BOULDER, Colo. -- The orbiting Hubble Space Telescope has yielded light buckets full of discovery and out-of-sight imagery.

But make way for a revolutionary class of 21^st century observing outpost - huge, high-tech facilities that could be assembled in space by a cadre of astronauts and robots.

Thanks to the march of technology -- in civilian, military, and intelligence-gathering circles -- space telescopes far larger than those now being planned appear workable. Major advances are in the offing, fostered to a great degree by the need for super-surveillance of world trouble spots, as well as more intensive scrutiny of Earth's complex global climatic condition.

A big picture view of space-borne astronomy was charted by some 60 technologists, astronomers, astronauts, and space project managers. They took part in a NASA-sponsored meeting, Future Large Optical Systems in Space, held here May 1-2.

"The more we explore 'out there'…the more sophisticated our understanding is of ourselves, our world, and its place in space and time," said Harley Thronson, Technology Director for the Office of Space Science at NASA Headquarters in Washington, D.C. and meeting leader.

There are a host of "killer applications" for large optics in space.

Thronson said orbiting mega-telescopes could look back in time to where the earliest birth of star formation takes place. Conditions in the early universe that created galaxies would also be observable. Furthermore, the ins and outs of how planets take shape around young stars could be studied, he told SPACE.com.

"Identifying, prioritizing and investing in the technologies that make possible these type of observations will be a challenge worthy of our most creative young scientists and engineers," Thronson said.

The goal of the two-day gathering was to create the systems, priorities, and relationships necessary to make possible the large space optical systems of the next decade, Thronson said.

The confab of experts tackled observatory technology; needed infrastructure; how best to orchestrate long-term projects; ways to mobilize management; as well as define roles for humans and robots.

To help harness needed technologies, a series of "stepping stone missions" were advocated. The crafting of a roadmap for placing large optical systems in space would meld NASA expertise with that of the U.S. Air Force, the Defense Advanced Research Projects Agency (DARPA), and other agencies.

The time is ripe for "mind stretching", said Robert Cassanova, Director of the NASA Institute for Advanced Concepts. He urged attendees to think beyond current NASA plans for space-based observatories.

Doing so means exploring the limits of what is currently thought to be technically feasible, Cassanova said. He advised that "evolutionary" thinking must be replaced by "revolutionary" concepts that are inspiring a new class of enabling technologies.

One outcome of the gathering is the likelihood of building space-based telescopes far larger than the James Webb Space Telescope (JWST).

The JWST is an orbiting infrared observatory and assigned a parking spot at the L2 Point, some 930,000 miles (1.5 million kilometers) from Earth. Using 36 mirror segments that unfold to form its primary mirror, JWST is on tap to take the place of the Hubble Space Telescope at the end of this decade.

"I think there are wonderful possibilities for future large observatories," said John Mather, JWST's Senior Project Scientist at the NASA Goddard Space Flight Center in Greenbelt, Maryland. There are no laws of physics or engineering against increasing telescope sizes by another factor of three above the JWST aperture of 21.3 feet (6.5 meters), he said.

Telescopes sporting 98-feet (30-meter) apertures to monster mirrors nearly 165-feet (50-meters) in size were broached by working groups at last week's gathering.

While great advances are foreseen and eventually required, Mather said that the pathway to those advances is not yet clear. For one, the technologies for fabricating mirror segments are not in hand. Other top priorities for working in near-infrared and shorter wavelengths involve better performing mirror technology - in terms of surface accuracy, high stiffness, low mass, coupled with faster, less-risky, and cheaper processing techniques. For ultraviolet wavelengths, a push in detector technology is necessary, he added.

For the longer term it's important to develop technologies for assembling and servicing observatories in space, Mather pointed out. "Tremendous ingenuity has been shown in developing methods for assembling and deploying equipment in space, and the International Space Station is a shining example," he said.

"I think that as soon as our mirror technologies can support telescopes much larger than JWST, we will be able to complete the engineering of space deployment, assembly, and servicing for them. This will almost surely require astronauts with remote manipulators -- dumb robots or smart tools -- because our newest telescopes are exposed and fragile and sensitive to contamination," Mather said.

The Hubble Space Telescope (HST) has brought a useful perspective and experience in looking outward to deploying future space observatories, said Rud Moe of NASA's Goddard Space Flight Center.

Drawing upon his background as Servicing Mission Manager for the HST, Moe said that humans are valuable "system agents".

"Humans greatly enhance or enable system performance overall, even in space. The HST servicing missions are great examples of the value humans operating in-space for satellite servicing can bring to space science and other programs," Moe told SPACE.com.

"For ambitious NASA goals beyond the near term, perhaps in the next two decades, the limits of remote operation of deployable structures will be reached. Assembly in space will be needed," Moe said. "The best tools for such operations in this timeframe will be tele-operated robotics. Human presence and participation on-the-spot will be required for use of tele-operation far from Earth," he advised.

There are red flags, however, in piecing together any large optical systems in space program.

A worry expressed at the meeting centered on ground and astronaut talent in future years. Beyond HST's last servicing in 2005, or perhaps out as far as 2009, loss of capability in this arena is likely. Moreover, the graying of NASA means the knowledge base in orbital servicing will, quite literally, walk out the door.

Then there's the issue of how to enable in-space assembly operations at far-flung sites, be it high Earth orbits, lunar orbit, on the Moon's surface, or out at Sun-Earth libration points.

To support these goings-on, work is needed on such items as high-capability launch vehicles and in-space transportation. Also deserving of attention is assuring human safety in radiation environments and for extended sojourns in less than a one-gravity environment.

Although tough issues need to be grappled with, a rolling up the sleeves attitude is taken by Michael Kaplan, Director of NASA Electro Optical Payloads for Boeing.

"This new paradigm could be the synergy between the human and space science programs that many have been searching for in Washington, D.C.," Kaplan said. Every large aperture astronomy mission after the James Webb Space Telescope needs to look at this new paradigm, he said.

The time is now to identify and begin developing new technologies, Kaplan said. Modest demonstrations and tool building could be carried out on existing assets, such as the space shuttle or the International Space Station, he said.

"Human/robotic in-space assembly, integration and testing, and servicing could be a very viable solution for all future large aperture space astrophysics missions," Kaplan said. "All of these steps could and should happen very soon," he concluded.