NASA bets on asteroid mission as best path to Mars

Some scientists question whether redirect plan would get humans any closer to Red Planet

illustration of astronaut sampling an asteroid

ROCKY ROAD TO MARS  NASA has billed its Asteroid Redirect Mission as a stepping stone to Mars. In one mission concept, illustrated here, an astronaut collects a sample from a bagged asteroid orbiting the moon.


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Somewhere above the clouds, way up into the deep space of the inner solar system, there’s an asteroid tumbling near Earth with NASA’s name on it.

Within the next decade or so, the space agency wants to snag the space rock and haul it to the moon. And they’ve hatched two fantastical plans to do it. One would snare an asteroid with a gigantic inflatable bag; the other might send a sticky-fingered robot out to grab a golf cart–sized boulder off an even bigger rock.

Both would help humans prepare for an eventual trip to Mars. At least that’s what NASA says.

“We would have access to a completely new alien body that no one had ever touched or seen,” says planetary scientist and former NASA astronaut Tom Jones, who studied the feasibility of the mission. What’s more, he says, astronauts might be able to mine the rock for resources, instead of relying only on supplies hauled up from Earth for voyages into deep space.

Mars has long been one of NASA’s targets for human space exploration. Many believe that tackling challenges closer to home, such as the Asteroid Redirect Mission, could help scientists learn how to prepare for the difficulties of traveling to the Red Planet. JPL/NASA

But not everyone’s convinced that the plan, called the Asteroid Redirect Mission, or ARM, brings people any closer to the Red Planet. Since NASA announced the mission last year, the so-called stepping stone to Mars has sparked a bristling debate.

Many scientists believe that the mission’s link to the fourth planet from the sun is hazy, at best. At worst, critics say that NASA has slapdashed together an outlandish stunt to find something — anything — that fits in with the president’s budget and vision for humans in space.

“NASA’s just looking for a place to go,” says asteroid scientist Alan Harris, retired from NASA’s Jet Propulsion Laboratory in Pasadena, Calif. The ARM doesn’t carry a whole lot of scientific weight, he says, though “it is good entertainment.”

A crowd-pleasing mission might be just what the agency needs to electrify a sluggish human space exploration program.

And NASA is running out of options. Its space shuttle fleet retired in 2011, the International Space Station has support only through 2024, and the agency’s budget has plummeted from a 1960s high of about a nickel of every tax dollar spent to less than a penny. Even if the ARM is a kooky scheme that brings humans only marginally closer to Mars, shoehorning the unlikely mission into place could be a shrewd way to secure Americans’ spot in deep space — before it’s too late.

Two grand plans

If NASA can swat away the doubts and drive the ARM forward, the out-there mission would be the stuff of sci-fi lovers’ dreams.

In one ARM concept, a solar electric propulsion spacecraft — the largest ever built — will blast off from Earth in 2019 and sail through space toward its massive target: a rock about half the diameter of the one that exploded over Chelyabinsk last year (SN Online: 2/15/13). The spacecraft will rendezvous with the asteroid and then, when positioned just right, nab it with a blow-up bag.

Story continues below infographic.

illustration of bagged asteroid in moon orbit
The spacecraft could shuttle the captured asteroid into an orbit around the moon. Astronauts would then travel there to explore the rock and bring samples home. Nicolle Rager Fuller
“Think of it like a bounce house,” says JPL aerospace engineer Brian Muirhead. All inflated, the bag — thin yellow plastic — will stretch about as tall as a three-story building and hold up to 1,000 tons of asteroid. After swallowing the mighty rock, the plastic would cinch shut like a garbage sack.

Then the spacecraft will fire up its engines and slowly, gently begin nudging the asteroid into a new orbit. With only about a third of a pound of thrusting force, the spacecraft will be kind of wimpy — like a blue jay tugging a jumbo jet off course.

But scientists think years of steady effort will shift the asteroid just enough so that it slingshots around the moon into a stable orbit, perhaps sometime in 2024 — though the date depends on which rock NASA selects. (The agency has already picked several candidates.) Then astronauts launched toward the moon could meet up with the asteroid and go exploring. The two-person crew could slice open the plastic or tear off Velcro patches to expose the bagged goods and chip off chunks to bring home.

In the second asteroid-capture idea, a robot — with three arms and three legs, or two arms bearing hundreds of little hooks, or some combination of the two — would snatch a boulder off a space rock perhaps longer than a football field. Then the spacecraft would shuttle the prize to the moon for an astronaut crew to explore later.

And NASA has been waiting decades for the chance to stretch its space exploration muscles.

Story continues below infographic.

illustration of robotic arm
The robotic system for plucking a boulder off an asteroid could use several arms and legs (left), two arms with hundreds of tiny grippers (bottom) or some combination of the two (right). Nicolle Rager Fuller
NASA hopes to choose between the bag and the robotic arm ideas in late 2014. Either approach, the agency says, will test-drive asteroid-moving technology and give astronauts spacewalking experience that would bring humans one step closer to getting to Mars.

The ARM is NASA’s latest attempt to launch humans beyond low-Earth orbit — a feat that hasn’t been accomplished since the Apollo days, more than 40 years ago. Mars, one of Earth’s nearest neighbors, is a tempting target because it may have once hosted life. Trekking out to the Red Planet could help scientists find out for sure. In April, NASA Administrator Charles Bolden even called getting people to Mars — and becoming a multi­planet species — necessary for human survival. 

American aspirations

Exploration runs deep in Americans’ blood. From the vast plains of Kansas to the gold veins of California, “we’re a nation founded by explorers,” says space historian Valerie Neal, a curator at the Smithsonian National Air and Space Museum in Washington, D.C. “It’s kind of in our DNA.”

The fledgling idea of human spaceflight first took off among Americans in 1958, when President Dwight D. Eisenhower established NASA. Less than two years later, the agency sketched out a slow and steady approach to get humans into space:  First send humans into low-Earth orbit, then build a space station and then venture out to the moon and nearby planets sometime after 1970. In 1961, President John F. Kennedy scrapped the slow approach for speed.  

“He said, ‘Let’s go to the moon and let’s do it quickly!’ ” says Neal. Just eight years later, Apollo 11 landed two American astronauts on the moon and NASA was riding high. The agency next set out to launch humans to Mars, and pronto — by 1981.

But the nation’s interest lagged. “Everybody felt as if we had won the space race,” says Neal. “So we didn’t need to keep having an expensive, fast-paced space program.”

NASA’s funding nose-dived from the sky-high levels of the Apollo days. The gleaming ambition of traveling to the Red Planet slipped out of reach.

President George H.W. Bush tried to rekindle the dream on the 20th anniversary of the Apollo 11 landing. Standing on the steps of the Air and Space Museum, he proposed sending humans back to the moon and on to Mars. But he never sent a budget to Congress to fund the plan, Neal says, “so that idea just died on the vine.”

In 2004, President George W. Bush revived his father’s withered vision and unveiled a grand plan for human space exploration. The Constellation Program called for building a family of launch rockets and a deep-space craft named Orion to carry astronauts to the International Space Station, then to the moon by 2020 and then on to Mars. “The next giant leap has begun,” promised Constellation’s slogan.

Yet once again, the lofty goal of getting humans to Mars barely got off the ground. When President Obama took office in 2009, he enlisted a group of experts to review Constellation’s progress and the future of human spaceflight. Called the Augustine Committee, the group released its report the following October. Constellation was over budget and behind schedule.

Obama canned the program four months later, and then announced a new idea in April. Standing in front of a space shuttle engine at the Kennedy Space Center in Florida, with NASA’s flag at his left and Apollo 11 astronaut Buzz Aldrin in the audience, Obama pledged to send humans to an asteroid by 2025 and to Mars by the mid-2030s.

To get there, NASA would use two vehicles: a new crew-and-cargo rocket, called the Space Launch System, and the Orion spacecraft.

The agency just needed to pick an asteroid.

Birth of a mission

As NASA delved into the nitty-gritty details of its new plan, prospects began to look grim.

It quickly became apparent that the Space Launch System wouldn’t be able to hurl the Orion space capsule far enough into the solar system to reach most near-Earth asteroids, Jones says. And the capsule wouldn’t have enough room for the supplies a crew would need on the six- to 12-month mission.

illustration of asteroid formations
Asteroid candidates may be a pile of rubble (depicted on the left) or a solid rock within a cloud of debris (right). JPL-Caltech/NASA
What’s more, trying to find an asteroid that’s the right size, the right speed and streaking by Earth during the early 2020s is a daunting task. There aren’t many good options out there, says astronomer Robert McMillan, who runs the asteroid-tracking Spacewatch Project of the University of Arizona in Tucson. Most asteroids knock around farther away, in the massive ring of space rocks known as the main belt, between the orbits of Mars and Jupiter.

As NASA grappled with these problems, a group of scientists cooked up an idea that could have been inspired by Bruce Willis’ space cowboy antics in Armageddon: Instead of sending astronauts to an asteroid, they suggested, why not bring the asteroid to the astronauts?

A think tank called the Keck Institute for Space Studies, or KISS, pulled together 34 experts to explore the scheme’s feasibility and published its report in the spring of 2012. NASA latched onto the concept like a lifeline.

When NASA announced its budget for 2014, a plan to capture an asteroid, which NASA named the Asteroid Redirect Mission, took center stage.

“We were totally flabbergasted and surprised that NASA picked it up officially and put it into their program so quickly,” says Jones, one of the experts on the KISS team.

The space agency had been in a pickle: It had to meet the president’s requirement to visit an asteroid, and it had to do it with a vehicle combo that couldn’t actually reach a near-Earth asteroid, he says. “NASA’s coping with reality,” Jones says. The asteroid redirect idea “sort of bails them out.”

But NASA bungled the rollout. When the agency introduced the idea last year, administrators didn’t say much about how capturing an asteroid would help humans get to Mars — the grand finale of the president’s plan for human space exploration. Instead, NASA focused on the mission’s potential for technological innovations, scientific discoveries and defense against asteroids headed for Earth.

Critics pounced. “There’s nothing about pushing around a tiny space rock that has anything to do with getting humans to the moon or Mars,” says MIT planetary scientist Richard Binzel, an expert on near-Earth asteroids.

Though the mission jibes with what the president outlined, says former NASA astronaut Buzz Aldrin, NASA won’t be sending humans out to where asteroids really live: “It’s just some hokey orbit around the moon.”

And the idea that towing a small asteroid with a spacecraft could eventually help NASA defend Earth from a massive collision is thinkable, but perhaps a little far-fetched.

“A threatening asteroid is not something we’re ever going to put in a bag,” says planetary scientist Clark Chapman of the Southwest Research Institute in Boulder, Colo. Although, he admits, learning about small asteroids could offer clues about how to move larger ones. And if NASA chooses the robotic arm concept to pluck a boulder off a large asteroid, the agency wants to tug on it with a gravity tractor, a way of — potentially — nudging huge rocks off path using the tiny attraction between the boulder-hugging spacecraft and the asteroid.

The prospects for scientific discovery are a little iffy, too. “Bringing back a sample of a near-Earth asteroid doesn’t excite me terrifically,” says asteroid scientist Harris. “Nature dumps these things in our backyard all the time.” Museums are full of them, he says.

illustration of asteroid size range
NASA has found several candidate asteroids to which the spacecraft could travel. The mission could either remove a boulder (1.5 to 3 meters in average diameter) from the surface of a larger asteroid or use a bag to capture a space rock roughly 3 to 8 meters across. NASA Asteroid Initiative Opportunities Forum, adapted by S. Egts
What’s more, NASA already has plans to nab some rocks from space. So do space agencies in Europe and Japan. Ten years ago, the European Space Agency sent the Rosetta spacecraft across the solar system to an icy comet hundreds of millions of kilometers away. And the Japan Aerospace Exploration Agency is gearing up for a second trip to an asteroid in late 2014, with the robotic explorer Hayabusa 2.

 In 2016, NASA will launch a similar mission. The OSIRIS-REx spacecraft will pluck samples off the near-Earth asteroid Bennu. Mission leader Dante Lauretta, a planetary scientist at the University of Arizona, is happy to see NASA bring home more asteroid nuggets. Scientists can study them to learn about planetary building blocks and even the origins of the solar system. “We love new samples from space,” Lauretta says. But even he’s not so sure they’re worth the ARM’s cost.

At roughly $1.25 billion, the mission doesn’t include the cost of the Space Launch System rocket or the Orion space capsule or the astronauts. And some scientists believe NASA is low-balling the price tag.

Getting to deep space

Since the plan’s debut, the space agency’s leadership has begun to explain more clearly how they see the ARM’s connection to Mars. And NASA’s not just spinning the story; the agency has been brainstorming ways to use the ARM as a launch pad for deep-space exploration.

“They’ve learned their lesson,” says former astronaut Jones. “They got criticized, and I think they’ve gone and done their homework. In the past year, NASA’s learned a lot more about how to apply this technology to Mars.”

In April, Jones and other experts, including JPL and other NASA scientists, got together for a three-day KISS workshop to think about how the agency could build upon the ARM.

NASA has a long list of ideas. The ARM would advance solar electric propulsion, or SEP, technology, for one, says NASA Associate Administrator Robert Lightfoot. The low-thrust power system would use xenon gas instead of rocket fuel, tug-tug-tugging spacecraft along instead of blasting them through space. SEP systems soak up energy from the sun, accelerate xenon atoms and then spew the glowing blue particles into space, propelling spacecrafts forward.

illustration of solar electric propulsion system
ARM would use a solar electric propulsion system, illustrated at left. This type of engine would use a propellant composed of xenon gas, which glows blue, as seen in a prototype thruster at right. From left: Analytic mechanics associates; JPL-Caltech/NASA
NASA has worked with SEP before — to send the Dawn spacecraft out to the biggest residents in the main belt — but the ARM spacecraft would be about 16 times as powerful. Such an efficient system could one day haul cargo to Mars, so astronauts wouldn’t have to bring everything with them, Lightfoot says. Shooting cargo into space is expensive, and even a mission that just cruised around Mars and back could require thousands of tons of supplies.

Digging into an asteroid could also be a boon. A water-rich asteroid, for example, could save NASA the trouble of toting water up from Earth. Mining asteroids could even offer astronauts shielding materials for radiation, a big health problem for humans in space (SN: 7/26/14, p. 18).

Even if the ARM is more like a baby step toward Mars than a giant leap, that might be OK, says planetary geologist Raymond Arvidson of Washington University in St. Louis, a leader of the Mars rover missions. “Going to Mars is incredibly difficult — hugely difficult,” he says. “You need to have waypoints.”

Some scientists still aren’t on board. Binzel thinks extending human crews into deep space is the right next step, but instead of pushing an asteroid around, he’d rather see NASA use SEP to place a cache of supplies in deep space. That, he says, would extend a mission’s duration and distance, which are necessary for getting humans to Mars.

NASA’s Lightfoot doesn’t expect to please everybody. “If there’s one thing I’ve learned in this industry, it’s that people are going to have different approaches and ideas they’d like to try,” he says.

“The primary goal for us is to get humans to Mars,” he says. “To us, the Asteroid Redirect Mission is the most logical and affordable step.”

Jones is sympathetic to the space agency’s plight. He thinks the ARM may be the best bet right now for advancing human space exploration.

“If the Asteroid Redirect Mission is squashed or defunded by Congress or criticized to death,” he says, “then NASA will do nothing with human spaceflight for the next 10 years.” 

ASTEROID COLLECTION  NASA wants to bag an asteroid using robotic arms or an enormous sack and place the rock in the moon’s orbit for study. This may keep astronauts working but not, as NASA claims, get them Mars-ready.

Animations courtesy of NASA; Narrated by Chris Riotta; Produced by Ashley Yeager

This article appears in the August 23, 2014, issue with the headline, “A rocky road to Mars.”

Editor’s note: The video accompanying this article was removed on August 9, 2014, and reposted on August 12, 2014, to correct an incorrect number. The story was also updated on August 26, 2014, to correct the number of Apollo 11 astronauts that landed on the moon.

Meghan Rosen is a staff writer who reports on the life sciences for Science News. She earned a Ph.D. in biochemistry and molecular biology with an emphasis in biotechnology from the University of California, Davis, and later graduated from the science communication program at UC Santa Cruz.

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