As early as Oct. 10, a small piece of Colorado will begin its more than six-year journey to Jupiter's mysterious moon Europa-which, scientists believe, may harbor a vast ocean of water beneath its icy surface.
The SUrface Dust Analyzer is a $53 million instrument designed and built by a team at the Laboratory for Atmospheric and Space Physics (LASP) at CU Boulder. It's one of nine instruments and a gravity science investigation flying to Europa aboard NASA's flagship Europa Clipper spacecraft. Europa Clipper will arrive at the moon in 2031 and, over the subsequent four years, will explore whether it has conditions that could support life.
SUDA is an important part of that search, said Sascha Kempf, principal investigator for the instrument. The apparatus is gold plated, weighs almost 35 pounds and is shaped like a bucket. As Europa Clipper swoops past the moon during its planned 49 flybys, SUDA will collect and analyze tiny particles of ice flying above the surface-potentially grabbing a taste of the hidden ocean below.
"Where SUDA really flourishes is with detecting trace amounts of stuff embedded in ice," said Kempf, an associate professor at LASP and the Department of Physics.
Europa Clipper is set to launch from NASA's Kennedy Space Center in Florida on a SpaceX Falcon Heavy rocket.
Here's a closer look at the incredible SUDA instrument, by the numbers:
10,000 miles per hour
You can think of SUDA almost like a mobile chemistry laboratory for ice in space.
Here's how it works: Europa is surrounded at all times by a cloud of ice particles-bits of the surface that tiny meteorites have knocked into space. During flybys, SUDA will sweep through this cloud moving at speeds of around 10,000 mph, or roughly 4.4 kilometers per second, in some cases encountering thousands of particles in the process.
That's fast-so fast, in fact, that those grains of ice will vaporize instantly when they hit an impact target at the back of SUDA.
"That impact is so energetic that it actually ionizes the material," said Scott Tucker, SUDA project manager at LASP. "The particles will break up into their molecular and atomic components."
SUDA will then extract those ingredients, focusing them toward a detector known as a time-of-flight mass spectrometer. Small building blocks, such as lone hydrogen ions, will reach the detector faster than heavier stuff, such as larger molecules. Bit by bit, SUDA will create a complete list of everything inside each grain of ice.
Artist's depiction of Europa Clipper in orbit around Jupiter. (Credit: NASA/JPL-Caltech)
1 part per million
It's remarkably sensitive. SUDA is capable of detecting a vast range of compounds that could be in Europa's ocean-from salts to much larger and more complex molecules like amino acids or fatty acids.
On Earth, those organic molecules are basic ingredients for life, although they can also be found in clouds of gas in space and other sterile environments. Scientists don't know whether they exist on Europa. If they do, SUDA could identify them down to concentrations of just one part per million, and could even distinguish between different types of amino acids.
Artist's depiction of a cross section of Europa, where an ocean that may contain twice as much saltwater as all of Earth's oceans combined lies under a thick layer of ice. (Credit: NASA/JPL-Caltech)
An engineer makes an electrical connection to the sensor head for Europa Clipper's dust analyzer. (Credit: NASA/CU Boulder/Glenn Asakawa)
12 kilometers
The instrument's detective work doesn't stop there. When ice particles enter SUDA, they first pass through a sort of mesh that records their speed and orientation, Tucker said. With that information, researchers can recreate the path the particles took to reach the instrument.
"We can track the ballistic trajectories of the particles back to the ground," he said.
In other words, they can find where the ice came from on the surface of Europa-in some cases, to within 12 kilometers (7.5 miles).
That, in turn, will allow the researchers to put certain regions of the moon under the microscope. Hsiang-Wen (Sean) Hsu, the deputy principal investigator for SUDA, is especially eager to study two regions known as Thrace Macula and Thera Macula. They are what geologists call "chaos regions," places where huge slabs of ice have broken through the moon's normally smooth surface-a sign that ocean water may be welling up from below.
"By measuring the composition of materials from those regions, we can actually get a peek at the processes occurring below the surface," said Hsu, a research scientist at LASP.
250 nanometers
The researchers also have to ensure that the impact target at the back of SUDA is incredibly clean-they don't want any atoms or molecules from Earth flying off when particles hit this target, contaminating data from Europa.
To achieve that feat, the SUDA team got some help from scientists at JILA, a joint research institute between CU Boulder and the National Institute of Standards and Technology (NIST). The group figured out a way to coat the impact target at the back of SUDA in a layer of ultra-pure iridium metal just 250 nanometers thick, or hundreds of times thinner than the width of a hair.
Iridium is among the densest metals on Earth, which means that it won't break apart easily, even when it takes a pummeling in space.
27 months
For now, the team will have to wait. The researchers won't be able to open SUDA's door until after Europa Clipper crosses Mars' orbit for the last time a little more than two years from now-at that point, they can begin sampling particles of dust in space to check that the instrument is performing as expected.
Tucker, however, is eager for the launch. He's traveling to Florida in October to watch the spacecraft blast off with more than 20 people from LASP and around 10 SUDA team members from other institutions.
"I'm really excited," he said. "Of course, you're always a little nervous when a launch comes up."
Managed by Caltech in Pasadena, California, JPL leads the development of the Europa Clipper mission in partnership with the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, for NASA's Science Mission Directorate in Washington. The Planetary Missions Program Office at NASA's Marshall Space Flight Center in Huntsville, Alabama, executes program management of the Europa Clipper mission.
