during the early Apollo years NASA scientists and engineers anticipated the
need for a vehicle to aid the astronauts in exploring the moon it was expected
that bulky spacesuits limited life supplies and other inherent weaknesses
would decrease man's mobility on the lunar surface in 1964 with conceptual
design of the mobile laboratory or mo lab NASA began research on lunar surface
vehicles over the next few years an entire spectrum of vehicles was designed
and studied from these efforts came the knowledge that contributed directly to
the development of the lunar roving vehicle its development required
solution of many challenging technical problems for which there were no
precedents in terrestrial vehicle design and operation for example the lack of an
atmosphere on the moon the extremes of surface temperatures plus or minus 250
degrees Fahrenheit the very weak gravity one-sixth of Earth's and the many
unknowns associated with the lunar soil and topography all these factors imposed
severe and unique requirements on the LRV
the first man landing on the moon Apollo 11 and subsequent missions confirmed the
long recognized need for a lunar vehicle a vehicle which would allow astronauts
to cover more area to conserve energy and life support materials to transport
additional equipment and to returned with more lunar soil samples or even
before these practical demonstrations in May of 1969 NASA decided to proceed with
the design and development of a lunar roving vehicle the Marshall Space Flight
Center at Huntsville Alabama where the saturn v moon rocket had been developed
was assigned overall direction of the LRV program
prime contractor was the Boeing Company using facilities at Huntsville and Kent
Washington major subcontractor was GM's Delco electronics division in California
the LRV would be a two-man four wheeled vehicle 10 to 2 inches long 44 inches
high with a seven and a half foot wheelbase weighing 460 pounds earth
weight and capable of carrying a total payload of 1080 pounds the LRV would
have five major systems mobility crew station navigation power and thermal
control the mobility system which must be able to cross 12 inch high obstacles
and 28 inch diameter craters consists of the wheels traction drive suspension
steering and drive control electronics the system was designed developed and
tested by General Motors the first assemblies were put through development
tests to measure strength deflection endurance and other factors for example
driven on a rolling road fixture the wheel assembly was tested under earth
conditions and later in test chambers reproducing the environmental conditions
of the moon the LRV tires are made of a woven mesh of zinc coated piano wire -
which titanium threads are riveted in a chevron pattern to keep the wheels from
sinking into the soft lunar soil long duration torture testing on this so
called a carousel simulating the lunar surface verified the durability of the
wheel design the test assembly was supported by Springs to relieve most of
its weight thus simulating the one-sixth gravity of the moon a mobility test unit
was used in early phases of development to validate the LRV mobility system the
astronauts participated as they did in all aspects of LRV development - 36 volt
silver zinc batteries provide the vehicle's power each wheel is
individually powered by a 1/4 horsepower electric motor
a highly efficient harmonic drive system originally developed by the u.s. shoe
Machinery corporation for other purposes is used with each motor eliminating the
need for a transmission and it's gears the suspension consists of a damper or
shock absorber supported by triangular arms that pass the suspension loads to
torsion bars other systems were also being developed for example a simple
navigation system which would allow astronauts to drive beyond sight of a
lunar module and yet be able to return to it by the most direct route the
system works by recording direction and distance traveled from a starting point
in order to assure the proper physical relationship or interface between the
vehicle and the astronauts in their pressurized spacesuits several so called
crew station reviews were conducted first in normal gravity conditions and
later in simulated 1/6 g the L RVs crew station consists of the control and
display console seats and seat belts armrests
foot rests hand and toe holds floor panels and fenders for other cruise
station reviews and development testing an LR V mock-up was installed in a
kc-135 aircraft which flew parabolic flight paths this provided brief periods
of low gravity simulating lunar conditions one example of interface
problems was the initial difficulty in getting onto and off of the LRV
addition of a simple toehold plus astronaut training proved to be the
solution another interface problem was the design of control switches which
could be easily manipulated by a gloved hand similar problems were involved in
operation of the uniquely designed hand controller located between the two
astronauts which provides steering speed and banking commands to the vehicles
drive control electronics and mechanical brake system a major milestone in the
lunar roving vehicle development program was delivery by General Motors of the 1g
trainer vehicle to be used for astronaut training though
heavier and stronger than an actual moon rover since the crew and equipment
weighs six times more on earth the trainer was practically identical in
size shape and handling characteristics one simple difference was the use of
ordinary pneumatic rubber tires because of the extra weight of the vehicle at
the manned spacecraft Center the 1g trainer was operated using
counterbalance Springs to simulate the moon's gravitational field through
operation of the trainer in this mode astronauts were able to become
accustomed to the LRV months before actual use during their mission storage
and deployment of the vehicle provided major design challenges as shown here by
this special test unit built to equal on earth the L RVs lunar weight the vehicle
had to fit within the tight wedge-shaped confines of one small section of the
lunar module about the volume contained in a family station wagon conversely on
the moon the LRV has to be centrally unfold itself by means of Springs and
deploy to the lunar surface locked in its operating configuration all with
minimum assistance from the astronauts
further deployment tests were conducted using a full weight l RV called a
qualification test unit the vehicle was deployed from a lunar module mock-up at
the Grumman aircraft company contractor for the lunar module during these tests
technicians manually assisted the vehicle throughout the procedure since
the deployment mechanisms were designed for the moon's weaker gravity and could
not overcome the stronger gravity of the earth the main purpose of the
qualification test unit was to make absolutely sure that nothing had been
overlooked in terms of clearances and hardware operation manufacturing of the
first flight LRV proceeded concurrently with the rigorous testing of non flight
units as evidenced in this wheel fabrication skilled in detailed hand
crafting was involved in many of the LRV components early in 1971
production and testing of the first flight LRV neared completion vibration
tests were conducted with the vehicle and both the folded and unfolded modes
to determine critical frequencies other acceptance tests checked and rechecked
every facet of the vehicle the first flight model LRV was formally delivered
to NASA by the prime contractor Boeing on March 10th 1971 two weeks ahead of
schedule it had been less than 18 months since inception of the LRV program only
13 months since the prime contract was awarded an accomplishment reflecting the
outstanding effort and dedication of the joint NASA industry development team
after government acceptance of the vehicle it was folded covered and crated
for shipment to the Kennedy Space Center after delivery to KSC the vehicle was
unfolded and completely checked out again and another crew station review
was conducted the LRV was then folded for the final time and installed in its
flight position inside the lunar module of the Apollo 15 spacecraft several
months before launch the LRV had received its final go while the rest of
the Apollo and the saturn v launch vehicle would undergo further checkouts
then the entire Saturn Apollo vehicle was moved aboard the giant transporter
from the Vehicle Assembly Building three and 1/2 miles to the launch pad where it
would undergo constant check and recheck right up until launch date on July 26th
1971 Apollo 15 carrying the first lunar roving vehicle aboard was successfully
launched
after a three-day translunar coast the landing site was spotted the rugged
Hadley Apennine region a potentially hazardous but scientifically interesting
area of the Moon - one - one six percent fuel in feet - one eight feet - water
contact the landing was successfully achieved Apollo 15 commander David Scott
became the seventh man to set foot on the moon with live color TV coverage
beamed back to earth lunar module pilot James Irwin followed soon afterward and
they said about deploying the lunar roving vehicle for their first drive
over the lunar surface with minor difficulty deployment and setup were
successfully accomplished in 26 minutes during initial check out of the LRV
astronaut scott discovered that the front steering mechanism was inoperable
however the first lunar traverse of a scheduled three proceeded satisfactorily
using only rear-wheel steering before the second Traverse the astronauts and
LRV specialists on the ground succeeded in freeing the front steering mechanism
in overall performance the LRV more than met its standards giving a total of
three hours and two minutes of stop-and-go driving on the moon the
vehicle traveled a total of five kilometers about 15 statute miles
astronaut scott and urban covered almost four times as much lunar terrain as the
total covered by the crews of the apollo 11 12 and 14 missions before them the
lunar soil proved much less troublesome than expected with the LRV wheel treads
leaving tracks only about half an inch deep the suspension system worked
extremely well the astronauts reported keeping the vehicle very stable even on
several rather sharp turns to avoid lunar obstacles average speed was nine
kilometers about six miles per hour more than one mile an hour faster than
planned the energy usage rate was much less than expected only about 52 amp
hours compared to anticipated usage of 102 the vehicle still had about 80
kilometers of driving capability remaining when it was parked after the
final Traverse the navigation system performed well averaging a miss distance
of only one tenth of one kilometer upon return to the lunar module after each
Traverse all in all the lunar roving vehicle proved to be in the words of
astronaut scott about as optimum as you can build after almost 67 hours on the
moon scott and urban rillette at the lunar module with their collection of
scientific samples for the return to earth their liftoff in the ascent stage
was photographed by the remote controlled television camera left behind
on the LRV a spacecraft with wheels the lunar
roving vehicle has proven itself invaluable an extending man's ability to
explore the moon