GOLDEN, Colo -- Explorers eager to trek across the Moon's battered surface or Mars' dusty plains may be stranded here on Earth but our planet offers an array of locations that, in varying degrees, mimic those otherworldly landscapes.

Scientists and engineers view these lookalike places as training grounds for future expeditions. They are called analog sites.

By networking analog sites, early shakeout of equipment -- from space suits and land rovers to drills and robotic devices -- becomes viable and can be rated ready for flight. Habitat construction ideas and science-gathering tasks and procedures could be practiced. Even appraising the team spirit of individuals laboring in dangerous and remote environments is feasible.

"A good analog facilities program can repay itself many times over in reduced costs and increased safety when we finally send people to the Moon and Mars," said Michael Duke, space geologist at the School of Mines and workshop chairman.

"We can use analog facilities to improve our understanding of human and robotic exploration operations on the Moon and Mars," Duke said. "Facilities on Earth are sufficient for much of that testing, and are much less expensive than space facilities. The more one understands the potential difficulties of seemingly straightforward tasks when carried out in the space environment, the lower the risk of failure or injury to people and equipment," he told SPACE.com.

A little retrofire into the space past proves the point.

For the "dusty dozen" Apollo astronauts that moonwalked between 1969-1972, each benefited from field trips on Earth.

Astronauts make treks to the Grand Canyon and the Rio Grande Gorge. Volcanic fields were traversed pre-flight by crewmembers in and around Big Bend National Park in Texas. Meteor Crater in Flagstaff, Arizona was also used for outdoor training, as was Bend, Oregon and the Valles Caldera.

Lessons learned from the Apollo era are worth remembering.

That's the counsel of William Muehlberger of the Department of Geological Sciences at the University of Texas in Austin. He was principal investigator for geology for the Apollo 16 and 17 missions to the Moon, and has continued as an instructor and advisor to the astronauts on Earth observations from Skylab, Apollo-Soyuz, Space Shuttle, and the International Space Station.

"Once a crew had been assigned to a landing site, training became specific to that site," said Muehlberger said. "Field trips were operated as if the crew was on the Moon and Mission Control was in Houston. They became progressively more complex and as close to the actual traverses they would be doing on the Moon as was possible," he recounted.

In fact, those on the last three Apollo landings had enough exposure to rock hounding to be comparable to a typical Master's Degree candidate in geology.

"Even so, they were shy about naming lunar rocks as they collected them for fear that they would give them a wrong name and embarrass themselves to the world," Muehlberger said. That changed on the last lunar mission, given the expertise of Apollo 17's Jack Schmitt, a highly qualified geologist/astronaut.

Looking toward tomorrow's off-world geologists, Muehlberger offered sage advice. For astronauts heading back to the Moon or those that plant their boots on Mars, they won't have to go through all the basic geology training as geologists are now part of the astronaut corps, he said.

"However, they'll still have to learn the basic camera steps to document the scene, to document where the sample came from, and to describe the features of interest to the world," Muehlberger noted.

Several Mars exploration analog sites are already up and running.

Teams of researchers make use the NASA Haughton-Mars Project planted on Devon Island, in the Canadian high Arctic. Also operating there is the Flashline Mars Arctic Research Station, run under the auspices of the Mars Society. Similarly, the society operates a Mars Desert Research Station that sits in the American desert, west of Hanksville, Utah.

"We need to determine what modes of exploration are most effectivein the field, in the lab, and in telescience consultation with Earth," said Robert Zubrin, President of the Mars Society. "Then you can develop the technologies that allow those exploration tactics to be implemented," he said.

Mars analog operations research on Earth is critically important, Zubrin said. "It makes no sense to spend hundreds of billions of dollars developing technologies if they are the wrong technologies for doing the job that needs to be done."

The Devon Island and Utah encampments are valuable in their own right. But there are many pages to the big book of space exploration.

In other words -- and particularly for Mars -- that planet is so diverse and complex no single analog site fits the bill.

Antarctica, as example, is one place on the planet where human beings are in perpetual peril. Environmental conditions are severe. Supply lines of food, fuel and equipment linked to that remote continent are critical. It's tough sledding in more ways than one.

For loads of reasons, Antarctica resembles exploration programs that NASA would implement on either the Moon or Mars, suggests Dean Eppler, senior scientist for Science Applications International Corporation (SAIC) in Houston, Texas.

Eppler recently spent time on the ice in search of meteorites. He reported that Antarctica is an "extremely fertile testing ground" for keeping humans alive and performing useful work in a cold, hostile environment like Mars.

"In order to understand how to initiate and support long-term, sustained activities on planetary bodies off the Earth, the experience gleaned by the United States Antarctic Program since its inception in the 1950s will be very important for NASA to understand," Eppler said.

Lessons learned from Antarctica and other analog sites need to be gathered, "so we can understand what we're not doing and what needs to be done," Eppler told SPACE.com.

"Antarctica is a good source of information in terms of how much time you spend doing science versus staying alive," Eppler said. "The bottom line is, if you don't bring enough foodyou don't bring enough powerand you don't bring enough whatever, you are going to lose the crew. I don't think that's an acceptable solution," he added.

Another vote for Antarctica as a dress rehearsal gateway to not only human exploration of Mars, but the Moon and asteroids too, comes from James Rice, a planetary geologist at Arizona State University in Tempe.

Rice was one of two Americans invited in the early 1990s on a six-month long NASA/Russian science outing to remote, rugged, and very isolated Eastern Antarctica.

"If you start thinking about home, you'll start missing it. That is a serious, slippery slope. You can go down hill if you're not careful," Rice warned. Going to Mars is partly a human factors issue. Danger is literally around the corner, or down inside a crater.

"When you are in Antarctica, the hazards are always in the back of your mind. But you never really talk about it. That's kind of taboo," Rice said.

One way to sharpen the mental and technical sharpness of a crew heading out to Mars is to use the International Space Station (ISS), Rice said. After a tour-of-duty on the ISS that fakes an interplanetary cruise, the crew returns to Earth. On landing they are given a medical once-over, then quickly spirited down to a test site in the dry valleys of Antarctica. Once there for an extended stay, the crew would find shelter in a home-away-from home Mars-like habitat.

This astronaut role-playing would be a high-fidelity trial run of the people, food and water supply needs, science duties, and equipment required to support a future Mars mission. Making it all the more valid would be delayed round-trip communications to and from mission control, Rice advocated.

"Make it as real as possible. I think you'd find a lot of bugs in the system," Rice said.

Stephen Hoffman, a systems engineer for SAIC in Houston, Texas, said there are different levels of analog sites.

Analogs can be housed in a lab setting with a controlled environment to more exotic surroundings that challenge a human and or a machine. "That's how analogs fit, but at different times, different places, and for different reasons," Hoffman said.

"There's no place that I know of that would, in a compact area, give you everything you ever would want to look at," Hoffman said. "So you are always going to have a bunch of them."

A next step is identifying individual attributes of far-flung analog sites, suggested Thomas Farr, Deputy Project Scientist for the Shuttle Radar Topography Mission at the Jet Propulsion Laboratory (JPL) in Pasadena, California.

"We need to really pull that together. It's a daunting task," Farr said.

Farr said better coordination between supporters of individual analog locations is needed. Likewise, matching technology testing to specific sites, and vice versa, would be desirable. Furthermore, international partners, as well as different parts of NASA itself, he said, should work together to help advance and support greater use of terrestrial analogs here on Earth.

For one, there are crossover interests between Earth remote sensing scientists and the Mars exploration community, Farr said.

One attention getting analog site is that of Svalbard, Norway. It is rife with glaciers, ice caps, warm springs, volcanoes and gullies. Over the last six months, the idea of developing Svalbard into a Mars analog site has gained momentum, said Knut Oxnevad of JPL's Modeling and Simulation Technologies Group.

Oxnevad said that Svalbard has the potential of becoming a first-class Mars analog site, he said, ideal for testing robot planes, surface and subsurface systems, submarines, and for training of astronauts.

In 2000, a JPL-developed an ice-burrowing cryobot was tested at Svalbard.

This coming August, a major expedition into pristine areas within the area is to be staged. A probing of volcanoes and other features is on the agenda of experts in geophysics to astrobiology, said Hans Amundsen, a researcher at the University of Oslo's Physics of Geological Processes in Norway.

"It's just waiting for us to come use it," Oxnevad said.

Scientific site selection, robot testing, crew field training, a far side lunar base, exploring Mars first from an orbiting, people-carrying research ship, then on the surface -- there is no phase of exploration that does not profit from research at analog sites here on Earth.

So says Patricia Wood Dickerson, a space geologist from the University of Texas in Austin. Her message is clear: "Start in the realm of the known."

"There's need to use the space station as a platform for a lot of skills needed to go farther out," Dickerson said. Running rovers on Earth from the ISS should be considered. Why not task station crews to hone their observational aptitudes by pinpointing and documenting Moon and Mars-like analogs while they circle Earth, she said.

"There is no shortage of vision. Our mission is to sharpen the focus," Dickerson said.