Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/jplnews/0393.ZIP/0393.PR

Text File | 1993-04-21 | 14KB | 254 lines

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

FOR RELEASE:  After 11:00 A.M., PDT, Thursday, June 16, 1966.

         The National Aeronautics and Space Administration's
Surveyor I spacecraft made a perfect low-speed, three-point
landing on the moon on June 1, 1966, after a 63-hour, 36-minute
flight from Cape Kennedy.
         During the following 12 days and 10 hours, before the
sun set on Surveyor's landing site in the Ocean of Storms last
Tuesday, the sps survey television camera scanned for
transmission to Earth 10,338 high-resolution pictures of the
lunar surface.
         With its camera shut down for the duration of the
two-week-long lunar night, Surveyor is now periodiclly queried
concerning its condition--voltages, temperatures and battery
power capacity--by round-the-world stations of NASA's Deep
Space Network.
         In a few days, the spacecraft will go deeper into
"hibernation", conserving its stored electrical energy and
expending only enough to keep itself warm in an effort to
survive the long, cold night.  The only systems which will
function in this power-conservation fashion are the radio
receivers to accept Earth commands at lunar dawn and thermal
control heaters for the protection of temperature-sensitive  L

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electronics.  The surface of the moon reaches a temperature of
about 260 degrees F. below zero at lunar midnight.
         Designed and built for NASA by the Hughes Aircraft
Company of Culver City, California, under technical direction
of the Jet Propulsion Laboratory, Surveyor greatly exceeded its
primary objectives by gathering surface data necessary to the
Apollo manned lunar landing program.
         The first of seven lunar soft landing missions planned
for 1966 and 1967, Surveyor I was designated an engineering
test flight for demonstration of the Atlas-Centaur launch
vehicle; mid-course and terminal maneuvers by the spacecraft; a
radar-and-rocket-controlled soft landing; and maintenance of
constant communications between the spacecraft and the Deep
Space Network ground stations during the flight and after
landing.
         Surveyor I lifted off Pad 36-A at Cape Kennedy within
one second of its planned launch time--7:41:01 a.m. Pacific
Daylight Time--on May 30.
         The perfect countdown was followed by a boost into
space by the Atlas-Centaur that would have put the spacecraft
on the moon within 250 miles of the aiming point.  The precise
launch made the requirement for a trajectory correction some 16
hours later one of minimum proportion.  At the mid-course man-
euver, the velocity change was 45 miles per hour, only a
fraction of which was applied to the slight injection error. T

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         All launch vehicle and spacecraft events through
Canopus acquisition occurred satisfactorily and at nominal
times with the exception of the deployment of one of Surveyor's
two low-gain omnidirectional antennas.
         Both antennas and the spacecraft's three landing legs
were commanded by the Centaur programmer about 12 minutes after
liftoff to extend from their folded launch position to the
flight and landing position.  Signal strength received from the
transmitter connected to Antenna A indicated that it apparently
had not deployed fully, if at all.
         Two-way communications lock--ground command capabilit-
ity--was achieved by the Deep Space Net station in Johannesburg,
South Africa, at liftoff plus 28 minutes, transferring control
of the mission from the Eastern Test Range to the Space Flight
Operations Facility at the Jet Propulsion Laboratory in Pasa-
dena, California.  Commands were transmitted immediately to
Surveyor to deploy the antenna in question, but telemetry and
signal strength readings indicated no change.
         Although the minor faiure was not expected to jeopard-
ize the mission--either from the standpoint of communications
or the slight change in the spacecraft's center of gravity--the
exact position of Antenna A remained undetermined throughout
the flight, a concern in itself.
         (Later, however, after Surveyor I touched gently down
on the moon, signal strength from the antenna had risen to
normal, indicating that it was properly extended.  Television  X

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pictures from Surveyor's camera of the both the antenna and its
latching mechanism provided verification of this.  It remains
unknown whether the antenna deployed during retro fire or upon
spacecraft contact with the lunar surface.)
         Surveyor's original aiming point was 3.25 degrees
south of the lunar equator and 43.83 degrees W. Longitude in
the southwest portion of the Ocean of Storms.  In planning the
mid-course maneuver, executed at 11:45 p.m. PDT May 30, the
Surveyor space science analysis team selected a new target
about one degree farther north in latitude.  The new coord-
inates were 2.33 degrees South, 43.83 degrees West, a point
scientists expected to be smooth enough for a safe land-
ing.  Tracking data throughout the remainder of the flight
indicated Surveyor landed at 2.356 degrees South and 43.36
degrees West, about nine miles from the modified aiming point.
         The critical terminal descent began 31 minutes and
2000 miles from the moon at 10:46 p.m. PDT June 1 with roll and
yaw maneuvers to align Surveyor's retro rocket with its approach
direction, just five degrees from vertical.
         At 11:14 and 39 seconds, an altitude marking radar
sensed the nearness of the moon--59.35 miles altitude--and
started the automatic sequence that fired the spacecraft's main
retro motor 10 seconds later.
         The 9000-pound-thrust solid propellant rocket ignited
at two minutes and 46 seconds before touchdown when Surveyor I
was 46.75 miles above the moon and travelling at a velocity of
5840 miles per hour. V

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         The 38-second main retro phase slowed the spacecraft
to 267 miles an hour at 35,000 feet altitude.  The rocket motor
case was ejected at 31,000 feet, and three smaller rocket
engines, which stabilized the spacecraft during main retro fire
and earlier powered the mid-course maneuver, continued to slow
the descent.
         Throttled by information from Surveyor's radar alti-
meter and doppler velocity sensor (RADVS), the verniers reduced
the spacecraft's speed to 71.4 miles per hour at 1000 feet
altitude and 2.8 miles an hour when they cut off about 10 feet
above the surface.
         Surveyor free-fell the last 10 feet of the flight, its
first leg touching the lunar surface at 11:17:35.651 p.m. PDT.
Within 19 milliseconds it had three feet on the moon.  Landing
speed was about 7.5 miles per hour.
         Strain gauge readings from the three landing legs re-
corded a "second touchdown" less than one second later, indi-
cating that the spacecraft bounced about four or five inches.
         Television pictures taken by Surveyor during the next
several weeks showed that at least one of the three crushable
blocks under its frame gouged the lunar surface as the shock
absorbers compressed at touchdown.  The aluminum honeycomb
block made a "cookie cutter" imprint on the moon just below the
spacecraft.
         After a series of engineering interrogations to
confirm that all spacecraft system had indeed survived the  V

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landing, Surveyor I took the first of more than 10,000 pictures
at 11:53 p.m. PDT June 1.  The 200-scan-line, wide-angle (25-
degree field of view) picture showed a portion of the space-
craft framed against the surface of the moon.
         Thirteen additional 200-line pictures were transmitted
to the Pioneer station of the Goldstone Space Communications
Complex in California before the solar panel was positioned for
power conversion and Surveyor's high-gain antenna was poined at
the Earth for transmission of higher quality 600-line pictures.
         With the high-gain antenna so positioned and the ease
with which it was maneuvered during the following days, the
Surveyor camera never returned to the 200-line mode.  Picture
count at lunar sunset on June 14 was 200-line pictures, 14;
600-line pictures, 10,324.
         A scan conversion system at JPL made it possible to
display Surveyor pictures in real time on conventional TV
monitors at the Laboratory as they were relayed from the moon
via microwave from Goldstone.  During the night of June 1 and
the morning hours of June 2 when Surveyor took its first 144
pictures, commercial television networks further relayed the
live lunar program throughout the nation.  The Early Bird
satellite carried the pictures even further--to Europe.
         Nearly all the television pictures were commanded and
recorded by the Goldstone station during communications periods
that varied from 8 to 10 hours each day.  A few picture
sequences originated at the Deep Space Net station at Canberra,
\

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Australia, which, along with the Johannesburg station, served
as prime monitors of engineering telemetry from Surveyor.  The
Madrid, Spain, station and the Mars Site (210-foot antenna) at
Goldstone were backup stations during the mission.
         More than 82,000 ground commands to Surveyor were
transmitted from the Goldstone station from May 30 to June 14.
During its most productive session over Goldstone, last Friday,
Surveyor took 1758 pictures of the moon and received and acted
upon more than 12,000 commands.  Six hours and 37 minutes of
the 10-hour, 20-minute communications pass were devoted to
picture transmission.
         Early in the mission, it was expected that the camera
would necessarily be shut down for several days at lunar mid-day
because of the extreme heat.  However, at lunar high noon on
June 7, as the moon's surface temperature approached 250 degrees
F., the camera was shaded by the solar panel and the high-gain
antenna and continued to operate within its thermal limits.
The camera was de-activated June 8 and 9 when it was exposed to
the sun.
         In addition to the lunar surface pictures taken by
Surveyor's camera from its vantage point only four feet above
the surface, the spacecraft performed a number of other post-
landing operations.  Moon's-eye views of the bright stars Sirius
and Canopus were photographed by the camera in an effort to
ascertain more closely the exact location of Surveyor on the
lunar surface. \

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         On June 6, an attempt was made to photograph a portion
of the Earth, but the planet was just out of view, above the
elevation range of the tilting mirror of the camera.
         Several attempts were made to disturb the lunar surface
or create a small dust cloud near one of the spacecraft's three
landing feet by firing bursts of nitrogen gas from Surveyor's
attitude control jets.  No disturbance or dust was discernible
in TV pictures taken during and after the firings.
         Because of the continuing excellent condition of the
spacecraft after it had operated on the moon for more than a
week, it became apparent that Surveyor had a strong chance of
surviving the lunar night.  This possibility was taken into
account during formulation of plans for the spacecraft's
opration on the final day of sunlight June 14.
         During the final Goldstone pass, the camera recorded
another 523 pictures as the sun sank lower toward the horizon.
Many of the pictures taken with the low sun behind the space-
craft showed perfect silhouettes of Surveyor shadowed against
the moon's surface.
         At lunar sunset, 9:18 a.m. PDT June 14, the camera was
commanded to point toward that portion of the horizon where the
fireball disappeared and a number of pictures were taken of the
solar corona, the sun's upper atmosphere.
         Surveyor I made its last picture at 9:37 a.m. PDT after
night had fallen on the spacecraft's small segment of the Ocean
of Storms.  A single picture, taken in the camera's special  Z

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"integrated mode" with a four-minute exposure time, portrayed
Surveyor's footpad No. 2 lighted only by the sun's reflection
off the Earth.
         When the camera was turned off for the 14-day-long
lunar night, temperatures already were dropping rapidly on the
spacecraft.  The battery, however, was nearly fully charged
with a capacity of 162 ampere hours.  Maximum capacity of the
battery is 165 hours.  At touchdown on June 1, telemetry
indicated 57 ampere hours.
         If Surveyor survives the night, it is expected that
several days after dawn it will have "defrosted" to the point
where a slow charge of the battery from the solar cells might
spring the spacecraft back to life.  The solar panel has been
positioned so that the sun will not strike the power-converting
cells, sending a sudden surge of current into the chilled
electronics systems.
         With the radio receivers still operating, ground
commands would slowly step the panel toward the sun for a slow
and easy charge and possibly another lunar day of life for
Surveyor I.

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JPL Release No. 393
6/21/66 L