BOULDER, COLORADO -- European advanced planners are sketching out a master plan for stepping out into space, beyond the International Space Station.

The European Space Agency (ESA) has given the go-ahead to start a new European long-term initiative for robotic and human exploration of the solar system.

Tagged the Aurora program, the call-to-action agenda includes dispatching robotic and human space missions to bodies elsewhere in the solar system. In particular, the effort puts at high premium those celestial objects that hold promise for traces of life.

The first year in a three-year "preparatory period" for Aurora is now underway, a time period dedicated to hammering out relevant technologies and types of future missions.

ESA's new Aurora Program aims to plot out Europe's solar system exploration plans for the next 30 years. That blueprint could include human expeditions to the Moon, Mars, the asteroids and even beyond.

Aurora gained formal approval last November -- one outcome of an ESA Ministerial Council meeting held in Edinburgh, Scotland.

"Looking back 30 or 50 years from now, it may well look like the most important decision taken in Edinburgh," says Franco Ongaro, who spearheads Aurora at ESA's Advanced Concepts and Studies Office in Paris, France.

"I think Aurora is a key program for the future of European space. It is the key to the new technology stimulus, to an attractive challenge for new generations, to the search for life elsewhere than on our planet, and to the future of manned exploration," Ongaro told SPACE.com.

Science is a vital ingredient of Aurora, but not a sole driving force.

"We need to balance our technological objectives, our science objectives and our budgets. We hope to come up with plans and missions that coordinate the efforts of national space agencies and help build up proven European competence in space engineering exploration," Ongaro explains.

Aurora is meant to look beyond Europe's current focus for human spaceflight -- the International Space Station (ISS). ESA is a major player in that multi-billion dollar mega-project. But after the ISS, what comes next?

Ongaro cautions that Aurora is still in its first, open-ended planning stage.

But despite the blue-sky status, an Aurora team is to sift through more than 300 European ideas over the next three years. These include concepts for reusable launchers, advanced space drives, broadband interplanetary communications, dealing with the effects on humans from extended space travel, and the search for life.

The objective is to cull these ideas, Ongaro says, picking concepts to move beyond drawings to machined metal. Obviously, the best ideas are those that combine long-term technological development with missions that make scientific sense now, without blowing the budget, he adds.

While robotic probes can take their time reaching destinations, human exploration missions will benefit greatly by getting there faster.

ESA is working on electric propulsion systems. That technology gets an in-space shakeout via ESA's own SMART-1 lunar probe, slated for launch this coming October. As the technology matures and becomes more reliable, electric thrusters are seen being installed on long-haul spacecraft, including human-carrying vehicles.

But for express lane travel, new transport technologies are required.

Nuclear thermal propulsion systems are potentially superior to nuclear electric power systems in terms of thrust levels.

Controlled nuclear fusion rockets are hundreds of times more efficient than anything used today. Fusion rockets would transform space travel within the solar system. For example, an expeditionary sojourn to Mars could take as little as a day or two.

ESA has recently initiated an assessment of the possible evolution of space propulsion in the next two decades. Called "Propulsion 2000," the ESA-led review is investigating, in concert with the European industry, space propulsion notions not only tied to space markets, but exploration scenarios too. The results of that study are expected later this year, and will serve as a road map for new development policy in Europe.

A lunar mission is a possible target for the Aurora program.

"If space is an ocean, then the Moon is our nearest island," Ongaro points out.

The once oft-trodden lunar surface now remains as forgotten as a beach in winter, and even the technology that planted footprints there has been scattered and lost. Apollo 17 moonwalkers -- Eugene Cernan and Harrison Schmitt -- left the barren and stark surroundings of the Taurus-Littrow highlands in 1972. ESA's Aurora program might well see people back on lunar soil, Ongaro believes.

New data about the Moon, collected by NASA's Lunar Prospector and the U.S. Pentagon's Clementine mission, have made Luna more attractive than in the Apollo days. Hints of lunar water ice, even a modest water supply, could guarantee an on-the-spot source of cheap rocket fuel. There is oxygen bound up in the lunar rocks too, Ongaro points out.

A return to the Moon is not considered an easy task. Europe needs to develop its own soft-landing technologies for preliminary robot missions. A polar lander would have to deploy robotic units that plunge into the sunless depths of likely water-bearing craters. Moreover, another agenda item is building and testing the hardware and systems to carry men and women to the Moon, and support them there, Ongaro says.

If the pioneers of the Earth's great age of exploration were required to carry all their supplies upon their backs -- food, water and even air to breathe -- most of our planet, Ongaro argues, would still be an uncharted wilderness. Yet the men and women who will explore the solar system in the 21st century must bear just such a burden. Unless, as their predecessors did on Earth, space explorers can learn to "live off the land" too.

The Aurora program has the task of taking human spaceflight beyond the ISS and out into the solar system over the next 30 years. Along the way, Aurora will be guiding the development of improved soft-landing technology and broadband interplanetary communications, as well as sophisticated robot science packages.

But there's a limit to what robots can do, Ongaro notes.

The debate regarding human versus robot skills is alive and well in Europe, just like in America, Ongaro told SPACE.com. The Aurora strategy in this respect is akin to what is occurring in our daily lives -- robots and humans working in tandem rather than one versus the other, he explains.

"Robots are built to perform a task exploration is a need of the human race. Robots will always be needed before and in support of humans," Ongaro says.

Aurora is looking toward a strong robotic program to build and qualify the technologies needed to pave the way to a human mission, and to test and learn as much as possible before humans are on the way.

Ongaro serves up two thoughts in scoring human exploration skills contrasted to the wherewithal of space robots.

"There is no environment on Earth where humans will not go as soon as technology allows them to, be it ocean floors or the calderas of volcanoes. Also, which is the most significant picture of the 20th century -- Neil Armstrong or the Russian Lunakhod moon rover?"

The search for life is a major element in all future Mars missions. ESA's Mars Express orbiter -- that will drop off the Beagle 2 lander -- is already on tap for liftoff in 2003. As a step in the Aurora program, a robotic sample return mission to Mars is under discussion.

"Ideally, we want to bring back not just any random rock," Ongaro emphasizes. "We want to be able to tell the spacecraft: That rock over there!"

If Aurora comes up with broadband interplanetary communications links between Earth and Mars, millions of people could share the adventure of Mars exploration via the Internet, Ongaro says.

Eventually, a human Mars mission, perhaps with the Moon as a first target, or even as a way station to the Red Planet, would represent the culmination of the program's efforts. And just incidentally, Ongaro adds, it would also guarantee that there was life on Mars -- human life.

Additionally, Aurora planners envision asteroids as part of Europe's long-term space vision.

ESA's yet-to-be-launched Rosetta probe is targeted to a rendezvous with comet Wirtanen in 2011. En route, the spacecraft is to encounter asteroids 4979 Otawara and 140 Siwa. While these will be fleeting glimpses, Rosetta is set to add more data to the slender asteroid database.

Learning more about asteroids makes scientific sense. Moreover, these rocky mini-worlds offer rich opportunities for mineral exploitation, he adds.

And there appears to be a more pressing reason to understand these celestial wanderers, Ongaro believes.

An asteroid hitting the Earth would yield devastating results. While the odds against such an event are high, gaining more knowledge about the makeup of asteroids and the ability to move their orbits would act as a kind of insurance policy for Earth. ESA is sponsoring Spaceguard, a worldwide project tasked to plot the orbits of all Earth-crossers. Hundreds have been logged so far.

How independent is the Aurora program to seed humans outward to the Moon, Mars and other targets?

Given the somewhat befuddling cooperation between ESA and NASA in building the International Space Station, Aurora might be viewed as a go-it-alone endeavor.

"I believe that future exploration missions will be international for plenty of good reasons ... economics, technology, diplomacy, etc.," Ongaro says. "The ISS cooperation will clearly teach us a lot on how to manage such cooperation. One lesson seems clear already, however. The best cooperation takes place among equal partners," he told SPACE.com.

Europe is setting its own goals and strategy through Aurora, Ongaro stresses. Cooperation will evolve, first by finding a fit with other partners, rather than merely following the lead of a single partner.

"In this sense, it will be key for Aurora to mature the European technology capacity -- and resolve -- to the level of a key and indispensable partner. And this for the benefit of all partners," Ongaro concludes.