Radiation Tolerance Meets Commercial Space
June 30, 2020
Published in Military & Aerospace Electronics
Written by John Keller
Demand for access to space — for communications, surveillance and reconnaissance, remote sensing, internet access, and space experimentation — never has been higher than it is today, and is expected to grow through the foreseeable future. Satellites are under construction ranging in size from softballs to 18-wheel tractor-trailer rigs, as potential sponsors ask for high performance, relatively low costs, and quick turnaround.
As this demand puts advanced electronics at a premium for space, there still are environmental constants that no one can change. Chief among these is the radiation that occurs naturally in space. Orbiting electronics must be able to withstand bombardment of radioactive particles at different levels, based on their intended orbits. This means that today’s space electronics must be high-performance, radiation tolerant, and affordable.
Space electronics designers confront these challenges in a variety of ways, ranging from exhaustive testing, to enhancements and shielding, to designing electronic parts from the ground-up to function through space radiation for long durations. Test experts have come up with clever ways of screening commercial-grade electronics to separate those that can stand up to the rigors of space radiation, and those that can’t.
While some semiconductor designers have found ways to alter commercial electronics designs to boost their radiation tolerance, there still are established integrated circuit manufacturers with long histories of designing special radiation-hardened parts for the most demanding space applications.
It all boils down to balancing requirements for electronics performance, costs, mission durations, and the radiation environment of chosen orbits. Low-Earth (LEO) orbit, for example, can be among the most benign space environments for radiation. High-altitude geosynchronous Earth orbit (GEO), on the other hand, can be among the most severe. High-altitude polar orbits can be the harshest radiation environments of all.
One of the biggest applications drivers in today’s space electronics market is so-called “new space,” which describes commercial endeavors to create large constellations of inexpensive small satellites for uses like cell phone communications and internet access. In this market cost is king. In addition, requirements for resistance to orbital radiation effects often can be relaxed because of relatively short mission durations.
“Radiation hardened and radiation tolerant are two different things,” explains Jerry Festa, space product line manager for the Curtiss-Wright Corp. Defense Solutions activity in Newtown, Pa. Radiation tolerant, which is the target of most new space applications, represents using commercial off-the-shelf (COTS) parts as a foundation, and screening or enhancing these parts to survive the intended space orbit and duration. Radiation tolerant also can involve shielding sensitive components. “Radiation tolerant is an evolution from COTS parts and making them radiation tolerant, and we have focused on that for the past nine or 10 years,” Festa says.