Why do it? The mission’s goal is to send back detailed data on the comet that will help us understand the origin of the solar system, perhaps even of the origin of water and life on Earth, which may have come through comet impacts. Comets are left over from the formation of the solar system billions of years ago. “How did the solar system begin?” is a fascinating question. But it’s also an incredibly abstract one, far removed from the kinds of questions most of us try to answer in our lives, let alone during our workdays. So what draws the scientists behind Rosetta to this pursuit? I tracked down several of the scientists behind Rosetta and asked them about it. What makes you dedicate decades of work and attention to the study of distant bundles of rock and ice and gas circling the sun?
“It’s real exploration, and what’s more exciting than that?”
Mark Hofstadter, a radio astronomer, has been working on Rosetta for 20 years. When he started, he was the youngest radio astronomer the team leader knew (anticipating the long lifespan of the mission, the team leader wanted young scientists involved). When I asked Hofstadter what kept him interested in the mission for such a long time, he told me about measuring the composition, velocity and temperature of the gases in the coma (the cloud of gases surrounding the comet) and the subsurface of the comet’s nucleus. And then he said this: “Really, you go to all the scientists, and what they are interested in is seeing something no one else has seen, understanding something that has been a mystery. And that’s so cool. It’s that emotional thing that really gets us going every day and keeps us up late at night.”
Alan Stern and Joel Parker, who work together on an ultraviolet spectrometer that helps determine the composition of the comet’s surface and tail, also say it’s the element of discovery that keeps them dedicated. The Rosetta project is truly a first. “It’s real exploration,” says Stern, “and what’s more exciting than that?” Parker offers a similar reason: “Firsts are exciting for good reason: you don’t know what the unknowns are. You can guess at them, but you don’t really know.”
Philae’s landing on P67 was a giant first technologically, and also likely the first that most of us have heard of the Rosetta mission. But there were many other milestones along the way. The mission was first conceived in the late ’70s, approved in 1993, and launched in 2004. Hofstadter describes another earlier landmark moment with obvious relish: “When your instrument survives the launch, mechanically, then you turn it on for the first time, and you get the first image, what we call first light. And we go, ‘ah!’” (Rosetta, with many different instruments onboard, had several different “first light” moments.) Next, the spacecraft chased comet P67 out beyond Jupiter, so far from the sun that its solar panels couldn’t generate enough power and it went into hibernation mode for over two years. Mark Bentley, who studies the dust environment of the comet, says the most exciting moment for him wasn’t this week’s landing, but the moment when the Rosetta spacecraft awoke from its hibernation in January. It’s unusual for a spacecraft to be out of communication for so long, and no one was sure whether Rosetta and its instruments would still be working.
“I have colleagues working on the lander, and for them this was the big week,” says Bentley (his instrument is on the orbiter, not the lander). “I was in Darmstadt on the landing day and it was a mixed bag—it was great to be involved in this really tense and exciting moment, but I was also quite happy that my stressful moment was out of the way, and to just be watching others have theirs.”
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Collaboration is also a big part of the project. The data that the Rosetta and Philae teams are collecting aren’t a monolith: some scientists are studying dust, some ice, some gases. It’s all of that data working in concert that will start to yield answers to the big questions. Paul Weissman studies the nucleus, the core of the comet itself. He’s looking forward to finding out about the interior of the comet because it will tell us “how the first macro-scopic bodies formed in the solar nebula 4.5 billion years ago, an important first step toward learning how the planets were formed.”
Hofstadter, meanwhile, is studying the relationship between the surface of the comet and the coma, and how both change as the comet swings around the solar system and changes temperature. “You have to understand how that nucleus changes every time it goes around the sun so that you know how to extrapolate to the formation of the solar system,” explains Hofstadter. Each is working individually, but the information each investigator discovers becomes meaningful when put together. “We focus on very specific things,” Hofstadter continues, “and then once in a while we step back and ask, ‘Am I making progress toward the big initial goal?’”
Many of the Rosetta scientists explained that their passion for their work has two sides. “Head and heart,” is how Bentley describes the dichotomy. “On one hand are the technical aspects, the nitty gritty, figuring out how we do this. And on the heart side is the joy of science, finding something you don’t know about the universe and our place in it, and trying to find an answer.” Parker is equally philosophical: “I sometimes see science like art. People don’t necessarily see the connections to how it makes their lives better—this is not going to give them a better toaster, or something like that—but there is this feeling, just like with art, that this is important in some way. It is worth expending vital resources on, whether it’s tax money or people’s focus. It just feels worthwhile to do.”