TESS Will Find Strange New Worlds Close to Home

Artist illustration of NASA's Transiting Exoplanet Survey Satellite (TESS) in high-Earth orbit.  (NASA)

Have you ever gazed up at the night sky and wondered which stars might have planets, what those worlds may be like, or if there could be some form of life on any of them? When I was a child, I did a lot of that sort of imagining — decades before the first scientific detection of an extrasolar planet.

We now live in an era of knowing that the galaxy teems with planets, and that probably most, if not all stars possess multiple worlds. Anyone born after 1992 has lived their entire life without needing to imagine if there are planets around other stars — we know they are there!

On April 16th we enter another era of exoplanet discovery, with the launch of NASA's Transiting Exoplanet Survey Satellite spacecraft. TESS will be propelled by a SpaceX Falcon-9 rocket into a high-Earth orbit, a lofty vantage point that will offer sweeping views of space.

Artist illustration of the seven Earth-sized exoplanets discovered in the nearby TRAPPIST-1 system. Three of these are located within their star's habitable zone, and could have liquid water on their surfaces.
Artist illustration of the seven Earth-sized exoplanets discovered in the nearby TRAPPIST-1 system. Three of these are located within their star's habitable zone, and could have liquid water on their surfaces. (NASA/Goddard Space Flight Center)

From that high orbit, TESS will engage in a two-year survey of 500,000 stars across the entire sky, searching for planets by the "transit" method: measuring the temporary dimming of a star's light when one of its planets passes in front of it.

What We Know About Exoplanets
The search for extrasolar planets is not a new thing. We've been finding them since 1992, 26 years ago! As of April 2018, a total of 3,711 exoplanets of all sizes have been confirmed to exist. Their abundance tells us that most, if not all, stars in the galaxy likely possess at least one, and probably multiple, planets.

Sponsored

NASA's Kepler spacecraft, launched in 2009, set out to find the more elusive "Earth-like" exoplanets: world's close to Earth's size that could support liquid water on their surfaces, within their star's "Habitable Zone." Among the 2,600 exoplanets that Kepler has discovered, at least a couple dozen fall into this category.

The "transit method" of detecting exoplanets relies on a planet passing in front of (transiting) its star and causing a detectable dimming in the star's light.
The "transit method" of detecting exoplanets relies on a planet passing in front of (transiting) its star and causing a detectable dimming in the star's light. (NASA)

Kepler's sampling suggests that there may be billions of these Earth-like worlds in the galaxy.

Naturally, scientists want to know more about these potential other-Earths. (So do I!) What are they made of? Do they have atmospheres? Do they have oceans? Most tantalizing of all, do they support life?

Unfortunately, most of the potentially Earth-like worlds we have discovered are too far away for us to learn much more than their sizes and how close they are to their stars. Their great distances from us make more detailed investigations extremely challenging, to say the least.

Illustration comparing the regions of stars observed by Kepler and those to be surveyed by TESS.
Illustration comparing the regions of stars observed by Kepler and those to be surveyed by TESS. (Zack Berta-Thompson)

What's New About TESS?

Unlike the Kepler mission, which focused on very distant stars in one small patch of the sky, TESS will survey the nearest stars in our neighborhood of the galaxy, and across the entire sky.

TESS will detect exoplanets of all types, but its main goal is to look for small, Earth- and super-Earth sized planets, orbiting stars much closer to us and much brighter than those Kepler observed.

Both of these factors will make detailed investigation by other observatories and spacecraft possible — including the upcoming James Webb Space Telescope, which will be tasked with measuring the temperature and atmospheric composition of these nearby worlds.

This may tell us if a planet has the necessary ingredients for life--liquid water and organic compounds. We might even detect the chemical telltales of life itself.

Graph showing the size and brightness of stars observed by Kepler and those to be observed by TESS. TESS will focus on brighter, nearby stars that are much easier to investigate with follow-up observations.
Graph showing the size and brightness of stars observed by Kepler and those to be observed by TESS. TESS will focus on brighter, nearby stars that are much easier to investigate with follow-up observations. (MIT)

How Strange Might Strange New Worlds Be?
As that child gazing up at the starry skies, I imagined some pretty wild possibilities for those yet-undiscovered worlds.

Imagine a planet-wide desert, stretching pole to pole, that is so cold that carbon dioxide lies frozen on the ground. Or a searing hot landscape with a corrosive atmosphere that is so thick it would crush you like an aluminum can. Or a cloud-darkened milieu where the rain, rivers and seas are cryogenic liquid methane and you would weigh only 20 pounds. Or a world covered entirely by a hundred-mile-deep ocean hiding under a crust of ice.

Imaginative poster art produced by NASA illustrating future human explorers enjoying the strange environments of some exoplanets we have discovered.
Imaginative poster art produced by NASA illustrating future human explorers enjoying the strange environments of some exoplanets we have discovered. (NASA)

And these are only descriptions of some of the planets and moons in our own solar system.

Sponsored

TESS is projected to find at least 1,500 exoplanets orbiting nearby stars, and of these at least 300 are expected to be near-Earth sized. Once we begin to probe the environmental conditions on those planets, imagine what we might find.

Volume
KQED Live
Live Stream
Log In ToPledge-Free Stream
LATEST NEWSCAST
KQED
NPR
Live Stream information currently unavailable.
Share
LATEST NEWSCAST
KQED
NPR
KQED Live

Live Stream

Live Stream information currently unavailable.