How is NASA's Europa Clipper mission looking for life?

What will the Europa Clipper mission consist of? There’s perhaps nobody better to help us than Britney Schmidt. Britney is an associate professor of earth and atmospheric sciences at Cornell University and has played a major role in the Europa mission...

Britney - On Europa's surface, we have only about 10% of it covered in what we call high resolution. But in this case, high resolution is anything greater than about 300 metres per pixel, which in most images you would miss the building that I'm sitting in. Compare that to Mars where most images you would probably see my laptop. So we've got a lot of work to do. So one of the things that Clipper will do is just get really, really in detail. We're going to have better than a hundred metres per pixel coverage of most of the surface. We'll get better than 10 metres per pixel over a significant portion of the surface. And that's going to allow us to do things like see the surface up close and think about where we might land in the future. Along with those camera images, we'll be getting spectrometry, so telling us what the surface composition is all about. We'll also be getting temperature readings of the surface and we'll be getting ice penetrating radar at the same time. And that's kind of like taking an X-ray of the ice shell. We'll actually be able to see into the deep subsurface, potentially all the way down to the ocean for the very first time. Then we add in the magnetic field data that'll give us a chance to understand the depth and potential salinity of the ocean. Then we've got this really amazing synergistic picture of how Europa works and where we might go in the future to actually start this real search for life

James - Unfathomable, the sort of level of detail you're describing for something so many hundreds of millions of miles away. The Europa Clipper mission is obviously, you know, focused on Europa, the moon of Jupiter, but it's not going to be orbiting around the site of most interest. It's orbiting around the planet Jupiter itself. Why is that?

Britney - Well, this is a great story and it's actually why Europa Clipper is so interesting. When we thought about sending a mission back to Europa, we all imagined that it would be an orbiter, that we'd go in and we'd orbit Europa and get really close to the surface. Jupiter has these huge radiation belts and Europa lives inside those radiation belts, and so it's a terrible place to be a spacecraft. So by actually doing these unique orbits that we call crank over the top orbits, it allows us to do the same science that you would do if you were orbiting Europa. But it allows you to do it by doing multiple different flybys. And so we're going to flyby the surface of Europa during the prime mission with about 50 close flybys. So that's within a hundred kilometres or so of the surface. So we'll get in close and then we'll do a burn and leave on a different trajectory. It also means that we can send back all of our data because we get out farther away. We can radio back for long periods of time and we don't have to live in the radiation belt, so it also allows us to use solar panels. So it really helps the mission with its lifetime, we'll be able to take more data, probably survive longer, potentially have extended missions, all because of this different style of orbit that we wanted to have for this mission. And so it's really a tale of innovation in how we think about orbiting spacecraft.

James - So we have the probe transmitting information back to Earth while it's out of the harmful radiation in the immediate atmosphere of Europa. But let's go into a bit more detail there if you don't mind. I mean, what the actual practicalities are of communications between the Clipper probe and the teams back here on Earth?

Britney - Jupiter's really far away. It's 5.1 astronomical units from the sun. So it's five times as far from the sun as we are. And so it takes between about 30 minutes and almost an hour, depending on where Jupiter is in its orbit, for signals to reach the Earth. And so we have already planned out most of the orbits. We can tweak it and so we'll be able to respond to what's happening. But we have this great plan already in place that allows us to kind of just execute when we get there and onboard the spacecraft. We have the ability to pre-process data to either compress it or to make decisions about what to send back first.

James - The dream would be for that data it's sending back to show some evidence of life. But as you kind of alluded to earlier, it's not really designed specifically for that per se, is it? It's more looking for the signs that life might be possible, that the moon might be able to support life more likely. The hope is that this sets us up for a future mission where we can perhaps get a lander on the surface of the moon.

Britney - Yeah, exactly. We're going to be able to understand its chemistry better. We're gonna know where water is inside the moon. Are there places where it's really close to the surface that we might go down and explore? Are there plumes coming off of the surface that we can get in close and sample the chemistry of? So we'll get some indications that might point in the direction of life, but it's really, really complicated. Planets are complicated beasts. Very famously the first life detection experiments that went to Mars, depending on who you ask, are kind of failures because we didn't know enough about Mars when we asked those questions. We sent experiments that reacted with the atmosphere as opposed to being something that organisms were eating, for example. And so one of the things that's really important and that we've learned in planetary exploration is that you really need to understand the system very well in order to design a good search for life or a good experiment. And that's true in any kind of science. And so what we're doing with Europa Clipper is we're taking several leaps from what we understood with Galileo much better chemistry data. Famously, the Galileo spacecraft didn't handle the radiation environment very well, and in particular the chemistry instrument, the spectrometer, really didn't. And so we have open questions about what the surface is made out of, what the salts are made out of, what are these dark patches on the surface. And so we'll get a chance to see that. Finding a place to land, finding really cool places to explore and places that are likely to have that kind of process going on, energy for life. That's what we're really looking for.