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Subject: SPACE Digest V13 #684

SPACE Digest                                     Volume 13 : Issue 684

Today's Topics:
 Re: Missing the point about tethers (was Re: SPACE Digest V13 #541)
      Information sources for frequent space questions (2 of n)

Administrivia:

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Date: 2 Jun 91 00:56:56 GMT
From: agate!spool.mu.edu!think.com!rpi!news-server.csri.toronto.edu!utgpu!utzoo!utdoe!torag!w-dnes![e-mail]  (Walter Dnes )
Subject: Re: Missing the point about tethers (was Re: SPACE Digest V13 #541)

[e-mail] (Ron Carter) writes:

> In article <[e-mail]> [e-mail] (Walter Dnes) write
  ...
> >assume that the first tether is a 1-meter-thick cable 500km long.
>
> What do you need a 1 meter thick cable for?  And why 500 km?

     There are times when it's best to admit that I've goofed and
cut my losses. I'll admit that when I jumped into this thread, I
wasn't familiar with the concept of tether-tapering. The
assumption of a non-tapered tether led to some ridiculous results
in my calculations. I apologize for wasting bandwidth. I'll admit
that tethers are theoretically possible. There will obviously be
teething problems, as with any new technology. Assuming that we
learn how to make properly tapered cables of sufficient length,
the only question is whether the final operating version will
result in sufficient energy savings to pay for itself.
     As for "beanstalks", I stand by my message of May 31. There
are severe *PRACTICAL* challenges which look very daunting at the
present moment.

Walter Dnes
-------------------------
[e-mail]
[e-mail]

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Date: 2 Jun 91 11:32:07 GMT
From: data.nas.nasa.gov!amelia![e-mail]  (Eugene N. Miya)
Subject: Information sources for frequent space questions (2 of n)


   Subject: Planetary Probe posting for Frequently Asked Questions

    XXX asked the following questions about these planetary space probes:

    >> Viking 1,2    1975    Still sending any signals?
    >>            If not, when did they stop?

    VIKING 1 was launched from Cape Canaveral, Florida on August 20,
1975 on a TITAN 3E-CENTAUR D1 rocket.  The probe went into Martian
orbit on June 19, 1976, and the lander set down on the western slopes
of Chryse Planitia on July 20, 1976.  It soon began its programmed
search for Martian micro-organisms (there is still debate as to whether
the probes found life there or not), and sent back incredible color
panoramas of its surroundings.  One thing scientists learned was that
Mars' sky was pinkish in color, not dark blue as they originally
thought (the sky is pink due to sunlight reflecting off the reddish
dust particles in the thin atmosphere).

    The VIKING 1 orbiter kept functioning until August 7, 1980, when
it ran out of attitude-control propellant.  The lander was switched
into a weather-reporting mode, where it had been hoped it would keep
functioning through 1994; but after November 13, 1982, an errant
command had been sent to the lander accidentally telling it to shut
down until further orders.  Communication was never regained again,
despite the engineers' efforts through May of 1983.

    An interesting side note:  VIKING 1's lander has been designated
the Thomas A. Mutch Memorial Station in honor of the late leader of the
lander imaging team.  The National Air and Space Museum in Washington,
D.C. is entrusted with the safekeeping of the Mutch Station Plaque
until it can be attached to the lander by a manned expedition.

    VIKING 2 was launched on September 9, 1975, and arrived in Martian
orbit on August 7, 1976.  The lander touched down on September 3, 1976
in Utopia Planitia.  It accomplished essentially the same tasks as its
sister lander, with the exception that its seisometer worked, recording
one marsquake.  The orbiter had a series of attitude-control gas leaks
in 1978, which prompted it being shut down that July.  The lander was
shut down on April 12, 1980.

    The orbits of both VIKING orbiters should decay around 2025.

    The next United States Mars mission will be the Mars Observer,
scheduled for launch in 1992.  Although there are no definite U.S.
Mars probe plans after that, some possibilities are a lander which
will return samples of Martian soil to Earth (this may be a
cooperative project with the Soviets), and a rover/walker vehicle,
in preparation for manned missions, which may also be international
in scope.

    >> Mariner 1,2    1962    Did we get any data?

    MARINER 1, the first U.S. attempt to send a spacecraft to Venus,
was destroyed in 1962 over the Atlantic Ocean by the Range Safety
Officer when its rocket veered off course due to a program command
failure.

    MARINER 2 became the first successful probe to flyby Venus in
December of 1962, and it returned information which confirmed that
Venus is a very hot (800 degrees Farenheit, now revised to 900 degrees
F.) world with a cloud-covered atmosphere composed primarily of carbon
dioxide (sulfuric acid was later confirmed in 1973).

    >> 3-7    1963+    Do we even know where they are?

    MARINER 3, launched on November 5, 1964, was lost when its
protective shroud failed to eject as the craft was placed into
interplanetary space.  Unable to collect the Sun's energy for power
from its solar panels, the probe soon died when its batteries ran
out and is now in solar orbit.  It was intended for a Mars flyby.

    MARINER 4, the sister probe to MARINER 3, did reach Mars in
1965 and took the first close-up images of the Martian surface (22
in all) as it flew by the planet.  It is now in solar orbit.

    MARINER 5 was sent to Venus in 1967, and it reconfirmed the data
on that planet collected five years earlier by MARINER 2, plus the
information that Venus' atmospheric pressure at its surface is at
least 90 times that of Earth's, or the equivalent of being 3,300
feet under the surface of an ocean.

    MARINER 6 and 7 were sent to Mars in 1969, and expanded upon
the work done by MARINER 4 four years earlier.

    >> 8        Crashed in the ocean right?

    MARINER 8 ended up in the Atlantic Ocean in 1971 when the rocket
launcher autopilot failed.

    >> 9    1971    What was the mission?

    MARINER 9, the sister probe to MARINER 8, became the first craft
to orbit Mars in 1971.  It returned information on the Red Planet
that no other probe had done before, such as reveal huge volcanoes
on the Martian surface, as well as giant canyon systems, and evidence
that water once flowed across the planet.  The probe also took the
first detailed closeup images of Mars' two moon, Phobos and Deimos.

    >> 10    1973    Venus.  Any data?

    MARINER 10 used Venus as a gravity assist to Mercury in 1974.
The probe did return the first close-up images of the Venusian
atmosphere in ultraviolet, revealing previously unseen details in
the cloud cover, plus the fact that the entire cloud system circles
the planet in four Earth days.

    >>  ??        That's all of them Right?

    Technically, yes, although VOYAGER 1 and 2 were originally
going to be part of the MARINER series (11 and 12), but their names
were changed partly to spark new public interest in the program,
plus the fact that NASA also felt these vehicles were different in
both design and mission scope from the MARINER craft before them
to warrant a new designation.

    >> Pioneer    1-3        Failed moon trajectories?

    Although PIONEER 1 through 3 did fail to meet their main objective,
to photograph the Moon close-up, they did reach far enough into space
to provide new information on the area between Earth and the Moon,
including new data on the Van Allen radiation belts circling Earth.
All three craft had failures with their rocket launchers.  PIONEER 1
was launched on October 11, 1958, PIONEER 2 on November 8, and
PIONEER 3 on December 6.

    >> 4-9        All Moon related?

    PIONEER 4 was a Moon probe which missed the Moon and became
the first U.S. spacecraft to orbit the Sun in 1959.  PIONEER 5 was
originally designed to flyby Venus, but the mission was scaled down
and it instead studied the interplanetary environment between Venus
and Earth out to 33 million miles in 1960, a record until MARINER 2.
PIONEER 6 through 9 were placed into solar orbit from 1965 to 1968:
PIONEER 6 and 8 are still transmitting information at this time.
PIONEER E (would have been 10) suffered a launch failure in 1969.

    >> 10,11        Jupiter,Saturn Still operating?

    PIONEER 10 became the first spacecraft to flyby Jupiter in 1973.
PIONEER 11 followed it in 1974, and then went on to become the first
probe to study Saturn in 1979.  Both vehicles are still functioning
and are heading off into interstellar space, the first craft to do so.

    >> Pioneer
    >> Venus    1    1978    Where are they now? How do you know?
    >> Venus    2        Probes released? What about them?

    PIONEER Venus 1 (also known as PIONEER Venus Orbiter, or PIONEER
12) is still orbiting Venus and returning data to Earth.  It is
expected to enter the Venusian atmosphere and burn up by 1991.
PVO made the first radar studies of the planet's surface via probe.
PIONEER Venus 2 (also known as PIONEER 13) sent four small probes
into the atmosphere in December of 1978.  The main spacecraft bus
burned up high in the atmosphere, while the four probes descended
by parachute towards the surface.  Though none were expected to
survive to the surface, the Day probe did make it and transmitted
for 67 minutes on the ground before succumbing to the intense surface
heat.  I only know what NASA tells me. :^)

    >> Ranger    3-9    1965+    All Moon related?  Any data coming in?

    RANGER 3, launched on January 26, 1962, was intended to land an
instrument capsule on the surface of the Moon, but problems during the
launch caused the probe to miss the Moon and head into solar orbit.
RANGER 3 did try to take some images of the Moon as it flew by, but
the camera was unfortunately aimed at deep space during the attempt.

    RANGER 4 had the same purpose as RANGER 3, but suffered technical
problems enroute and crashed on the lunar farside, the first U.S.
probe to reach the Moon, albeit without returning data.

    RANGER 5 also contained a capsule lander, but it too had launch
problems that forced it to miss the Moon and go into solar orbit.

    RANGER 6 through 9 were more modified lunar missions:  They
were to send back live images of the lunar surface as they headed
towards an impact with the Moon.  RANGER 6 failed this objective
in 1964 when its cameras did not operate, but RANGER 7 through 9
performed well, returning thousands of lunar images through 1965,
the first U.S. Moon probes to do so.

    >> Lunar Orbiter        ???? What was this for?

    LUNAR ORBITER 1 through 5 were designed to orbit the Moon and
image various sites being studied as landing areas for the manned
APOLLO missions of 1969-1972.  The probes also contributed greatly
to our understanding of lunar surface features, particularly the
lunar farside.  All five probes of the series, launched from 1966
to 1967, were essentially successful in their missions.  They were
also the first U.S. probes to orbit the Moon.

    >> Surveyor    1968    Just for landing site research?

    The SURVEYOR series were designed primarily to see if an APOLLO
lunar module could land on the surface of the Moon without sinking
into the soil (before this time, it was feared by some that the Moon
was covered in great layers of dust, which would not support a heavy
landing vehicle).  SURVEYOR was successful in proving that the lunar
surface was strong enough to hold up a spacecraft.

    Only SURVEYOR 2 and 4 were unsuccessful missions.  The rest became
the first U.S. probes to soft land on the Moon, taking thousands of
images and scooping the soil for analysis.  APOLLO 12 landed 600 feet
from SURVEYOR 3 in 1969 and returned parts of the craft to Earth.
SURVEYOR 7, the last of the series, was a purely scientific mission
which explored the Tycho crater region in 1968.

    >> SOVIET PROBES:  Any info at all would be interesting.
    >>            Luna
    >>            Venera
    >>            Mars
    >>            Others?

    Since there have been so many Soviet probes to the Moon, Venus,
 and Mars, I will highlight only the primary missions:

    Moon -

    LUNA 1 - Lunar impact attempt in 1959, missed Moon and became
             first craft in solar orbit.

    LUNA 2 - First craft to impact on lunar surface in 1959.

    LUNA 3 - Took first images of lunar farside in 1959.

    ZOND 3 - Took first images of lunar farside in 1965 since
             LUNA 3.  Was also a test for future Mars missions.

    LUNA 9 - First probe to soft land on the Moon in 1966, returned
             images from surface.

    LUNA 10 - First probe to orbit the Moon in 1966.

    LUNA 13 - Second successful Soviet lunar soft landing mission in 1966.

    ZOND 5 - First successful circumlunar craft.  ZOND 6 through 8
             accomplished similar missions through 1970.  The probes
             were unmanned tests of a manned SOYUZ-type lunar vehicle.
             The project was abandoned in 1975.

    LUNA 16 - First probe to land on Moon and return samples of
              lunar soil to Earth in 1970.  LUNA 20 accomplished
              similar mission in 1972.

    LUNA 17 - Delivered the first unmanned lunar rover to the Moon's
              surface, LUNOKHOD 1, in 1970.  A similar feat was
              accomplished with LUNA 21/LUNOKHOD 2 in 1973.

    LUNA 24 - Last Soviet lunar mission to date.  Returned soil samples
              in 1976.

    Venus -

    VENERA 1 - First acknowledged attempt at Venus mission.
               Transmissions lost enroute in 1961.

    VENERA 3 - Attempt to place a lander capsule on Venusian surface.
               Transmissions ceased just before encounter and entire
               probe became the first craft to impact on another
               planet in 1966.

    VENERA 4 - First probe to successfully return data while
               descending through Venusian atmosphere.  Crushed
               by air pressure before reaching surface in 1967.
               VENERA 5 and 6 mission profiles similar in 1969.

    VENERA 7 - First probe to return data from the surface of
               another planet in 1970.  VENERA 8 accomplished
               a similar mission in 1972.

    VENERA 9 - Sent first image of Venusian surface in 1975.
               Was also the first probe to orbit Venus.
               VENERA 10 accomplished similar mission.

    VENERA 13 - Returned first color images of Venusian surface
                in 1982.  VENERA 14 accomplished similar mission.

    VENERA 15 - Accomplished radar mapping with VENERA 16 of sections
                of planet's surface in 1983 more detailed than PVO.

    VEGA 1 - Accomplished with VEGA 2 first balloon probes of
             Venusian atmosphere in 1985, including two landers.
             Flyby buses went on to become first spacecraft to
             study Comet Halley close-up in 1986.

    Mars -

    MARS 1 - First acknowledged Mars probe in 1962.  Transmissions
             ceased enroute the following year.

    ZOND 2 - First possible attempt to place a lander capsule on
             Martian surface.  Probe signals ceased enroute in 1965.

    MARS 2 - First Soviet Mars probe to land - albeit crash - on
             Martian surface.  Orbiter section first Soviet probe
             to circle the Red Planet in 1971.

    MARS 3 - First successful soft landing on Martian surface, but
             lander signals ceased after 90 seconds in 1971.

    MARS 4 - Attempt at orbiting Mars in 1974, braking rockets
             failed to fire, probe went on into solar orbit.

    MARS 5 - First fully successful Soviet Mars mission, orbiting Mars
             in 1974.  Returned images of Martian surface comparable to
             U.S. probe MARINER 9.

    MARS 6 - Landing attempt in 1974.  Lander crashed into the surface.

    MARS 7 - Lander missed Mars completely in 1974, went into a solar
             orbit with its flyby bus.

    PHOBOS 1 - First attempt to land probes on surface of Mars'
               largest moon, Phobos.  Probe failed enroute in 1988
               due to human/computer error.

    PHOBOS 2 - Attempt to land probes on Martian moon Phobos.  The
               probe did enter Mars orbit in early 1989, but signals
               ceased one week before scheduled Phobos landing.

    While there has been talk of Soviet Jupiter, Saturn, and even
interstellar probes within the next thirty years, no major steps have
yet been taken with these projects.  More intensive studies of Mars,
Venus, and various comets are planned for the 1990s, and even a Mercury
mission to orbit and land probes on the tiny world is planned for 2003.

    I also recommend reading the following works, categorized in three
groups:  General overviews, specific books on particular space missions,
and periodical sources on space probes.  This list is by no means
complete; it is primarily designed to give you places to start your
research through generally available works on the subject.  If anyone
can add pertinent works to the list, it would be greatly appreciated.

    Though naturally I recommend all the books listed below, I think
it would be best if you started out with the general overview books,
in order to give you a clear idea of the history of space exploration
in this area.  I also recommend that you pick up some good, up-to-date
general works on astronomy and the Sol system, to give you some extra
background.  Most of these books and periodicals can be found in any
good public and university library.  Some of the more recently published
works can also be purchased in and/or ordered through any good mass-
market bookstore.

    General Overviews (in alphabetical order by author):

      J. Kelly Beatty et al, THE NEW SOLAR SYSTEM, 1990.

      Merton E. Davies and Bruce C. Murray, THE VIEW FROM SPACE:
       PHOTOGRAPHIC EXPLORATION OF THE PLANETS, 1971

      Kenneth Gatland, THE ILLUSTRATED ENCYCLOPEDIA OF SPACE
       TECHNOLOGY, 1981

      Kenneth Gatland, ROBOT EXPLORERS, 1972

      R. Greeley, PLANETARY LANDSCAPES, 1987

      Douglas Hart, THE ENCYCLOPEDIA OF SOVIET SPACECRAFT, 1987

      Nicholas L. Johnson, HANDBOOK OF SOVIET LUNAR AND PLANETARY
       EXPLORATION, 1979

      Clayton R. Koppes, JPL AND THE AMERICAN SPACE PROGRAM: A
       HISTORY OF THE JET PROPULSION LABORATORY, 1982

      Richard S. Lewis, THE ILLUSTRATED ENCYCLOPEDIA OF THE
       UNIVERSE, 1983

      Mark Littman, PLANETS BEYOND: DISCOVERING THE OUTER SOLAR
       SYSTEM, 1988

      Eugene F. Mallove and Gregory L. Matloff, THE STARFLIGHT
       HANDBOOK: A PIONEER'S GUIDE TO INTERSTELLAR TRAVEL, 1989

      Frank Miles and Nicholas Booth, RACE TO MARS: THE MARS
       FLIGHT ATLAS, 1988

      Bruce Murray, JOURNEY INTO SPACE, 1989

      Oran W. Nicks, FAR TRAVELERS, 1985 (NASA SP-480)

      James E. Oberg, UNCOVERING SOVIET DISASTERS: EXPLORING THE
       LIMITS OF GLASNOST, 1988

      Carl Sagan, COMET, 1986

      Carl Sagan, THE COSMIC CONNECTION, 1973

      Carl Sagan, PLANETS, 1969 (LIFE Science Library)

      Arthur Smith, PLANETARY EXPLORATION: THIRTY YEARS OF UNMANNED
       SPACE PROBES, 1988

      Andrew Wilson, (JANE'S) SOLAR SYSTEM LOG, 1987

    Specific Mission References:

      Charles A. Cross and Patrick Moore, THE ATLAS OF MERCURY, 1977
       (The MARINER 10 mission to Venus and Mercury, 1973-1975)

      Joel Davis, FLYBY: THE INTERPLANETARY ODYSSEY OF VOYAGER 2, 1987

      Irl Newlan, FIRST TO VENUS: THE STORY OF MARINER 2, 1963

      Margaret Poynter and Arthur L. Lane, VOYAGER: THE STORY OF A
       SPACE MISSION, 1984

      Carl Sagan, MURMURS OF EARTH, 1978 (Deals with the Earth
       information records placed on VOYAGER 1 and 2 in case the
       probes are found by intelligences in interstellar space,
       as well as the probes and planetary mission objectives
       themselves.)

    Other works and periodicals:

    NASA has published very detailed and technical books on every
space probe mission it has launched.  Good university libraries will
carry these books, and they are easily found simply by knowing which
mission you wish to read about.  I recommend these works after you
first study some of the books listed above.

    Some periodicals I recommend for reading on space probes are
NATIONAL GEOGRAPHIC, which has written articles on the PIONEER probes
to Earth's Moon Luna and the Jovian planets Jupiter and Saturn, the
RANGER, SURVEYOR, LUNAR ORBITER, and APOLLO missions to Luna, the
MARINER missions to Mercury, Venus, and Mars, the VIKING probes to
Mars, and the VOYAGER missions to Jupiter, Saturn, Uranus, and Neptune.

    More details on American, Soviet, European, and Japanese probe
missions can be found in SKY AND TELESCOPE, ASTRONOMY, SCIENCE, NATURE,
and SCIENTIFIC AMERICAN magazines.  TIME, NEWSWEEK, and various major
newspapers can supply not only general information on certain missions,
but also show you what else was going on with Earth at the time events
were unfolding, if that is of interest to you.  Space missions are
affected by numerous political, economic, and climatic factors, as
you probably know.

    Depending on just how far your interest in space probes will go,
you might also wish to join The Planetary Society, one of the largest
space groups in the world dedicated to planetary exploration. Their
periodical, THE PLANETARY REPORT, details the latest space probe
missions.  Write to The Planetary Society, 65 North Catalina Avenue,
Pasadena, California 91106 USA.

    Good luck with your studies in this area of space exploration.
I personally find planetary missions to be one of the more exciting
areas in this field, and the benefits human society has and will
receive from it are incredible, with many yet to be realized.

    Larry Klaes  [e-mail]

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End of SPACE Digest V13 #684
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