WASHINGTON -- Two new studies looking at the feasibility of space-based solar power - orbiting satellites that would serve as high-tech space dams - suggest the concept shouldn't be readily dismissed and could generate both Earth-bound and space-based benefits.

These "powersats" would catch the flood of energy flowing from the Sun and then pump it to Earth via laser or microwave beam. On earth it would be converted to electricity and fed into power grids to be tapped by terrestrial customers.

The thought of beaming energy to Earth via satellite was first brought to light in the late 1960s by Peter Glaser, a technologist at Arthur D. Little in Cambridge, Massachusetts. Into the 1970s and 1980s, the challenges of Space Solar Power (SSP) were reviewed numerous times. NASA, the Department of Energy, other government, industry and private groups have given the concept the once-over.

Among them: The size, complexity, and cost of an SSP undertaking are daunting challenges. International legal, political, and social acceptability issues abound. Health or environmental hazards from laser or microwave beams broadcast from space appear worrisome. Additionally, in the battle of energy market forces on Earth, any SSP constellation may prove far too costly to be worth metering.

In 1995, NASA embarked on what's tagged as a Fresh Look study. SSP feasibility, technologies, costs, markets, and international public attitudes were addressed. In general, NASA found that the march of technology and America's overall space prowess has re-energized the case for SSP. NASA did point out, however, that launch cost to orbit remains far too high - but that this problem was being attacked.

For the last few years, interest in SSP has grown, not only at NASA, but also in the U.S. Congress and the White House Office of Management and Budget. For its part, the space agency has scripted a research and technology, as well as investment roadmap. This SSP stepping stone approach would enhance other space, military, and commercial applications.

A special study group of the National Research Council (NRC) has taken a new look at NASA's current SSP efforts. Their findings are in the NRC report: Laying the Foundation for Space Solar Power - An Assessment of NASA's Space Solar Power Investment Strategy.

Richard Schwartz, dean of the Schools of Engineering at Purdue University in West Lafayette, Indiana, chaired the 9-person NRC panel.

While not advocating or discouraging SSP, the advisory team said "it recognizes that significant changes have occurred since 1979 that might make it worthwhile for the United States to invest in either SSP or its component technologies." The study urges a sharper look at perceived and/or actual environmental and health risks that SSP might involve.

The NRC study group singled out several technological advances relevant to SSP:

• Improvements have been seen in efficiency of solar cells and production of lightweight, solar-cell laden panels;
• Wireless power transmission tests on Earth is progressing, specifically in Japan and Canada;
• Robotics, viewed as essential to SSP on-orbit assembly, has shown substantial improvements in manipulators, machine vision systems, hand-eye coordination, task planning, and reasoning; and
• Advanced composites are in wider use, and digital control systems are now state of the art - both developments useful in building an SSP.

Overall, the NRC experts gave NASA's SSP approach a thumbs-up. The space agency's current work is directed at technical areas "that have important commercial, civil, and military applications for the nation." A top recommendation is that industry experts, academia, and officials from other government agencies -- such as the Department of Energy, Defense Department, and the National Reconnaissance Organization -- should be engaged in charting SSP activities, along with NASA.

The panel said that significant breakthroughs are required to achieve the final goal of SSP cranking out cost-competitive terrestrial power. The ultimate success of the terrestrial power application of powering-beaming satellites critically depends on "dramatic reductions" in the cost of transportation from Earth to geosynchronous orbit, the group reported.

Furthermore, the SSP reviewers call for ground demonstrations of point-to-point wireless power transmission. NASA should study the desirability of ground-to-space and space-to-space demonstrations. In this area, the International Space Station could act as a platform to test out SSP-related hardware, the study group said.