Space & Innovation

To Get to Mars, Pit Stop at the Moon

Humanity's most efficient path to Mars includes a pit stop near the moon, a new study suggests.

Humanity's most efficient path to Mars includes a pit stop near the moon, a new study suggests.

Mars-bound crewed spacecraft should launch with just enough fuel to get to filling stations near the moon, and these stations would then dispense propellant derived from lunar water-ice, according to the study.

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Such a strategy would reduce the mass of a Mars mission by up to 68 percent at launch, resulting in significant cost savings, researchers said. (It currently costs thousands of dollars to put 1 lb., or 0.45 kilograms, of payload into Earth orbit.) [Visions of Deep-Space Exploration in Pictures]

"This is completely against the established common wisdom of how to go to Mars, which is a straight shot to Mars, carry everything with you," study co-author Olivier de Weck, a professor of aeronautics and astronautics and of engineering systems at the Massachussets Institute of Technology (MIT), said in a statement.

"The idea of taking a detour into the lunar system ... it's very unintuitive," de Weck added. "But from an optimal network and big-picture view, this could be very affordable in the long term, because you don't have to ship everything from Earth."

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Permanently shadowed craters near the moon's poles are thought to harbor large quantities of water ice. This ice can be processed into hydrogen and oxygen molecules - the chief components of rocket fuel, which could then be used to fill up the tanks of voyaging spaceships.

Exploiting lunar resources in this way could greatly reduce the cost of spaceflight, helping open up the solar system to human exploration, moon-mining advocates say.

The new study, which was published recently in the Journal of Spacecraft and Rockets, comes to the same basic conclusion.

The researchers - led by Takuto Ishimatsu, now a postdoc at MIT - developed mathematical models to determine the most efficient ways to get humans to Mars. The scientists found that the best option relies on "gas stations" positioned at gravitationally stable places in the Earth-moon system called Lagrange points. The fuel doled out at these depots would come from lunar water-ice.

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The first crewed trip to Mars may not utilize this infrastructure, but such a system could help pave the way for Red Planet settlements, researchers said.

"Our ultimate goal is to colonize Mars and to establish a permanent, self-sustainable human presence there," Ishimatsu said in the same statement. "However, equally importantly, I believe that we need to 'pave a road' in space so that we can travel between planetary bodies in an affordable way."

The new study has caught the attention of NASA, which aims to put boots on Mars in the 2030s.

"The paper shows clearly that leveraging water and other valuable in-space resources will lower the cost for human exploration of the solar system," William Gerstenmaier, associate administrator for human exploration and operations at NASA Headquarters in Washington, D.C., said in the same statement.

"NASA had previously planned on using Mars resources to reduce propellant needs at Mars," added Gerstenmaier, who was not involved in the paper. "This study, along with others, is showing the potential advantages of using lunar resources as well."

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An illustration depicts how a Mars mission may benefit from fuel stations on the moon.

Forget about the wonders of space and the philosophical implications of seeing Earth as a blue dot in a star-filled black sky. Astronaut Mark Watney, the lead character in "The Martian," a book by Andy Weir, is more concerned about staying alive, and for that there's nothing like good old-fashioned engineering and technical know-how. Which is why NASA is so excited about the upcoming debut of a film by the same name, starring Matt Damon and directed by Ridley Scott. Without giving away too much, the story revolves around Watney's trials and tribulations soloing on Mars after he is inadvertently left by his evacuating crewmates. The U.S. space agency, which is slowly moving toward a mid-2030s human expedition to Mars, is eager to connect the dots between its ongoing development efforts and engineering finesse the fictional Watney employs to boost his chances of survival. Here is a look at some Mars technologies currently under development.

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Watney needs a place to shelter from the harsh climate and high radiation of Mars. Back on real Earth, engineers are testing a prototype deep-space habitat called HERA, short for Human Exploration Research Analog, that has living quarters, work space, a bathroom and a simulated airlock. So far, NASA has run Mars habitat simulations lasting two weeks. It plans to increase the experiments to 60 days, a small fraction of a crew's estimated year-long Mars stay.

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Astronauts aboard the International Space Station last month ate their first crop of space-grown lettuce. NASA says future Mars crews won't be able to depend solely on cargo ships from Earth and are counting on space gardens to fill the gap. "If we're ever going to go to to Mars someday -- and we will -- we're going to need a spacecraft that is much more sustainable ... Having the ability for us to grow our own food is a big step in that direction," said NASA astronaut Mark Kelly, currently the station's commander.

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Along with food, future Mars crews will need water to survive. Aboard the space station, water from urine, perspiration and condensation is recycled, but the system is not perfect. NASA is working on technologies to completely close the loop, a challenging endeavor since fluid physics completely changes in microgravity.

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No sense going to Mars if astronauts never go outside. But leaving the safety of a habitat to pick up samples and conduct experiments presents a whole new set of challenges, such as dealing with the planet's ubiquitous dust. Systems under development include docking ports so astronauts can climb into out of their spacesuits as needed without bringing them inside. An artist's rendering of a prototype Mars spacesuit is pictured here.

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Human expeditions to the Red Planet are expected to last more than a year, but to make good use of the time astronauts will need a way to travel farther than they can walk. The Multi-Mission Space Exploration Vehicle, pictured above, is one vehicle under consideration.

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By electrically charging gas, such as argon or xenon, spaceships can efficiently, but slowly navigate to very distant destinations. In "The Martian" the crew's spaceship uses ion engines, a technology currently employed by NASA's Dawn spacecraft, now circling the dwarf planet Ceres. Engineers are working on advanced ion thrusters, pictured above, for future missions.

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