Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/spacedig/V15_1/V15NO154.ZIP/V15NO154

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Date: Wed,  2 Sep 92 05:00:05
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #154
To: Space Digest Readers
Precedence: bulk


Space Digest                Wed,  2 Sep 92       Volume 15 : Issue 154

Today's Topics:
                 20 Questions About the Delta Clipper
                                DCX??
             Failed post from a long while ago:  (2 msgs)
            Fireball over The Netherlands Wasn't (2 msgs)
                         NASA speakers sought
          Single Stage to Orbit - How does it work? (2 msgs)
                       TOPEX Update - 08/31/92
                 Upload Astronomy Lab for MS Win 3.x
                       Venus orbiters (2 msgs)
          What is the speed of light measured from? (2 msgs)

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

Date: Tue, 1 Sep 1992 14:40:07 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: 20 Questions About the Delta Clipper
Newsgroups: sci.space

This was prepared as part of a packet of information on the SSRT project
and the DCX and DCY vehicles. Permission is granted to reproduce and
distribute any way you want.

   Allen
--------------------------------

                  20  question about the Delta Clipper

1>   What is the Delta Clipper?
     A new spaceship that will take off straight up and land the
same way, not gliding but under power, just like the rocketships
in the 1950's science-fiction movies.  Because of its improved
engines, high-tech light-weight materials, and airline-like
service procedures, the Delta Clipper could reduce the cost of
getting to and from space by 90% or greater. Because it will be
certified for flight like an aircraft, it will be able to operate
from spaceports located in any state.

2>   What will it look like?
     The production model Delta Clipper will be conical shaped,
approximatley 130 feet high and 40 feet accross the base. It will
have eight or more rocket engines, providing safe return engine out
capability like any airliner. The Delta Clipper will not have wings
like the Shuttle but will use small moveable flaps to help maneuver.
It will not require strap-on external tanks or boosters.

3>   When will it be flying?
     A 1/3 sized experimental vehicle, the DC-X, is on schedule for
launch in April of 1993. The full sized orbital prototype, the DC-Y,
could be ready to fly as early as the summer of 1997.

4>   Where will it launch from?
     Test flights will be from White Sands Missile Range, New Mexico,
but when the Delta Clipper goes into production any state in the Union
will be able to have its own spaceport.  Unlike the Shuttle, the Delta
Clipper won't need a long runway, huge Vehicle Assembly Building, or
Mission Control but only a 200 foot diameter concrete pad, a maintenance
hangar, and a hydrogen/oxygen fuel facility.  It will use existing global
positioning satellites for navigation.

5>   What will it cost to design and build the 1st Delta Clipper?
     The total cost of developing the first flight certified Delta
Clipper will be comparable to or less than the development of a new
commercial airliner. The cost of building an experimental prototype vehicle
to demonstrate the concept and validate the operating and cost goals would
be substantially less.

6>   What will I have to pay to fly the Delta Clipper?
     The ticket price for early versions of the Delta Clipper, if it
met current cost goals, could be less then the price for a  round-the-world
cruise on the QE2 ($40,000 to $140,000). A second generation vehicle could
further reduce this cost.

7>   How dangerous will it be?
     Once fully operational the Delta Clipper will be safe as flying
on a typical commercial airliner. Delta Clipper will have engine out and
all altitude abort capability. Plans are to have the Delta Clipper
certified by the Department of Transportation, Office of Commercial Space
flight.

8>   What about air pollution, especially near the ozone layer?
     The Delta Clipper will burn only hydrogen and oxygen. Its exaust
consists primarily of pure water vapor.

9>   What about sonic booms and noise when launching or landing?
     When an airplane flies above the ground faster than sound,
it generates a cone-shaped shock wave which we experience as a
sonic boom.  For this reason, the Concorde jet can't fly
supersonically to inland airports in the US.  Since the Delta
Clipper launches straight up, the sonic boom is largely restricted
to the spaceport area. When landing, the Delta Clipper will slow
down to sub-sonic speed at about 70,000 feet altitude, thus minimizing
the sonic boom to a barely audible level.

10>  Who's building it?
     McDonnell Douglas, under a contract from the Strategic
Defense Initiative Organization (SDIO), is building the DC-X for
demonstration of the technological and operational feasibility of single
stage rockets for supporting either suborbital flights. Based on successful
testing of the DC-X, SDIO is interested in developing a fully reusable
suborbital rocket to support their numberous suborbital test missions. The
design, test results, and concepts will be available to other agencies to
develop and demonstrate the orbital vehicle, the DC-Y. We hope to find
another "home" for the DC-Y and Delta Clipper in DoD or NASA.

11>  How much will the Delta Clipper be able to carry?
     Two crew members and 10 tons of cargo and/or passengers to
Low Earth Orbit or 2 crew members and 5 tons of cargo/passengers
to Polar Orbit.

12>  Will it be able to fly to the Moon?
     A Delta clipper derivative vehicle, re-fueled in Low Earth Orbit,
would be able to fly to the Moon, land there, and then return to Earth.
The modifications required, however, would be substantial.

13>  How often will the Delta Clipper be able to fly?
     The anticipated turn-around time for the Delta Clipper is a maximum
of seven days. However, a one day turnaround may be feasible.

14>  Why haven't we built a single-stage rocket before?
     The reason most rockets, including the Shuttle, have parts that
drop off (stages) is this: every additional pound of vehicle that we
lift all the way to orbit requires additional pounds of fuel.  The
additional fuel requires a little larger, and heavier, fuel tank,
which then requires even more fuel to carry, and so on.  There
are three ways to deal with this problem: 1) make the rocket so
huge (and expensive) that it can carry enough fuel to lift itself
all the way to orbit, or 2) toss off empty tanks as you go (the
traditional multi-stage method), or 3) make your engines and vehicle
structure so efficient and light weight that you don't need to carry
huge amounts of fuel or throw away pieces of your ship. This last is
the principle behind the Delta Clipper. It is only recently, under
such programs as NASP, and aircraft developments that we have
sufficently developed and demonstrated light weight materials that
will allow the Delta Clipper to work.

15>  What if something goes wrong during a flight?
     Commercial airplanes don't need all their engines to fly
safely.  The same principle will be used with the Delta Clipper.
If there is an engine malfunction during the assent, the Delta Clipper
will be capable of either continuing on to orbit orreturning to the
spaceport. If the Delta Clipper needs to return from orbit sooner than
expected, it will be able to maneuver over 1200 miles to either side.
Unlike the Shuttle, which requires a three mile long landing strip, the
Delta Clipper will be able to land on nbalmost any reasonably flat spot.

16>  Why should I believe all these claims for the Delta Clipper
     when similar ones were made for the Shuttle twenty years ago?

     The Shuttle's design was "frozen" in the 1970's.  Using the technology
available then would have resulted in a SSTO that was extremely large and
expensive. A Delta Clipper sized SSTO based on 1970's technology would not
have ben able to reach orbit. In the 20 years since then, we have learned
a lot about design, light-weight materials, trajectory optimization, avionics,
computers, and engine design.

     In addition, the Delta Clipper is being designed with supportability
and operability as priority considerations. For example, the engines
on the Delta Clipper won't run at 110% of their design capacity, as the
Shuttle's do, so they won't have to be torn down and repaired before each
flight. If on-board diagnostic instruments indicate a problem with a
Delta Clipper engine or any other component, it is designed so components
(called line replaceable units) can be pulled and replaced quickly after
landing.

17>  Why isn't NASA building the Delta Clipper?
     The task of proving the technology availability for a single stage
rocket vehicle was assigned to SDIO. SDIO with its streamlined management
style is an excellent agency for developing and demonstrating new
technology initiatives. Once the technology demonstration is completed,
the concept will be available for either Department of Defense or NASA to
develop an orbital capable Delta Clipper.

18>  Why isn't industry building the Delta Clipper?
     McDonnell Douglas and its teammates have already made a significant
investment in the basic technologies and the skills and facilities
necessary to develop a SSTO. The government needs to take the next step
of funding an experimental prototype vehicle to prove the Delta Clipper's
basic concepts and technologies. Once demonstrated, the commercial sector
may be interested in investing in an operational system. Such a system
could have an enormous impact on the development of space as an commercial
market as well as the future of the US space program.

19>  What factors could cause the Delta Clipper program to founder?
     Money: Though the Delta Clipper program is cheaper than many
Federal programs, it still is in danger from a budget-conscious
Congress who may not be aware of the benefits of the Delta Clipper or
who feel the program has no real constituency.  We hope to change
their minds about this.

20>  What can I do to help?
     Get on our mailing list, be willing to write letters to Congres
when asked, learn about the Delta Clipper, ask all your friends to
support it too.

--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "If they can put a man on the Moon, why can't they     |
|  [e-mail]     |  put a man on the Moon?"                               |
+----------------------234 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: Tue, 1 Sep 1992 14:37:18 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: DCX??
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Patrick Chester) writes:

>Pardon me for seeming clueless, but what is the dcx?

DCX is a 1/3 scale prototype of a Single Stage to Orbit vehicle. It will
be used for suborbital testing next summer. If all goes well another
agency will pick up development and develop a full scale vehicle which
can achieve orbit. If it works, it will reduce the cost to orbit by one
to two orders of magnitude.

We have a document called '20 questions on SSTO which I will post in a
bit. It should answer most of your questions. If you want to help make
this happen, contact me.

  Allen

--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "If they can put a man on the Moon, why can't they     |
|  [e-mail]     |  put a man on the Moon?"                               |
+----------------------234 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: Tue, 1 Sep 92 13:01:49 -0500
From: [e-mail] (Phil G. Fraering)
Subject: Failed post from a long while ago:

This is a follow-up that never made it...
It just about sums up my feelings about manned space shots
as entertainment...

Date: Sun, 2 Aug 92 21:54:11 -0500
From: pgf (Phil G. Fraering)

[e-mail] (Richard Ottolini) writes:


>I don't know if anyone else feels the same way,
>but I find the space shuttle missions this summer to be more
>interesting than the Olymnpics and presidential conventions.
>I still get a thrill when I see a manned spacecraft and takeoff
>even though I've been watching them for 30 years.

You might as well feel thrilled. It cost enough money.
If you don't at least feel thrilled, you're left with
the scientific justification for the mission, which
according to some groups is dubious...

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

Date: Tue, 1 Sep 92 13:04:33 -0500
From: [e-mail] (Phil G. Fraering)
Subject: Failed post from a long while ago:

This is a follow-up that never made it...
It just about sums up my feelings about manned space shots
as entertainment...

Date: Sun, 2 Aug 92 21:54:11 -0500
From: pgf (Phil G. Fraering)

[e-mail] (Richard Ottolini) writes:


>I don't know if anyone else feels the same way,
>but I find the space shuttle missions this summer to be more
>interesting than the Olymnpics and presidential conventions.
>I still get a thrill when I see a manned spacecraft and takeoff
>even though I've been watching them for 30 years.

You might as well feel thrilled. It cost enough money.
If you don't at least feel thrilled, you're left with
the scientific justification for the mission, which
according to some groups is dubious...

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

Date: Tue, 01 Sep 92 14:39:21 EST
From: [e-mail]
Subject: Fireball over The Netherlands Wasn't

Regarding the August 19, 1992, event over The Netherlands, Harm Munk
writes (Mon, 31 Aug 1992 07:42:08 GMT):

>So, what was it? Rumours in the newspapers suggested that it was that
>highly secretive airplane that Lockeed is developing for the DoD: the
>two stage get to orbit plane (like DynaSoar and Saenger ?). Now,
>this plane has been sighted in the US a few times.

Here is an article from Aviation Week & Space Technology, August 24, 1992,
about this "highly secretive airplane":

RECENT SIGHTINGS OF XB-70-LIKE AIRCRAFT REINFORCE 1990 REPORTS FROM
EDWARDS AREA
William B. Scott/Lancaster,Calif.
  A large aircraft having a planform reminiscent of the Air Force/North
American XB-70 supersonic bomber of the 1960s has been seen flying on
the U.S. East and West coasts over the last two years.
  Two recent detailed reports of large, light-colored, XB-70 like
aircraft - one in Georgia and the other in California's Mojave desert -
provided new data that reinforce past sightings near Edwards AFB, Calif.
Since September, 1990, residents of Mojave, Calif., and workers at
Edwards AFB have seen a large, delta-shaped, light-colored aircraft
flying in the area. A total of five separate sightings of this vehicle
has been reported to AVIATION WEEK & SPACE TECHNOLOGY.
  Observers said they first saw a large, primarily delta-shaped aircraft
at night during the summer of 1990. On Sept. 13, 1990, and Oct. 3, 1990,
the same type of aircraft was seen flying near Mojave, Calif., in the
late evening. Mojave is about 16 naut. mi. northwest of Edwards AFB.
  The dusk sightings yielded descriptions and sketches of the aircraft
planform, nose and main landing gear door locations, leading edge
tile-like patterns, and lightings layout. Observers consistently
reported a red light beneath the nose, amber lights near the delta's
wingtips, and a white light between the main gear doors.
  Engine noise associated with the aircraft seen on Sept. 19 was
described as a low-pitched rumble. However, noise from two chase
aircraft - one was an F-16, the other was not identified - may have
combined with that of the large aircraft, distorting the latter's
sound. Afterburner flames from twin exhaust ports located under the
wing trailing edge and immediately outboard of the aircraft centerline
during the Oct. 3 sighting.
CLUES ABOUT POSSIBLE MISSION
  A similar aircraft was seen in April, 1991, at about 11 a.m., flying
north of Edwards AFB at an estimated altitude of 5,000-10,000 ft. An
observer said it was large - dwarfing an F-16 chasing it - and was
light colored, possibly white.
  Independent sightings this year produced detailed sketches that
correlate well with earlier ones and provide additional clues about
the aircraft's possible mission. The first sighting this year was
near Atlanta, Ga., on May 10. Glenn Emery, now a writer associated
with Cable News Network, said a large, unidentified aircraft was
flying eastbound at about 5 p.m. Because its size was unknown, its
altitude was difficult to judge, but was estimated to be 10,000-
15,000 ft. The vehicle was clearly higher and faster than the airline
traffic descending for landing at Hartsfield Atlanta International
Airport. It was not leaving a contrail.
  He described the aircraft's planform as large, somewhat like an
XB-70, but with a large forward wing or canard. Its dual engines were
"extremely noisy", producing a deep-pitched, perioding beating sound,
he said. Suggestions that he had seen the British Aerospace Concord
or a Beech Starship were discounted by Emery, who said the shape,
size and sound were inconsistent with either of those aircraft.
  Another sighting, on July 12 at 11:45 p.m., occurred near a
Lockheed-operated radar cross section (RCS) test range in the Mojave
desert. Described as an "XB-70-like" shape, the aircraft tuned its
landing lights on while at fairly high altitude, then descended
quickly, following an S-pattern flight track. It made a final turn
at about 200 ft. above a road, crossing less than a mile in front of
a motorist who had watched its descend. Ambient noise masked any
sounds from the aircraft.
  Bright moonlight illuminated the aircraft's upper surfaces, giving
the observer a good look at the planform during the turn. The aircraft
rolled out, presenting a side view as it descended and landed at a
private Helendale airport adjacent to the Lockheed RCS test facility.
  Located about 15 naut. mi. southwest of Barstow, Calif., Helendale
Airfield's three runways are close to civil pilots on current aero-
nautical charts. However, Lockheed aircraft still land there when
shuttling personel between its Burbank site and the RCS facility.
  Although weather was clear and calm at the Helendale field that
night, several thunderstorms were reported in the Las Vegas area and
through the highly classified range complexes in central Nevada.
  Based on observer reports, this unidentified aircraft's features
include:
# Large size, estimated to be close to 200 ft. in length. Observers
near Edwards AFB said the vehicle "dwarfed" F-16 chase aircraft.
# A large aft section with a clipped-delta platform. A narrower,
blended fuselage extends from the delta's vertex forward to a clear-
canopied cockpit and sharp nose. The main delta section has a
prominent, raised spine along the top centerline. Upward-canted
vertical fins rise at each outboard tip of the delta planform.
# A prominent dark line extending longitudinally along part of the
aft raised section. At the aft end of the line, just ahead of the
trailing edge and between the engine nozzles, a broken visual
pattern was seen, but observers could not describe it.
# A forward wing or canard of fairly long spane. The canard, possibly
used only for takeoff, landing and slow-speed regimes, may pivot or
sweep aft for internal stowage during high-speed flight (Some
observers reported a dominant canard, while others did not recall,
suggesting it can be stowed).
# Dual rectangular engine exhaust nozzles at the aircraft's trailing
edge.
# Light-colored top and bottom surfaces, with dark leading and
trailing edges.
  Although the propulsion system is unknown, observers have reported
a "very loud, low-pitched roar" with a rhytmic beat to it. They did
not hear a series of detonations, which have been associated with
high-speed "pulser" vehicles that create "donuts-on-a-rope" contrails
(AW&ST May 11, p. 62)
(end of article)

With this article, there is an "artist's composite" of the craft. It
is said in the caption that "The aircraft configuration suggests a
variety of mission roles, including carriage and high-speed launch of
an unmanned vehicle into orbit". At least this last point should
interest sci.space subscribers !

In the same issue of AW&ST, there are two other related articles:

UNITED 747 CREW REPORTS NEAR-COLLISION WITH MYSTERIOUS SUPERSONIC
AIRCRAFT, by Michael A. Dornheim/Los Angeles.

SECRET AIRCRAFT ENCOMPASSES QUALITIES OF HIGH-SPEED LAUNCHER FOR
SPACECRAFT, by William B. Scott/Lancaster, Calif. (sci.space
subscribers should be interested in this one !)
._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._.

Now a few comments.
1) It is not the first time that "large, primarily delta-shaped
   aircrafts" are reported near Edwards AFB. Since the end of 1989,
   a "big wing" has been seen several times over Antelope Valley.
   See AMERICA'S NEW SECRET AIRCRAFT, Popular Mechanics, December
   1991 (I posted this article twice on sci.space, but it seems
   that practically nobody was interested). However, this "big
   wing" was said to be silent, and could hover in any position
   (hence the airship hypothesis). It seems that the XB-70-like
   object goes fast, and is generally noisy.
2) A contributor to the "Skeptical Inquirer" assured me that
   all secret aircraft tests are over the deserts of California
   and Nevada. What was this aircraft doing over Atlanta, Georgia,
   on May 10, (1992 ?).
3) "Large, primarily delta shaped aircrafts" appeared over Belgium
   in November 1989, and have been seen thousands times during about
   two years. Though U.S. citizens are highly civilized (?), I am not
   sure that five U.S. witnesses = some ten thousands Belgian
   witnesses.
4) Though most of time only delta shapes have been seen in Belgium,
   there were a number of reports of "narrower fuselage" and/or "forward
   wing", especially in year 1991. A drawing made by a witness looks like
   the AW&ST "artist's composite". Some Belgian inquirers suggest
   the possibility of composite structures (Lego type).
5) "Large size, estimated to be close to 200 ft. in length." This fits
   well the size of the Belgian object: a triangulation made from one
   of its hovering stations gave: isocele triangle, 50 meters basis,
   55 meters height.
6) Though the Belgian object was generally silent, in some occasions
   very loud roars were reported.
7) It seems that F-16s like very much chasing these objects. In Belgium
   there has been an unsuccessful chase during the night March 30-31,
   1990 (see the Belgian Air Force report I posted on sci.space on
   February 28, 1992). By the way, the Belgian Center of Electronic
   Warfare is still studying the video record of the interception. I
   know a bit more about that, but since my info comes from private
   mails, and since nobody on sci.space seems interested in that, I
   will keep it for myself.
8) As said Harm Munk in his posting,
>And why would the DoD start testing a secret plane outside US territory?

J. Pharabod

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

Date: Tue, 1 Sep 92 13:40:56 GMT
From: Dean Adams <[e-mail]>
Subject: Fireball over The Netherlands Wasn't
Newsgroups: sci.space,sci.astro

[e-mail] (Gerald Cecil) writes:
 >According to Aviation Week & Space Technology (aka AvLeak) in
 >issues prior to Aug. 24,

Uh, there was a considerable amount of NEW information in the August 24th
issue.  WHY would you want to limit your reply only to the old info?

 >this aircraft is an SR 71 replacement developed by Lockheed Skunkworks.
 >Speeds estimated at 3500+ mph.  *Not* a 2 stage to orbit plane.

NO.  The 8/24 AW&ST *specifically* talked about a vehicle which
potentialy DOES have a 2-stage to orbit mission capability.

 > described as `bat-like'' similar to the B2 airfoil.

Now it sounds like you are talking about the *subsonic* TR-3A,
which is something totally different from the Aurora(s).

 >Daytime photos of peculiar corkscrew contrails that have been attributed

Now you're back to the older Aurora/pulser concept. I tend to think this
is a *different* (and smaller) vehicle from the large "Concorde-like"
aircraft reported in Europe, and also described in the recent AW&ST.

 >presumably because the DoD has now sunk so much money in to it and
 >distributed its contractors into so many Congressional districts

The Lockheed Burbank Skunk-Works is likely the main contractor.
With such an ultra-black project I doubt it was spread around that much.

 >Yet another multi-billion dollar aerospace program to
 >protect US airspace from the Bosnian airforce.

NO, it is to "protect" us from being ignorant about the world around us.
Intelligence gathering is something that will always have considerable
value, with or without any "evil empire" to be worried about.

-{ DA }-

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

Date: 1 Sep 92 16:16:25 GMT
From: David M Chelberg <[e-mail]>
Subject: NASA speakers sought
Newsgroups: sci.space

I am interested in finding out if NASA has any program to allow their
researchers to give talks at Universities.  What policies does NASA
follow with regards to invited lectures from their scientists?  Does
NASA have some kind of distinguished speaker program?  I would think
that they do, as it would be great publicity, and work well with their
educational goals.  If anyone has information on how to arrange NASA
speakers, please email me.  In particular, I am interested in speakers
with a CS emphasis.  Thanks,

 -- Prof. David Chelberg ([e-mail])
   __                     _ _ _        __          _
  /  )              /    ' ) ) )      /  ) /      // /
 /  / __. , __o  __/      / / /      /    /_  _  // /___/> __  _,
/__/_(_/|_\/ <__(_/_     / ' ( o    (__/ / /_</_</_/_) (__/ (_(_)_
                                                               /|
                                                              |/

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

Date: Tue, 1 Sep 1992 13:00:47 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Single Stage to Orbit - How does it work?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Tom Nugent       ) writes:

>From what I understand, 5 years ago you could not get into space without
>stages.

Depends. With expendables it looks like getting to LEO with a single stage
has been possible technically for some time.

Reusable SSTO's are likely just now possible. The Aerospace Corporation
study (done before SSRT Phase I) used Max Hunters design. They concluded
that the vehicle could now just barely be built with a payload of between
20,000 and -600 pounds (the latter means it is 600 pounds too heavy to
lift off).

They said engine improvments of a few seconds of impulse and materials
only a few % lighter make it possible. SSTO is a game of inches.

  Allen
--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "If they can put a man on the Moon, why can't they     |
|  [e-mail]     |  put a man on the Moon?"                               |
+----------------------234 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: 1 Sep 92 15:29:43 GMT
From: "KEVIN D. DAWSON" <[e-mail]>
Subject: Single Stage to Orbit - How does it work?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>From: [e-mail] (Henry Spencer)
>Subject: Re: Single Stage to Orbit - How does it work?
>Date: Fri, 28 Aug 1992 16:53:29 GMT

>As currently planned, SSTO will use very ordinary engine technology,
>except that it will probably use either a "plug nozzle" (which puts the
>entire base area of the rocket to work as the nozzle) or telescoping
>nozzles that can be made longer in flight.  Both of these basically just
>optimizes the nozzle design to match changing outside pressure; neither
>has flown, although both look workable.  Last I heard, the feeling was
>that telescoping nozzles looked less risky.

I Take it the Telescoping nozzle on the Peacekeepers upper stage doesn't
count because it only telescopes for storage?
-Kevin-

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

Date: Tue, 1 Sep 1992 22:56:19 GMT
From: Ron Baalke <[e-mail]>
Subject: TOPEX Update - 08/31/92
Newsgroups: sci.space,sci.astro

Forwarded from:
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. [phone]

                  TOPEX/POSEIDON STATUS REPORT
                         August 31, 1992

          The TOPEX/Poseidon satellite has fully recovered from
the safe hold that it experienced last Thursday.  Today the
satellite is performing nominally and is healthy.  Attitude
control, solar array, batteries, telecommunications, and the on-
board computer are all functioning normally.

          Today, the NASA altimeter is in the track mode and
obtaining good data.

          Since launch, the navigation team and the precision
orbit determination team have been observing a slight decay in
orbit.  It is currently about 10 cm a day, which is down from 30
cm a day last week.  The 10 cm/day appears to be expected drag on
the satellite.  The higher decays observed previously were
probably due to outgassing.

          The next major satellite event is the In-Plane Maneuver
One is planned for Wednesday, Sept. 2, 1992.

                             ######
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Anything is impossible if
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | you don't attempt it.
|_____|/  |_|/       |_____|/                     |

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

Date: Tue, 1 Sep 92 16:24:13 GMT
From: David Fuzzy Wells <[e-mail]>
Subject: Upload Astronomy Lab for MS Win 3.x
Newsgroups: comp.windows.ms.programmer,comp.windows.ms.misc,comp.ibm.pc.misc,comp.os.ms-windows.apps,sci.space,sci.astro,sci.edu

This file is available at ftp.cica.indiana.edu in the windows area.
            Fuzzy

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Date: Tue, 1 Sep 1992 14:10:12 GMT
From: David Knapp <[e-mail]>
Subject: Venus orbiters
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (John Roberts) writes:
>
>
>Will the trajectory of Pioneer Venus as it burns up provide useful
>information for the planning of the Magellan aerobraking experiment?
>(Density and drag at various altitudes, etc.)


The density and drag at various altitudes is strongly correlated to solar
activity.  This is one factor which will help determine the time of demise
of the PVO itself.  Since we cannot know exactly what the solar activity
will be in the future, planning for aerobraking is somewhat like weather
forecasting.

--
David Knapp                                      University of Colorado, Boulder
Highly Opinionated, Aging  and                      [e-mail]
Perpetual Student of Chemistry and Physics.
            Write me for an argument on your favorite subject.

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

Date: Tue, 1 Sep 1992 23:10:48 GMT
From: Ron Baalke <[e-mail]>
Subject: Venus orbiters
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (John Roberts) writes...
>Will the trajectory of Pioneer Venus as it burns up provide useful
>information for the planning of the Magellan aerobraking experiment?
>(Density and drag at various altitudes, etc.)

That is the plan.  The Magellan and Pioneer projects are working together
to collect the data from Pioneer Venus to be applied toward Magellan's
aerobraking next year for Cycle 5.  Of course, this is assuming that Magellan
isn't turned off at the end of Cycle 4.  Magellan is in Cycle 3 right now with
Cycle 4 due to start on September 14.  Each cycle lasts 243 days, or one
Venusian day.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Anything is impossible if
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | you don't attempt it.
|_____|/  |_|/       |_____|/                     |

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

Date: Tue, 1 Sep 1992 11:18:00 GMT
From: pete <[e-mail]>
Subject: What is the speed of light measured from?
Newsgroups: sci.space

In article <[e-mail]>,
[e-mail] (robert.f.casey) writes...
>Makes you wonder how the "particle" of light "knows" how fast or slow to
>speed up by to be travelling at the -speed o' light- at or near the
>local frame of reference.  Does it "feel" the local gravity, or something?
>

What you have to understand is that c is not just a velocity.
The way this universe is constructed, it's like a point that
time and space both pivot on. You could say that c is infinitely
fast, for anything travelling at it, it's just that the geometry
- in fact the _logic_  - of the universe requires that it not
be seen as infinitely fast by other observers. For instance,
if you board some wonderful rocket, which can sustain constant
acceleration ( in your frame of reference ) and commence
accelerating, it will seem to you that you just keep getting
faster and faster, and you pass c without incident. The only
catch is that in the rest of the universe you travel through,
time seems to be going by faster and faster relative to yourself,
such that to observers in other frames, your velocity never
quite reaches c. They also see your time slowing down, so they
can understand why you might think yourself going faster than
c ( for simplicity I've left out all the interesting details
of how times can be compared between reference frames).

    Now for light, and anything else travelling at c, duration
of time has slowed to 0 as seen from any other reference frame,
so this can be seen as equivalent to travelling infinitely
fast. This sort of solves the problem that led Einstein to
relativity in the first place - how, if one were in the frame of
reference travelling with light, and observed the (now stationary)
electromagnetic fields which comprise it, one would see
the EM fields vary in amplitude periodically
in space, which according to Maxwell's equations shouldn't
be possible without electric charges at the local maxima.
The solution is that in relativity, this frame of reference
is not well defined, and it occupies no time, so it's
never really there to contradict Maxwell. Thus light always
knows how fast to go: as fast as possible.
    The moral of the story is that the world is not at all
as it seems, and nothing like our naive Aristotelian/Newtonian
intuitions.
========================================================================
Wait until time is fully dilated                          Pete Vincent
before releasing tangent bundle...

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

Date: Tue, 1 Sep 92 18:19:25 BST
From: [e-mail]
Subject: What is the speed of light measured from?

>> Where is the speed of light measured relative to?

> The  speed of light does not add and subtract to other velocities,
> like  relative velocities of anything else.

Well, correct in intent, but not quite true mathematically. The plus
and minus operators are not the linear 2+2=4 operation you learn as a
small child, although with small velocities in a given frame of
reference they approximate it. Adding two large velocities results in
a smaller than expected result because of the relativistic effects.
The "addition" works such that the resultant velocity never exceeds
c.

Moving from one frame to another utilizes mathematical rules which
preserve this constancy by modifying space and time metrics. (This is
one way to look at it.) The atomic clocks and meter sticks of
observers in different reference frames have different seconds and
meters. They differ in such a way as to insure the constancy. It's
just the way space-time is built.

Look up the Lorentz factor in any physics book. There also may be
info on this in the FAQ. Not certain of that, but it has come up
many, many times before.

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End of Space Digest Volume 15 : Issue 154
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