NASA’s Kepler exoplanet telescope ran out of fuel and died

An
illustration of NASA’s Kepler space telescope.

NASA

• The Kepler space telescope was
  launched in 2009 and has stared down more than 500,000
  stars.
• However, NASA said on Tuesday that Kepler has run out
  of fuel and will be retired.
• Kepler discovered roughly 4,000 planets beyond the
  solar system, a handful of which might be Earth-size and even
  habitable.
• Kepler’s more powerful follow-on mission, the Transiting Exoplanet Survey
  Satellite, is already in operation.

For 9 years, a car-size telescope in space called Kepler has
dutifully stared down more than half a million stars.

In doing so, Kepler discovered thousands of planets beyond the
solar system — a handful of which might be Earth-size
and possibly
habitable to alien life.

But as NASA revealed on Tuesday, Kepler’s mission has come to an
end: The spacecraft ran out of fuel, the space agency said on
Tuesday, which means it is effectively dead.

“While this may be a sad event, we are by no means unhappy with
the performance of this marvelous machine,” Charlie Sobeck,
project system engineer at NASA’s Ames Research Center in
California, told reporters on a conference call. “Kepler’s
nine-and-a-half year flight was more than twice the original
target.”

Kepler is currently orbiting the sun at a distance of about 94
million miles from Earth. Its positioning system broke down in
2013, about four years after its launch, though scientists found
a way to keep it operational.

Now that it has no fuel, the telescope can’t correct its very
specific orbit, so it is drifting farther and farther from our
planet. Mission engineers will eventually turn off its radio
transmitters, NASA said.

Legacy of an exoplanet hunter

ESO/NASA

NASA launched the Kepler telescope on March 6, 2009, to learn if

Earth-like planets that might harbor life are common or rare
in other star systems.

During its mission, Kepler found 2,681 confirmed planets and
another 2,899 candidates, bringing its tally to 5,580. That
number includes
about 50 worlds that may be about the same size and
temperature as Earth.

The Kepler telescope laid bare the diversity of planets that
reside in our Milky Way galaxy.

NASA’s Kepler space
telescope, built in part by Ball Aerospace, before its launch in
2009.

NASA/JPL-Caltech/Ball

Its findings indicate that billions of distant star systems are
teeming with planets — perhaps trillions in the Milky Way galaxy
alone. Kepler even helped pinpoint the first moon known outside
our solar system.

“Basically, Kepler opened the gate for mankind’s exploration of
the cosmos,” William Borucki, Kepler’s now-retired chief
investigator, told reporters.

Borucki described his favorite exoplanet, named Kepler 22B,which
is located more than 600 light years from Earth and was first
spotted by the telescope in 2009. It is a possible “water world”
the size of Earth, perhaps covered with oceans and with a
water-based atmosphere. Water is considered a key ingredient for
life.

Kepler’s data also provided a new way to assess whether a planet
had a solid surface, like Earth and Mars, or is gaseous, like
Jupiter and Saturn. The distinction helped scientists zero in on
potential Earth-like planets and better the odds for finding
life.

Kepler used a detection method called transit photometry, which
looked for periodic, repetitive dips in the visible light of
stars caused by planets passing, or transiting, in front of them.

Kepler’s next-generation replacement

An
illustration of the Transiting Exoplanet Survey Satellite (TESS)
detecting potentially habitable alien worlds.

NASA

Kepler was succeeded by the
Transiting Exoplanet Survey Satellite (TESS), which NASA
launched in April. TESS is on a two-year, $337 million mission.

The telescope is currently
scanning 85% of the night sky, staring down distant solar
systems and hunting for small, rocky, Earth-like planets in the
process.

A handful of small planets have already been found, but the
mission could potentially reveal thousands of new worlds within
about 200 light-years of Earth — a cosmic stone’s throw away from
our world.

The
TESS exoplanet search zone compared to that of the Kepler
Mission.

Zach
Berta-Thompson/NASA

TESS will use a technique to find planets that’s similar to
Kepler’s approach, yet it will be an eminently more powerful
mission. If Kepler’s search area was like a shotgun blast, then
that of TESS is an exploding grenade or bomb.

“[W]e know there are more planets than stars in our universe,”
Paul Hertz, NASA’s director of astrophysics, said in a press release about TESS. “I
look forward to the strange, fantastic worlds we’re bound to
discover.”

Researchers working on TESS expect to find at least 50 rocky,
Earth-size worlds for scientists to scrutinize — perhaps double
what Kepler has found. However, TESS is likely find many more
than that, as it is viewing more stars (and Kepler defied its
creators’ projections).

Once TESS’ discoveries are confirmed, they could prove vital to
the work of NASA’s upcoming and powerful James Webb Space
Telescope (JWST), which is scheduled to launch sometime in 2021.

That next-generation observatory will rival the abilities of the
Hubble Space Telescope and will be the largest observatory ever
launched into space. JWST will take pictures in infrared light,
which is invisible to human eyes yet perfect for studying planets
through the clouds of gas and
dust in space that typically obscure distant worlds.

Giant
new ground-based telescopes are also being built, and those
might even be able to study the atmospheres of distant worlds and
seek out chemical signatures for life.

Reuters reporting by Joey Roulette in Orlando, Florida;
Writing by Ben Klayman in Detroit; Editing by Will Dunham