NetNews Usenet Archive 1993 #1/NN_1993_1.iso/spool/sci/space/19143

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From: [e-mail] (Ron Baalke)
Newsgroups: sci.space,sci.astro,alt.sci.planetary,comp.robotics,sci.geo.geology
Subject: Surveyor 7 - 25 Years Ago
Date: 11 Jan 1993 17:27 UT
Organization: Jet Propulsion Laboratory
Lines: 170
Distribution: world
Message-ID: <[e-mail]>
NNTP-Posting-Host: kelvin.jpl.nasa.gov
Keywords: Surveyor 7, JPL
News-Software: VAX/VMS VNEWS 1.41

This is in honor of Surveyor 7, which was launched and landed
on the Moon 25 years ago.
-----------------------------------------------------------------

OFFICE OF PUBLIC INFORMATION
JET PROPULSION LABORATORY, CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA.  TELEPHONE [phone]

Sunday, December 31, 1967

       SURVEYOR VII TO COMBINE DIGGING, CHEMICAL TESTING
                 OF SURFACE OF MOON'S HIGHLANDS

         PASADENA, CALIFORNIA--Surveyor VII will both dig and
analyze the Moon's surface if all goes well next month in the
last and probably most difficult of the United States' series
of lunar surface probes.
         This Surveyor is scheduled to land in the rough south-
west highlands, 18 miles north of Tycho Crater.  The four suc-
cessful Surveyors all have descended in the relatively smooth
equatorial belt designated likely for later Apollo astronaut
landings.
         Scientific investigators of the National Aeronautics
and Space Administration and Caltech's Jet Propulsion Laboratory
hope to satisfy their curiosity about this more formidable area
of the Moon and add to the increasing knowledge of the composi-
tion of the Moon's soil.
         Scientific investigators of the National Aeronautics
and Space Administrations and Caltech's Jet Propulsion Labora-
tory hope to satisfy their curiosity about this more formidable
area of the Moon and add to the increasing knowledge of the
composition of the Moon's soil.
         Surveyor III last April utilized a claw-type digger to
probe the hardness of the lunar surface.  Dr. Ronald F. Scott,
Caltech civil engineering professor and experimenter on the
sampling device, said the digging showed the surface material
was granular and slightly cohesive, not unlike some Earth soil.
         The ASI readings from Surveyors V and VI indicate that
the lunar material analyzed is similar to terrestrial basalts
and basaltic achrondite, Dr. Anthony L. Turkevich, University of
Chicago, principal chemical investigator, reports.  The ASI gold
box enables scientists to correlate Moon components with the
chemical elements as well as Earth and meteoritic rock types.
         Basaltic achrondites form a small percentage of all
meteorites that have been found on Earth.  It seems possible to
scientists that they could be fragments of lunar rock, ejected
by the impact of a meteorites on the Moon, Dr. Scott says.
         Surveyor's digger, or surface sampler, operated by
Floyd Robertson, JPL engineer, and Dr. Scott, will scoop up
soil from below the Moon's surface and spread it for the ASI to
analyze.  The plan calls for the claw to dig as deeply as
possible--18 inches is the maximum--as well as scrape surface
material.
         The claw, on the end of a five-foot aluminum flexing
arm, also will be capable of picking up the analyzer box and
putting it down on excavated dirt anywhere within an area of a
few square feet.  On signal from JPL's Goldstone Station, the
claw will grasp a small knob above the box.  The box is attached
to the spacecraft by a nylon cord.
         The digger arm can be swung out in a 112-degree sweep,
nearly one-third of a circle.  It can be lifted as high as 40
inches, and dropped to break up clods or rocks.  The falling
scoop can exert a pressure of three pounds per square inch.
Surveyor III tests, however, found lunar rocks that withstood
up to several hundred pounds per square inch when squeezed by
the door of the motor-driven digger.
         Dr. Scott's conclusion about the surface where Surveyor
III landed was that it was mostly fine-grained, slightly cohe-
sive soil much like damp sand found on Earth, with some increase
in firmness and density with depth.  However, Surveyor III's
digger got down only seven inches.
         By digging deeper trenches, Dr. Scott believes it will
be possible to obtain more data on the bearing strength of the
lunar soil.  This is done by computing the difference in
electrical motor current required to move the scoop in various
phases of the digging.
         The bearing strength of the Moon in the four Apollo
belt areas has been measured at 3 to 8 pounds per square inch
at a depth of one to two inches.  It is suspected to be stronger
further down.  At any rate, NASA and JPL scientists now feel
there is no need to worry about the ability of any of the four
sites tested thus far to support astronauts.
         The digger's five-inch claw will have two small
U-shaped magnets at its base.  With the aid of the television
camera aboard, investigators will see whether anything sticks
to the magnets.  Previous Surveyor magnet tests indicate only
about 1/4 of one per cent of the Apollo belt soil is magnetic,
perhaps meteoritic iron.
         The January mission is the most sophisticated in the
Surveyor series.  The camera, digger and ASI all are operated
via the same radio channel, hence they cannot be commanded
simultaneously.  Any station in the JPL Deep Space Network can
give command signals to the camera and the ASI, but only
Goldstone will control the digger.  This limits its operation to
about five hours daily, with a like period allowed for taking
pictures of the excavating.
         The first post-landing day will be occupied with photo-
surveying the landing area near Tycho and warming up the alpha
scattering box for its first 20-hour analysis.  The digger will
be deployed on the second day and start scraping and scooping.
         With luck, the scientists hope to make at least two
thorough analyses of moon soil--at the surface and in depth--in
the first two weeks after the arrival of Surveyor VII.
----------------------------------------------------------------
From the "Solar System Log"

Surveyor 7
Launched: 0630 GMT, January 7, 1968
Vehicle: Atlas-Centaur 15 (Atlas No 5903C)
Site: ETR 36A
Spacecraft Mass: 1040kg at launch, 306kg on landing
Destination: Moon
Mission: Soft Landing
Arrival: Landed 010536 GMT, January 10, 1968, at 40.86 degrees S/47 degrees W.
Payload: TV Camera + stereo mirrors
         Alpha-scattering instrument
         Surface sampler
         Footpad magnet
End of Mission: February 21, 1968 (last contact 0024 GMT)
Notes: Seventh successful lunar lander (fifth U.S.)

     The four successful Surveyors satisfied Apollo requirements in
the Moon's equatorial zone, allowing Surveyor 7 to be released for a
scientific mission.  The ejecta blanket emanating from the bright,
fresh ray crater Tycho on the far south was chosen, the rough highland
region dictating a target area only 20 km in diameter instead of the
60 km of the earlier missions.  For this reason, two course corrections
were planned, but the first was so accurate - leaving Surveyor 7 only
2.5 km off target - that no further alteration was necessary.
     The three-legged vehicle touched at 3.8m/sec some 29 km north of
Tycho's rim after a 66 hour 35 minute flight.  The cameras revealed a
rough area covered in blocks but, surprisingly, with fewer crater than
the mare sites; there was a gentle slope of 3 degrees.  No other
spacecraft has landed further from the equator, a planned late Apollo
mission to Tycho never materializing.
     After 20.9 hours on the surface, a pyrotechnic squib was fired on
command from Earth to drop the alpha-scattering instrument to the
surface, but the spectrometer stayed put.  This was fortuitously the
first flight with both a sample arm and a spectrometer, and the scoop
was used to force the recalcitrant device to the ground.  That arm
later picked it up to analyze a rock and then the soil in a 1 cm deep
trench, accumulating 63 hours of data during the first lunar day.  The
main finding was a lower iron content than at the mare sites.
     The scoop was used in 16 surface bearing-strength tests, dug
seven trenches - one 40 cm long and 15 cm deep - and turned over a
rock.  One rock sample was "weighed" by lifting it and recording the
required motor current; a value of 2.4-3.1 g/cc was obtained.  One
rock was fractured, and on several occasions material stuck to the
two magnets mounted on the scoop.
     Some 20,993 pictures were recorded during the first lunar day
and observations continued for 15 hours after sunset at 0606 GMT
on January 25.  Image of the Earth and the Sun's corona out to
50 solar radii were obtained.  Stereo imaging of small areas
was possible by using a 9x24 cm mirror mounted on the antenna mast,
and on January 20 the TV had registered two 1 W lasers aimed at the
lander from observatories in California and Arizona.  This demonstrated
the feasibility of using lasers for communications and measuring the
Earth-Moon distance with great accuracy (this was done later with
laser reflectors left by Apollo and Lunokhod).
     Surveyor 7 was reactivated at 1901 on February 12, 1968, but
the long, cold lunar night had taken its toll and only another 45
200-line pictures were returned before it succumbed on February 21.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Choose a job you love, and
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | you'll never have to work
|_____|/  |_|/       |_____|/                     | a day in your life.