CAPE CANAVERAL, Fla., Aug. 22 (UPI) -- The last time Earth and Mars were as close together as they will be on Aug. 27, Neanderthals roamed the planet. But despite all the technological progress humans have made in 60,000 years, visiting Earth's second-nearest celestial neighbor remains as distant as ever.
Every 26 months, Earth and Mars pass each other relatively closely in their respective orbits, like the hands of a clock that sweep past each other hourly. The planets' orbits are not circular however, and slight irregularities in their elliptical paths occasionally bring the two closer together than usual. Such is the case this year, when the mutual distance narrows to 34.6 million miles, or about 30 percent closer than usual.
U.S., European and Japanese space agencies are taking advantage of this year's close encounter to send a total of three landers and two orbiters to explore Mars. Politically, technically and financially, however, all proposed human ventures are grounded indefinitely.
Even before the fatal Feb. 1 Columbia accident derailed NASA's human spaceflight program, cost overruns and delays in completing the International Space Station had sidelined Mars exploration planning.
"Right now, a Mars mission is on no one's radar scope," said Karl Leib, an associate professor of political science at Wabash College in Wabash, Ind., and a co-author of "Space Policy in the 21st Century."
"What matters now is just getting the shuttle back into service and getting NASA back to the point where it can trust itself," Leib told United Press International.
When President George H.W. Bush was in office, he announced plans for a 30-year program to land humans on Mars by 2019. Saddled by a price tag that hovered in the $50 billion range, the plan grew old long before it grew legs.
"I think what we'll be seeing is a more incremental approach to space exploration," said Brian Chase, director of the National Space Society in Washington, D.C. "I don't see us going for another Apollo-type program," he told UPI. "I think what we're looking at a building-blocks approach to get us there."
One of those building blocks might turn out to be, of all things, the space shuttle.
Few people have dreamed of using space shuttle technology to get to Mars, but the demise of Columbia and the loss of seven astronauts not only once again illuminated the dangers inherent in space flight, but also brought a nagging and long-term problem squarely into focus: What will be the best spacecraft to ferry people to and from space?
The accident investigation report, scheduled to be released this month, primarily will focus on the shuttle, though it is expected to spark a wave of debate about the future of human space exploration.
"What the Columbia accident did was bring more public attention to bear on a problem that was already there," Chase said. "I expect the report will stir discussions for the next year or two in political circles about what we do from here."
There is no shortage of ideas about how to get to Mars or what to do once explorers arrive. NASA this year launched a $3-billion, five-year technology development program called Project Prometheus to investigate nuclear electric generators and nuclear propulsion.
In addition, the agency wants to test a prototype spaceship engine called the Mini-Magnetospheric Plasma Propulsion system, which uses onboard magnets to create a magnetic field that would expand as ionized gas is discharged from the engines. The force to move the ship would come from solar-produced charged particles, which would push the magnetic sphere like wind on a sail.
Engineers also are developing a hydrogen-fueled spacecraft that could get a crew to Mars in three months. With current technology, the trip takes about nine months, which raises another potential show-stopper for human journeys to Mars: space radiation hazards. Astronauts on the surface of Mars would be exposed to about the same radiation levels experienced by the space station crews -- roughly a daily dose of what the terrestrial-bound get in a year or two.
"The transit to Mars is the big difference," said Frank Cucinotta, director of space radiation health at NASA's Johnson Space Center in Houston. "It's three times higher than on the surface of Mars. A quick transit and a long surface time would be the best type of mission, from a radiation exposure standpoint."
On Earth, the atmosphere shields the planet from dangerous celestial radiation, which comes from three primary sources: the sun, trapped particles in Earth's magnetic field, and high-energy cosmic rays, which present the most severe health threat to astronauts. Radiation can damage human DNA and disrupt cells. Over time, the breakdowns can cause a variety of cancers. Radiation also is suspected of causing nerve damage and a host of other ailments, including cataracts.
To cope with threats, NASA currently limits an astronaut's time in space, depending on his or her age, gender -- women are more vulnerable to the harmful effects of radiation -- and prior exposure history. The agency wants to improve its understanding of radiation exposure risks and design effective countermeasures so that within 10 years the average cumulative space mission can be boosted from the current maximum of 250 days to 380 days in a space station-type orbit.
The agency this fall will open the country's first dedicated space radiation laboratory at the Brookhaven National Laboratory on Long Island, N.Y., to simulate the effects of various types of space radiation. Current radiation predictions stem from studies of atomic bomb survivors and are not readily applicable to the longer-term, lower-energy radiation doses astronauts experience in space.
Studies of a variety of shielding technologies and materials also are planned. Lead, for example, turns out to be not a good choice because high-energy radiation can fragment the material, causing its particles to become radioactive. The best shielding, researchers have found, is liquid hydrogen.
Scientists also want to test a variety of radiation countermeasures. At Tufts University in Boston, for example, James Joseph and his team have found rats fed extracts of blueberries, strawberries as well as other antioxidants did not suffer the behavioral breakdowns and neurochemical damage found in other rats that had not been given the nutrients. Both groups of animals were exposed to radiation similar to what astronauts on long-duration space missions would experience.
"They may want to take some of these extracts along with them and mix them in with their Tang or whatever it is they eat up there," said Joseph, whose next phase of research is looking at whether the extracts can help cells regenerate after radiation exposure.
Though Mars remains a distant dream, NASA has begun looking at steppingstone missions -- 60- to 90-day excursions designed around specific science objectives, such as servicing a future space telescope or tending to experiments on an orbital platform positioned between between the Earth and the sun.
"The idea is to make whatever investments we make to go as far as possible into the future," said Gary Martin, a mission architect at NASA headquarters in Washington. "Mars is certainly one of the milestones out there."
This year's Earth-Mars pass will be the closest until 2287. Perhaps by then, a Martian colony will be planning to explore the moons of Jupiter.
