The hybrid approach allows the design team to implement a radiation-hardened functional base incorporating the latest state-of-the-art COTS technology.

Before the boom in consumer electronics such as gaming, cell phones, wearables, and the Internet of Things (IoT), there was a time when the government/military electronics sector consumed a significant percentage of the semiconductor industry's output. This allows the military and space agencies to have a significant impact on the types of new products and manufacturing processes being developed by the semiconductor industry. This is no longer true as the military/aerospace market is no longer large enough to justify such investments by semiconductor suppliers. This has resulted in the continued use of traditional components developed many years ago, as well as on-screen commercial off-the-shelf (COTS) integrated circuits for space use. This is not an ideal situation for designers of space electronics systems.

Military and major aerospace suppliers are still conservative about using COTS because of their very stringent mission assurance models, and their rigorous approach to equipment certification has proven to be very effective over the years. However, there is a "new space" community of developers who have a higher tolerance for risk but expect significantly lower component costs. The growing popularity of small satellites further encourages this approach, as failure costs are low and constellations of small satellites (SmallSats) can be used to provide system-level redundancy to mask the failure of individual SmallSat units. (SmallSats are generally considered to weigh less than 300 kg, but are generally lighter; see also "What are SmallSats and CubeSats?")

A simplified view of the situation today is that there are two basic camps. The "traditional" camp has a low tolerance for failure and pays exorbitantly for specialized rad-hard semiconductors that are generally considered far from state-of-the-art. The "New Space" camp has a more relaxed attitude towards mission assurance and is willing to use low-cost COTS equipment with the latest technology. Given that the vast majority of new space satellites are used in Low Earth Orbit (LEO), their radiation environment is less extreme and the risk of catastrophic radiation-induced failure is low (LEO is thought to be between approximately 300 km and 1,000 km) from Earth and below the inner Van Allen radiation belts).

There are signs that members of the traditional camp are beginning to relax strict qualifications for semiconductor products to take advantage of the latest technology. This is evidenced by their willingness to use plastic packaging instead of traditional ceramic packaging on space missions. There are also signs that the new space camp has recognized that COTS products represent a well-founded risk, so they have been wise to deploy radiation-hardened components in space electronic systems to improve reliability. The upshot of all this is that traditional and new space engineers are gradually converging an approach to creating systems using more cost-effective but still radiation-hardened electronics.

In recent years, there have been many initiatives to reduce the high cost of traditional radiation-hardened components. These include leveraging innovative hardening technologies in high-volume commercial foundries, the use of commercial IP available for radiation-hardened integrated circuits such as Arm processors, and steps currently being taken to create plastic packaging specifications suitable for use in space . All of these measures are reducing the cost of radiation-hardened components to facilitate the convergence of the needs of traditional and new space developers.

One approach that is gaining momentum, especially in CubeSats, is the judicious use of radiation-hardened components to implement critical system functions and act as safety monitors or watchdogs to oversee the proper operation of COTS devices used in the system. This hybrid approach allows the design team to implement a radiation-hardened functional base incorporating the latest state-of-the-art COTS technology. A good example is the use of COTS graphics processing units (GPUs) in small satellites that require high-speed image processing from onboard cameras. COTS GPUs cannot mitigate radiation effects by themselves, but they can be managed by radiation hardened equipment to ensure that they function properly and reset if their operation is disturbed by radiation effects.

Using multiple copies of COTS devices for redundancy is still a popular approach, but it becomes more challenging given the size. Packing a lot of functionality into a CubeSat form factor is beneficial because it reduces launch costs and opens up more launch vehicle options. However, if a high degree of redundancy is designed into the system to compensate for the use of COTS equipment, it can be difficult to squeeze more functionality into a limited space.

A major factor affecting the overall cost and reliability of space electronics systems is software. Access to the latest commercial software development tools is undoubtedly a major benefit of creating robust code. When reliable software modules are created and verified, it is also a great benefit to be able to reuse them. The new space community in particular has shown a trend towards using software programmable architectures that can be developed, adapted and reused very quickly. This reduces product development time and improves reliability by reusing known good modules.

The cost of a small satellite can vary widely, depending on who is developing it, who is launching it, where it will operate, and its expected lifespan. When analyzing development, test, launch, and operational costs, it becomes clear that saving a few thousand dollars by using only COTS equipment and not including some radiation-hardened equipment is a relatively small part of the overall budget. Many small satellite developers have recognized this and have taken steps to upgrade their mission assurance for mission-critical functions by selectively implementing radiation-hardened components. This trend will accelerate as the availability and cost of next-generation radiation-hardened components continue to increase.

Want to delve deeper into space electronics? Check out other articles from the Aspencore Space Electronics Special Project:

A New Era of Space Electronics – The development of reusable rockets lowers barriers to space science and commercial exploration, stimulating interest and investment in space electronics. This special program exposes designers to the techniques and design practices required to create spatially valuable electronic designs. These may include but are not limited to ICs, ASICs, flex cables, connectors, thermal management of electronics, Rad hard technology, space related test methods, Apollo 1960 electronics, etc.

EMC in Space: James Webb Space Telescope – Testing EMC on a spacecraft is no different than testing equipment on the ground, except that spacecraft live in a different electromagnetic environment.

Artificial Intelligence and Machine Learning: Shaking the Space Industry – Today's increasingly ambitious mission demands require spacecraft with higher levels of autonomy and greater navigational precision, requiring more than logic-based artificial intelligence.

A brief history of electronics reliability in space, including today's risks and how to mitigate them – components of new space systems must still meet radiation tolerance and electrical, thermal and mechanical reliability requirements. However, new space plastic-grade ICs can offer cost and size advantages over traditional "all-space" components for low-altitude missions.

Changing Trends in Space Electronics Design – Space electronics have come a long way from the custom, radiation-hardened guidance computers and hand-woven memory used in the Apollo missions. Avionics today are millions of times more powerful than when humans landed on the moon!

Safe and affordable space travel starts with procurement — commercial space tourism is on the rise at a fraction of the cost of its predecessors, raising concerns about passenger safety. A key aspect of spaceflight safety is radiation shielding and mitigation, a problem that new space ventures have not fully addressed in the past. Traditional space radiation mitigation strategies are costly, but new space mitigation techniques may not be suitable for safety-critical missions. The solution to this cost-safety trade-off is Sub-QML hardware electronics, which are radiation-hardened by design, but are less expensive due to reduced screening levels.

Mission-Critical Spaceflight Systems Maintain Radiation Intensity – To understand the effects of radiation on electronic systems and components, we explored the effects of various space radiation environments and their impact on commercial "New Space" and NASA mission profiles.

Reviewing Editor: Peng Jing

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