Manned Lunar Roving Vehicle

8/6/2019 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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Manned Lunar Roving Vehicle