By akademiotoelektronik, 27/10/2022

LRV (Lunar Roving Vehicle): light to roll on the moon

Eric Bottlaenderspiscalist Espace 08 August 2021 at 5:17 p.m. Simple, efficient...iconic.The lunar jeep in its environment, during the Apollo 15 mission.NASA credits

Walking on the moon is good, but astronauts and managers of NASA quickly seized that to move away from the landing site, the lucky elected officials would need a vehicle.Light, enduring, foldable, reliable, inexpensive, powerful and above all mobile ... In short, a jeep do everything.And deliverable yesterday, if possible.

Yes, was a time when Boeing could create a lunar jeep from scratch in a year and a half.

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An old idea in the land of the car

Even before President Kennedy officially launched the United States in the race for the moon, the first concepts of lunar vehicle were being studied.Of course, this remained halfway between science fiction and engineering, since NASA had no special budget to inject into such a program ... For a very simple reason: to pilot a lunar rover, you have toBring astronauts to the moon.This is the priority, and that's why in the mid -1960s, a multitude of concepts were studied without going to the stage of the realization.The projects that seem the most promising are based on the idea of an independent "deposit" mission, during which the lunar vehicle is brought to the moon thanks to a dedicated rocket takeoff, and later joined by astronauts Apollolaid off.Suddenly, the architectures are complex, even exotic, with pressurized cabin, wheel and track systems, fuel cell and structure of several meters.

Certains prototypes compensaient la faible gravité par une taille démesurée (comme ici ce pré-prototype de Bendix).NASA credits

That said, there is also a simpler solution: that of making a radically simplified vehicle, which could possibly be on board withdrawn on the sides of the lunar module.Solution which, at the beginning of 1969, will impose itself because there is good news on the side of the production chain of the gigantic launchers Saturn V ... The copies from Apollo 15 will have an additional margin of power, allowingTake two more orbit tons, and therefore a few hundred additional kilograms to the Moon.Immediately, NASA (which is only a few months old to install astronauts on our natural satellite) officially launches its LRV program (Lunar Roving Vehicle) and puts the placard from the projects of large lunar trucks with cabins: you have toSimple, efficient and light vehicle.Easier to say than to do, until the landing of Armstrong and Aldrin, the lunar floor was barely documented ...

Lunar jeep or dunes scooter

Quite strangely, even if Boeing ends up winning the NASA tenders, the latter rather seriously considered a proposal for a small electric motorcycle.Light and robust, they could each have embarked an astronaut for a funny enduro outing.However, the American agency, after advanced tests, was afraid of constraints linked to the management of the warm -up (the void drives very badly) and the risk of breakdown.And here is Apollo engaged on the path of "Lunar Jeep".Designed by Boeing, associated with General Motors by main subcontractor, the vehicle will be produced in 4 final copies intended to drive on the Moon, and a whole string of copies intended for tests.The development is extremely short given the constraints: only 17 months ... and fortunately the Apollo mission 15 a few months late on the planning, otherwise Dave Scott and James Irwin would have made a cross on their long outings.

Les astronautes d'Apollo 17 s'entrainent à déployer leur LRV dès leur arrivée sur le sol lunaire.NASA credits

The LRV is 3.1 meters long and 2.3 m wide.It essentially consists of a chassis, with an electric motor (clear) for each of the four wheels.The main constraint lies in its mass, which was limited to 210 kilograms, including batteries.The latter, located at the front, are not rechargeable, and in theory Rover theory to roll about 90 km on the lunar surface, at a maximum speed of 14 km/h.It is equipped with two seats placed on the aluminum structure, and a rear space to deposit lunar experiences or rocks.Above all, by simplicity, the principle of the cabin is abandoned, which means that the combinations of Apollo astronauts will have to provide drivers with all their oxygen needs (and there too, their life system is improved to provide 7 hours of guaranteed oxygeninstead of 4).

Small series, but big success

Did you know ?After a few tests with the astronauts by plane 0G, the astronauts adopted the most "simple" way to sit on their lunar vehicle: jump in their seat with their space!Boeing and the subcontractors hesitate for a time on the indications to be provided to the pilot and his passenger, to finally return to the simplest: enough to get out of engine and direction at the front or back, a CAP indicator, and the"All -doing" lift in the center.Forward he accelerates, the rear he brakes (thoroughly and it is a handbrake) and the left and right for the direction.The tests are very numerous: with real size, on a small scale, with real mass or not, on slopes or dish ...

Le LRV une fois replié, juste avant un dernier pan sur les flancs du module lunaire. Un compromis à faire entre gain de place et praticité...NASA credits

For the crews that will use it, it's a good dose of fun but for NASA, Boeing and all those who designed it, the stake is double.First, it will be a new technological showcase on the lunar surface for typically American know -how.And on the other hand, nobody wants the rover to break down to the point furthest from the lunar module: hopping over a hundred meters is sympathetic, but organizing a hike for several kilometers is a dangerous exercise.At the time of the takeoff of Apollo 15, there are still many questions, especially on the behavior of the trellis wheels, or on the solidity of the system, which has long been folded in the space vacuum.

Bip bip ! Pas le temps de discuter... Montez !NASA credits

In reality, it is a brilliant success.The LRV (which quickly becomes in France, the "Lunar Jeep", even if it has nothing or almost to do with a Jeep) unfolds exactly as planned, and apart from a few minor concerns because of dust projections,contains even better than what had been envisaged.The batteries, in particular, keep a lot of capacity in reserve despite an episode of overheating on Apollo 15 ... and would indeed have allowed to drive on tens of additional kilometers.The trip record logically returns to Apollo 17 with 35.89 km made in 4 hours and 26 minutes and many stops.Because it is the great advantage: astronauts roll, and when they visualize an interesting site (or when the teams on the ground, in permanent contact, indicate it), they stop to collect or photograph.The addition of an adjustable color camera from Earth and whose image is transmitted live to televisions around the world is unanimously hailed, and will help leave imperishable memories to a whole generation in front of the post.

And the next?

Despite these successes, there were only 3 missions to use the LRV in the planned environment.The fourth copy is quickly cannibalized when Apollo 18 is canceled, and the long list of improvements that Boeing was going to offer for a next generation will remain in the boxes.Above all, as everyone knows, the Americans stopped going to the moon from 1972, to refocus (temporarily) on the low terrestrial orbit with the beginnings of space stations and shuttles.

Le "Lunar Cruiser" de Toyota est considéré très sérieusement par l'agence japonaise... Mais il faudra l'emmener sur place avec un lancement à part. Crédits JAXA/Toyota

However, lunar jeeps do not inspire that cinema and science fiction (appearances and cameo are legion), because now that more or less concrete projects return to the moon are in progress, it will necessarily ariseThe question of a controlled vehicle. Toyota planche déjà sur son propre grand design avec cabine… Et n'en doutons pas, d'autres tenteront une version XXI^e siècle du LRV au moment où les astronautes iront à nouveau fouler les poussières de la Lune.Their precursor has set the bar very high ...