No done deals
Still, HWO will have its work cut out for it. Even if it is lucky enough to detect a promising signal from a planet, Hammel says, the mission’s science team will need to be able to tease out all the relevant information they can to build up a complete picture of what the signal might mean in its context.
“You know there’s methane on Neptune, too, but that doesn’t mean that there’s cows there, right?” she said.
Focusing on stars like the Sun also comes with a tradeoff. While we know from our own experience that an Earth-like planet around a Sun-like star can host life, astronomers aren’t sure how common such worlds actually are. Current estimates range from roughly one potentially Earth-like world existing for every six stars, on average, to at least one such planet existing around every star. Though HWO is being planned with this range in mind, if Earth twins turn out to be rare, HWO could have too few targets for its survey to mean much.
Shkolnik, who is co-chair of the Community Science Instrument Team that helps guide HWO’s design, still says our “fastest bet” to finding life on exoplanets is through the mission.
“If I didn’t think HWO could do it, I wouldn’t be working on it,” she said.
Always tell me the odds
So, how close are we to finding life on exoplanets?
“I’m betting that we’re going to need Habitable Worlds to really answer the question, ‘Are we alone in the Universe?’” Hammel said. And yet, she adds, every planet JWST explores has the potential to surprise us.
“It’s always possible that something crazy happens,” Hammel said. “We could be one observation away.”