Driven by the intense interest created from the LEO constellations market and the need to reduce launch costs, microsat technology is fast coming of age.

Unlike manned spacecraft where payload weights are driven by other concerns, reductions in the cost of launching science and application spacecraft can be partly achieved by shrinking the overall mass of a spacecraft.

Furthermore, combined with new space proven technologies, spacecraft designers are starting to find that a similar level of science results can be often achieved just as effectively via smaller spacecraft, planetary landers and rovers such as Pathfinder and Sojourner.

One of the more prominent private companies currently working in the field of miniaturized spacecraft and space equipment is AeroAstro Inc. of Herndon, Virginia.

Established by Dr. Rick Fleeter in 1988, AeroAstro and its staff have since flown over 20 small satellites and space instruments.

Its customers have included the United State Air Force, NASA and JPL, MIT, the Canadian Space Agency, and corporations in Japan and Sweden. Building on these contract successes AeroAstro is now enjoying annual revenues in excess of $4 million.

AeroAstro's principle business is constructing spacecraft -- ranging from a new class of one kilogram satellites dubbed nanosats to the more traditional class of microsats that weigh around 250 kilograms. The cost of these satellites can range from $100,000 to several million dollars, with development cycles ranging from a few months to a few years.

AeroAstro has seen three of its satellites launched - and while the results have not been entirely happy, they show substantial promise for the future of microsat technology.

Fleeter told SpaceDaily that the company's first satellite, ALEXIS, was launched in 1993 to map stellar X-ray sources. "A combination of a subtle design error and stronger-than-expected vibrations in the Pegasus launch vehicle caused one of its four solar panels to be partially torn off and its attitude sensors seriously damaged," explained Fleeter. With the odds stacked against them, ground operators nonetheless found ways to work around all of these problems, and the satellite -- which was intended to work for six months -- has been providing ongoing scientific data for six years.

HETE-1. AeroAstro's second satellite, was less lucky. After its 1996 launch, the last stage of the then trouble-plagued Pegasus rocket failed to release it and another satellite. However, a replacement HETE is scheduled for launch in 2000 to study gamma-ray bursts.

The company's third satellite, TERRIERS, was launched last May to study the ionosphere. This time -- apparently due to a single software error -- the satellite failed to properly point its solar panels toward the sun and quickly ran out of electrical power.

"Over the next few months its solar panels should drift back in the general direction of the sun, and with a bit of luck TERRIERS could be reactivated and its software problem corrected - which is similar to what happened with the recovery of the ALEXIS mission in 1993." said Fleeter.

Undeterred by these problems, AeroAstro is moving beyond microsat platforms and is now actively designing a new class of nanosatellites that can weigh as little as one kilogram.

Indeed, its nanosatellite design - "Bitsy" - is designed to be "generic" and utilizes a basic kernel package - the size of a thick paperback book - that contains the satellite's electronic control and communications systems and some solar cells.

AeroAstro is also designing built-in interfaces that enable Bitsy to be connected to more enhanced power, communications, attitude control and propulsion systems in a modular fashion -- "a sort of "Lego" approach to spacecraft design we believe will prove to a major trend in future spacecraft design," said Fleeter.

Bitsy's first flight -- in which it will be attached to a Zero-G crystal growth experiment from the Marshall Space Flight Center and ejected from the Shuttle -- is scheduled for launch in January 2001.

While in November that same year a Bitsy kernel is scheduled to be launched on what is expected to be the first commercial space novelty mission dubbed "Encounter 2001".

Developed by Encounter 2001 Inc, a company whose primary shareholders include AeroAstro and space burial pioneer Celestris Inc, the mission will be used to kick start a new era of consumer oriented space missions.

The Encounter 2001 spacecraft will incorporate the Bitsy kernel that will in turn be attached to SPORT (Small Payload Orbital Transfer), a miniaturized spacecraft propulsion system developed by AeroAstro. Launched as a secondary payload via an Ariane 5, the spacecraft will be placed in GEO orbit where it will wait for an appropriate Earth escape window.

Using SPORT to propel itself into solar orbit, the Encounter 2001 spacecraft will use a flyby of Jupiter to obtain a gravity-assist boost that will accelerate it enough to achieve solar escape velocity thereby making it the fifth spacecraft to leave Sol for the stars - albeit in millions of years time.

Encounter 2001 is a kind of private interstellar time capsule that will contain recorded photos and messages from 4.5 million paying customers -- as well as tiny hair samples from many of them, from which their personal DNA codes could one day be reconstructed.

Although the chances of any space-traveling aliens stumbling across it and extracting its data is highly unlikely, the idea has an undeniable element of romance and could prove to be the first successful novelty space mission.

Moreover, the mission will provide a thorough test of both the Bitsy and SPORT systems -- and given its growing chances of commercial success there are even suggestions that NASA may add some lightweight scientific instruments to it.