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VIPER: Mapping water ice on the Moon

Rovers act like scientists' eyes and hands – they help analyze samples of rock, soil and volatiles on location, and send data back to Earth. Using their tools and instruments, they can help scientists learn more about important resources on the Moon that will be needed to establish a long-term presence on the Moon and send humans farther into space.

NASA's Volatiles Investigating Polar Exploration Rover (VIPER) will map water ice near the Nobile Crater at the south pole of the Moon. It is the first resource mapping mission on another celestial body. The solar-powered golf cart-sized rover will use several science instruments and a 1-metre drill to collect samples in precise locations selected by experts and analyze them on site.

Mosaic of more than 1500 images taken by the Clementine spacecraft of the Moon's south polar region

This mosaic image of the south polar region of the Moon is made up of more than 1500 images taken by the Clementine spacecraft. The region around the Nobile Crater is where VIPER will roam. Nobile crater is circled. Since the Moon's axis is nearly perpendicular to the Sun, sunlight does not reach the bottom of craters at the poles. The Moon's south pole therefore contains many areas that are permanently shadowed – making it an attractive target for water-seeking exploration. (Credit: NASA/JPL/USGS/Canadian Space Agency)

What are lunar volatiles?

Volatiles are chemical elements or compounds that can be easily vaporized. Some examples of volatiles are hydrogen, water, helium, and carbon dioxide. When heated, these substances can be released as a gas, making them difficult to handle. However, lunar volatiles are likely to play a key role in the sustainable presence of humans on the Moon because they could be used as a fuel source, to create breathable air, or as a source of water.

Volatiles within the lunar regolith (the soil present on the surface of the Moon) can have different origins:

  • Chemically trapped when the Moon was originally formed;
  • Delivered by the solar wind, or the impact of a comet or meteorite; or
  • Redistributed from different areas on the Moon.
An artist's concept of VIPER on the lunar surface

An artist's concept of VIPER on the lunar surface. Equipped with headlights, VIPER will help determine the distribution of ice water on the surface and subsurface down to depths of one metre. (Credit: NASA Ames/Daniel Rutter)


The objectives of the VIPER mission are to:

Challenges of designing a lunar rover

Creating a rover that can survive on the Moon is no easy task. Engineers must uniquely adapt VIPER to be able to survive and work in high-contrast lighting conditions, extreme temperature ranges, diverse soil types, and steep crater walls. The rover also needs to be able to communicate with Earth.

Extreme contrasts in light

High-contrast lighting differences between the sunlit and shadowed areas on the Moon will pose a unique challenge. On Earth, particles in the air reflect and scatter sunlight so shadows are not fully dark, but dimly lit with indirect light. On the airless lunar surface, there are no particles to reflect and scatter sunlight – leading to regions exposed to very bright sunlight, and extremely dark areas. Shadows at the south pole are long and fast-moving due to the low angle of the Sun on the horizon. The low angle of the Sun combined with some topographical features can result in some areas never being exposed to the Sun; these are called permanently shadowed areas. These lighting issues can affect a rover's depth perception and ability to detect hazards.

Intense temperatures

Equipped with headlights, VIPER will be able to explore the pole's permanently shadowed craters. The Moon's lighting conditions demand the use of a specialized lighting and camera system. And the contrast doesn't stop at lighting – the change from sunlight to shade also means extreme temperature changes. The temperature difference between shaded and sunlit areas can range from −248 to 123 degrees Celsius.

The permanently shadowed craters near the lunar south pole are some of the coldest locations in the solar system, where it is suspected that ice has been stored for billions of years. Since the water has remained frozen for a very long time, mission scientists will be able to investigate where the water on the Moon came from and how much water exists there. Since the rover is solar-powered, VIPER will have to recharge its batteries in the Sun and use its heaters to remain warm enough to travel to sampling locations in the shaded craters.

Route planning

To conserve energy, VIPER will need to be able to move to a "safe haven" and go into hibernation. Places with shorter nights are called safe havens. For VIPER, a place where slivers of sunlight can reach the rover's solar panels is important to keep its batteries charged. Getting VIPER to a safe haven is vital to keep its internal components warm.


The rover's wheels need a lot of agility to be able to drive on a variety of soils and navigate the craters. VIPER can drive sideways, diagonally or even spin its wheels in a circle and drive backwards without changing what direction it is facing. In case the rover encounters soft soil, VIPER can even operate each wheel separately. The all-metal wheels can tackle slopes with inclines of up to 30 degrees.

A prototype rover undergoes testing at the Simulated Lunar Operations Laboratory within NASA Glenn Research Center

Credit: NASA/GRC/Bridget Caswell

Close up of a prototype rover with all-metal wheels

Credit: NASA/GRC/Jef Janis

Rover wheels and prototypes must undergo lots of testing. Pictured here at the Simulated Lunar Operations Laboratory within NASA Glenn Research Center, the all-metal wheels traverse steep slopes, soft material, and rocks.

Communicating with the rover

Direct line-of-sight radio communications with Earth allow the team to operate interactively in near real time. The communications will be sent over the Deep Space Network. The delay will only be 6 to 10 seconds compared to 10 to 20 minutes when sending commands to Mars. This will allow rover drivers to make decisions quickly based on obstacles the rover encounters.

From to , six Apollo missions brought back 382 kilograms of rocks, sand, dust and core samples from the Moon. As part of the Soviet Union's Luna program, three missions returned 300 grams of lunar samples to Earth in , and .

Studies of lunar rocks give information about the origin of the Moon, the formation of the Moon's crust, and a history of solar activity. Orbiter and impact missions showed the presence of some water ice.

VIPER aims to travel up to 20 kilometres to directly sample frozen water at different depths and temperatures. Its mission will help scientists identify the distribution, origins, and permanence of frozen water on the Moon.

Canada's role in the mission

Myriam Lemelin

Dr. Myriam Lemelin, professor of applied geomatics at the University of Sherbrooke. (Credit: Université de Sherbrooke)

The Canadian Space Agency is providing funding to the University of Sherbrooke to support the participation of Dr. Myriam Lemelin, professor of applied geomatics, in her role as a member of the mission science team.

Dr. Lemelin was selected by NASA as one of the experts who will enhance the scientific value of the samples to be analyzed by remote sensing instruments on the rover: the Near InfraRed Volatiles Spectrometer System (NIRVSS) and the Ames Imaging Module (AIM). Dr. Lemelin will contribute her expertise in remote sensing to help learn more about the composition of volatiles, including water ice, and geological processes occurring in the south pole region.

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