Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/spacedig/V15_1/V15NO158.ZIP/V15NO158

Internet Message Format | 1993-07-13 | 34KB

Date: Thu,  3 Sep 92 05:00:08
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #158
To: Space Digest Readers
Precedence: bulk


Space Digest                Thu,  3 Sep 92       Volume 15 : Issue 158

Today's Topics:
                        Antarctica (was: SPS)
       Diffs to sci.space/sci.astro Frequently Asked Questions
             Laser Communications experiment with Galileo
                   Mars Observer Update - 09/01/92
                   Pioneer Venus Closes In On Venus
             Sizing of launch vehicles (was Saturn Class)
                                 SPS
                    Whales and Dolphins...again...
          What is the speed of light measured from? (2 msgs)

    Welcome to the Space Digest!!  Please send your messages to
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    (THENET), or [e-mail] (Internet).
----------------------------------------------------------------------

Date: 2 Sep 92 14:45:06 GMT
From: "Frederick A. Ringwald" <[e-mail]>
Subject: Antarctica (was: SPS)
Newsgroups: sci.space

In article <[e-mail]>
[e-mail] (John Roberts) writes:

> -Then there's the cosmic ray project, to
> -analyze waves in the interplanetary medium. (They wanted to hire me to
> -take care of it, but I turned them down. Living at the South Pole would
> -be fun, for three weeks, but they wanted me to stay for 53 weeks!
>
> I don't blame you - I wouldn't want to stay at the South Pole for 53
> weeks either! :-)

Yes, and it puzzles me: why are people who wax rhapsodic about living
in space not more enthusiastic about Antarctica? You don't even have to
make your own air and water in Antarctica!

A graduate student in the experimental space physics group here, whose
thesis on ionospheric plasma waves is based on data from a radio
receiver he designed and built here and set up at the South Pole, is
the best potential astronaut I know. I gave him a copy of Eugene Miya's
FAQ article on how to become an astronaut, and he's interested. All he
needs to do is take up flying as his #1 hobby, which will be a lot
easier once he's graduated and making real money. Perhaps this would be
at a job doing something else at NASA, perhaps an NRC postdoc. He's got
everything else mentioned: working on Ph.D. in something directly
space-related and mandatorily hands-on, and NOT software development;
athletic; easy to get along with; clean nose. No, he isn't my student,
and he's not paying me to write this. (Perhaps he should...)

Fred

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

Date: 2 Sep 92 18:53:44 GMT
From: Jon Leech <[e-mail]>
Subject: Diffs to sci.space/sci.astro Frequently Asked Questions
Newsgroups: sci.space,sci.astro,news.answers

Archive-name: space/diff

DIFFS SINCE LAST FAQ POSTING (IN POSTING ORDER)

(These are hand-edited context diffs; do not attempt to use them to patch
old copies of the FAQ).

===================================================================
diff -t -c -r1.11 FAQ.net
*** /tmp/,RCSt1a21482    Wed Sep  2 14:49:44 1992
--- FAQ.net    Wed Sep  2 14:48:22 1992
***************
*** 1,5 ****
  Archive-name: space/net
! Last-modified: $Date: 92/07/24 00:27:15 $

  NETWORK RESOURCES

--- 1,5 ----
  Archive-name: space/net
! Last-modified: $Date: 92/09/02 14:48:21 $

  NETWORK RESOURCES

***************
*** 19,25 ****
      One mechanism is the mailing list, in which mail is sent to a central
      distribution point which relays it to all recipients of the list. In
      addition to the general lists for space (called SPACE Digest for
!     Internet users, and SPACE-L on BITNET), there are a number of more
      specialized mailing lists described below.

      A second mechanism is Usenet 'netnews'. This is somewhat like a bulletin
--- 19,25 ----
      One mechanism is the mailing list, in which mail is sent to a central
      distribution point which relays it to all recipients of the list. In
      addition to the general lists for space (called SPACE Digest for
!     Internet users, and SPACE on BITNET), there are a number of more
      specialized mailing lists described below.

      A second mechanism is Usenet 'netnews'. This is somewhat like a bulletin
***************
*** 76,81 ****
--- 76,85 ----
      [e-mail] saying "SUBSCRIBE SEDSNEWS your name" to join.
      Email saying "INDEX SEDSNEWS" to list the archive contents.

+     Ron Baalke ([e-mail]) runs a mailing list which
+     carries the contents of the sci.space.news Usenet group. Email him
+     to join the list.
+
      As a general note, please mail to the *request* address to get off a
      mailing list. SPACE Digest, for example, relays many inappropriate
      'please remove me from this list' messages which are sent to the list

***************
*** 136,144 ****
      Ron Baalke ([e-mail]) posts frequent updates from
      JPL, Ames, and other centers on the Ulysses, Gailileo, Pioneer,
      Magellan, Landsat, and other missions.
-
-      The updates posted by Ron and Peter are also available on a mailing
-      list. Contact either one to be added to this list.

      ORBITAL ELEMENT SETS
      TS Kelso ([e-mail]) posts orbital elements from
--- 140,145 ----

===================================================================
diff -t -c -r1.11 FAQ.data
*** /tmp/,RCSt1a21487    Wed Sep  2 14:49:45 1992
--- FAQ.data    Wed Sep  2 14:48:10 1992
***************
*** 305,321 ****
      accessed 24 hours/day at 300, 1200, or 2400 baud using 8 data bits, 1
      stop bit, no parity.

!     This information is also available via anonymous FTP from
!     nachos.ssesco.com (192.55.187.18) in directory sat_elements/nasa
!     (address problems with the server to [e-mail]), as well as
!     kilroy.jpl.nasa.gov (128.149.1.165) in pub/space/elements/nasa and
!     pub/space/elements/molczan (contact [e-mail]).

!     Orbital elements for the Hubble Space Telescope are posted periodically
!     to sci.astro by Mike Rose ([e-mail]), and a Macintosh program for
!     interpreting this information is available by FTP from stsci.edu
!     (130.167.1.2) in Software/hstmap-3.4.0.sit.hqx. This program has also
!     been posted to comp.binaries.mac.


      SPACE DIGEST ARCHIVES
--- 305,324 ----
      accessed 24 hours/day at 300, 1200, or 2400 baud using 8 data bits, 1
      stop bit, no parity.

!     Orbital element sets are available via anonymous FTP from the
!     following sites:

!     archive.afit.af.mil (129.92.1.66)       NASA,TVRO,Shuttle
!     directory: /pub/space
!
!     ftp.funet.fi (128.214.6.100)          NASA,TVRO,Molczan,CelBBS,
!     directory: /pub/astro/pc/satel          Shuttle (*)
!
!     kilroy.jpl.nasa.gov (128.149.1.165)     NASA,Molczan
!     directory: /pub/space/
!
!     nachos.ssesco.com (192.55.187.18)       NASA,Molczan
!     directory: /sat_elements


      SPACE DIGEST ARCHIVES

===================================================================
diff -t -c -r1.11 FAQ.references
*** /tmp/,RCSt1a21497    Wed Sep  2 14:49:49 1992
--- FAQ.references    Wed Sep  2 14:48:30 1992
***************
*** 126,150 ****

      DC-X SINGLE-STAGE TO ORBIT (SSTO) PROGRAM

!     SDI's SSTO (Single Stage To Orbit) project is trying to build a fully
!     reusable spacecraft with one stage and no jettisoned parts, which simply
!     takes off and goes into orbit. This is technically demanding but is now
!     tentatively thought to be feasible, using materials developed by NASP
!     and more-or-less off-the-shelf engine technology. The objective is
!     10,000 lbs or so into low orbit at a cost of $100-300/lb with a vehicle
!     turnaround time of one week. It is being done as a high-risk fast-track
!     effort, with little publicity, a tight schedule, and a firm attempt to
!     avoid pioneering technology unnecessarily.

!     McDonnell-Douglas got the contract. They're currently building DC-X, a
!     subscale suborbital unmanned demonstrator that will check out the basic
!     concept, flying in mid-1993 (that is not a typo). They hope they will
!     then get funding for DC-Y, a full-scale orbital manned prototype. This
!     would then, with luck, lead to the DC-1, a production spaceship
!     certified to airliner-like standards for commercial service. McDD calls
!     the whole project Delta Clipper, whence the DC designations (which also
!     have some historical significance for McDD). So far, only DC-X has firm
!     funding.


      LLNL "GREAT EXPLORATION"
--- 126,140 ----

      DC-X SINGLE-STAGE TO ORBIT (SSTO) PROGRAM

!     SDI's SSRT (Single Stage Rocket Technology) project has funded a
!     suborbital technology demonstrator called DC-X that should fly in
!     mid-1993. Further development towards an operational single-stage to
!     orbit vehicle is uncertain at present; for considerably more detail on
!     the SSRT program, get the document

!      ames.arc.nasa.gov:pub/SPACE/FAQ/DeltaClipper
!
!     by anonymous FTP or through the email server.


      LLNL "GREAT EXPLORATION"

===================================================================
diff -t -c -r1.11 FAQ.mnemonics
*** /tmp/,RCSt1a21507    Wed Sep  2 14:49:51 1992
--- FAQ.mnemonics    Wed Sep  2 14:48:20 1992
***************
*** 79,86 ****

      Uranian Satellites:
      MAUTO
      (Miranda, Ariel, Umbriel, Titania, Oberon)
-

  NOTE: the remaining FAQ sections do not appear in sci.astro, as they cover
      material of relevance only to sci.space.
--- 79,87 ----

      Uranian Satellites:
      MAUTO
+      Mispronunciations Afflict Uranus Too Often
+      My Angel Uriel Takes Opium
      (Miranda, Ariel, Umbriel, Titania, Oberon)

  NOTE: the remaining FAQ sections do not appear in sci.astro, as they cover
      material of relevance only to sci.space.

===================================================================
diff -t -c -r1.11 FAQ.new_probes
*** /tmp/,RCSt1a21527    Wed Sep  2 14:49:56 1992
--- FAQ.new_probes    Wed Sep  2 14:48:24 1992
***************
*** 1,12 ****
  Archive-name: space/new_probes
! Last-modified: $Date: 92/07/24 00:27:16 $

  UPCOMING PLANETARY PROBES - MISSIONS AND SCHEDULES

!     This covers only NASA and Japanese (ISAS, NASDA) missions. Hard data on
!     other nations' (ESA, CIS) plans, and updates due to the usual delays and
!     budget cuts would be welcome. Source: NASA fact sheets, Cassini Mission
!     Design team, ISAS/NASDA launch schedules.


      GALILEO - Jupiter orbiter and atmosphere probe, in transit. Has returned
--- 1,11 ----
  Archive-name: space/new_probes
! Last-modified: $Date: 92/09/02 14:48:23 $

  UPCOMING PLANETARY PROBES - MISSIONS AND SCHEDULES

!     Information on upcoming or currently active missions not mentioned below
!     would be welcome. Sources: NASA fact sheets, Cassini Mission Design
!     team, ISAS/NASDA launch schedules, press kits.


      GALILEO - Jupiter orbiter and atmosphere probe, in transit. Has returned
***************
*** 54,55 ****

      CASSINI - Saturn orbiter and Titan atmosphere probe. Cassini is a joint
--- 53,64 ----
      start 11/93 for one martian year (687 days).


+     TOPEX/Poseidon - Joint US/French Earth observing satellite, launched in
+     August 1992 on an Ariane 4 booster. The primary objective of the
+     TOPEX/POSEIDON project is to make precise and accurate global
+     observations of the sea level for several years, substantially
+     increasing understanding of global ocean dynamics. The satellite also
+     will increase understanding of how heat is transported in the ocean.


      CASSINI - Saturn orbiter and Titan atmosphere probe. Cassini is a joint
***************
*** 114,140 ****
      on updated shuttle manifests; corrections and updates are welcome.

      1992 Missions
-      o Atmospheric Lab for Applications and Science (ATLAS) [Apr, STS-45]
-          Shuttle, this manned lab will study variations in the solar
-          spectrum and Earth's atmosphere.
-
-      o Extreme Ultraviolet Explorer [May, Delta II rocket]
-          This satellite will study the evolution and population of
-          stars and galaxies.
-
-      o US Microgravity Laboratory [Jun, STS-50 USML-01]
-
-      o TOPEX/Poseidon [Jun, Ariane 4 V52 rocket]
-          TOPEX will study the relationship of ocean systems to climate.
-          (Someone want to fill in the lineage of this mission? Presumably
-          it's primarily ESA.)
-
-      o Tethered Satellite System [Aug, STS-46 TSS-1]
-          Shuttle, attached by tether to the shuttle bay, system will
-          study electrical fields and gas clouds in space while
-          demonstrating the capabilities of deploying and retrieving a
-          tethered satellite.
-
      o Spacelab Japan [Sep, STS-47 SL-J]

      o Laser Geodynamics Satellite [Sep, STS-52 LAGEOS II]
--- 116,121 ----

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

Date: 2 Sep 92 13:48:56 GMT
From: Jeff Bytof <[e-mail]>
Subject: Laser Communications experiment with Galileo
Newsgroups: sci.space

A long time ago, I read an article that described a laser
communication experiment to be performed with the
Galileo spacecraft.  The experiment would
consist of a laser sending a data sequence
to Galileo's CCD camera, and the data would be
compared with a copy of the sequence sent up by conventional
[microwave] means.  Has this been done yet?  Is it still planned?

Jeff Bytof
[e-mail]

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

Date: 2 Sep 92 23:33:54 GMT
From: Ron Baalke <[e-mail]>
Subject: Mars Observer Update - 09/01/92
Newsgroups: sci.space,sci.astro

Forwarded from Glenn Cunningham, Mars Observer Deputy Project Manager

                          MARS OBSERVER
                 DAILY ACTIVITIES STATUS REPORT
                            FROM THE
      KENNEDY SPACE CENTER/CAPE CANAVERAL AIR FORCE STATION

                      Launch Minus 23 Days

Date of report:     9-2-92         Time of report:     8:00 AM EDT

Cleaning of the spacecraft and the payload instruments was
completed yesterday afternoon.  The MOLA (Mars Observer Laser
Altimeter) and TES (Thermal Emission Spectrometer) covers have been
replaced and a new removable cover for the MOC (Mars Observer Camera)
has been developed and installed.  The MOLA and the new MOC cover
will remain on the instruments until shortly before launch.

TOS (Transfer Orbit Stage) and the payload fairing have also been
cleaned.  All elements again meet the cleanliness inspection
requirement of VC-2.

Activities to remove the work platforms around the spacecraft and
TOS was started at 10 PM last night.  This was followed by final
cleaning of the Titan boattail and extension module.  The
encapsulation process will begin no later than 6 PM tonight.  The
Titan pre-encapsulation review will be held today.  A spacecraft
post-cleaning review will be held this morning.

The contamination investigation continues.  No definitive source
has been found at this time, but numerous protective measures are
being taken to limit exposure to any new contamination from many
sources in the launch processing flow.  The special investigative
board on the contamination incident meets here tomorrow and Friday.

Titan had a lightning strike very near the pad last Saturday after
the spacecraft was back in the PHSF (Payload Hazardous Support
Facility).  As a result, Titan found some damage to their electronics
and will replace some units.  The Titan damage search continues.

TOS, as previously reported, has identified a probable sneak
circuit which they believe caused their inability to turn-off
during a test on the pad before the cleaning activities.  There are
several options for corrective action which will be decided upon
today.

A new schedule events was established last night and is shown
below:

     o    Remove work platforms         9-1-92 at 10 PM
     o    Start encapsulation           9-2-92 at 6 PM
     o    Transport to LC-40            9-4-92 early morning
     o    Titan Combined Systems Test   9-14-92
     o    Spacecraft Launch Readiness
          Review                        9-15/17-92
     o    Diaz' Pre-Flight Integration
          Review                        9-17-92 PM
     o    Launch Day Dress Rehearsal    9-16/18-92
                                        (Simulated launch day is
                                        9-17-92)
     o    Headquarters' Mission
          Readiness Review              9-21-92 PM
     o    Launch Readiness Review       9-23-92
     o    Mission Director's Review     9-24-92
     o    Launch                        Not earlier than 9-25-92
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     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: 3 Sep 92 01:26:16 GMT
From: Ron Baalke <[e-mail]>
Subject: Pioneer Venus Closes In On Venus
Newsgroups: sci.space,sci.astro

Paula Cleggett-Haleim
Headquarters, Washington, D.C.            September 1, 1992
(Phone:  [phone])

Pete Waller
Ames Research Center, Mountain View, Calif.
(Phone:  [phone])

RELEASE:  92-140

NASA'S PIONEER VENUS ORBITER CLOSES IN ON VENUS

     Between now and year's end, the Pioneer Venus Orbiter
will skim closer to Venus than ever before, returning
significant new knowledge of the planet.

     It will explore upper atmosphere regions never before
reached, helping answer questions about Venus' environment
-- whether there is lightning on the planet and whether
Venus once had oceans.  The orbiter then will enter Venus'
atmosphere at hypersonic speed and burn.  This is expected
to happen in October, November or December.

     "Completing the picture of Venus' outer environment
will be a major achievement," said Richard Fimmel of NASA's
Ames Research Center, Mountain View, Calif.  "It will
culminate 14 years of receiving information since the
spacecraft was launched in 1978."

     Pioneer Venus provided data for the first topographic
maps of 90 percent of the planet's previously unknown
surface.  It identified mountain ranges, plateaus, plains
and deep depressions.

     The expected findings about Venus' outer environment,
Fimmel said, relate to atmosphere/plasma interactions.

     Plasmas (electrically charged gases) are the most
common form of matter in the universe.  The million-mile-an-
hour solar wind is an ionized gas which continuously batters
Venus' atmosphere .  The solar wind and Venus' atmosphere
interact in many ways.

     Studying these complex interactions on Venus may
increase knowledge of similar interactions in the
atmospheres of comets, planets, moons and star systems as
well as processes in the early solar system and interstellar
gas clouds.

     Researchers also hope to find out more about Venus'
water-loss mechanisms by measuring for the first time the
top of Venus' "mixed" atmosphere and the densest part of the
planet's ionosphere.

     In the final phase, gravity will bring Pioneer's orbit
down into Venus' upper atmosphere.  With Pioneer about 84
miles above the planet, NASA Ames officials will raise the
low point of its orbit by firing thrusters early on Sept. 7
and then every 5 days thereafter until the estimated four
pounds of remaining hydrazine propellant is gone.  Then, the
spacecraft will plunge into the Venusian atmosphere and
burn.

     The Pioneer Venus mission has had three phases.  NASA
researchers held the orbit's lowest point, known as
"periapsis," at 93 miles above Venus' surface to map and
study the ionosphere and atmosphere during the first 19
months at Venus.  In phase two, with only 10 percent of
propellant left, they allowed solar gravity to gradually
raise periapsis to 1,500 miles and then return it to low
altitude.

     By June of this year, with periapsis at 125 miles, the
orbiter's instruments began to measure Venus' ionosphere
again.  By Sept. 7, the sun will pull periapsis down to 82
miles.  If enough hydrazine remains, thrusters will be fired
to raise periapsis eight more times.

     By Nov. 22, solar gravity will briefly raise periapsis
to about 98 miles, but will pull it down to about 87 miles
by Dec. 10.  Officials then plan to fire any remaining fuel
to obtain more data from farther into Venus' "day side"
before the orbiter's final entry into the atmosphere.

- end -
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     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: 1 Sep 92 18:34:40 GMT
From: Dani Eder <[e-mail]>
Subject: Sizing of launch vehicles (was Saturn Class)
Newsgroups: sci.space

[e-mail] (Frank Crary) writes:

>In article <[e-mail]> [e-mail] (Dani Eder) writes:

>>Now, for the space station delivery job alone, you have a need to
>>deliver 75 tons per year (5 Shuttle loads), for say 10 years.  Thus
>>you have a total delivery requirement of 750 tons, or 750,000 kg.
>>To find total cost, we need to add recurring and development costs,
>>with the development cost spread over the launched mass:

>This neglects  the use of pre-existing systems (e.g. ones where the
>development costs have already been paid for.)

>But more importantly, you are treating the Space Station as a constant-mass
>payload, which need only be delivered to orbit. Assembling the pieces
>will also be required, and clearly assembly of 75 10-tonne pieces is
>much harder than assembly of (say) 15 50-tonne pieces.

>I suspect the difference in costs (which was only around a 10% difference
>between 10 and 25 tonne payloads) would be overshadowed by the changes
>in on orbit assembly costs.

I'm sorry I wasn't clear enough in my original posting.  The mass of the
Space Station at assembly complete is about 200 tons.  The rest of the
mass represents supplies, experiments, and orbit maintenance propellant.
The five flights per year is the figure being planned for by the space
station logistics people.

My intent in the posting was was to show that the development cost has
to be considered in any launch vehicle selection.  At the traffic rates
for the space station support job, the optimal new vehicle size is
pretty small.  Note that in the 1986 study I worked on, we considered
F1 and F1-A engines as booster engines.  They turned out to be un-economic
for the job we were designing for - launching a combined SDI and civilian
traffic model.  The actual answer we got was that for mostly eastern
launches you actually want a fully reuseable two stage shuttle, sized
so it flies about 20-25 times per year (take your total annual traffic
and divide by 20-25, and that gives you the payload size).  This rule
holds across a range of vehicle sizes for this reason:

As you go to larger and larger rockets, you still have to develop them,
build them and launch them.  The test facilities, assembly buildings,
and launch pads all get bigger the larger the rocket gets, and thus cost
more.  You want to spread these fixed costs over a large number of
launches to minimze them.  On the other hand, launch operations costs
tend to go with the number of launches, not the size of the vehicle.
The point where the incremental facilities cost balances the incremental
operations cost comes out to 200-250 launches.  If you project a 10
year operating life, then you size for 20-25 launches per year.

Another reason for getting to rates of 2 a month is production efficiency.
The 737 production line takes 20-30 days to run the aircraft from delivery
of sections (fuselage sections, wings, landing gear), through installation
of systems (engines, avionics), to rolling a near-complete aircraft out
the door (it can fly, but painting, and customer-specific items get put
in elsewhere).  During this time the aiplane moves through several
'stations' in the assembly line, spending a few days at each station.

So, the assembly stations, which are all needed, have natural rates
of several a month.  If you build at a much lower rate, like 6 times
a year, your factory is not being used efficiently.  I maintain that
a rocket is inherently simpler than an airplane to build, and therefore
the efficient factory production rate will be even higher.

I agree with your comment about simplicity of assembly.  It is even
stronger than you state. A Station built of larger pieces actually
will mass less than one built of smaller pieces, since you eliminate
the connectors (electrical, hatches, etc) between sections.  This tends
to make larger launch vehicles look more attractive than otherwise.
To my knowlege, no one has ever taken a combined look at Space Station
and launch vehicle costs to look for a global optimum (after all, the
programs are under different associate administrators).  The Space
Station has mandated from the beginning that they will use the Space
Shuttle for delivery, so the question never was asked.

Dani Eder

--
Dani Eder/Boeing/Advanced Civil Space/[phone](w)/232-7467(h)/
Rt.1, Box 188-2, Athens AL 35611/Member: Space Studies Institute
Physical Location: 34deg 37' N 86deg 43' W +100m alt.
***THE ABOVE IS NOT THE OPINION OF THE BOEING COMPANY OR ITS MANAGEMENT.***

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

Date: 2 Sep 92 14:41:54 GMT
From: "Frederick A. Ringwald" <[e-mail]>
Subject: SPS
Newsgroups: sci.space

In article <[e-mail]>
[e-mail] (John Roberts) writes:

> -SPS is also not without its own unique problems. Microwave power
> -transmission presents safety problems, and terawatts of transmitted
> -power may well generate enough static to interfere with
> -telecommunications, not to mention cause the demise of ground-based
> -(i.e., inexpensive) radio astronomy.
>
> You would handle it like microwave ovens - allocate a narrow frequency
> band for the transmission of power. Well away from that band, there
> shouldn't be much of a problem.

Well, I don't know. The 1991 November Physics Today (v.44, p. 41)
addresses this issue in an article on interference in radio astronomy.
Of course, radio astronomers have very low thresholds of pain, but
we're talking gigawatts-to-terawatts of power, more than enough to
generate plenty of static even far off band. The particulars will
depend on the particular transmitters: masers or lasers might help
here, but even so, I think we've got more immediate problems to worry
about.

Like for example, why is ground-based astronomy in the U.S. being
allowed to die on the vine, and just as revolutionary new techniques
are coming out? These include 8-m class telescopes and adaptive optics,
both of which will rival Hubble Space Telescope in power in the optical
and near-IR (but importantly, not in the UV), and at a tiny fraction of
its cost.

This throws plans for astronomy from the Moon, on the cover of the 1992
September Sky & Telescope, into sharp relief: nothing like the cold
light of reality intruding into otherwise neat ideas. If you can't
afford a $30 million a year program of demonstrated scientific merit,
how are you going to construct a $100 billion plus base, except
strictly as a paper dream? (Yeah, I know, they could take over 3000
years to do it...and in the meantime, do no science at all!)

Fred

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

Date: 02 Sep 1992 10:07:38 -0500 (EST)
From: I'll get you my pretty and your little dog too!!!
Subject: Whales and Dolphins...again...

Guys, I don't mean to flame, but this is the Space digest and not the
PETA/ALF list.  I don't think discussions on the intellegence of whales
and the ethics of their use in experiments belong on here.

Thanks,

Deb

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

Date: Wed, 2 Sep 1992 11:26:00 GMT
From: pete <[e-mail]>
Subject: What is the speed of light measured from?
Newsgroups: sci.space

In article <[e-mail]>, [e-mail]
(Steven Moon) writes...
>In article <[e-mail]>,
[e-mail] (pete) writes:
>
>|> 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
>
>This is not true.

Yes it is. Work it out.

>In order to measure the velocity of your 'wonderful' rocket
>you must make some measurements.  You take you watch and meter stick and measure
>some object at rest w.r.t. the inertial frame you started in (say the Universe)
>So measure the position of some Star at two different times.  You will not
>come up with some velocity > c.

Neglecting the engineering problems of high speed travel through an
imperfect vacuum, you can travel light centuries in subjective
hours if you accelerate long enough. If you arrive at the Andromeda
galaxy 2 weeks after leaving earth, you could be justified in
thinking you travelled faster than c. It's just that the rest of
the universe will have aged 2x10^8 years.

>|> 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).
>
>I would suggest brushing up on your SR.  A.P.French's book is, in my
>opinion, one  of the best.  Some wonderful light reading would include 'Mr.
>Tompkins in Paperback.'  The first story is about a place where the speed of light
>is quite small and SR effects can be observed with a bike.

I will not respond in a similar vein. Rather than impune your
understanding of physics I will give you the benefit of the doubt
that you simply misunderstood me.
>
>|>     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.
>
>I, honestly don't know how to respond to this.

You could start by losing your atitude.

>Study special relativity.
>Getting all your information second hand from popularized books and TV shows
>is quite dangerous.

So is learning the math without acquiring a visceral grasp
of the subject.
>
===========================================================================
A cynic's world is comprised                          Pete Vincent
of fools and other cynics

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

Date: 2 Sep 92 15:43:30 GMT
From: Brad Wallet <[e-mail]>
Subject: What is the speed of light measured from?
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Richard Ottolini) writes:
|> In article <[e-mail]> [e-mail] (pete) writes:
|> >Neglecting the engineering problems of high speed travel through an
|> >imperfect vacuum, you can travel light centuries in subjective
|> >hours if you accelerate long enough. If you arrive at the Andromeda
|> >galaxy 2 weeks after leaving earth, you could be justified in
|> >thinking you travelled faster than c. It's just that the rest of
|> >the universe will have aged 2x10^8 years.
|>
|> No. You would not feel you are going faaster, but the universe got smaller
|> and slower.  These are stardard result of Special Relativity.


Bare with me a second because I am not a physicist.  Why can't it be said
that the frame containing the Earth was moving relative to the traveller's
frame.  If this is the case, the traveller would age more than the Earth.

-------------------------------------------------
Brad Wallet                 Mathematician
[e-mail] Naval Surface Warfare Center
[phone]               (AVN)249-4950
DSMAC - "Tomahawk's Eyes"

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End of Space Digest Volume 15 : Issue 158
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