Project by Dom Malfetano and Chris Keenan on FPGAs in Space Applications
FPGA for Space Applications
By Domenic Malfetano and Christopher Keenan
CPE487 Digital Systems Design
Thanks to the recent advances made by companies such as SpaceX and NASA, our dreams of traversing the final frontier are coming to fruition. With all the talk of space exploration and the mission of getting to Mars, the cosmos have never seemed so exciting. It would appear that humanity is destined to expand its reach among the galaxy, but this feat does not come without its challenges. Outer space is an incredibly harsh environment, providing no air and extreme levels of radiation. These conditions make it difficult for engineers and scientists to develop technology that would otherwise work perfectly under the conditions of our home planet. Field Programmable Gate Array (FPGA) devices play a massive role in space-flight systems, and have been steadily increasing in capacity and performance over the past decade. This paper will discuss how FPGAs are used in space applications as well as the challenges faced in designing them with respect to the harsh conditions faced in outer space.
Though not originally accepted for space systems, reprogrammable devices are becoming more widely used as their capacity has increased from tens of thousands to millions of gates. This has allowed FPGAs to move from basic glue logic to complete subsystem platforms that have the ability to combine several real time functions on a single chip. As their potential is steadily increasing, FPGAs are opening the door to new applications and are replacing many ASICs in critical systems.
When building FPGAs for space systems, engineers have to design them to be able to withstand the harsh conditions that outer space imposes. A big issue faced by FPGAs in space are Single Upset Events (SEU) caused by sensitivity to radiation. SRAM FPGAs are basically just big memory devices, and because the most common fault caused by radiation is bit flipping in memory elements, the configuration logic itself is vulnerable. Remediation schemes such as triple-module-redundancy (TMR) that are able to prevent some effects of radiation can be implemented on all registers of an FPGA, but this process is sometimes difficult to implement.
Current Solutions and Products :
Actel (now Microsemi) and Xilinx have been among the leaders in providing specialized FPGAs used for space systems. Historically, there have been two basic options for FPGAs in space applications. The first are high-density, re-programmable, SRAM-type FPGAs repurposed and modified for space use (made by Xilinx for payload applications). The second are lower-density, non-volatile, one-time-programmable, antifuse devices designed by Microsemi specifically for mission-critical flight control and similar applications.
FPGA made by Xilinx to be Used in Satellite Applications
Most FPGAs have their own advantages and disadvantages and are typically chosen for their own specific purposes. Xlinix has a family of FPGAs used for space exploration. These products are the Virtex®-5QV FPGAs and the Virtex-4QV FPGAs. The Xilinx Virtex®-5QV FPGAs is offered as an off the shelf prototyping FPGA as well as two other versions that are more ready for space application. This Xilinx product is typically used for sensor processing, modems, and communication. The Xilinx Virtex-4QV FPGAs have little to no prototyping ability but are extremely space ready. These FPGAs are extremely resistant to radiation and bit flipping making them far more ready for space.
In conclusion the practice of using FPGAs for space applications is rapidly expanding. FPGAs were once thought to be unreliable due to the possibility of bit flipping because of radiation. They also lacked the processing power needed for guided space flights. Companies like Xilinix and Microsemi have made enormous strides in the field. FPGA’s now have much higher processing power and have systems to limit radiation. In the future expect to see expansion of space exploration as a whole due to the availability of lower cost flight computers and FPGA systems.
References:
https://www.eejournal.com/article/20150414-space/
https://www.xilinx.com/applications/aerospace-and-defense/space.html