By John Keller
NEWPORT BEACH, Calif. - The shift among military electronic systems designers toward using commercial off-the-shelf (COTS) components is starting to have a telling effect on the space community.
The problem is the ever-shrinking pool of engineers who have a deep understanding of how radiation can influence the workings of electronic equipment.
This phenomenon is evident from the growing numbers of attendees at radiation effects conferences who are starting from square-one, and who need basic tutorial information on how to design electronics that resists radiation, say officials of the recent Nuclear and Space Radiation Effects Conference (NSREC) in Newport Beach, Calif.
Prior to the 1990s, the majority of cutting-edge electronic ngineers came from the military and aerospace community, where the most advanced components were designed. Today, however, the cream of electronics engineers are experienced in commercial-grade systems, where radiation effects seldom are an issue.
"Most electronics designers don`t care if there is an upset," explains Klaus Kerris, a physicist in the Source Physics Branch of the U.S. Army Research Laboratory in Adelphi, Md., and one of the NSREC framers.
"Now the trend is on cheaper, faster, better, commercial-grade electronics; not on radiation hardening," points out Ronald Pease, engineer at RLP Research Inc. in Albuquerque, N.M., and the NSREC chairman for 2000.
Few commercial-grade electronic systems are vulnerable to radiation-induced problems. In the rare event a radiation failure occurs, most commercial systems can simply reboot, with trivial consequences.
Radiation of interest to systems designers occurs naturally in space, at high altitudes, and results from nuclear weapons explosions. Radiation can damage electronics in a variety of ways. The most catastrophic involve systems burnout from radiation spikes or electromagnetic pulse. The most benign - yet most insidious - come from single-event upsets (SEUs) in solid-state memories.
SEU happens when a charged particle causes a bit flip in a memory chip and corrupts its data. The bit flip itself can be serious, and the small amount of data corruption it causes can place the validity of all stored data in doubt.
Engineers with experience designing systems for radiation environments harden their equipment in a variety of ways, including using specially manufactured rad-hard semiconductors, using metal shielding, or using special software that detects and corrects bit-flip SEU.
Several factors are exacerbating the problem of the apparently dwindling expertise in the rad-hard field.
First is the proliferation of commercial satellites, such as the Motorola Iridium communications constellation. Designers of these systems are under intense pressure to use the least-costly components appropriate for the environment. No one except insiders at Motorola knows for sure what is the level of radiation-induced failures of Iridium satellites thus far, industry experts say.
Second is the ever-tightening integration of modern electronic components. As chip geometries shrink, they become ever more susceptible to single-event upsets and other radiation-induced problems.
Third is the growing number of embedded electronic systems that people rely on for their jobs and for their lives. It is exceedingly rare when people die as a result of a PC crash. That may not be so in the future in air traffic control systems, commercial aircraft avionics, medical heart pacemakers, and the like.
As rad-hard engineering competence dries up, users of military systems, communications, medical devices, and other job- and life-critical systems may see a growing number of failures.
People evidently are starting to ponder these issues. Witness the attendance at NSREC. "We planned for 350 people this year, and 600 showed up. We are growing at a 25-percent clip," Kerris says. "Every year we see a decrease in government lab attendees, and an increase in private industry."
About one-third of the NSREC attendees every year are attending that conference for the first time, Pease says. Conference officials plan to increase the amount of tutorial-level training in their short courses next year, he says.
The 1999 NSREC conference, sponsored by the Institute of Electrical and Electronics Engineers, will be July 12 to 16 at the Norfolk Waterside Marriott in Norfolk, Va. For more information, contact Teresa Farris of UTMC Microelectronic Systems in Colorado Springs, Colo., by phone at 719-594-8035, or contact the NSREC page on the World Wide Web at http://www. ieee.org/nps.nsrec/nsrec.html.
