Over the past two months the team has been busy working on a new
mission concept, called K2, which would repurpose the Kepler space
telescope.
On Jan. 30, in response to an
invitation from NASA Headquarters, the Kepler team submitted a proposal to
the 2014 Astrophysics Senior Review of Operating Missions to continue scientific
observations with the Kepler spacecraft in this new two-wheel mode of operation.
The team is very excited about the science opportunities the new K2 mission
could enable. We continue to run demonstration tests to learn the nuances of
operating the spacecraft, and progress has been good.
During a spacecraft operation performance test in
Jan. 2014, one transit of the previous known exoplanet WASP-28b was captured.
The data were obtained at 1 min intervals. The observation proves the repurposed
spacecraft can still detect planets!
Image Credit: NASA Ames/T. Barclay
The K2 mission definition continues to mature. The mission can explicitly
address continued exoplanet discovery, but perhaps of greater interest is that
it can find planets around bright and nearby stars. Continuing additions to the
exoplanet catalog give us more targets for follow-up observations and will
inform future missions to better characterize the nature of these planets,
including their atmospheres. The K2 mission also would open a window on
well-known star-forming regions and stellar clusters of varying ages, providing
insight into stellar evolution. Observations of other galaxies, supernovae and
even gravitational microlensing events, are also exciting new opportunities with
K2.
During one of the demonstration tests, the known planet-hosting star WASP-28
was observed while in K2's field of view. Three days of data were collected and
a transit was captured of WASP-28b, a Jupiter-sized planet orbiting its star
every three and a half days. The observation proves the repurposed spacecraft
can still detect planets!
Another very good sign from spacecraft operations is that we’ve been able to
demonstrate that we can use the fine guidance sensors mounted on the focal plane
to control the spacecraft pointing. While this doesn’t improve the pointing
stability to the quality we had before the failure of reaction wheels #2 and #4,
it does ensure that the pointing is controlled by sensors that are adjacent to
the science detectors. This will ensure we have no significant misalignment
issues during science data collection.
Star trackers mounted toward the back of the spacecraft, well-separated from
the focal plane, are the alterative to control spacecraft pointing. As Kepler
orbits around the sun, the solar illumination changes. As a result a
differential expansion of the structures on the spacecraft occurs, and during
science data collection, the alignment of the star trackers changes slightly.
The effect is about a hundredth of a degree, but 40 times worse than needed for
pointing control. This effect must be removed through careful calibration.
By using the fine guidance sensors, the additional calibration step is
eliminated entirely. We are prepared to operate either way, but the successful
demonstration of this fine guiding capability is a welcome development.
The new mission concept, first unveiled at the Kepler
Science Conference II, was further detailed at the 223rd AAS
Meeting in January, where a preliminary set of observing fields were distributed
for public comment and initial targets were solicited. We are currently
reviewing the target requests from 126 proposals and will begin our first
science verification observations in March. The first science observation run
will be called "Campaign 0." The primary purpose of this campaign will be to
calibrate the star tracker alignment, but we will be collecting science data as
we do.
Also at the AAS meeting, the team reported
on four years of ground-based follow-up observations targeting Kepler's
exoplanet systems. These observations confirm the numerous Kepler discoveries
are indeed planets and yield mass measurements of the ubiquitous and enigmatic
worlds that vary in size between Earth and Neptune. As a result, scientists
confirmed 41 of the planet candidates discovered by Kepler and determined the
masses of 16.
On March 6, 2009 at 10:49 p.m. EST, Kepler lifted off on a Delta II rocket
from Cape Canaveral Air Force Station in Florida in search of new worlds. To
celebrate and reflect on the contributions the mission has made so far, we are
preparing activities to properly mark the 5-year anniversary milestone. Please
watch Facebook and Twitter for more details.
Meanwhile, the team continues to sift through four years of data collected
during Kepler's prime mission. More than a year of that data remains to be fully
searched and analyzed.
The year has started strong for Kepler and for the new mission concept of K2.
We look forward to exciting announcements in the weeks and months ahead!
Regards,
Roger
Roger
NASA
Guillermo Gonzalo Sánchez Achutegui
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