Narrator: In the last few decades
we have found thousands of worlds around other stars.
A new NASA astrophysics mission will help us find
many more. Elisa Quintana: TESS, the Transiting Exoplanet Survey Satellite,
is NASA's newest exoplanet mission. It's being led out of MIT,
and it's going to find thousands of new planets orbiting bright nearby stars.
And it's going to build upon the legacy of the Kepler mission,
only it's going focus on nearby bright stars that are sprinkled across the whole sky,
and it's going to help us answer a really important question. And that is: which of
our nearest stellar neighbors has planets? Narrator: During its
two year survey, TESS will look for signs of planets, ranging
from Earth size, to giants larger than Jupiter.
TESS will search for these new worlds, or exoplanets, using
transits, the same method as the Kepler mission.
As a planet passes in front of its star, it blocks some of the
light, causing a slight drop in brightness.
TESS can detect those subtle dips, and even use them to
determine some basic features of the planets, such as their size,
and orbit. Each of TESS's cameras has
a 16.8-megapixel sensor, covering a 24-degree square--
large enough to contain an entire constellation.
TESS has four of these cameras, arranged to view a vertical strip of
the sky, called an observation sector. George Ricker: The coverage of
the TESS cameras is unprecidented in terms of the amount of sky
that they can actually see at any given time and also their
ability to cover such a broad portion of the sky.
The types of targets that TESS will allow us to find,
will enclose essentially all of the bright nearby stars.
Narrator: TESS will watch each observation sector for about 27 days
before rotating to next one, covering first the south, and then the north
to eventually build a map of 85 percent of the sky.
This coverage--about 350 times
what Kepler first observed--will make TESS the first
exoplanet mission to survey almost the entire sky.
TESS will fly in a highly elliptical orbit that maximizes
the amount of sky the spacecraft can image and is carefully timed with the orbit
of the moon. It will spend most of each 13.7 day
orbit collecting data, and then, as it passes closer to Earth,
it will transmit that data to the ground.
Because TESS's observation sectors overlap, it will have
an area near the pole under constant observation.
This region is easily monitored by the James Webb Space Telescope,
which allows the two missions to work together to first find, and then
carefully study exoplanets. Since most of the exoplanets
found by TESS will orbit bright stars, missions like Webb will be
able to measure the spectra of starlight absorbed by the planets' atmospheres,
which can indicate what they're made of. Ground-based measurements
of the TESS Exoplanets can determine their masses. Combining
the masses with TESS's size measurements reveals densities, allowing
scientists to better understand the exoplanets' compositions.
Jennifer Burt: The thing that we're really excited about with TESS is the way that it'll actually build
on the momentum that we started with Kepler. So TESS is going to take that same
search approach, but apply it to the vast majority of the sky, which still hasn't
really been looked at in detail when searching for exoplanets. And by focusing
especially on planets that orbit bright nearby stars, TESS allows us to start looking
at things like composition and atmospheric makeup, and that'll then be crucial when we
want to start looking around stars that are even further away and in deeper parts of the galaxy as well.
Narrator: TESS is the vanguard of a new
era of exoplanet study, and will forever expand
our understanding of worlds beyond our own.
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