A new lunar “4x4”

It really ought to be “12x12” to be exact as NASA is working on a prototype for a 12 wheel drive lunar vehicle!

 

NASA's Lunar Electric Rover (LER) Credit: NASA

No air, temperatures ranging from -200°C in the shade to +110°C in the Sun* with dangerous cosmic and solar radiation: the Moon is a hostile environment for Man.. Humans cannot survive outside the spaceship that takes them there or the full EMU spacesuits used for walking on the Moon’s surface.

Mobility: a new challenge
NASA is currently preparing to put astronauts back on our natural satellite in the year 2020 as part of its Vision for Space Exploration. The main courses of action involved in the challenge of living and working on the Moon’s surface are known thanks to the legacy from Apollo which, to date, is the only programme to have put Man on the Moon.. But 40 years after Neil Armstrong’s first historic step, the American agency means to take up the additional challenge of a vastly increased mobility. If you consider that during the last manned moon mission (Apollo 17 in December 1972), astronauts Gene Cernan and Harrison Schmitt travelled a total of 35 km in their jeep during 3 spacesuited outings, but they never went more than 5 km from their spaceship. And yet, the surface of the Moon is as big as the entire continent of Africa! Mobility is an issue that cannot be avoided if scientists are to be able to better study our natural satellite.

The Apollo LRV, Lunar Roving Vehicle, nicknamed “lunar jeep”, was used on missions 15, 16 and 17 and considerably increased the astronauts’ exploration possibilities. But, to be able to go further, NASA now envisages a vehicle equipped with a pressurised cabin. Credit: NASA

A house on wheels
Following this line of thought, NASA is currently testing a prototype dubbed LER, Lunar Electric Rover, behind which lies some very robust ambitions: to accomplish 1,000 km journeys whilst accommodating two people for 14 days. We will go further, and we will stay longer as the longest human beings have spent on the Moon is 3 days.

The LER, Lunar Electric Rover. 1 - Pressurised cabin equipped with sanitary and sleeping facilities. 2 - Cockpit. 3 - 6 pairs of driving-steering wheels. 4 - Airlock for docking with a base or lunar module. 5 - Spacesuits positioned outside the vehicle. 6 - The independent, motorised chassis can operate without the cabin. Credit : NASA

The main scenario adopted makes use of two LER. First of all, they could be delivered by automatic landers near to a base that is already in existence or they could arrive in advance at a pre-determined site and then be joined by 4 astronauts. These astronauts would then leave their moon module or base and move into the LER, in pairs. The principle of exploring in twos has been adopted to combine efficiency and security. This way if one of the vehicles breaks down and cannot be repaired, the other can accommodate the 4 expedition members and ensure that they get safely back to their base or spaceship. If only one LER was to be used, the explorers would have to restrict their journey to a distance compatible with the autonomy of their EMU spacesuit as this would be their only means of getting back to where they started from. The pressurised LER is, in fact, a house on wheels. Once inside, the astronauts, in shirtsleeves (less tiring than wearing a full spacesuit), have sanitary facilities, food and somewhere to sleep as well as being protected from the dangerous solar radiation by a water tank incorporated into the cabin. In addition to its role of absorbing radiation, this water will obviously be used by the crew during the 14 days of exploration as well as in the onboard equipment cooling circuit.

Left-hand photograph: the LER in the spotlight as it closed the inaugural parade of President Obama (with his wife in the top right corner). Right-hand photograph: the cockpit has been simplified in order to reduce the size of the instrument panel as much as possible. Credit: NASA/Bill Ingals

An electric vehicle...
Although the LER closed the inaugural parade of President Obama in January 2009, it is still a prototype which has to enable the engineers and astronauts testing it to improve on the original concept in order to get it to the required operational level. The current vehicle is not, yet, capable of travelling on the Moon as its lithium-ion batteries only provide 125 Watts per hour, per kilo onboard. The performance required for our natural satellite is 200 Watts per hour, per kilo of battery. According to NASA, this amounts to developing an electric family car capable of travelling 800 km before it needs recharging! However, although the agency admits that “the development of these more advanced technologies will not be easy”, it is counting heavily on a working arrangement with car manufacturers (more and more interested in electric cars), universities, other government agencies and international partners.
In the meantime, tests continue on the LER using terrains that partly reproduce the difficult driving conditions that exist on the Moon; for example, Moses Lake sand dunes (Washington State) and the volcanic desert of Black Point Lava Flow in Arizona.

The LER is tested on rocky, sandy terrain so as to get close to use conditions on the Moon. Credit: NASA

... that is versatile
These areas qualified as resembling the moon are also used for assessing different procedures and practical solutions. Consequently, a maximum of the driving of the LER as well as the controlling of all its minor functions are carried out via a computer terminal not only for ergonomic reasons but also to avoid the considerable size of a more classical instrument panel with its numerous buttons and levers. The wide windows could have accumulation problems as regards lunar dust (described by the Apollo astronauts as “sticky”): the engineers envisage repelling this dust by means of static electricity, thus avoiding windscreen wipers and any possible mechanical problems. From an operational versatility point of view, the two spacesuits are permanently positioned outside on the back of the vehicle. Rehearsals carried out show that the astronauts can be ready for a moonwalk inside 10 minutes as they can slip into the back of the suits from inside the rover. The procedure used avoids having to completely empty the air out of the LER (loss of reserves) and also greatly limits the amount of dust brought into the cabin. And finally, the mobile chassis, which comprises 12 steering-driving wheels, is designed to operate without the pressurised cabin. It then becomes a particularly agile platform (possibility of turning on the spot or moving sideways like a crab) capable of transporting astronauts over short distances as well as acting as a construction machine for the building of a lunar base! In short, a versatile vehicle, a type of mobile lunar Swiss army knife.

Without its pressurised cabin, the LER becomes a mobile chassis, driven by spacesuited astronauts, able to accomplish different tasks, including those of a bulldozer once fitted with a blade! Credit: NASA

(*) The notion of temperature on the Moon is very different from the one we are used to on Earth. When we say “it’s 20°C”, we are talking about the temperature of the ambient air. But our natural satellite does not have an atmosphere, therefore, the temperatures mentioned are those that objects on its surface might reach depending on whether they are exposed to the Sun or positioned in the shade.

Published on 2 June 2009

A video about the LER on EnjoySpaceTV