XCOR Aerospace is shaping its plans to pursue a suborbital space plane. Preliminary designs of the vehicle have been released, depicting a craft capable of handling several unique space markets, including passenger space travel.

Called the Xerus (pronunciation: zEr'us) project, XCOR is eyeing three space businesses: Suborbital payloads traditionally flown on sounding rockets; delivering microsatellites into low Earth orbit; and kick-in-the-pants hops for passengers to the edge of space.

XCOR Aerospace is a California corporation, based in Mojave, California. The company is in the business of developing and producing safe, reliable and reusable rocket engines and rocket powered vehicles.

"We are very excited about the new engine since it moves us closer to our goal of a reliable and economical vehicle for space tourism as well as educational and commercial uses," said Jeff Greason, XCOR Chief Executive Officer.

The XR-4K5 makes use of readily available and nontoxic fuels, a plus not only for reliability but to help control costs in operating suborbital vehicles, Greason said in an XCOR press statement.

Xerus would wing its way skyward to satisfy a trio of lucrative markets.

"So like the good entrepreneurs that we are, we like to show a business plan," said Dan DeLong, XCOR Chief Engineer at Space Access '03, held last month in Scottsdale, Arizona.

Those markets are:

• Suborbital payloads are primarily science experiments that are currently launched by sounding rockets. Examples are materials processing experiments, and zero-g checkout of small space shuttle payloads. Delivering these payloads with a reusable vehicle will significantly cut costs and lead-time. Because of the low flight price, experiments now flown as secondary payloads can have a dedicated flight on demand;

• Microsatellite launches via Xerus would have the space plane function as a reusable first stage that carries an expendable upper stage. The vehicle releases the upper stage, which has its own rocket engine and is capable of putting a microsatellite into low Earth orbit. Xerus would service the current small payload market as well as customers who today are not in the satellite launch market for reasons of expense and lengthy lead times to orbit a satellite;

• Passenger flight in Xerus would give a person a high-energy ride to near orbital altitude, though not orbital velocity. This exhilarating boost up to nearly 62 miles (100 kilometers) would give a person the ultimate joy ride - some three minutes of microgravity and an over-the-top view of Earth surrounded by a black sky filled with stars.

The Xerus project is part of a joint marketing agreement between XCOR Aerospace and Space Adventures of Arlington, Virginia. That pact provides Space Adventures the first 600 flights to suborbital altitude of the vehicle outfitted to support a space tourist, while slapping their wallet for $98,000 per trip.

According to XCOR, the same Xerus vehicle can serve all three markets. Changing from tourist carrier to sounding rocket would require removal of a rear ejection seat and installation of experiment package attach points and power connector. The upper stage for launching satellites would be carried on the outside of the space plane.

As to when Xerus will first fly, and price tags for services, those details have yet to be issued.

XCOR officials said they are very aware that the entrepreneurial space industry has suffered damage from companies and individuals that promise the sky, literally, but fail to deliver.

"This creates a skeptical customer base that inhibits the formation of customer relationships and investor capital," notes an XCOR overview of the project. "Therefore, we are releasing this information not as a promise of what we will do, but as an illustration of the general type of vehicle we are pursuing."