FEATURE
CULPRiT Technology Successfully Demonstrated On Orbit
Development Could Lead to More Efficient Spacecraft Design
Goddard technologists have successfully demonstrated a radiation-hardened computer chip that consumes significantly less power than traditional chips, opening the door to more efficient spacecraft design in the future, say the technology’s developers.
The CMOS Ultra-Low Power Radiation Tolerant (CULPRiT) technology, developed by Goddard Scientist Pen-Shu Yeh and the University of Idaho’s Center for Advanced Microelectronics and Biological Research (CAMBR), flew on NASA’s Space Technology 5 (ST-5) mission. Sponsored by NASA’s New Millennium Program, the mission assessed state-of-the-art miniaturized subsystems on three micro-satellites.
“The ST-5 validation is a milestone for ultra-low power technology because they’ve demonstrated it on orbit,” said Mike Johnson, Assistant Chief for Technology at Goddard’s Electrical Engineering Division. “It’s a step in the right direction.”
Technology Applied to the Encoder
For the ST-5 demonstration, Yeh and CAMBR applied the CULPRiT technology to a Reed-Solomon encoder. Encoders modify scientific data from data systems, thereby creating the ability to correct communications errors when the information is received on the ground. Data can be corrupted by any number of reasons, including space radiation and severe weather. To determine the effectiveness of the chip, code word produced by the CULPRiT Reed-Solomon encoder was compared with that of a standard logic radiation-tolerant Reed-Solomon encoder.
An analysis determined that the CULPRiT encoder performed the same as a standard encoder but used only .5 volts of power — a 100 to 1 reduction in power consumption. “The validation data came back clean. It works perfectly,” Yeh said. “This chip in ST-5 is much more powerful in functionality than anything available commercially.”
Effort Began a Decade Ago
The quest to design and build a radiation-tolerant, ultra-low power (ULP) chip began more than 10 years ago when Goddard began funding CAMBR, headed by Gary Maki. Developing a circuit chip that could withstand the effects of space radiation and still be fabricated in a commercial foundry represented the first major breakthrough, Maki said. To take the concept to the next level, Maki’s group married the radiation tolerant technology to ULP electronic circuitry to produce CULPRiT, he said, adding he built the technology based on mathematical models developed by Yeh.
“We knew that CULPRiT devices were more efficient than other available flight technologies,” said Johnson, referring to the efforts that led up to the successful demonstration. “Maki also showed theoretically that the chip could be radiation tolerant. But he needed more than theory and ground tests.” He needed a flight opportunity, which ST-5 afforded.
The Possibilities
Internal research and technology development funding will be more focused in the future. I will give priority to those efforts that target realistic funding sources. Having spent years at Headquarters, I have a good idea of which future missions have a chance. I’m looking for investments that will clearly improve our competitiveness in the short- to mid-term. I also will approve a portion of our investments targeting the longer term; that is, those that create realistic opportunities 10 to 20 years from now.
Although challenges remain, the technology has the potential to significantly reduce electrical power requirements on space missions, Yeh said. For solar energy-powered spacecraft, for example, a reduction translates into smaller solar panel, mass, and battery requirements. “Considering the difficulty and the cost associated with developing photo-voltaic technology to increase solar cell efficiency by merely a few percentage points, NASA simply cannot afford overlooking the potential payoffs that this technology provides,” Maki said.
In addition to supporting the ST-5 encoder development, Goddard also is funding an effort to apply CULPRiT to a Motorola microprocessor in a project called ColdFire.
Historically, instruments are our strength. However, I’d like us to win some planetary missions with greater involvement than simply providing the instrument. I’d also like to see us fly low-cost missions out of Wallops. Most people don't realize this, but Wallops is NASA’s only launch range. The Air Force owns Cape Canaveral and provides the launch-range support for the Shuttle. Think about it, Goddard has its own dedicated launch range at Wallops. It should be used more aggressively to carry out NASA’s low-cost missions. For that matter, Goddard should creatively use all of its unique capabilities to carry out NASA’s mission. |
Pen-Shu Yeh created the algorithms used to build the Ultra-Low Power Radiation Tolerant technology.
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