We know there are superhabitable planets out there. We’re working on getting a closer view.
Not to disrespect our home planet in the Earth issue, but there might be planets out there better suited to supporting complex life. Scientists have identified two dozen of these “superhabitable” exoplanets, chronicled in the journal Astrobiology. Just because these superhabitable planets have many of the right conditions doesn’t mean they currently support life, or ever did.
“Thus, when we discuss the possibility of habitable or superhabitable planets, we do not necessarily assume that these planets host life and thus do not address (at least directly) the notoriously difficult question on how, where, and under what conditions life originates) — conditions that might be very different from those under which life thrives,” the researchers, led by University of Washington astrobiologist Dirk Schulze-Makuch, wrote.
But that doesn’t mean they don’t have anything to teach us. And given that there might be 40 billion terrestrial planets in the Milky Way galaxy alone — our best estimate right now is that there are about 2 trillion galaxies in the universe — it’s likely there are many more superhabitables out there, and quite possibly several forms of life. The 24 superhabitable exoplanets humans have so far identified are all at least 100 light-years away, making it extremely difficult to study them. But help might come in the next two decades.
The ideal conditions that make a planet superhabitable are being slightly bigger, warmer, wetter, and older than Earth. They might have a moon that’s bigger and closer than ours, and they revolve around a K dwarf star. These stars aren’t as big, as hot, or as bright as the sun, but they have a much longer life span. They can last from 20 to 70 billion years, much longer than the 10-billion-year life span our sun has, which is almost halfway up. The researchers think 5 to 8 billion years into a star’s life is the best time for life to thrive on a nearby superhabitable planet.
“We have to focus on certain planets that have the most promising conditions for complex life. However, we have to be careful to not get stuck looking for a second Earth because there could be planets that might be more suitable for life than ours,” Schulze-Makuch said.
A planet about 1.5 times the size of Earth, rocky, about 8 degrees Fahrenheit warmer but with plenty of liquid water — think rainforest conditions throughout — might offer the best chance for superhabitability. But there’s a lot more to learn about these exoplanets, and slight changes could throw the whole balance off.
“It’s sometimes difficult to convey this principle of superhabitable planets because we think we have the best planet,” Schulze-Makuch told CNN. “We have a great number of complex and diverse lifeforms, and many that can survive in extreme environments. It is good to have adaptable life, but that doesn’t mean that we have the best of everything.”
We don’t know what other intelligent life there might be — just because conditions might be right doesn’t mean there is life or has been on a superhabitable planet — and how much they might explore around the universe. But we know we on Earth have great resources and seemingly unending curiosity about what’s going on out there.
Habitable Worlds Observatory
The National Academies of Sciences, Engineering, and Medicine’s decadal survey on astronomy and astrophysics called for an $11 billion telescope that could search for habitable exoplanets. A successor to the just-launched Webb Space Telescope and the forthcoming Nancy Grace Roman Space Telescope (May 2027 launch date), NASA’s Habitable Worlds Observatory is slated for its phase of development in 2029 and should launch in the early 2040s.
The HWO plans call for a 6-meter telescope sensitive to UV, optical, and near-infrared photons. The first in a series of telescopes in a Great Observatories program, the HWO will specifically search for habitable exoplanets and any life that might be on them.
When it launches, HWO will station itself 1 million miles from Earth at a spot called Lagrange point 2 (where the Webb telescope also sits). Highly sophisticated equipment will be crucial to the observation of any habitable worlds, and so regular maintenance and servicing will be required. Obviously, humans can’t get there, so robots will do the servicing.
“In 10, 15 years, there are going to be a lot of companies that can do very straightforward robotic servicing at L2,” Mark Clampin, director of NASA’s astrophysics division, said at the January meeting of the American Astronomical Society. “It gives us flexibility, because it means we don’t necessarily have to hit all of the science goals the first time.”
The HWO could contain a segmented mirror that would need to be perfectly shaped down to 1 picometer (1 millionth of 1 millionth of a meter). It will need a coronagraph powerful enough to block out light from 10 billion times than the habitable planets near them so that researchers can get a better view of what’s happening on the planets themselves. That takes a lot of human ingenuity and some well-programmed repair robots. But just imagine what we might discover.