Photo Illustration: Lazaro Gamio / Axios

On Friday, the 20-year-long Cassini mission to Saturn will end. The spacecraft has flown through the planet's rings and discovered subterranean oceans on its moons. To protect the moons from the risk of being contaminated, it will plunge into Saturn's atmosphere and disintegrate. Axios spoke with scientist and engineer Jo Pitesky, who has been with the project for 13 years, about Cassini's discoveries and what it means to be part of a decades-long space mission.

The highlights:

  • The end: The spacecraft's final moments will be scientifically invaluable and the information gained will be "incredibly precious," says Pitesky. "There could be no better requiem for [Cassini]."
  • The feeling: "You think you know what this stuff is going to look like, and then it just knocks your socks off. I don't think any of us will ever, ever, ever get tired of that."
  • What's next: "I fully expect that there will be any number of science surprises coming from Cassini's dataset for decades."

More of that conversation, edited for length and clarity, is below.

What can we learn from Cassini's last moments?

There will be some photos, but that pales compared to the data we'll get about the composition of Saturn's upper atmosphere. We've dipped our toes into it, but we haven't had an atmospheric probe yet. And we might not get one — a real one — for another couple decades. So getting this information is just incredibly precious, we have nothing else like it in the entire mission.

What are some of your favorite Cassini findings?

One of the wonderful things NASA does is create these enormous flagship projects which are just bristling with instruments and capability. They're able to discover things that we've never imagined.

I think everybody's favorite has to be the liquid water oceans below the surfaces of at least two of Saturn's icy moons. And, you know, you never know what else you'll find. I fully expect that there will be any number of science surprises coming from Cassini's dataset for decades.

Some of Cassini's images changed our view of the solar system when they came out. When was the first time photographs of other planets changed your understanding of space?

I have this thought a lot, actually. I remember when I was maybe in high school? Middle school? And the first images from the Voyager flyby of Jupiter came back. It went from being this round stripy ball to being modern art.

Sometimes, in planetary science things change, just like that. And suddenly our understanding and view of the solar system changes, and you can't go back. There are so many moments where I look at Cassini images and I'm struck. You think you know what this stuff is going to look like, and then it just knocks your socks off. I don't think any of us will ever, ever, ever get tired of that.

You've worked on Cassini for over half its life. What's it like to be part of such a long-lived space mission?

It is a tremendous thing. We are so fortunate to be involved in something that is one of the best things humanity can do. To be able to explore, to be able to represent us as a country and as a species, it's an incredible thing.

This is a project that stretches across generations and countries. I first came to JPL when I was 11 years old, brought by a family friend named Fred Scarf. That's when I knew this was where I wanted to work. He was a mentor until he died in his late 50s. So it was a shock to me, a few years ago, when I saw a proposal to send a long-lived mission to Saturn. It was dated from the early 1980s. And one of the names on it was Fred Scarf.

So here I am, three decades later. Helping to finish a mission that he never lived to see launch. When I say that these missions stretch across generations, it's not an exaggeration.

This requiem for Cassini seems like a unique occurrence. Most other spacecraft just kind of keep going into space. Or crash. This has an end date, and it's not from an accident. Is that a strange feeling?

It is, it's a very strange feeling. And yet, there can be no better end for the spacecraft and the mission. The Grand Finale lets us do science that is utterly unique, that we could never have done otherwise. There could be no better requiem for her.

Cassini is a her?

Well, all ships are she, you know? Some say spacecraft shouldn't be anthropomorphized, but obviously, I know that she is a she.

But you know, it makes sense to think of them that way. These craft are extensions of us. They are us. And we put onto them all of our capabilities and hopes and dreams and mistakes. And we send them into space.

So what will you be doing when Cassini ends? Where will you be?

I'll be gathered with almost all the flight team, a lot of alumni, friends and family. We'll be watching. And we'll be crying, because she's been part of our lives for so long.

My two daughters, who are 24 and 21, will be there as well. I have a picture of the youngest from when Cassini arrived in orbit at Saturn. She's a little kid, sitting there with a Burger King Cassini toy, wearing a purple shirt — the official farewell color for Cassini, though we didn't know it then. And now she's a senior in college. And she'll be at this gathering, wearing a purple shirt again.

And she can't remember a time when Cassini hasn't been in space?

No. Cassini has always been there.

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