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Tricorder Tech: Exploring Europa with Silicon Germanium Transistor Technology

Tricorder Tech: Exploring Europa with Silicon Germanium Transistor Technology

Europa is not just one of Jupiter’s many moons. It’s also one of the most promising places in the solar system to search for extraterrestrial life.

Under 10 kilometers of ice lies an ocean of liquid water that can sustain life.

But it’s also one of the most inhospitable places in the solar system, with a surface temperature of minus 180 degrees Celsius and extreme levels of radiation. A new application of silicon-germanium transistor technology research at the Georgia Institute of Technology could enable exploration of Europa in the coming years.

Professor John D. Cressler and his students at the Regents’ School of Electrical and Computer Engineering (ECE) have been working on silicon-germanium heterojunction bipolar transistors (SiGe HBTs) for decades. .

“The manufacturing method allows these devices to actually withstand these extreme conditions without making any changes to the underlying technology itself,” said Kressler, an investigator on the project. . “You can build it for whatever you want to do on Earth, and you can use it in space.”

The researchers are in the first year of a three-year grant to the NASA concept for the Ocean World Life Detection Technology (COLDTech) program to design the electronic infrastructure for the upcoming Europa surface mission. NASA plans to launch Europa Clipper in 2024. This is an orbiting spacecraft that maps Europa’s oceans, and will eventually send a lander, the Europa Lander, to drill through the ice and explore the oceans. But it all starts with electronics working in the extreme environments of Europa.

Kressler and his students, along with researchers from NASA’s Jet Propulsion Laboratory (JPL) and the University of Tennessee (UT), described this adversary in a paper presented at the IEEE Nuclear and Space Radiation Effects Conference in July. We have demonstrated the capabilities of SiGe HBTs to the environment. .

Europa challenge

Like Earth, Jupiter also has a liquid metal core that produces a magnetic field, generating high-energy proton and electron radiation bands from the impinging solar wind. Unfortunately, Jupiter’s moon Europa sits squarely in these radiation belts. In fact, technology designed for Europa’s surface would have to withstand not only cold temperatures, but also the worst radiation encountered in the solar system.

Fortunately, SiGe HBTs are perfect for this harsh environment. SiGe HBT introduces a nanoscale Si-Ge alloy inside a typical bipolar transistor to nanoengineer its properties, maintaining the economies of scale and low cost of traditional silicon transistors while achieving much more. Effectively produce high-speed transistors. SiGe HBTs have the unique ability to maintain performance under extreme radiation exposure, and their properties naturally improve at low temperatures. Such a unique combination makes it an ideal candidate for Europa exploration.

“We’re not just doing basic science to prove that SiGe works,” Cressler said. “In fact, NASA is developing electronics for use on Europa. We know SiGe can withstand high levels of radiation. What we didn’t know was whether it would be possible to do both simultaneously for Europa’s ground mission.”

transistor test

To answer this question, GT researchers used JPL’s Dynamitron. He tested his SiGe in a Europa-type environment, a machine that emits high-flux electrons at very low temperatures. They exposed his SiGe HBT to 1 million volts of electrons at 300, 200, and 115 Kelvin (-160 Celsius), a radiation dose of 5 million rads (200-400 rads is lethal to humans). Did.

“What hadn’t been done before was to use electronics like we did in that experiment,” Kressler said. We literally went to great lengths to get results that are, in essence, conclusive proof that what we claimed to be SiGe surviving Europa’s surface conditions is indeed true.”

Over the next two years, GT and UT researchers plan to develop real circuits from SiGe that can be used in Europa, such as radios and microcontrollers. More importantly, these devices can be used seamlessly in virtually any space environment, including the Moon and Mars.

“Europa is the worst environment in the solar system, and if you can build these to work on Europa, they will work everywhere,” Kressler said. It ties together the past research that we have been doing for a long time and shows some very interesting and novel applications of these technologies.We are using our research to open up new innovative horizons and thereby new applications. We are proud to be able to

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