, since I don't read UFO reviews).

How could it be??  Are members of the Royal Observer Corps just as serious
as people who constantly see "aliens"?  What about people who live near
military bases and are familiar with their operations and the sort of
aircraft typically flying?  AW&ST publishes only a handful of "sightings",
and all typically when there is corroborating information involved.
"UFO reviews" publish sightings by the dozen, and most I doubt have even
a fraction of the reputation and journalistic integrity of Aviation Week.
I still see no comparison...

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

Date: Wed, 16 Dec 1992 15:43:10 GMT
From: Nick Haines <[e-mail]>
Subject: Aurora
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Colin Tinto) writes:

   [Aurora sightings off Scottish Western Isles, speculated Aurora
    range of 5000 miles]

   Hang on - 5000 miles - that means it can just reach Scotland from the East
   Coast USA before having to turn back ?   Something not quite right...

Assuming that it's launching from the continental USA. Seems much more
likely to me (given the sightings over the Netherlands as well) that
one of the long-runway US bases in the UK or Germany is `home' to an
Aurora.

(Btw: is there _any_ basis for the name `Aurora' except that
unexplained budget line back in the mid-80s?)

Nick Haines [e-mail]

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

Date: Wed, 16 Dec 92 07:58:24 EST
From: John Roberts <[e-mail]>
Subject: Chase planes

-From: [e-mail]
-Subject: Aurora
-Date: 15 Dec 92 15:00:50 GMT

-I was speaking only of the sightings reported in the August 24, 1992,
-AW&ST issue. I was not speaking of previous articles, such as:

-I still think that the sightings reported in this August 24 issue
-are not better than UFO sightings:

-2. April 1991 sighting: daytime, but the craft was said "dwarfing an
-   F-16 chasing it". This casts a doubt on this sighting: is it usual
-   that US military planes chase US secret aircrafts? (well, maybe it
-   was an exercise). Same questions about the witnesses.

It's common to have chase planes flying along with an aircraft undergoing
tests. One of the two Valkyrie supersonic aircraft was destroyed when a
chase plane crashed into it.

STS-1 (and perhaps other Shuttle flights) had chase planes active during
the landing approach.

John Roberts
[e-mail]

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

Date: 16 Dec 92 16:35:32 GMT
From: Henry Spencer <[e-mail]>
Subject: DoD launcher use
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Philip Young) writes:
>|>                                ... unless
>|> you have realtime downlink in the footprint of the satellite...
>
>Ever hear of relay satellites?  Do you believe DoD doesn't have anything
>at least as good as TDRSS, in quantity?

DoD *has* TDRS, in quantity. :-)  One of the complications in scheduling
TDRS coverage for things like Hubble and the shuttle is that there is
extensive DoD use of the TDRS system.  I'm told you need a security
clearance to even get involved in scheduling.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: 16 Dec 92 02:42:57 GMT
From: Philip Young <[e-mail]>
Subject: DoD launcher use
Newsgroups: sci.space

[e-mail] (Gary Coffman) writes:

[...]
|>                                ... unless
|> you have realtime downlink in the footprint of the satellite, very close
|> to your target, you wait for the satellite to pass over your downlink station
|> and download the image. This can take up to another 12 hours. [...]

|> Gary

Ever hear of relay satellites?  Do you believe DoD doesn't have anything
at least as good as TDRSS, in quantity?

--
Philip

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

Date: Wed, 16 Dec 92 07:46:33 EST
From: John Roberts <[e-mail]>
Subject: Galileo's atmospheric probe

-From: [e-mail]
-Subject: Re: Galileo's Atmospheric Probe Passes Health Checks
-Date: 15 Dec 92 21:39:37 GMT
-Organization: Digital Equipment Corporation

-In article <[e-mail]>,
[e-mail] (Ron Baalke) writes:
->     Entry into Jupiter's atmosphere is the most hazardous in the
->solar system because the planet's immense gravitational pull
->creates tremendous speeds.  At maximum deceleration, as the craft
->slows from 115,000 mph to 100 mph, the probe will hurtle against a
->force 350 times Earth's gravity.

-I have always wondered what was done to the instrument package to allow it to
-survive such forces. I have some awareness of "ruggedization" necessary to
-allow various electronic components to survive launching from an artillery
-piece, and tactical missiles/rockets. I also have some knowledge of the
-accellerations experienced by the Sprint system and HIBEX experiments...
-none of which came CLOSE to 350G!

-How does NASA and JPL expect the probe to survive the deceleration? It must
-be pretty close to slamming into a piece of boilerplate!

-John B.

"Smart" artillery shells experience accelerations *much* greater than 350G -
tens of thousands of gravities might be considered typical.

Striking an immovable object at even modest velocity also results in
acceleration greater than 350G.

What was the acceleration of Sprint? I seem to recall it as being around
100G.

John Roberts
[e-mail]

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

Date: Tue, 15 Dec 1992 21:39:37 GMT
From: [e-mail]
Subject: Galileo's Atmospheric Probe Passes Health Checks
Newsgroups: sci.space,sci.astro,alt.sci.planetary

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

..
>     The probe will make history's first entry into the atmosphere
>of an outer planet on Dec. 7, 1995.  It will slam into Jupiter's
>atmosphere at 115,000 mph, fast enough to jet from Los Angeles to
>New York in 90 seconds.  Deceleration to about Mach 1 -- the speed
>of sound -- will take just a few minutes, causing a buildup of heat
>so intense it will be like flying through a nuclear explosion.

..


>     Entry into Jupiter's atmosphere is the most hazardous in the
>solar system because the planet's immense gravitational pull
>creates tremendous speeds.  At maximum deceleration, as the craft
>slows from 115,000 mph to 100 mph, the probe will hurtle against a
>force 350 times Earth's gravity.

>     Its incandescent shock wave will be as bright as the sun and
>reach temperatures up to 28,000 degrees Fahrenheit.  After entry,
>the fore and aft heat shields of the deceleration module will be
>shed by deploying a small pilot parachute and then a large main
>chute, exposing the descent module to Jupiter's hydrogen/helium
>atmosphere.

>     The probe's total weight is 747 pounds.  The deceleration
>module weighs 484 pounds.  The inner descent module carries seven
>scientific instruments, weighing 66 pounds.

..

>     As the probe passes through Jupiter's colored cloud layers,
>its computer will receive information, process it and transmit the
>coded signal to the Galileo orbiter, which will relay the data by
>radio to Earth.  The probe descent mission will last about 75
>minutes.  At this point, a combination of extreme heat, high
>pressure and degraded battery power will silence the probe forever.


OK...

I have always wondered what was done to the instrument package to allow it to
survive such forces. I have some awareness of "ruggedization" necessary to
allow various electronic components to survive launching from an artillery
piece, and tactical missiles/rockets. I also have some knowledge of the
accellerations experienced by the Sprint system and HIBEX experiments...
none of which came CLOSE to 350G!

How does NASA and JPL expect the probe to survive the deceleration? It must
be pretty close to slamming into a piece of boilerplate!

At first it seemed that if the probe survived entry, the pressures and temps
it experienced would be trifling in comparison...but the heat shields that
would/could have protected it must be jettisoned.

Realistically...what chances do the scientists, engineers, and planners
at JPL give the probe of being able to fulfill its mission objectives?

Regards (and kudos to the designers and builders of the probe!),

John B.

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

Date: 16 Dec 92 16:33:23 GMT
From: Henry Spencer <[e-mail]>
Subject: Galileo's Atmospheric Probe Passes Health Checks
Newsgroups: sci.space,sci.astro,alt.sci.planetary

In article <[e-mail]> [e-mail] () writes:
>I have always wondered what was done to the instrument package to allow it to
>survive such forces. I have some awareness of "ruggedization" necessary to
>allow various electronic components to survive launching from an artillery
>piece, and tactical missiles/rockets. I also have some knowledge of the
>accellerations experienced by the Sprint system and HIBEX experiments...
>none of which came CLOSE to 350G!

Smart artillery shells experience thousands of gees at launch.  A few
hundred is no big deal; dropping the probe a meter or two onto a hard
floor would expose it to much more (and with faster onset, too).

Actually, the surprising thing is how *little* special design is needed.
I dimly recall reading an article about the electronics packaging for
the Copperhead laser-guided shell:  basically, they just built very
high-grade printed-circuit boards, made sure the components were securely
anchored to them, and made sure the boards weren't very big and were
solidly supported at their edges.

If you want to see special design in the Galileo probe, look not at the
instrument package but at the heatshield...
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: 15 Dec 92 22:19:31 GMT
From: "Stick,CommoSigop" <[e-mail]>
Subject: Micro-g in KC-135
Newsgroups: sci.space

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

>In article <[e-mail]> [e-mail] (Claudio Egalon) writes:
>>What causes the microgravity in the KC-135, the centripetal
>>acceleration at the top of the parabola, which may cancel the gravity
>>acceleration,  or something else???

>You don't "cancel" the gravitational acceleration, you fall with it.  The
>KC-135 flies the exact trajectory that it would follow if it were falling
>free in a vacuum.

>That trajectory isn't exactly a parabola; it is in fact a segment of an
>elliptical orbit (one that intersects the Earth's surface).  It's very
>close to being a parabola.  It would *be* a parabola if the Earth were
>flat and gravity did not diminish with altitude.

   Interesting.  The way I see it, the -135, after nosing up, pushes over
in such a manner that its acceleration towards the Earth's surface exactly
matches the acceleration of gravity.   And, I don't know for sure if its
flight path would be that of a parabola, it doesn't maintain its lateral
velocity vector.  The speed vector parallel to the Earth's surface would be
at its greatest when the aircraft was in level flight.

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

Date: 16 Dec 92 02:17:03 GMT
From: Gregory Aharonian <[e-mail]>
Subject: Need information on Infinite Universe Models
Newsgroups: sci.space,sci.physics,talk.philosophy.misc

Check out  "Fractal gases of zero momentum with respect to all inertial
frames",  Am.J.Phys. 58(6), June 1990, page 581.

Interesting way of questioning your thoughts.

Greg Aharonian
--
**************************************************************************
Greg Aharonian
Source Translation & Optimiztion
P.O. Box 404, Belmont, MA 02178

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

Date: Wed, 16 Dec 92 01:44:12 GMT
From: Ryan Korniloff <[e-mail]>
Subject: Re : Relay to Follow Galileo?
Newsgroups: sci.space

>Path: mnemosyne.cs.du.edu!mercury.cair.du.edu!copper!vexcel!ncar!destroyer!caen!uunet!portal!cup.portal.com!BrianT
>From: [e-mail] (Brian Stuart Thorn)
>Newsgroups: sci.space
>Subject: Re: Relay to Follow Galileo?
>Message-ID: <[e-mail]>
>Date: 15 Dec 92 03:27:47 GMT
>References: <[e-mail]>
>Organization: The Portal System (TM)
>Lines: 25
>
>>Well why did the HGA have to be cloed up in the first place? If it is too
>>big, then couldn't they have used a more powerful transmitter? I would
>>have rather tried to avoid such a chance for failure. If thay don't get
>>that HGA open then %30-%40 of the mission objectives will be lost. Or is
>>the radio frequncy have something to do with he size of the HGA???
>>
>>
>>        -- Ryan Korniloff
>>        -- [e-mail]
>
>  Ryan...
>
>  Galileo's umbrella-type High Gain Antenna was left in the folded
>  position because it was thought that the high temperatures it would
>  encounter during the Venus flyby portion of the mission could warp
>  the antenna. They attempted to open the antenna only after the Venus
>  flyby, when Galileo flew farther from the Sun. It was jammed.
>
>  Cassini, I think, will have a standard hard HGA, similar to the
>  Voyager and Magellan antennae. I hope the Galileo problem does not
>  prevent future spacecraft from using the folding antenna design. It
>  worked quite well on the TDRS satellites.
>
>  -Brian


But we're talking about a multi-Billion dollar program here. I just
wouldn't want to take that risk. That is a lot of money the throw away
because the "stupid" antanna won't open.. And this will further make the
image of NASA tarnish even more. Yet another American blunder.. we don't
need it. How are we going to argue that we need to go to this planet and
that planet if we can't build the hardware to do the job???


        -- Ryan Korniloff
        -- [e-mail]


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

Date: Wed, 16 Dec 1992 13:43:48 GMT
From: Bruce Dunn <[e-mail]>
Subject: SSTO vs. 2 stage
Newsgroups: sci.space

> Pat writes:
>
> Gary.  demonstrate how staged rockets can deliver lower costs then SSTO,
> and
> you will have a point.


        Although I am strongly in favor of spending money on the DC-X and
successors, I will take a quick crack at demonstrating this.

        In a posting a couple of weeks ago, I presented the results of
calculations which showed the result of using a DC-1 as the upper stage of a
two stage vehicle, rather than as an SSTO.  The first stage I assumed was a
reusable stage approximately the same size as the upper stage, but much
heavier and less stressed.  It used kerosene/LOX in existing engines
(ex-Soviet RD-170), had full engine out capability, and would likely cost
considerably less to develop than the DC-1.  A two stage vehicle, with the
DC-1 as an upper stage, delivered approximately 5 times the payload to LEO as
the DC-1 in SSTO mode.

        If one assumes that development costs are "sunk" and not to be
applied against flights (or alternately assumes that large amounts of
material are being launched and thus development costs can be spread over
hundreds of flights), then the cost of launching revolves around the cost of
refueling and refurbishing the reusable vehicles.  As pointed out by many
posters, this is largely driven by manpower requirements.

        If a DC-1 in SSTO mode can launch 10 tons to LEO and the two stage
vehicle using the DC-1 as an upper stage can launch 50 tons to LEO, then we
have the following costs for launching 50 tons:

DC-1 in SSTO mode:  5 flights needed, incurring 5 DC-1 stage turnaround costs

DC-1 in 2 stage mode:  1 flight needed, incurring 1 DC-1 stage turnaround and
1 lower stage turnaround cost.

       I will assert that turnaround cost of the lower stage will not exceed
the turnaround cost of the upper stage (the lower stage is much less stressed
than the DC-1 upper stage, and uses cheap kerosene and LOX as propellants).
Therefore, as far as turnaround costs go, the two stage vehicle costs 2/5, or
40% as much as the SSTO.  This will be offset somewhat by the fact that
facilities, spares etc for two different stages must be maintained, but I
doubt that this will eat away all of the apparent advantage of the 2 stage
design.

        I will further note that using the DC-1 as an upper stage does not
prevent it being used in SSTO mode for lighter payloads when this would be
desirable.  It also offers the opportunity to boost individual payloads 5
times greater than that achievable in SSTO mode.  A two stage design is thus
more flexible than the SSTO.

        A final advantage to the two stage design comes from the time
necessary to perform turnaround.   Since the lower stage can be inspected and
prepared for another flight while the upper stage is making an orbital
delivery, the frequency of flights will be governed by the turnaround time of
the upper stage after it gets back.  Say that turnaround time is 1 week.  If
you spend your money on two DC-1 vehicles and operate them in the SSTO mode,
then it will take 5 weeks to put 100 tons in orbit (two flights delivering 10
tons each per week).  If you spend your money on one DC-1 and 1 lower stage,
then the same 100 tons can be put into orbit in two weeks (two flights, each
delivering 50 tons).  This ability to put up a lot of payload in a very short
time may be of advantage for situations such as trying to fill the
propellants tanks of a lunar expedition vehicle with cryogenic propellants.



--
Bruce Dunn    Vancouver, Canada   [e-mail]

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

Date: 16 Dec 92 15:07:51 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Terminal Velocity of DCX? (was Re: Shuttle ...)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Gary Coffman) writes:

>>Also note that the cost of one Shuttle flight is about the same
>>as the entire DC development program.

>One Shuttle flight is a bit less than half the projected cost of DCX
>development to flight test.

DC-X from concept to end of flight tests costs $60 million. A Shuttle
flight costs $550 million.

If you took the cost of a single Shuttle flight, put it in a good
mutual fund for a year, you would make enough money to pay for the
entire DC-X and then use the principle to buy the Shuttle flight.

  Allen

--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------129 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: Wed, 16 Dec 1992 03:09:38 GMT
From: Steven Cooper <[e-mail]>
Subject: What is DC ??
Newsgroups: sci.space

Pardon my ignorance folks, but what is this DC thing?

I get the idea that it's a single stage to orbit vehicle which lands vertically
under power. Is this true?
Who is designing/building it?
From other posts I gather some initial tests will happen next year.

Now, I'm really confused about how you make an SSTO. As far as my meagre
understanding goes, the final velocity of a rocket is the exhaust velocity
times the logarithm of the mass ratio. How easy is it to get 5 miles per second
with a single stage? I thought that exhaust velocities were only about 3000 m/s
which would require a mass ratio of about 14. With payload and fuel for landing
this sounds quite difficult.

I'd be grateful for any information.

Thanks in advance,

Steven Cooper ( c/- C.Smith's account)

[e-mail]

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

Date: Tue, 15 Dec 1992 17:16:32 GMT
From: "Edward V. Wright" <[e-mail]>
Subject: what the little bird told Henry
Newsgroups: sci.space

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

>Without researching it much, it seems to me that the time it took USAF to
>build and deploy a new aircraft roughly doubled when he [McNamara] took over.
>Ditto for price.

If only that was true.  Until the early sixties, the usual time
to design, build, test, and acquire a new aircraft was four years.
A crash program could do it in considerably less time.  (The P-51
Mustang was, literally, a 90-day wonder and the SR-71 was designed
and built in 18 months.)  Today it takes about 15 years.  If McNamara's
reforms *only* doubled the time to acquire a new airplane, we would
be much better off today.

It's estimated that stretching out an aircraft development program by
one year adds something like 30% to the cost.

McNamara brought to DoD the skills of scientific management that he
had used at Ford Motor Company, where he was responsible for such
successes as the Ford Edsel and singlehandedly remolded Ford into
the modern, scientific company that would dominate the world auto
industry for next two decades.;-)  After leaving DoD, he went on
to the World Bank, making loans to countries that could never repay
them.  He has, in short, made an entire career out of failure, and
is still considered one of the "best and the brightest" for it.  I
agree, "success-oriented" is probably not one of his favorite words.

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

Date: Wed, 16 Dec 1992 12:22:52 GMT
From: Gary Coffman <ke4zv!gary>
Subject: what the little bird told Henry
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Edward V. Wright) writes:
>
>If, instead of building the XP-59, we had embarked on a long research
>program like the X-30, the first US jet aircraft would have flown
>sometime after the Korean War.  Meanwhile, Russian MiGs would been
>blasting our Mustangs out of the sky.

Actually there were Mustang Aces in the Korean War. Tackling a Mustang
in a Mig-15 wasn't easy since the Mustang could consistently turn inside
the Mig. The one thing a Mustang couldn't do was pursue a fleeing Mig.

Gary

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

End of Space Digest Volume 15 : Issue 556
------------------------------