New mission profile in space means COTS is now an acceptable riskStory
May 31, 2018
New mission profiles in space mean that suppliers of radiation-hardened (rad-hard) and radiation-tolerant electronics are able to meet less stringent requirements. The end result: Lower cost and faster time to market for parts used in space applications.
Today’s mission profile is determining the level of testing electronic components necessary for enduring space radiation effects; both the Department of Defense (DoD) and designers are coming closer and closer to accepting the risks associated with sending commercial off-the-shelf (COTS) components into space.
One major reason is that “Technology is evolving at a very rapid pace; in my view, at least, government/military type programs generally owned a large share of space-based applications,” says Alan Murphy, Product Line Manager in Aerospace Instrumentation at Curtiss-Wright Defense Solutions (Austin, Texas). Of course, that view has evolved as “that equation has changed very dramatically in the last several years.”
Accepting the risk factors under new mission profile
“Rad-hard applications are trending more toward compromise and reduced radiation performance requirements,” explains Eli Kawam, Product and Business Development Manager of Microchip’s Aerospace and Defense business unit (Chandler, Arizona). “For example, based on accumulated measurement in flight, the level of total ionizing dose (TID) [of radiation] may be relaxed.” To be clear, however, “since the technology trend is toward deep submicron technology and high levels of system-on-chip (SoC) integration, more testing must be performed to detect and mitigate single-event effects.”
The risk of sending anything to space is still there: “High-reliability and radiation-hardened performance is still a focus for military rad-hard applications,” says Michelle Mundie, Business Area Director of Standard Products at Cobham Semiconductor Solutions (Colorado Springs, Colorado). “Cobham has seen an uptick in requests for rad-hard components that have superior prompt dose performance as well as single-event effects for military rad-hard applications.”
Yet the mission profile will overrule any major testing if it is deemed not necessary. “We are also seeing our customers customize satellites to the specific mission, like orbit, timeline, etc.,” says Chris Hart, Director of Marketing, Aerospace & Defense for Microsemi (McKinney, Texas). “By doing this, our customers are able to lessen their margin, which can mean lower radiation or quality requirements.”
Even the production of megaconstellations and groups of small satellites are having an effect on the industry. “There is some influence from the megaconstellations/small satellites,” says Josh Broline, Product Line Director for the Intersil High Reliability and Space Products at Renesas Electronics Corp. (Melbourne, Florida). “However, the space environment is not changing. In fact, there have been some studies recently that there’s actually more of a higher accumulative radiation level than we originally expected.”
Broline clarifies, saying that it’s the risk profile that is changing. “What I see is mainly driven by the flight duration of these different mission profiles or programs. For example, the mission and risk profile changes dramatically from a 15- to 18-year mission that’s in a GEO-high [geostationary orbit] orbit, down to a LEO [low-Earth orbit] for five years or so.”
Cost is also a major factor when determining the mission profile. “These programs may also be more sensitive to acquisition cost, service entry dates, and even a technology refresh plan, so they are attempting to find savings by using components with lower levels of qualification and screening,” Hart says. “Typically, military rad-hard applications require very high levels of qualification and screening, up to QML [qualified manufacturer list] class V for ICs, JANs [joint Army/Navy] for discretes, and class K for hybrids. But some programs will definitely follow a similar path to commercial and civilian rad-hard applications. In general, it’s all about trade-offs between performance, cost, operating lifetime, and time to market.”
That trade-off trend seems to be felt throughout the industry. “Some programs require components and hybrids with high levels of qualification and screening, up to QML class V and class K level,” says Ken O’Neill, Director of Marketing, Space and Aviation, Microsemi (San Jose, California). “Other programs are more sensitive to acquisition cost and service entry dates, and are attempting to save in these areas by requiring components with lower levels of qualification and screening. In this regard, military rad-hard applications are following a similar path to commercial and civilian rad-hard applications.”
“The combination of these factors on the rad-hard system evolution has culminated in fewer constraints on radiation performance, leading to new types of solutions for rad-hard applications,” Kawam adds.
Making the decision
So what does the rad-hard decision come down to? “The mission profile is going to ultimately determine the kind of components to use and the screening levels required,” Broline says. “In the commercial satellite world, there’s definitely a pause, because they are paying attention to the larger constellations. The large constellation providers are treading their own path, because they have their own mission.”
In addition, the DoD is sending satellites into space with specific missions, which means that designers, suppliers, and buyers of rad-hard and rad-tolerant components need a much wider range of how much radiation these embedded components will be withstanding in space.
“If you’re putting a satellite in orbit for a long period of time, then clearly the exposure to radiation is the bigger issue,” Murphy explains. “Depending on the nature of the mission and the nature of the functioning application within that mission, that will define the mission profile. In other words, what the electronics are actually doing – that will be a big driver as to how rad-tolerant you really need to make this work the way it needs to work.”
In response to more relaxed requirements, “There are some military satellite providers that are potentially taking more risks,” Broline says. “Meaning they may be more and more willing to take COTS products and do an upscreen for space applications. We’re seeing a little bit more of that, but not for mission-critical aspects of a particular satellite. It’s not sweeping the industry by any means at this point, as far as taking on more risks on their component selection or screening.”
When it comes to the risk profile, “I could pay a large amount of money to find a chip set for my needs that are ‘rad-hard,’” Murphy explains. “What we’re exploring is the boundary between traditional rad-hard applications and rad-tolerant applications, where customers would have said this is a space application, we want it rad-hardened, and that’s the only solution we’ll consider. That conversation has changed dramatically to: This is the mission profile and it will be in a space environment, but the nature of the mission doesn’t necessarily need a rad-hard hardware solution.”
COTS in space
New mission profiles provided by the burgeoning market for megaconstellation and small satellite groups have delivered an opportunity for COTS suppliers to send their components into space.
This means that with new mission profiles, “The demand for COTS technology in space applications continues to increase,” Murphy says. “What we found is that the starting point is COTS technology. Then we look at how we need to modify the COTS products for use in space based on the radiation characteristics of the application’s environment and other unique customer requirements.”
“These megaconstellations of small satellites are possibly enabling new applications and new ideas and new things that haven’t been thought about before, at least for satellites; so my five or ten-year outlook is that ultimately it’s going to be a larger servable market,” Broline says.
The most interesting part is that “We’re finding more and more that users want COTS, ‘as-is’ with very little modification for the space environment,” Murphy says. “An increasing trend for the manufacturers, those who know the challenges and are well-versed in the space industry, is that people are asking for real COTS, as-is products.”
For companies like Cobham, such requests have driven them “even further to innovate and provide differentiated and integrated solutions thereby addressing not only SWaP [size, weight, and power] but also driving down our costs to make our products more affordable,” Mundie says. (Figure 1). “An example of this is 32-bit Arm Cortex –M0+ Microcontroller.”
Figure 1: Cobham integrated both volatile and nonvolatile memories to make a rad-hard microcontroller that can read/write in space applications. Photo courtesy of Cobham.
Given the risk profile of sending a component to space that is not fully rad-hard, the DoD and users are willing to attempt to use rad-tolerant devices to reduce the cost. “NewSpace and other critical aerospace applications require faster development and reduced costs,” Kawam says (Figure 2). “Microchip has developed an approach for taking a proven automotive-qualified device and creating a pinout-compatible version in both high-reliability plastic and space-grade ceramic packages. They are tested to specified radiation performance. Customers can begin development of hardware, firmware, and software with the COTS device immediately. When the final system is ready for the prototype phase or production, the COTS device can be replaced with a pinout-compatible, radiation-tolerant version in a 32-lead ceramic package (QFP32), for example, with the same functionality as the original device.”
Figure 2: Microchip’s COTS-to-radiation-tolerant approach includes two devices: The ATmega128S and ATmega64M1. Photo courtesy of Microchip.
With two types of users in space – military and commercial – “We have noticed our space customers typically require a higher level of support than our commercial customers simply due to the complexity and reliability requirements of the application,” O’Neill says. “Further, given the relatively small quantities of components which constellation programs will purchase – hundreds of parts per year, which is very low compared to the millions or tens of millions of parts sold into consumer or automotive applications – many commercial COTS component suppliers will not be willing to spend time performing failure analysis, extended temperature screening, radiation characterization, or other technical support activities for constellation programs.”
For the foreseeable future, COTS for space will continue to evolve before the technology finds a comfortable resting place as “high-volume suppliers often do not provide traceability (some devices, for instance, may source parts from three fabs under the same product number) or notify about changes in foundry or packaging subcontractors,” O’Neill adds.
Satellites in space will increase and will ultimately “drive down costs, but satellite electronic design is not based on the size or the number of satellites, but what radiation tolerance and error rate is needed for their mission,” Mark Tiddens, Product Manager, Radiation Hardened Microelectronics at Data Device Corp. (DDC, Bohemia, New York) says. “Any satellites, including small sats as small as cube sats, need system designs and parts which meet the radiation and error-rate requirements of their mission and the criticality of their function.”
It’s also important to note that using COTS in space comes with a warning label: “We also anticipate that space programs will run into situations where accidental damage may happen to components that are intended for, or already integrated into, flight hardware,” O’Neill says. “For space programs attempting to acquire lower cost systems using COTS components, the need for technical support from component suppliers to support mission-assurance objectives should be kept in mind.
“Product consistency, technical support, and traceability are all significant concerns for space systems seeking to use COTS components,” O’Neill adds.