The engineers huddled around a telemetry screen, and the mood was tense. They were watching streams of data from a crippled spacecraft more than 50 million miles away -- so far that even at the speed of light, it took nearly nine minutes for a signal to travel to the spacecraft and back.
It was late August 2013, and the group of about five employees at
Ball Aerospace in Boulder, Colorado, was waiting for NASA's Kepler space
telescope to reveal whether it would live or die. A severe malfunction
had robbed the planet-hunting Kepler of its ability to stay pointed at a
target without drifting off course.
The engineers had devised a remarkable solution: using the pressure
of sunlight to stabilize the spacecraft so it could continue to do
science. Now, there was nothing more they could do but wait for the
spacecraft to reveal its fate.
"You're not watching it unfold in real time," said Dustin Putnam,
Ball's attitude control lead for Kepler. "You're watching it as it
unfolded a few minutes ago, because of the time the data takes to get
back from the spacecraft."
Finally, the team received the confirmation from the spacecraft they
had been waiting for. The room broke out in cheers. The fix worked!
Kepler, with a new lease on life, was given a new mission as K2. But the
biggest surprise was yet to come. A space telescope with a
distinguished history of discovering distant exoplanets -- planets
orbiting other stars -- was about to outdo even itself, racking up
hundreds more discoveries and helping to usher in entirely new
opportunities in astrophysics research.
"Many of us believed that the spacecraft would be saved, but this was
perhaps more blind faith than insight," said Tom Barclay, senior
research scientist and director of the Kepler and K2 guest observer
office at NASA's Ames Research Center in California's Silicon Valley.
"The Ball team devised an ingenious solution allowing the Kepler space
telescope to shine again."
A little more than two years after the tense moment for the Ball
engineers, K2 has delivered on its promise with a breadth of
discoveries. Continuing the exoplanet-hunting legacy, K2 has discovered
more than three dozen exoplanets with more than 250 candidates awaiting
confirmation. A handful of these worlds are near-Earth-sized and orbit
stars that are bright and relatively nearby compared with Kepler
discoveries, allowing scientists to perform follow-up studies. In fact,
these exoplanets are likely future targets for the Hubble Space
Telescope and the forthcoming James Webb Space Telescope (JWST), with
the potential to study these planets' atmospheres in search of
signatures indicative of life.
K2 also has astronomers rethinking long-held planetary formation
theory, and the commonly understood lonely "hot Jupiter" paradigm. The
unexpected discovery of a star with a close-in Jupiter-sized planet
sandwiched between two smaller companion planets now has theorists back
at their computers reworking the models, and has sent astronomers back
to their telescopes in search of other hot Jupiter companions.
"It remains a mystery how a giant planet can form far out and migrate
inward leaving havoc in its wake and still have nearby planetary
companions," said Barclay.
Like its predecessor, K2 searches for planetary transits -- the tiny,
telltale dip in the brightness of a star as a planet crosses in front
-- and for the first time caught the rubble from a destroyed exoplanet
transiting across the remains of a dead star known as a white dwarf.
Exoplanets have long been thought to orbit these remnant stars, but not
until K2 has the theory been confirmed.
K2 has fixed its gaze on regions of the sky with densely packed
clusters of stars, which has revealed the first transiting exoplanet in
such an area, popularly known as the Hyades star cluster. Clusters are
exciting places to find exoplanets because stars in a cluster all form
around the same time, giving them all the same "born-on" date. This
helps scientists understand the evolution of planetary systems.
The repurposed spacecraft boasts discoveries beyond the realm of
exoplanets. Mature stars -- about the age of our sun and older --
largely populated the original single Kepler field of view. In contrast,
many K2 fields see stars still in the process of forming. In these
early days, planets also are assembled, and by looking at the timescales
of star formation, scientists gain insight into how our own planet
formed.
Studies of one star-forming region, called Upper Scorpius, compared
the size of young stars observed by K2 with computational models. The
result demonstrated fundamental imperfections in the models. While the
reason for these discrepancies is still under debate, it likely shows
that magnetic fields in stars do not arise as researchers expect.
Looking in the ecliptic -- the orbital path traveled around the sun
by the planets of our solar system and the location of the zodiac -- K2
also is well equipped to observe small bodies within our own solar
system such as comets, asteroids, dwarf planets, ice giants and moons.
Last year, for instance, K2 observed Neptune in a dance with its two
moons Triton and Nereid. This was followed by observations of Pluto and
Uranus.
"K2 can't help but observe the dynamics of our planetary system,"
said Barclay. "We all know that planets follow laws of motion but with
K2 we can see it happen."
These initial accomplishments have come in the first year and a half
since K2 began in May 2014, and have been carried off without a hitch.
The spacecraft continues to perform nominally.
Searching for far out worlds
In April, K2 will take part in a global experiment in exoplanet
observation with a special observing period or campaign, Campaign 9. In
this campaign, both K2 and astronomers at ground-based observatories on
five continents will simultaneously monitor the same region of sky
towards the center of our galaxy to search for small planets, such as
the size of Earth, orbiting very far from their host star or, in some
cases, orbiting no star at all.
For this experiment, scientists will use gravitational microlensing
-- the phenomenon that occurs when the gravity of a foreground object,
such as a planet, focuses and magnifies the light from a distant
background star. This detection method will allow scientists to find and
determine the mass of planets that orbit at great distances, like
Jupiter and Neptune do our sun.
Design by community
What could turn out to be one of the most important legacies of K2
has little to do with the mechanics of the telescope, now operating on
two wheels and with an assist from the sun.
The Kepler mission was organized along traditional lines of
scientific discovery: a targeted set of objectives carefully chosen by
the science team to answer a specific question on behalf of NASA -- how
common or rare are "Earths" around other suns?
K2's modified mission involves a whole new approach -- engaging the
scientific community at large and opening up the spacecraft's
capabilities to a broader audience.
"The new approach of letting the community decide the most compelling
science targets we're going to look at has been one of the most
exciting aspects," said Steve Howell, the Kepler and K2 project
scientist at Ames. "Because of that, the breadth of our science is vast,
including star clusters, young stars, supernovae, white dwarfs, very
bright stars, active galaxies and, of course, exoplanets."
In the new paradigm, the K2 team laid out some broad scientific
objectives for the mission and planned to operate the spacecraft on
behalf of the community.
Kepler's field of view surveyed just one patch of sky in the northern
hemisphere. The K2 ecliptic field of view provides greater
opportunities for Earth-based observatories in both the northern and
southern hemispheres, allowing the whole world to participate.
With more than two years of fuel remaining, the spacecraft's scientific future continues to look unexpectedly bright.
Ames manages the Kepler and K2 missions for NASA's Science Mission
Directorate. NASA's Jet Propulsion Laboratory in Pasadena, California,
managed Kepler mission development. Ball Aerospace & Technologies
Corporation operates the flight system with support from the Laboratory
for Atmospheric and Space Physics at the University of Colorado in
Boulder.
For more information about the Kepler and K2 missions, visit: http://www.nasa.gov/kepler
Media Contact
Whitney Clavin
Jet Propulsion Laboratory, Pasadena, California
818-354-4673
whitney.clavin@jpl.nasa.gov
Michele Johnson
Ames Research Center, Moffett Field, Calif.
650-604-6982
michele.johnson@nasa.gov
Source: JPL-Caltech
