The 3-foot-wide contraption that was built in First Mode’s Seattle workshop looks like something from a science-fiction movie, complete with spinning cogwheels and a flashing light beam — and it really does have an out-of-this-world purpose: helping scientists interpret readings from Mars.
Even the word that describes the gizmo has a sci-fi sound: “goniometer.”
Today, First Mode‘s engineering team delivered the 3-D goniometer to Western Washington University’s Mars Lab in Bellingham, Wash., where it’ll be used in connection with NASA’s Perseverance rover mission.
First Mode worked with Western to design the goniometer under the terms of a $302,000 contract from NASA, and it’s already picked up a suitably NASA-esque name. It’s known as the Western TANAGER, with an acronym that stands for “Three-Axis N-sample Automated Goniometer for Evaluating Reflectance.”
The name pays tribute to the Western Tanager, a bird that can be spotted in Washington and other Western states. “I tied it in by saying that with bird feathers, their color depends both on the pigment but also on the angle that you look at it,” First Mode systems engineer Kathleen Hoza told GeekWire.
Western’s new goniometer may look like something Buck Rogers would use in the 25th century, but such devices actually go back to the 16th century. Goniometers are designed to make precise measurements of angles, much like the protractors used in elementary school.
The Western TANAGER kicks things up a notch by measuring angles in three dimensions. Why is that important for Mars? Because knowing the precise angles of reflection for the sunlight that hits Martian rocks could help scientists unlock some of the Red Planet’s geological secrets.
Virtually every Mars mission has at least one spectrometer that can determine the composition of rocks, based on their absorption levels for different wavelengths of light. If there’s a dip in the light levels at specific wavelengths, geologists can figure out the proportions of elements that are present in a given rock.
“The component that this adds is, you can look at that dip … and you can say, ‘Well, is that absorption feature the same at all geometries?’ If you move the light source around, does that absorption feature change, or does it stay exactly the same?” Hoza explained.
Seeing how the absorption levels change at different angles of reflectance — for example, as the sun moves through the Martian sky, or as the Perseverance rover moves around the rock — could lead geologists to fine-tune their analysis of the rock’s composition.
“You might even be able to use that to learn new things,” Hoza said.
If the rock’s reflectance varies in specific ways when observed from different angles, that could tell scientists there’s a fine layer of silica coating the rock. And that silica could serve as a clue that liquid water once covered the region surrounding the rock — which would be a key finding, pointing to potential habitability in ancient times.
That’s where the Western TANAGER comes in: Researchers on Earth will be able to use the goniometer to replicate the conditions under which the observations on Mars were made. Sophia Kim, a staff engineer at First Mode who focused on building the goniometer’s mechanical systems, said the gizmo serves as a “lookup table” to match Martian data with earthly geological features.
Some of the rocks being used as reference samples were collected from regions in eastern Washington state that have long served as stand-ins for Martian terrain.
Hoza began working with goniometers during her studies at Western. She built a 2-D goniometer for her master’s thesis, and went on to play a leading role in building the more intricate 3-D version at First Mode.
The Western TANAGER is due to roost in the lab of WWU planetary scientist Melissa Rice, who is part of the science team for Perseverance’s Mastcam-Z camera system. Like Mastcam-Z, the earthly goniometer can take spectral readings in visible and near-infrared wavelengths — which makes for a perfect pairing.
Hoza said the instrument built by First Mode could come into play for interpreting the results from Mastcam-Z, but that’s not all.
“That’s one of the neat things, how broad the applications are,” she said. “We could actually go back and visit spectral data from all the different missions and look at measurements that were made in correlation with viewing geometries, and see if that has an impact.”
Now that the Western TANAGER has landed in Bellingham, Hoza is starting to focus on her next project at First Mode: helping out with the hardware for NASA’s Psyche mission to a metal-rich asteroid.
“Being a person who understands both the scientific questions and also the engineering considerations is a big goal that I have,” she said.
Hoza aims to bridge the gap that often develops between science and engineering.
“I think that wires can get crossed, and messages can be missed,” she explained. “You can have engineers focusing on problems that don’t really matter, and you can have scientists not phrasing their questions in the right way so that an engineer will know what the right system to build is. So I’m really excited about opportunities that let me work at the intersection of those two things.”