Beyond Earth

light brown planet with white splotches
NASA/JPL/MSSS

"The space shuttle is 20 years old,” said Pat Dasch, a consultant on space policy and the former executive director of the National Space Society, a citizens' group “committed to bringing about a spacefaring civilization,” according to the group's literature. Not only is the shuttle “rather old technology,” noted Dasch, “there's nothing [else] in sight”—no cutting-edge propulsion system that can cost-effectively move humans or robots around in space, to service and maintain satellites, to build telescopes and space stations, to travel more swiftly to distant realms.

Dasch was speaking just seven days before the shuttle Columbia broke up when re-entering the Earth's atmosphere.

“We've been going to space with the same sort of rocket for 40 years,” she said, in the opening address for the series “Beyond Earth: Living on Other Worlds,” the 2003 edition of the Penn State Lectures on the Frontiers of Science. Dasch is the editor of Space Sciences, a four-volume reference encyclopedia brought out by Macmillan Reference USA, and Icy Worlds of the Solar System, to be published by Cambridge University Press. She has testified about space issues to Congress and directed NASA's Dial-A-Shuttle live-news program at the Johnson Space Center in Houston.

It's time, she said, to move “beyond liquid-fuel rockets”—perhaps to nuclear propulsion, in which energy from a nuclear reaction heats up a propellant such as hydrogen to thousands of degrees Celsius; the expanding gas shoots through a nozzle, providing thrust. Or perhaps a plasma engine, wherein radio waves superheat the fuel. According to Franklin Chang-Diaz, a veteran space shuttle astronaut and the primary researcher into plasma propulsion today, “Rockets tend to work much better the hotter the exhaust is,” and the plasma technology, under development at Johnson Space Center, boosts temperatures into the millions of degrees.

Dasch sketched out for the audience the space elevator, a concept first advanced by the science fiction writer Arthur C. Clarke, in which an object with a large mass—a captured asteroid or a satellite in geosynchronous orbit—combines with magnetic levitation to give a space vehicle a “running start,” letting it break free from Earth's gravity with a minimal expenditure of fuel. The craft would scoot along on a launching track (one proposal has a 22,000-mile cable heading heavenward from a 31-mile-tall tower on Earth) built of carbon nano-tube material. At a workshop held recently at NASA's Marshall Space Flight Center in Huntsville, Alabama, Bradley Edwards—a physicist at Los Alamos National Laboratory who is researching space elevators through a NASA Institute of Advanced Concepts grant—suggested a cable-to-space system could be up and running in 10 to 20 years. “The major hurdle is the required carbon nanotubes,” Edwards said, “but that's getting closer each day.”

Dasch averred that “Science will be the driving theme for NASA in the future.” Referring to space travel, she said: “We're not going to do it just because it's cool, just because it's exciting.” Rather, we will keep moving into space to conduct science and develop new technology— technology that may yield important benefits on Earth. Dasch listed some of the space spin-offs now affecting our lives: advanced weather forecasting, automated teller machines, and global positioning system devices (all relying on satellites), bar code readers, laser surgery, digital cameras, cordless drills, miniaturized heart pumps.

Although it is versatile and reusable, the space shuttle has certain limitations, Dasch said. It is hugely expensive to launch and operate. And it's a near-earth vehicle: You wouldn't travel to Mars in it. We need to take bigger steps, she said, some of which have been outlined by the NASA Exploration Team, or NEXT, created by the agency three years ago to dream up ideas for future space exploration. Perhaps it's as scientist and author Carl Sagan said, in defending his idea of putting nutrients on the outside of the Viking landers, on the chance that a mobile Martian might amble over for a snack: “Someone has to propose ideas at the boundaries of the plausible, in order to so annoy the experimentalists or observationalists that they'll be motivated to disprove the idea.”

One idea involves deploying a new generation of space-based telescopes to study neighboring stars, around which Earth-resembling planets may orbit. To outperform the Hubble Space Telescope and NASA's recently approved James Webb Space Telescope (due for deployment in 2010), these powerful third-generation ‘scopes would require mirrors more than 10 meters across. Too large to be carried into space in one piece, they could be made of a flexible “gossamer” material that would fold up for lift-off, then unfurl once in position.

The best sites for space telescopes may be the so-called Lagrangian points, whose existence was deduced by the 18th-century French astronomer Joseph-Louis Lagrange. According to Dasch, these “oases in space” occur “where the gravitational pull of two bodies, such as the Earth and the Moon, cancel each other out, providing a stable location to position spacecraft.”

To build and service powerful, deep-space telescopes, humans would have to take up residence farther from Earth than ever before. The closest Lagrangian point, L1, exists 380,000 kilometers into space—about five-sixths of the way to the Moon. Dasch suggested that humans could live at L1 in a lightweight inflatable space station. Such a habitat is under development at NASA: TransHab, projected to become the living quarters on the International Space Station, perhaps as early as 2005. TransHab looks like a big squarish balloon; packed up for launching, it is 14 feet across, but once deployed it inflates to a diameter of 27 feet and a height of 23 feet. The 12,000-cubic-foot module has three levels and includes a galley, dining area, six sleeping compartments, astronauts' personal storage areas, computer entertainment center, exercise space, medical areas, and bathrooms. The foot-thick shell, composed of 19 separate layers, is designed to blunt the impact of tiny meteorites, space debris that can travel seven times the speed of a bullet.

In an article in the 26 October 2002 New Scientist, Dasch writes that an L1 station would become “a gateway for human missions to the rest of the Solar System, providing a haven where crews could prepare and train before departing to the Moon, nearby asteroids or other planets.” Dasch said: “Going from a Lagrangian point to Mars, you don't have to escape Earth's gravity—you'd use much less fuel.”

Dasch reminded lecture attendees that more than 30 years have passed since astronauts walked on the Moon. She said, “I think we'll go back there to test a lot of the technology we might use on Mars”: rover transporters, equipment for extracting sub-surface water and minerals, and habitat modules. Astronauts could be monitored for harmful effects of living in space, and they'd be close enough to Earth to be brought home quickly if problems arose.

When asked by a reporter if she yearned to live in space, Dasch smiled. “I'm basically a coward,” she said. “I don't think I'd travel to Mars, but I would like to go to the Moon. When there's a Lunar Hilton.”

Dasch made earthly realities—political and economic ones—sound as forbidding as Martian dust storms and galactic radiation. The United States, she said, is fast losing its lead in space technology. Of 59 successful space launches in 2001, only 25 were by the United States or had U.S. ties, including six joint U.S.-Russia projects. “How does our country view space? Less than one quarter of the population believes space exploration is important to our future.” Despite these gloomy portents, Dasch waxed enthusiastic about the doability of space travel. She seemed to embrace without reservations the credo advanced by the National Space Society, the citizens' group she headed from 1997 to 2001: “It is our human destiny to live, work and play among the stars in permanent space communities.” She predicted that, if provided with adequate resources, Americans could make it to Mars by 2010. “I'd like to think we're planning for a 20-year horizon,” she said, “and I'd be surprised and disappointed if we don't do it in the next 50 years.”

Last Updated May 01, 2003