Even for proliferated Low-Earth Orbit, it's all about availability

Space is new again. After 20 years of nearly static enterprises, the last decade has brought a flurry of activity from new organisations, like the U.S. Space Force and operators including SpaceX and Planet, to new objectives such as joint all-domain operations. Low-Earth Orbit (LEO) has swelled with new satellite constellations that use massive proliferation to counter Keplerian motion, which assures that any single satellite is usually in the wrong place at the wrong time. But one thing about space hasn’t changed at all. Savvy customers want their mission delivered when it counts every time. As a society, we depend on space assets for national security, navigation, weather forecasting, banking and communications, to name a few things. So, operational availability matters.

Yet, commercial microelectronics, commonly referred to simply as ‘chips,’ are not designed to handle the harsh space environment. Cosmic rays and trapped particles in the Van Allen radiation belts can strike the chips and change zeros-to-ones and ones-to-zeros. These Single Event Effects (SEE) can result in data corruption, functional disruption, or physical destruction. The accumulation of a Total Ionizing Dose (TID) causes transistors to short out over time. We have generally observed that microelectronics at finer geometries are becoming more resistant to TID at the expense of increased susceptibility to SEE.

Companies like BAE Systems, with decades of experience in developing radiation-hardened electronics for space applications, have been at the forefront of addressing these challenges. From standard components to single-board computers and payloads, space missions require radiation-hardened flight controls, security and communications to deliver the effects that customers can consistently depend on.

“Today, we can create circuit card assemblies that deliver “always on” levels of availability by using RHBD devices at the most critical points of a system and surrounding them with automotive and aviation-grade commercial components”

Radiation-Hardened By Design (RHBD) uses the same processes at the same foundries as commercial electronics but adds design features in silicon to mitigate data loss, upset and destruction. By applying RHBD techniques to commercial chip designs, such as processor cores and analog-to-digital converters, you create purpose-built chips which provide the same operational availability as their terrestrial counterparts, just in space. While RHBD chips can be expensive due to high non-recurring engineering costs associated with design and fabrication, those costs are bounded by using standard fabrication flows. RHBD is a vital component of the space ecosystem for various environments, such as interplanetary, cislunar, geosynchronous Earth orbit, medium Earth orbit and even higher low Earth orbit (LEO) above 900 km. In fact, it’s these environments that continue to drive the development of RHBD chips today.

With the pivot to lower LEO (below 650 km), proliferated constellation operators are experimenting with commercial electronics in space to meet cost targets. The argument is that “the architecture” will provide redundancy through numbers so that any individual satellite can be in the process of reset and recovery while the system provides space-enabled capability through another satellite. This may be true for a massive constellation such as Starlink (>5000 satellites), but the numbers are not sufficiently dense in defense and intelligence missions to guarantee that a sensitive operation won’t be interrupted. Defense and intelligence customers require a diverse set of capabilities, including more types of satellites. This means even fewer of the right mission configurations – maybe only one – will have access to a particular slice of real estate at any one time. This is no time for a reboot!

There is another way to approach low LEO that is more relevant for defense and intelligence. New RHBD chips, including RISC-V processors, channelisers, network endpoints and software-defined radios are being developed for the tough environments. Today, we can create circuit card assemblies that deliver “always on” levels of availability by using RHBD devices at the most critical points of a system and surrounding them with automotive and aviation-grade commercial components. Instead of falling back to availability at the “architectural” level, or by “testing assurance into” an inherently susceptible system, this Graded Mission Assurance approach guarantees availability by hardening the most critical elements in the system. And it does so at a price that is affordable for proliferation.

So, it is true that there are a lot of changes in space. It is wonderful to see so much innovation, inspiration and invention. Defense and intelligence space missions are evolving at a rate not seen since the 1970s. However, at the end of the day, operational availability never goes out of style. And at the core of any space system that is “always on” lie RHBD microelectronics.