In 1964, NASA’s Electronics Research Center (ERC) opened in Massachusetts, serving to develop the space agency’s in-house expertise in electronics during the Apollo era. The center’s accomplishments include development of a high-frequency (30-GHz) oscillator, a miniaturized tunnel-diode transducer, and a transistor more tolerant of space radiation. Another development was in the area of holography. At the ERC, holography was “used for data storage, and has permitted a remarkable degree of data compression in the storing of star patterns.”
Although the ERC closed in 1970, it set the foundation for NASA’s technological innovations in electronics development. Many of these technologies resulted in breakthroughs in commercial electronics, beginning in the 1970s with space electronics miniaturization techniques, then to the 1980s with the production of Large Scale Integrated (LSI) circuits, the 1990s with shape memory alloy connectors, and the 2000s with radiation-tolerant FPGAs.
Today, NASA’s research into space electronics has far-reaching applications in commercial industries.
Cooling Integrated Circuits
Future integrated circuitry is expected to look a lot like skyscrapers — units will be stacked on top of one another, and interconnects will link each level to its adjacent neighbors, much like how elevators connect one floor to the next. The problem is how integrated circuit designers can remove heat from these tightly packed 3D chips. The smaller the space between the chips, the harder it is to remove the heat.
Although circuit designers are still working on this challenge for commercial applications, the problem is especially difficult for those designing 3D integrated circuitry for space-based uses. Because of the unique space environment, removing heat from powerdense electronics always has presented challenges, sometimes leading to inefficient designs, according to Franklin Robinson, a NASA thermal engineer at Goddard Space Flight Center in Maryland. He and his team are studying different cooling techniques so that NASA might benefit from this emerging technology in the future.
“These 3D-stacked integrated circuits are coming; they will be commercialized. We need to get ahead of the curve when they do become available,” Robinson said.
To make sure NASA benefits from this emerging 3D circuit technology, Robinson and his team have begun investigating a technology that would remove heat by flowing a coolant through embedded channels about the size of a human hair within or between the chips.
In contrast, removing heat in more traditional 2D integrated circuits is significantly different. Designers create a “floor plan,” keeping the heat-generating devices as far apart as possible. The heat travels into the printed circuit board, where it is directed to a clamp in the sidewall of the electronics box, eventually making its way to a box-mounted radiator.
“This approach is not applicable to chip stacks because one or more of the chips in the stack is not in contact with the printed circuit board,” he said. “However, we can remove the heat by flowing a coolant through these tiny, embedded channels.”
To further improve the microchannel coolers, the team also is investigating the effectiveness of “flow boiling,” where the coolant boils as it flows through the tiny gaps. According to Robinson, the technique offers a higher rate of heat transfer, which keeps devices cooler and, therefore, less likely to fail due to overheating. It also relies on the working fluid’s latent heat of vaporization, which reduces the flow rate, minimizing pumping power.
Under his research, Robinson is evaluating two-phase flows in miniature channels, with the goal of producing a list of criteria for channel dimensions, flow parameters, and fluid properties that produce gravity insensitivity.
Faster Link Gives Scientists the Speed They Need
For scientists studying the voluminous amounts of data collected daily by NASA’s Soil Moisture Active Passive (SMAP) mission, speed is everything. A new NASA-developed data-transmission technology installed at the U.S. Antarctic Program’s McMurdo Station in Antarctica is giving them the speed they need.