The U.S. space community has grown to include robust national security, civil, and commercial sectors. In national security, space operations have become increasingly crucial to communications, command and control, reconnaissance and surveillance, and positioning, navigation, and timing. Space operations are also increasingly integrated into civilian activities such as Earth observation, weather prediction, research, and exploration. In recent years, there is also an independently growing commercial and philanthropic space sector. Relatively new and emerging companies such as SpaceX, Chandah, Planet, Blue Origin, and others are bringing new architectures and commercial practices to the space community in an attempt to reduce costs, increase access, and make new missions economically practical. Some concepts involve supplementing expensive, highly reliable, long-lifetime satellites with hundreds or even thousands of cheaper, disaggregated satellites that use standard commercial parts and achieve mission assurance through scale.
Spacecraft conducting these missions are exposed to different radiation environments. For example, most terrestrial orbiting satellites are impacted by solar and galactic particles as well as by the trapped radiation in the Van Allen belts, with the nature and the intensity of radiation varying by the altitude and inclination of the orbits. Spacecraft that leave Earth orbit for deep space face both solar and galactic particles as well as the unique radiation environments of the areas they visit. For example, satellites orbiting around Jupiter see a different and much more severe radiation environment than a rover on the surface of Mars.
Electronics used in these spacecraft have shown a susceptibility to the effects of radiation—and the impact of these effects differs as feature sizes decrease, semiconductor technologies change, and alternative technologies arise. Due to the evolution of the global electronics industry, specially screened and radiation-hardened electronics often lag the state of the art for non-screened, untested, or non-hardened parts. When a design calls for a part (see Box 1.1) that has not been tested or is now being built with a new process or on a new manufacturing line, the designer either assumes some risk for adverse on-orbit radiation impacts or must plan for new testing to ensure that the part’s performance will be satisfactory in the space environment. If U.S. spacecraft manufacturers are not able to adequately characterize, test, and capitalize on emerging technologies, there are two possible outcomes: they will have to either rely on heritage components (which are most often less capable) or take the risk that the spacecraft will not be able to meet mission requirements due to untested parts. Either outcome increases some risks for the United States. If the United States depends on heritage parts, there is the risk of diminishing supply for these parts as the microelectronics industry advances to new generations of parts. If the United States uses currently untested, but more advanced parts, there is the risk of on-orbit failure or anomalous behavior due to single-event effects (SEEs) or more demand for testing in an infrastructure that is already stressed.
The facilities available for electronics testing represent only one part of the issue. The other is the changing nature of the users of these facilities. Currently, the user base is evolving in new ways. The combination of new space companies, increased interest in using space for new missions and with larger constellations using “more commercial” parts, and the fast evolution of electronics away from the more familiar space-qualified parts may put more stress on the current radiation-testing infrastructure.
To better understand the emerging stresses on the infrastructure, the Department of Energy, the U.S. Air Force, and NASA requested that the National Academies of Sciences, Engineering, and Medicine evaluate the current capabilities and future needs in the United States to ensure electronic components planned for future U.S. space programs are able to withstand the radiation stresses they will be subjected to during their intended mission life. In conducting the study and preparing its report, the Committee on Space Radiation Effects Testing Infrastructure for the U.S. Space Program was directed to
- Assess the existing infrastructure for verifying the ability of existing and emerging microelectronic, optoelectronic, and photonic components to operate properly in the space radiation environment;
- Characterize the infrastructure that will be needed in fiscal year (FY) 2018 and beyond (nominally through 2030, particularly in the case of particle accelerators) to adequately provide the required capabilities for new and emerging electronic technologies, and identify the principal gaps that exist between existing and needed infrastructure;
- Recommend steps needed to establish within the United States an effective infrastructure that eliminates, or reasonably minimizes, any identified gaps; and
- Recommend steps required to provide effective stewardship of the necessary radiation testing infrastructure for the foreseeable future.
Appendix A includes the full statement of task for the committee.
This report describes the types of radiation effects that spacecraft electronics can face, as well as the various testing facilities for simulating these effects. As discussed in Chapter 2, the committee focused its effort on one particular type of effect called single-event effects (SEEs), which can result in consequences ranging from self-recovering disturbance of device outputs to catastrophic failure of the device.
The focus of this report is on the effects of radiation on electronics, not on the human body. The ensuing chapters address the issues above. Chapter 2 will discuss the space environment and its effect on spacecraft electronics. Chapter 3 will discuss the current state of radiation hardness assurance and the infrastructure that is currently available—focusing on the test equipment, including facilities, databases, standards and guidelines, modeling and simulation tools, and staffing. Chapter 4 will discuss future needs based on trends in the space environment, current silicon technologies, as well as projected devices based at least in part on alternative technologies. Chapter 5 will include recommendations to ensure an adequate testing infrastructure.
Finally, the committee notes that space is not the only environment where SEEs are a concern. In the terrestrial environment, SEEs in avionics and server farms represent threats to reliability. SEEs due to terrestrial neutrons, muons, and other energetic particles will likely be a significant challenge for development of autonomous vehicles (e.g., self-driving cars). In addition, SEEs can also constitute a significant reliability threat for accelerators, reactors, and other high-radiation environments where reliable operation is required. However, this report focuses on SEE infrastructure specific to the space environment.