Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/JPLNEWS1/0464.PR

Text File | 1993-04-21 | 6KB | 113 lines

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

FOR RELEASE:  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,
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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.
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         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
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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.


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