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Credit: NASA/JPL-Caltech

How a tiny space robot can change your life

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Mar 25, 2021, 9:00 PM EDT (Updated)

Star Stuff is a weekly column by rocket scientist & astrophysicist Summer Ash highlighting some amazing things happening every day on and off the planet, especially great science done by and/or for women. She harnesses her science communication powers to smash the patriarchy and advocate for equality and inclusion across all time and space. Throwdowns with pseudoscience may occur.

Two thousand and four was a busy year for NASA. In January, they landed two rovers on Mars and six months later at the start of July, they inserted a spacecraft into orbit around Saturn. None of those missions were predicted to last into 2017, yet two of them did. Opportunity is still on the world’s longest Martian road trip and Cassini sent data back from Saturn until the very last second before it disintegrated last week.

Thousands of people have worked on these missions, and thousands more have been affected by them, both personally and professionally. Many of them gathered at NASA’s Jet Propulsion Laboratory and the California Institute of Technology as the Cassini spacecraft made its final maneuver, plunging into Saturn’s upper atmosphere. Given one of the missions of this column is to highlight women in science and technology, I spoke with four women about how Cassini impacted their lives.

Sarah Hörst is currently an Assistant Professor at Johns Hopkins University in the Department of Earth and Planetary Sciences, but back in 2004, she was just starting graduate school at the University of Arizona. “I'm a child of Cassini,” said Hörst. “I was a proto-scientist when Cassini arrived at Saturn.”

Hörst’s advisor was on the science team for the spacecraft’s ion and neutral mass spectrometer (INMS), but he had a chance encounter in the hallways with another scientist who worked on the Cassini Plasma Spectrometer (CAPS), which caught his attention. CAPS had discovered a previously unknown source of oxygen in Titan’s atmosphere. Neither Hörst’s advisor or the CAPS team had any interest in this data because their focus was Saturn, not Titan, but she ended up designing experiments to explain how that oxygen got there in the first place. “My PhD basically changed course entirely because of this one discovery," she said. "I was never directly working on Cassini data during grad school, and yet, it defined the path of my career and, ultimately, that of my students, too.”


Credit: NASA/JPL/University of Arizona/University of Idaho

Emily Lakdawalla was a middle school science teacher before Cassini launched in 1997, but in 2004 she was wrapping up an education and public outreach (EPO) project with The Planetary Society. Lakdawalla recalled, “The Planetary Society tapped me to switch from doing primarily education projects behind the scenes to start writing for the website. There was a whole lot of new stuff happening in space, and I started with Cassini.”

Lakdawalla has degrees in both geology and planetary science, so she set to work processing images as they came in and blogging about the science behind them. Prior to Cassini’s arrival at Saturn, there had only been a trickle of images as the ringed giant slowly grew from a point of light to a glowing orb, eventually resolving into its full glory. Less than a month before the spacecraft dropped orbit in the Saturn system, it flew by Saturn’s moon Phoebe. “This fly-by was a big deal,” said Lakdawalla. “I did the first of what actually kind of became a tradition for me, which is to write a very detailed timeline of the science plans for observations. And almost immediately, I was doing the sort of work I still do today, which is to take esoteric science and engineering planning information and turn it into text that's a little bit more accessible for the interested public.”


Cassini arrival (left) and departure mosaics of Phoebe. Credit: NASA/JPL-Caltech/Space Science Institute 

Post Cassini, Lakdawalla is making some changes. After a decade and a half of blogging regularly, she wants to build something more permanent. She hopes to train more members of the public to process the treasure trove of data from Cassini and many other missions.

Powtawche Valerino was initially interested in astronomy, but after witnessing the tragedy of the Space Shuttle Challenger, she became drawn to engineering. “That impacted me enough to wanna learn more about engineering and why things work or how they work and why this tragedy occurred,” she said.

Valerino went on to study mechanical engineering and landed at NASA (and on Cassini) after graduate school. Her specialty was optimizing spacecraft trajectories with low thrust technology and so was JPL’s so it was a perfect match. “They have a specialized group or section that just focuses on navigation and mission design,” she told me. “It's so wonderful to be around the experts and the authors of papers you've read in grad school, they're all here.”

The Cassini mission was originally supposed to last for only four years, but the spacecraft performed so well, thanks to the careful planning of navigational engineers like Valerino, that used a lot less propellant than expected. And since they had such a high return of science, the team uniformly decided to extend the mission. The first extension was for two years. Called the Equinox mission, it was just as ambitious as the primary mission. Again they were so efficient with spacecraft maneuvers, relying strongly on Titan flybys for course adjustments, that they had enough propellant for another mission extension, pushing Cassini’s mission lifetime to 13 years. Saturn orbits the Sun once every 30 years, which meant that the Cassini team had the unique opportunity to observe the planet through nearly half of its seasons. 



Cassini's 13 years orbiting Saturn. Seasons for the northern hemisphere shown along the bottom. Credit: NASA/JPL-Caltech

Valerino is already hard at work on her next mission, the Parker Solar Probe, applying the skills and lessons she learned from Cassini. “If you think about that whole process from having a flagship mission, all these scientists involved, and then making all those changes during operations,” she reflected. “It was a lot of skills that I wouldn't have experienced on any other mission.”

Nora Alonge is another woman at JPL for whom Cassini has played a major role. Growing up, she wanted to know how the Universe worked, so she chose to study physics in college and graduate school. She joined Cassini ten years ago during the Equinox mission, its first extension, as a science planner for the Solstice mission.

Science planning involves balancing the spacecraft’s resources, such as power, data volume, propulsion, with the science objectives. This is much more difficult for orbiters than it is for rovers: “It's different than a landed mission say on Mars where they can choose to stay another day if they want to do more science. We fly by and then we're gone.” For the second extension, the mission lost close to half its funding for engineers and about a third of its funding for science. Alonge acted as a liaison between the scientists and the engineers, cross-training people and revamping processes used in the primary and Equinox mission phases to do the same science, but with fewer people, less time, and less money. As anyone who followed Cassini knows, she and her team were clearly successful. The images and the science coming out of the mission were phenomenal up until the very end.


For now, Alonge is working on archiving the legacy of Cassini and capturing the lessons learned that can be passed on to future missions, like one she might find herself on in the future. She’s had a couple other projects already inquire when she would be ready, one of which is a much smaller mission called a discovery mission (Cassini was a flagship mission). “Discovery missions have a much smaller team,” she explained. “Everybody does more, wears more hats on the project. And that would be a unique experience because Cassini was so big.”

There are over 5000 people who have worked on Cassini at one time or another since its inception decades ago, and a surprising (yet not yet normal, sigh) amount of them are women. “There are a lot of women managers, women scientists. Role models,” Alonge told me. “More so than I see in other missions. I didn't notice it happening but has given me more confidence. I feel more comfortable.”

Cassini has touched so many more lives than this, but due to the constraints of spacetime, I could only share these four stories with you. Sarah Hörst sums it up perfectly:

“I think that people sometimes don't realize the ripple effect that these missions can have. It's not just the people on the team. It's not just the people who are directly analyzing the data. Everything that we find inspires new lines of interrogation, new questions, new facilities that have to be developed. These missions ripple through the whole field, even for people who aren't directly working on them.”

Here’s hoping some of those ripples reach the next generation of women scientists and engineers who are already dreaming of flagship missions of their own.

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