Beyond Earth

According to Robert Zubrin, president of the engineering firm Pioneer Astronautics and founder and president of the Mars Society, NASA's current vision of sending humans to the red planet depends on a 1,000-ton, 100-meter-long spacecraft. Too heavy to launch through Earth's atmosphere, the ship would have to be “built on orbit,” said Zubrin, at an estimated cost of $400 billion. He characterized it as “a giant interplanetary spaceship” engineered by “a giant space agency.”

orange rocky landscape
NASA

It may look like Arizona, but Mars is a grim place for life. In this 1997 image, the Sojourner rover released by the Mars Pathfinder Lander gets up close and personal with a rock.

In contrast, Zubrin and two other colleagues developed the Mars Direct plan, which relies on existing technology (including space shuttle components), exacting logistics, a travel-light-and-live-off-the-land approach, and a $20 billion budget. Zubrin said, “We are much closer today to sending people to Mars than we were to sending people to the Moon in the early 1960s.” How soon could a manned Mars mission become reality if NASA or an international consortium of private or governmental space groups started gearing up today? Pronounced Zubrin: “A decade from whenever someone finally turns on the money.”

While at Lockheed Martin in the early 1990s, Zubrin headed a team to develop new strategies for space exploration, including Mars Direct. At the sixth and final lecture in Penn State's 2003 Frontiers of Science series, Zubrin laid out his plan, in which a series of biennial missions, both unmanned and piloted, would result in a base on Mars. Back in 1968, Zubrin and other enthusiasts had formed the Mars Society, whose goal is to further exploration and settlement of the red planet. The group, with 6,000 members in 40 countries, conducts public outreach and education and supports research on Mars exploration techniques currently underway at bases in the Utah desert and on Devon Island in arctic Canada. Zubrin said that an initiative to reach Mars in, say, 30 years probably would fail. Rather, we should launch within a decade: otherwise changing politics would likely arrest the venture's momentum.

At the heart of Mars Direct is a launch vehicle dubbed the Ares, similar in size and power to the Saturn V, NASA's now-obsolete workhorse that sent astronauts to the Moon in the 1960s. Ares consists of a modified space shuttle external tank, two solid-fuel rocket boosters, and four shuttle main engines mounted to the external tank's undersurface.

In Year 1 of the Mars Direct mission sequence, Ares would send an unmanned cargo lander to Mars. (For simplicity's sake, we'll assume that NASA makes Zubrin's day by accepting the plan and turning on the spending tap: Following a decade of development, year 1 translates to 2013.) In the lander launched in 2013 would ride an earth return vehicle, or ERV; a propellant factory; 5.8 tons of liquid hydrogen; a 100-kilowatt nuclear reactor on a small rover; and food for four people for nine months.

One problem with NASA's conceptual Mars ship, claimed Zubrin, is that “75 percent of its mass is fuel and oxygen needed [for astronauts] to come home.” Zubrin noted that early explorers like Lewis and Clark “lived off local resources—that's how exploration has always been done when it's been done intelligently.”

Back to 2013: “You send a 45-metric-ton payload to a soft landing on the Martian surface,” like the 1976 Viking mission. After touchdown, the food-stocked ERV sits waiting for hungry astronauts to arrive on a future mission. The robot truck wheels off to a natural depression, such as a shallow crater, and emplaces the reactor—“a putt-putt nuke sitting in the back of the truck,” said Zubrin. Sucking in CO2-laden Martian air, and powered by the nuclear reactor, the propellant factory uses the liquid hydrogen brought from Earth to produce “37.7 tons of methane and water.” Through a series of additional syntheses the fuel factory over the next year manufactures 107 tons of methane and oxygen propellants. Said Zubrin, “That gives you a fully fueled ERV waiting on Mars.”

In 2015, the next window when Earth and Mars are close enough for a mission to take place, two more Ares rockets lift off—one boosting a cargo lander like the craft already on Mars, the other a small piloted spaceship. “Looks like a tuna can,” Zubrin admitted as he presented the Powerpoint image. He showed a second graphic of the manned craft, drum-shaped, 27.5 feet in diameter, and 16 feet tall; after landing on Mars, it would become “a surface habitation.”

En route to Mars in the tuna can, the four-person crew resides in an upper level, while a lower level carries cargo, including a pressurized rover vehicle. To maintain gravity on board, the manned portion of the spacecraft stays hooked to the rocket's upper stage at the end of a 1,500-meter tether. Both masses spin around a common center at one rotation per minute; Zubrin claimed that the resulting artificial gravity, plus an exercise program, would reduce bone loss and muscle atrophy in astronauts to acceptable levels.

Alarms sound: Detectors have picked up potentially fatal radiation spawned by a solar flare. The astronauts ride out the event in a water-shielded chamber at the core of the habitat: “They'd be stuffed in there like passengers on the A Train for a few hours,” Zubrin said with a shrug. “It might happen once, maybe twice,” on the six-month journey. He dismissed the health effects of cosmic rays,” stating that the necessary two-and-a-half-year period of traversing space to and from Mars, sandwiched around a spell of living and exploring on the red planet, would boost an individual's chances of developing cancer by only 1 percent.

So now we're on Mars. It's 2015.

Depending on the accuracy of their landing, the crew either strolls over to the preceding unmanned lander or tools there in the pressurized rover, which, Zubrin said, has a 600-mile one-way range. Simultaneously, the partnering cargo lander begins to robotically manufacture fuel for a second crew, who will arrive in another two years.

brown bumpy rock
NASA/JPL/MSSS

A high-resolution image from Mars Global Surveyor reveals layered sedimentary rock in a 1.5- by 2.9-kilometer (0.9- by 1.8-mile) area in the Candor Chasma. Sunlight illuminates the outcrops from the upper left.

In the rover, “the explorers go on long traverses,” Zubrin said. The rover might cover 10,000 miles during a 500-day Mars stay. The astronauts study Martian rocks, prospect for water, hunt for bacteria. They try to answer the questions: “Was there—is there—life on Mars?

“If we find fossils, we can drill,” Zubrin said. “Maybe there's liquid water half a kilometer down: that's where life would have retreated” when the water dried up or otherwise ceased to exist on the Martian surface eons in the past. Microbes found by astronauts could be compared to Earth organisms. “Are they fundamentally similar, or are they different? Is life as we know it on Earth the basic pattern of life everywhere, or are we unique, only one part of a larger tapestry?”

After their 500 days are up, the crew lifts off in the first ERV using the methane and oxygen propellants manufactured from the Martian atmosphere. After six months of weightlessness in the albeit-cramped vehicle, the crew reenters Earth's atmosphere, and a parachute lands them safely.

A second and later a third four-person crew of astronauts descends on Mars, always following the successful deployment of a cargo lander. The missions succeed one another, with supplies and materials delivered by unmanned craft, creating “functional bases that could evolve into a mostly self-sufficient Mars settlement.”

Said Zubrin, “Life creates conditions friendly to the development and propagation of more life.” Plants on Earth, for instance, evolved to make oxygen that benefits other life forms. Ultimately Zubrin envisions human colonists setting up factories to produce greenhouse gases that would warm Mars up, thicken the atmosphere, melt subterranean ice, and start water flowing again in dry streambeds. Plants—genetically engineered varieties more efficient at photosynthesis—could be introduced to produce oxygen. In the minds of Robert Zubrin and his fellow disciples in the Mars Society, the red planet would be transformed. “Not only will humans bring life to Mars,” he said, “but they will bring Mars to life.

“Mars is a world with a surface area equal to that of all the continents on Earth put together,” Zubrin said. “We can make Mars habitable: I'm convinced that humanity will do that someday.

“If not us,” he said, “then who?

“If not now, then when?”

Last Updated May 01, 2003