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 would maintain life. However with floor temperatures at -180 Celsius and with excessive ranges of radiation, it is also some of the inhospitable locations within the photo voltaic system. Exploring Europa could possibly be doable within the coming years due to new purposes for silicon-germanium transistor know-how 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.
“As a result of method that they are made, these gadgets really survive these excessive circumstances with none modifications made to the underlying know-how itself,” stated Cressler, who’s the mission investigator. “You’ll be able to construct it for what you need it to do on Earth, and also you then can use it in area.”
The researchers are in yr 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 may map the oceans of Europa, after which ultimately ship a touchdown car, Europa Lander, to drill by the ice and discover its ocean. However it 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 Area Radiation Results Conventionin July.
Like Earth, Jupiter additionally has a liquid steel core that generates a magnetic area, 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 know-how 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.
Luckily, 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 skill to keep up efficiency underneath excessive radiation publicity, and their properties naturally enhance at colder temperatures. Such a singular mixture makes them perfect candidates for Europa exploration.
“It is not simply doing the essential science and proving that SiGe works,” Cressler stated. “It is really 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 might do each on the identical 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 at least one 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 executed was to make use of electronics like we did in that experiment,” Cressler stated. “So, we labored actually for the primary yr to get the outcomes which might be in that paper, which is in essence definitive proof that what we claimed is, the truth is, 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 could possibly be used on Europa, comparable to radios and microcontrollers. But extra importantly, these gadgets might then be seamlessly utilized in nearly any area atmosphere, together with on the moon and Mars.
“If Europa is the worst-case atmosphere within the photo voltaic system, and you may construct these to work on Europa, then they are going to work anyplace,” Cressler stated. “This analysis ties collectively previous analysis that we’ve got executed in my crew right here at Georgia Tech for a very long time and exhibits actually attention-grabbing and novel purposes of those applied sciences. We pleasure ourselves on utilizing our analysis to interrupt new progressive floor and thereby allow novel purposes.”