Episode for September 8th, 2023 Download

There’s no question that humanity is making fast progress in understanding, cataloging and classifying planets around other stars. So far we’ve found over five thousand five hundred of them. But let’s face it, we really want to know, maybe more than anything else, whether these planets have any life on them and whether they are habitable for us to, maybe, live on.

Finding habitable worlds has been a driving passion since we first learned there were other planets out there, and to find them, we are going to need a dedicated instrument that does nothing else but tries to locate and characterize them.

That’s where the Habitable Worlds Observatory comes in. NASA says “HWO is a concept for a NASA flagship mission, as recommended by the 2020 Astrophysics Decadal Survey, that would pursue a breadth of astrophysics goals, including searching for and characterizing potentially habitable planets beyond our solar system.”

The 2020 Astrophysics Decadal Survey - this is the body that helps astronomers prioritize what science they want to learn over the next ten years and recommends what to build to achieve those science goals.

They recommended HWO as NASA’s next flagship Astrophysics mission after the Nancy Grace Roman Space Telescope. HWO would be the first NASA mission designed specifically to look for signs of life on potentially habitable exoplanets, all while contributing to our broader understanding of the cosmos.

Astronomers from different institutions and agencies are convening now to decide what this telescope needs to be able to do in order to fulfill this mission. This project is just getting started but it’s not starting from scratch. Much work has already been done planning for another mission with a remarkably similar name: the Habitable Exoplanets Mission or HabEx.

HabEx was planned with virtually identical science goals in mind and the work done there will most likely be included with HWO.

But let’s you and I think for a minute, as a start, some of the things the observatory must be able to do, have the angular resolution to resolve the planet, which means that blocking out the light of the star is crucial. This means HWO will probably have either an onboard coronagraph, or a starshade will be placed between the spacecraft and the star system being studied to block out the host star so we can see the reflected light from the planet. That’s number 1.

Number 2: There will undoubtedly be a spectrograph of some sort that allows astronomers to tell if there is an atmosphere, and if so, what it’s made of. It is that spectrum that will tell us the compounds that exist that might make the exoplanet habitable and if life might already be there. Astronomers refer to these compounds as biosignatures: things that exist in the air that could only be put there by living organisms.

While there is no timetable for launch of this amazing mission yet, NASA is starting to get to work on our next flagship mission to study life elsewhere. After the launch and deployment of the Nancy Grace Roman Space Telescope, the Habitable Worlds Observatory will be our next gateway to finding life on other worlds.