It’s what we can’t see around Jupiter that Juno’s mission team had to prepare for. Intense radiation belts stretching past the moon Europa, or nearly 400,000 miles away from the tops of Jupiter’s clouds. Outside of the sun, no spacecraft has visited a place with more radiation in our solar system.
When Juno’s vault was being installed, Scott Bolton (Juno’s principal investigator) described the spacecraft as “basically an armored tank going to Jupiter.”
“Without its protective shield, or radiation vault, Juno’s brain would get fried on the very first pass near Jupiter,” Bolton added.
Did You Know: It’s not just the radiation from Jupiter Juno’s team had to account for. Io’s volcanic activity releases gas into Jupiter’s magnetosphere. This gas becomes ionized and energized and adds a little extra to the radiation problem.
The solution? A radiation vault. But not made of lead. The engineers at Lockheed Martin Space Systems opted for one made of titanium. Why? Lead works great as a radiation blocker, but isn’t strong enough to handle the intense shaking during launch. Titanium is.
The titanium box contains the most important parts of Juno. Command, data handling, power and data distribution are packed inside the vault along with 20 other electronic assemblies according to NASA.
Here’s what the vault radiation vault looked like when it was being installed in 2010.
Do you own an SUV? Take a peek in the trunk. That’s about how big the titanium vault is. Each titanium wall measures about 1 centimeter thick and weighs close to 40 pounds. Together, the vault comes in at just over 400 pounds.
Here’s one more image showing the vault sitting atop the propulsion module.
It’s important to note the titanium vault doesn’t stop every piece of radiation from zipping through the spacecraft. What it will do is keep Juno functioning long enough to complete its mission.
During Juno’s construction, engineers also looked at how the electronics of Martian orbiters and landers were built. Mars’ radiation environment is nowhere near as crazy as Jupiter’s, but it gave engineers a good base to build on. Pieces of Juno’s electronics were fashioned out of tungsten. And some of the other pieces of the spacecraft are enclosed in their own mini-vaults for protection. Wiring from various electronics was wrapped in copper and stainless steel braids to offer an extra level of protection.
Juno’s mission team can only do so much. Orbiting so close to Jupiter was always going to be risky. And at the end of the day, it’s the precise orbits they selected that will keep the spacecraft away from the majority of Jupiter’s strongest radiation belts.
That’s why they opted for orbits around Jupiter’s poles. The radiation belts are strongest near the planet’s equator.
Combine a titanium vault with just the right orbits, and you have a mission unlike any other. The images we will see next month will be stunning. Pluto blew us away last summer, but I have a feeling Jupiter will one-up the dwarf planet before this summer ends.
Image credits: NASA