Manned Lunar Roving Vehicle
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,o (ACCESSION"_BER)ROM: News _eau, The Boeing Company
Seattle, Washington 98124
Phone: Area 206, 655-0793 _ ,_
U (NASA CR OR TMX OR AD NUMBER)BACKGROUND INFORMATION
' (CODE)
(CATEGORY)
MANNED LUNAR ROVING VEHICLE
The National Aeronautics and Space Administration is developing a Lunar
Roving Vehicle (LRV) which viii be used to transport two astronauts as they
explore the lunar surface.
The first of three LRVs is scheduled to be carried on the Apollo 15 lunar
mission in July, 1971.
The Lunar Roving Vehicle is being built by The Boeing Company under a
contract awarded by NASA in October, 1969. Boeing's major subcontractor is General
Motors Delco Electronics Division at its Santa Barbara Operations in California.
Design and @evelopment are under direction of the NASA/Marshall Space Flight Center,
Huntsville, Alabama.
EARLY _SIGN STUDIES
Boeing was awarded the Lunar Roving Vehicle assigmment after a design coupe-
tition in which the finalists were Boeing and Bendix Corporation, Ann Arbor, Michigan.
Both organizations had conducted design studies on several types of specialized
spacecraft for travel on the moon's surface before the LRV concept was selected for
further development.
The two most i_portant Boeing studies were MOLAB (Mobile Lunar Laboratory),
196M-65 and LSSM (Local Scientific Survey Module), 1966-67. Both studies were
conducted under the direction of the Marshall Space Flight Center. The MOLAB study
resulted in a fat-wheeled vehicle that was much more than a means of transportation.
It was an enclosed traveling laboratory complete with an atmosphere, food and
equipment. The spacecraft was designed to be rocketed to the lunar surface in
advance of the astronauts by am unmannedLMdescent stage and checked out by remote
control, Each of its six wheels _s ind_vid_a%l!y powered and five feet in dismeter.
Top speed was about i0 miles per hour, similar to that of the _V. The electric,
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powered MOLAB could support two men for trips on the lunar surface of up to two
weeks and 250 miles distance.
LSSM was an open spacecraft designed from the standpoint of weight savings
and dependability. Also electric powered, it was little more than a frame, seat
and six wheels with woven-wire tires. Also with a speed of I0 miles an hour,
this wide-tracked craft was designed to carry only one astronaut (two in an
emergency) on exploration trips over the moon's surface in the interest of science.
The 985-pound craft could range over 200 square miles of moonscape.
SPACECRAFT ON WHEELS
The manned LRV actually being developed is deceptive in appearance. It
looks like a simple, familiar vehicle. In reality it is a specialized spacecraft
that has been designed to function safely in space conditions of vacuum, wide tem-
perature variances and over difficult terrain. By accident of function, it turns
out to be a spacecraft on wheels. It has been built to the exacting specifications
of all Apollo progr_ hardware, and has undergone a development, qualification and
acceptance test procedure to qualify it as a manned spacecraft.
The approximately _80-pound I_nar Roving Vehicle will provide transportation
for the astronauts, scientific equipment and lunar sawples collected during lunar
excursions. The driver will operate the vehicle much as he would on Earth, using
a hand control somewhat llke an aircraft or spacecraft "stick " rather than a
steering wheel. The vehicle will be able to move forward and backward at variable
speeds.
RELIABILITY AND BACKUP SYST_4S FEATURED
Reliability is obtained through simplicity in both design and operation and
through redundancy. For example, there are two complete battery systems, each
sufficient to power the vehicle. The Lunar Roving Vehicle is normally steered by
both the front and rear wheels; however, if one steering mechanism fails, it will
be disconnected and the vehicle can complete its mission using only the remaining
steering system.
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The Lunar Roving Vehicle will be I0 feet 2 inches long, approximately
6 feet wide and have a 7½ foot wheelbase. The four wheels will be individually
powered by electric motors. The vehicle will travel at speeds up to approximately
eight miles an hour on a relatively smooth surface.
SILVER-ZINC BATTERIES POWER SPACECRAFT
The vehicle's power source will be two 36-volt silver-zinc batteries. They
are being developed by Eagle Picher Industries, Electronics Division, Joplin,
Missouri. These are non-rechargeable batteries of plexiglass monoblock construction.
Silver zinc plates operating in potassium hydroxide electrolyte are used. Each
battery is designed for a c_pacity of 121 ampere hours and contains 25 cells. The
case material is magnesium.
Instruments used to measure the amount of discharge of electrical power from
the storage batteries will be supplied by Curtis Instruments, Inc., Mount Kisco,
N. Y.
Unlike the charge/dlscharge indicator on the dashboard of the standard auto-
mobile, these instruments, called ampere hour integrators, will perform a book-
keeping function. They will accumulate the total amount of current drawn from the
batteries and relay the information to a display console located between the seats
of the Rover.
The LRV will be able to carry a total weight of 1,000 pounds (earth weight)
which will include the two astronauts and their life s_pport system (400 pounds
for each man and his equipment) plus 130 pounds of scientific experiments. It also
must be able to carry up to 70 pounds of lunar soil and rock samples. This is
over twice its own weight. In comparison, the average family automobile can carry
only about half its weight.
The operational lifetime of the lunar vehicle on the moon will be 78 hours
during the lunar day. It will be able to make any number of sorties up to a
cumulative distance of 40 miles or 65 kilometers. Due to the limitations of the
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BOEING NAVIGATION SUBSYST_
The side-by-side seating for the crew is designed to make both front wheels
visible to both astronauts. They will navigate through a dead-reckoning navigation
system which will tell them direction and _istance to the Lunar Module at any point
during their sortie, and Will report the total distance traveled at any time om
the mission. The navigation system, built by Boeing's Aerospace Group Electronics
Organization, includes a directional gyro unit, a signal processing unit which is
essentially a small solid-state computer for working navigational trigonometry
problems, and the display units which show the heading and odometer readouts.
HEAT CONTROL
The LRV makes use of passive and seml-passive thermal control measures to
insure that it will not exceed operating temperature limits that could damage the
electronics equipment or the moving parts. Vehicle temperature constraint at
lii_coff is 70 + 5° F. Insulation and reflective coating maintains the temperature
of the vehicle by controlling heat loss during boost_ earth orbit t translunar
flight and lunar landing. Batteries are maintained between _O and 125 ° F, while
other equipment has tolerances that vary from -30° F up to 185 ° F. These tempera-
tures must be maintained through touchdown.
After reaching the moon, the vehicle's semi-passive thermal control system
also will be in operation. The requirement is to dissipate heat from operating
equipment in the forward chassis area, maintain the control and display console
within its operating limitations and protect the crew station from excessive heat.
Thls control system utilizes insulation, radiative surfaces, thermal mirrors,
thermal str_ps, fusible mass heat sinks (boxes containing a wax-like material which
melts as it absorbs heat) and special surface finishes. Passive protection is
provided by a multi-layered aluminized mylar and nylon netting with a beta cloth
(polished glass) material on the outside.
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Alumln_ thermal straps connected to electronic equipment transfer the
heat to the batteries and fusible mass heat sinks where it is stored.
At the end of a lunar axploratlon trip, the heat which has accumulated
in the Batteries and heat sinks is allowed to escape through radiation. The
astronauts open fiberglass dust covers to expose fused silica thermal mirrors
mounted on top of the l_&tterles, electronic co_onents and heat sinks. The
mirrors act as space radiators as they cool the equipment.
EIGHT TEST UNITS
Eight LRV test units have been completed leading to the manufacture of
the first flight model. The units include: a full-scale mockup, which has been
used in development of the vehicle's design; an LM-LRV test unit which has been
used to determine if the LRV's weight might cause stresses or strains in the
LM's structure; two one-sixth-weight units for developing and testing the
mechanism that will ease the vehicle from the LM to the lunar surface; a mobility
test unit to prove the propulsion system; a normal Earth-gravity unit for
astronaut training; a vibration unit which has been used to uncover any potential
weaknesses in the LRV's structure, and a qualification unit which will experience
vibrations, high and low telperatures and vacuum to aid in proving the moon car
will withstand the lunar environment.
Program management and engineering work is being performed at The Boeing
Company's Space Center near Seattle, Washington. Final assembly and testing of
the vehicles will be done at the Space Center. The first flight-model LRV is
scheduled to be delivered to NASA by April i, 1971, only 17 months from the formal
signing of the contract awarding the assignment to Boeing. This is believed to be
the shortest development, design, qualification and manufacture cycle of any major
item of equipment for the Apollo space program. In comparison the extremely
complex command and service module and the lunar module took 52 and 66 months,
respectively, from contract award to delivery of the first flight article. The
astronauts' portable life s_pport systems took TO months, and their spacesuits 60
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DELCO ELECTRONICS MAJOR S_CONTRACTOR
The Delco Electronics portion of the LRV work centers on the vehicle's
mobility system, which includes the wheels, suspension system, traction and drive
system. Design studies showed the best way to move over the moon's surface is on
a wheel. The wheels developed for the moon car are unique. _eight t dust and
traction were taken into consideration in their design. The wheel has a spun
aluminum hub, with a titanium bu_ stop mounted inside a woven wire "tire." The
tire is woven of zinc-coated piano wire. After studying reports from Apollo Ii
and 12, chevron treads of titanium were added to give "flotation" in deep dust ald
to give added traction. These treads are riveted to the wire mesh. Each wheel
weighs 12 pounds on earth and two pounds in moon gravity. Their design saves well
over I00 pounds over conventional wheels and rubber tires. The woven wire mesh not
only provides traction, but the "give" provides for a smooth ride for the crew and
absorbs the shock of driving over small moon rocks and surface irregularities. _a
addition, Delco Electronics built the special test unit to test the 'bower unit"
design and the Earth gravity unit for astronaut training.
TRAINIER HEAVIER AND STRONGER
Although it looks like the two-man flight-model Lunar Roving Vehicle, the
trainer is about twice the weight of the flight version. Added strength in the
frame, wheels, drive motors and suspension system is necessary because the vehicle,
the astronauts and their scientific p_yload are six times heavier on Earth than
they will be on the moon.
Because the training program calls for far greater use of the vehicle than
the flight models, and because of the trainer's greater weight, automobile-t_e
tires are used instead of the wire mesh wheels of the flight Yehicles.
Two nickel cadmium rechargeable batteries provide power for the trainer, but
the thermal mirrors and heat sinks used for cooling in the moon's environment will
not be used on Earth. The trainer uses electric fans for radiative cooling, thereby
capitalizing on the Earth's atmosphere.
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NASA CREW TRAINING
All crew training is under the direction of the Manned Spacecraft Center,
Houston, Texas. The trainer will be utilized by the crews of Apollo 15, 16 and
17 in planning and training for their missions. The vehicle is being driven
over a simulated moonscspe at Houston, and at a training area near Flagstaff,
Arizona.
The Lunar Roving Vehicle will more than double the time the astronauts_w!!!
be able to spend on the moon's surface during exploration, since by riding instead
of walking the explorers will expend less energy and will use their limited oxygen
and cooling water supply at a slower rate than t_ey would on foot. In addition,
with the aid of the LRV's navigation system they will be able to accurately place
scientific instrumemt packages on the mooa's surface, and chart the exact location
of geological features and saxples. Through use of the Lunar Rover each Apollo
exploration will be able to gather an increased amount of raw data about the moon
for further study on Earth.
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