A radiation-hardened Xilinx FPGA gives the Australian FedSat satellite powerful reconfigurable computing capabilities.

On the morning of December 14, 2002, the ground shook at the Yoshinobu Launch Range at the Tanegashima Space Centre, on the island of Tanegashima in southern Japan. The 170-foot H-IIA rocket streaked aloft, carrying with it a Xilinx XQR4062XL, part of the XC4000XL series FPGA. This radiation-hardened FPGA is the core of the high-performance computing (HPC-I) payload incorporated in the Australian scientific mission satellite FedSat (Figure 1). The spacecraft was developed by the Cooperative Research Centre for Satellite Systems (CRCSS) in Australia. The HPC-I payload (Figure 2) was developed for CRCSS at the Queensland University of Technology.

FPGAs have flown in space before, but HPC-I is the first intentional use by CRCSS of reconfigurable computing technology (RCT) in the standard operation of a spaceborne computing system.

According to Anwar Dawood, CRCSS principal research scientist and program leader, “Traditional fixed computer hard-ware is designed to perform a diverse range of functions. This results in an efficient processing for some tasks and a slow pro-cessing for other tasks, especially the recur-sive and intensive computing jobs.” Furthermore, fixed computer hardware is inflexible and unable to adopt changes when newly created functions are required, he added.

Dawood pointed out that RCT offers the promising alternative of flexible hardware, which can be reconfigured – either by remote command or dynamically through its own internal operations – to specialize its function to an arbitrary range of demanding applications.

The Xilinx-based HPC-1 is the prototype with which Dawood and his team expect to establish the viability of RCT in spaceborne computing – including the tolerance of the hardware to the intense radiation of outer space.

Second-Generation HPC-II

Dawood and the HPC team are now developing a second-generation HPC-II, which is built around the increased capacity and capability of a Xilinx FPGA. This second-generation project will emphasize critical space applications and onboard real-time data processing.

Dawood has initiated several application projects to exploit the efficiencies of space-based RCT, including:

• Disaster Detection and Monitoring System (DDMS) uses HPC technology for real-time or near-real-time image processing for detecting and monitoring natural disasters, such as forest fires and volcanic plumes.
• Satellite-Based Broadband Services (SBBS) utilizes HPC technology to provide multimedia commu-nications, Internet access, and education services to both urban and rural areas.
• Satellite Autonomous Navigation System (SANS) deploys HPC technology in conjunction with advanced GPS for onboard orbit determination for autonomous navigation.

Avoiding catastrophic satellite failure is an equally compelling motive for remote reconfiguration. Entire satellite constellations have been lost through tiny failures in computing circuitry.

The reconfigurability of Xilinx FPGAs enables satellites to be rewired without having to be retrieved. This raises the promise of adaptable spacecraft that could be reconfigured remotely to work around problems – or even be able to repair themselves. Retired spacecraft might also be reconfigured for new purposes.

An example of a catastrophic satellite loss was described by Mark Long in a February 5 article for e-inSITE (www.e-insite.net). In 1998, Hughes Space and Communications announced that electrical shorts were the most likely cause of a string of failures involving the spacecraft control processors (SCPs) onboard its 601 flight models. The SCPs controlled the satellites’ critical functions, including propulsion for attitude control, solar wing positioning, and antenna pointing.

Investigators finally traced the problem to a tin-plated latching relay that served as an on/off switch within the SCPs. Under certain combined conditions, the switch was shorted out by a tiny, crystalline growth less than the width of a human hair.

If the satellite operators had the ability to reconfigure their SCP systems on the fly, they might have found a way around the electrical shorts that led to the untimely demise of their satellite constellation.

Radiation-Hardened

In the same article, Long pointed out another potential application for radiation-hardened Xilinx products in the onboard signal processing systems of advanced, next-generation satellite computer platforms.

Later this year, Hughes will launch the first of its Spaceway satellite platforms. These platforms will feature onboard processors developed by TRW. The TRW processors have been designed to provide high-speed, onboard processing capabilities that will allow signals to pass directly between small aperture terminals without requiring the intervention of a gateway terminal.

The potent combination of onboard digital signal processing, packet switching, and spot-beam technologies is expected to enable single-hop connectivity throughout each of the system’s many beam coverage areas.

Similar technology is also expected to fly on two Astrolink satellites being constructed by Liberty Media.

Conclusion

The technology being developed by Xilinx for space-based applications promises to further enhance the capabilities of next-generation satellites to act as broadband routers in the sky.

For more information on Xilinx radiation-hardened FPGAs, visit www.xilinx.com/products/military/radhardv.htm.

To learn more about CRCSS, high-performance computing, and the FedSat satellite, go to www.crcss.bee.qut.edu.au/comp.shtml and www.crcss.csiro.au/.

Radiation-Tolerant FPGAs in Space
Space is a hostile environment. Streams of high-energy particles constantly bombard any exposed object. The Earth’s atmosphere provides a strong, protective barrier that absorbs most of this radiation. Satellites, however, are located well outside this protective shield, and their electronic circuitry is especially vulnerable to damage that might lead to catastrophic failure.
According to Howard Bogrow, marketing manager for the Xilinx Aerospace and Defense Products Division, high-energy particles can cause a secondary reaction in untreated silicon-based chips that can cause their circuits to latch up. To address this problem, the XQR4000XL devices utilize a 0.35 micron epitaxial CMOS process that provides latch-up immunity, high total-ionizing dose (TID) tolerance, and low probability of single event upsets (SEUs) induced by natural radiation in satellite and other space environments.
Xilinx is currently shipping radiation-hardened versions of two device families: 4000XL with up to 130,000 gates, certified radiation tolerant to 60 Krads Virtex™ FPGAs with up to one million gates, certified to 100 Krads.
Later this year, a radiation tolerant line of QPro™ Virtex-II series FPGAs with up to six million gates will be released (Figure 3). To determine the radiation tolerance of the company’s products, Xilinx conducts extensive testing of their TID (www.xilinx.com/prs_rls/radhard.html) and SEU characteristics (www.support.xilinx.com/support/techxclusives/1000-techX35.htm).

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