Europa is extra than simply one in all Jupiter’s many moons — it is also one in all most promising locations within the photo voltaic system to search for extraterrestrial life. Below 10 kilometers of ice is a liquid water ocean that might maintain life. However with floor temperatures at -180 Celsius and with excessive ranges of radiation, it is also one of the crucial inhospitable locations within the photo voltaic system. Exploring Europa might be attainable within the coming years due to new purposes for silicon-germanium transistor expertise analysis at Georgia Tech.
Regents’ Professor John D. Cressler within the Faculty of Electrical and Laptop Engineering (ECE) and his college students have been working with silicon-germanium heterojunction bipolar transistors (SiGe HBTs) for many years and have discovered them to have distinctive benefits in excessive environments like Europa.
“Because of the approach that they are made, these units truly survive these excessive circumstances with none modifications made to the underlying expertise itself,” mentioned Cressler, who’s the undertaking investigator. “You may construct it for what you need it to do on Earth, and also you then can use it in house.”
The researchers are in 12 months one in all a three-year grant within the NASA Ideas for Ocean Worlds Life Detection Know-how (COLDTech) program to design the electronics infrastructure for upcoming Europa floor missions. NASA plans to launch the Europa Clipper in 2024, an orbiting spacecraft that can map the oceans of Europa, after which finally ship a touchdown car, Europa Lander, to drill by the ice and discover its ocean. But it surely all begins with electronics that may perform in Europa’s excessive atmosphere.
Cressler and his college students, along with researchers from NASA Jet Propulsion Lab (JPL) and the College of Tennessee (UT), demonstrated the capabilities of SiGe HBTs for this hostile atmosphere in a paper offered on the IEEE Nuclear and House Radiation Results Conventionin July.
Like Earth, Jupiter additionally has a liquid metallic core that generates a magnetic discipline, producing radiation belts of high-energy protons and electrons from the impinging photo voltaic wind. Sadly, as a moon of Jupiter, Europa sits squarely in these radiation belts. In impact, any expertise designed for Europa’s floor wouldn’t solely want to have the ability to survive the chilly temperatures but in addition the worst radiation encountered within the photo voltaic system.
Happily, SiGe HBTs are perfect for this hostile atmosphere. The SiGe HBT introduces a nanoscale Si-Ge alloy inside a typical bipolar transistor to nano-engineer its properties, successfully producing a a lot quicker transistor whereas sustaining the economy-of-scale and low price of conventional silicon transistors. SiGe HBTs have the distinctive potential to take care of efficiency underneath excessive radiation publicity, and their properties naturally enhance at colder temperatures. Such a novel mixture makes them superb candidates for Europa exploration.
“It is not simply doing the essential science and proving that SiGe works,” Cressler mentioned. “It is truly creating electronics for NASA to make use of on Europa. We all know SiGe can survive excessive ranges of radiation. And we all know it is stays useful at chilly temperatures. What we didn’t know is that if it may do each on the similar time, which is required for Europa floor missions.”
Testing the Transistors
To reply this query, the GT researchers used JPL’s Dynamitron, a machine that shoots high-flux electrons at very low temperatures to check SiGe in Europa-type environments. They uncovered SiGe HBTs to 1 million Volt electrons to a radiation dose of 5 million rads of radiation (200-400 rads is deadly to people), at 300, 200, and 115 Kelvins (-160 Celsius).
“What had by no means been finished was to make use of electronics like we did in that experiment,” Cressler mentioned. “So, we labored actually for the primary 12 months to get the outcomes which might be in that paper, which is in essence definitive proof that what we claimed is, in reality, true — that SiGe does survive Europa floor circumstances.”
Within the subsequent two years, the GT and UT researchers will develop precise circuits from SiGe that might be used on Europa, akin to radios and microcontrollers. But extra importantly, these units may then be seamlessly utilized in virtually any house atmosphere, together with on the moon and Mars.
“If Europa is the worst-case atmosphere within the photo voltaic system, and you’ll construct these to work on Europa, then they’ll work anyplace,” Cressler mentioned. “This analysis ties collectively previous analysis that we’ve finished in my staff right here at Georgia Tech for a very long time and exhibits actually attention-grabbing and novel purposes of those applied sciences. We satisfaction ourselves on utilizing our analysis to interrupt new progressive floor and thereby allow novel purposes.”