Editing Lunar Roving Vehicle (section)

== Features and specifications ==
[[File:NASA Apollo 17 Lunar Roving Vehicle.jpg|thumb|upright=1.8|left|[[Eugene Cernan]] test drives the [[Apollo 17]] lunar rover shortly after unloading it from the [[Apollo Lunar Module|LM]] ''Challenger'']]

The Apollo Lunar Roving Vehicle is a [[battery electric vehicle]] designed to operate in the low-gravity vacuum of the Moon and to be capable of traversing the lunar surface, allowing the Apollo astronauts to extend the range of their surface extravehicular activities. Three LRVs were used on the Moon: one on Apollo 15 by astronauts [[David Scott]] and [[James Irwin|Jim Irwin]], one on Apollo 16 by [[John Young (astronaut)|John Young]] and [[Charles Duke]], and one on Apollo 17 by [[Eugene Cernan]] and [[Harrison Schmitt]]. The mission commander served as the driver, occupying the left-hand seat of each LRV. Features are available in papers by Morea,<ref name="Morea1988"/> Baker,<ref>Baker, David; "Lunar Roving Vehicle: Design Report," ''Spaceflight'', Vol. 13, July 1971, pp. 234–240</ref> and Kudish.<ref>Kudish, Henry. "The Lunar Rover." ''Spaceflight''. Vol. 12, July 1970, pp. 270–274</ref>

=== Mass and payload ===

The Lunar Roving Vehicles have a [[mass]] of {{convert|210|kg|lb|order=flip}}, and were designed to hold an additional [[Payload (air and space craft)|payload]] of {{convert|230|kg|lb|order=flip}}.<ref name="ApolloVehiclesNASA" /> This resulted in weights in the approximately one-sixth [[G-force|g]] on the lunar surface of {{convert|35|kgf|lbf|order=flip}} empty ([[curb weight]]) and {{convert|73|kgf|lbf|order=flip}} fully loaded ([[gross vehicle weight]]). The vehicle frame is {{convert|10|ft|m}} long with a wheelbase of {{convert|7.5|ft|m}}. The height of the vehicles is {{convert|3.6|ft|m}}. The frame is made of [[2219 aluminium alloy|2219 aluminum alloy]] tubing welded assemblies and consisted of a three-part chassis that was hinged in the center so it could be folded up and hung in the Lunar Module Quadrant 1 bay, which was kept open to space by omission of the outer skin panel. They have two side-by-side foldable seats made of tubular [[aluminum]] with nylon webbing and aluminum floor panels. An armrest was mounted between the seats, and each seat had adjustable footrests and a [[hook and loop fastener|Velcro]]-fastened seat belt. A large mesh dish antenna was mounted on a mast on the front center of the rover. The suspension consists of a double horizontal wishbone with upper and lower [[Torsion beam suspension|torsion bars]] and a damper unit between the chassis and upper wishbone. Fully loaded, the LRV has a ground clearance of {{convert|14|in|cm}}.

=== Wheels and power ===
[[File:Lunar Roving Vehicle wheel close-up.JPG|thumb|right|Close-up of wheel showing chevron treads]]

The wheels were designed and manufactured by General Motors Defense Research Laboratories in [[Santa Barbara, California]].<ref>"Lunar Rover", brochure, Delco Electronics, Santa Barbara Operations,1972</ref> [[Ferenc Pavlics]] was given special recognition by NASA for developing the "resilient wheel".<ref>[http://www.omikk.bme.hu/archivum/pavlics/dokumentumok/pavlicse0002-01.htm "NASA Certificate for Ferenc Pavlics for Inventing the Resilient Wheel"] (from Hungarian University of Engineering).</ref> They consisted of a [[spun aluminum]] hub and a {{convert|32|in|cm|adj=mid|-diameter}}, {{convert|9|in|cm|adj=mid|-wide}} tire made of zinc-coated woven {{convert|0.033|in|mm|adj=mid|-diameter}} steel strands attached to the rim. [[Titanium]] chevrons covered 50% of the contact area to provide traction. Inside the tire was a {{convert|25.5|in|cm|adj=mid|-diameter}} titanium bump stop frame to protect the hub. Dust guards were mounted above the wheels. Each wheel had its own electric drive made by Delco, a [[brushed DC electric motor]] capable of {{convert|0.25|hp|W}} at 10,000 rpm, attached to the wheel via an 80:1 [[harmonic drive]], and a mechanical brake unit. In the case of drive failure, astronauts could remove pins to disengage the drive from the wheel, allowing the wheel to spin freely.

Maneuvering capability was provided through the use of front and rear steering motors. Each series-wound DC steering motor was capable of {{convert|0.1|hp|W}}. The front and rear wheels could pivot in opposite directions to achieve a tight turning radius of {{convert|10|ft|m|0}}, or could be decoupled so only front or rear would be used for steering. The wheels were linked in [[Ackermann steering geometry]], where the inside tires have a greater turn angle than the outside tires, to avoid sideslip.

Power was provided by two 36-volt [[Silver-oxide battery|silver-zinc]] [[potassium hydroxide]] [[Primary cell|non-rechargeable batteries]] developed by [[Eagle-Picher]]<ref>{{Cite web |date=1971-07-15 |title=Press Kit Apollo 15|page=96 |url=https://www.nasa.gov/specials/apollo50th/pdf/A15_PressKit.pdf |access-date=2022-10-28}}</ref> with a charge capacity of 121 [[Ampere hour|A·h]] each (a total of 242 A·h), yielding a range of {{convert|57|mi|km}}.<ref>Young, Anthony; ''Lunar and planetary rovers: the wheels of Apollo and the quest for Mars''; Springer, 2007, p. 96; {{ISBN|0-387-30774-5}}</ref> These were used to power the drive and steering motors and also a 36-volt utility outlet mounted on the front of the LRV to power the communications relay unit or the TV camera. LRV batteries and electronics were passively cooled, using change-of-phase wax [[Thermal mass|thermal capacitor]] packages and reflective, upward-facing radiating surfaces. While driving, radiators were covered with mylar blankets to minimize dust accumulation. When stopped, the astronauts would open the blankets, and manually remove excess dust from the cooling surfaces with hand brushes.

=== Control and navigation ===
[[File:Lunar Rover diagram.png|right|thumb|Lunar Rover diagram (NASA)]]
[[File:James Webb lunar drivers license.jpg|left|thumb|Honorary lunar driver's license presented to then NASA Administrator [[James E. Webb]]]]

A T-shaped hand controller situated between the two seats controlled the four drive motors, two steering motors, and brakes. Moving the stick forward powered the LRV forward, left and right turned the vehicle left or right, and pulling backwards activated the brakes. Activating a switch on the handle before pulling back would put the LRV into reverse. Pulling the handle all the way back activated a parking brake. The control and display modules were situated in front of the handle and gave information on the speed, heading, pitch, and power and temperature levels.

Navigation was based on continuously recording direction and distance through use of a [[Heading indicator|directional gyro]] and [[odometer]] and feeding this data to a computer that would keep track of the overall direction and distance back to the LM. There was also a Sun-shadow device that could give a manual heading based on the direction of the Sun, using the fact that the Sun moved very slowly in the sky.