22 March 2014 sky & telescopeEasy Amateur Sciencebe not too hot and not too cold for water to exist in liquid
form. PH2 b is too large to be a rocky world and instead
is probably composed mostly of hydrogen and helium,
like Jupiter and Saturn. But if the planet has large, rocky
moons, they could potentially harbor liquid water on their
surfaces. Radial-velocity observations and adaptive-optics
imaging from Keck constrain the magnitude of the host
star’s wobble due to PH2 b’s gravitational tug as it orbits.
Analysis of these observations rule out the possibility of
a star or brown dwarf orbiting KIC 12735740, validating
PH2 b as a bona-fi de planet.Last May, Kepler suff ered a mechanical failure that has
potentially ended its mission (August 2013 issue, page 10).
Kepler requires very exact pointing to detect the drop in
light due to rocky exoplanets. Kepler uses reaction wheels
to carefully nudge the spacecraft to keep the 160,000 stars
nearly precisely on the same locations on the imaging
plane to achieve the required photometric sensitivity.
Kepler needs three reaction wheels to successfully point
at its target fi eld, and was launched with one spare. One
of the four reaction wheels had previously failed in July- With the malfunction of a second wheel in May
2013, Kepler lost its ability to point.
However, NASA engineers have come up with an
ingenious plan for using the Sun to steady the spacecraft,
balancing Kepler such that only two reaction wheels are
mainly needed. This means Kepler would no longer stare
at its original fi eld; it would point to new star fi elds along
the ecliptic that would be observed for shorter durations
(40 to 80 days) and with fewer numbers of monitored
stars. Engineering tests look promising, and the new mis-
sion concept, dubbed K2, recently passed its fi rst hurdle,
receiving the go-ahead from NASA to be considered in the
Senior Review that will decide if the two-wheeled mission
will be funded. NASA will soon make the fi nal decision
on whether the K2 mission will proceed.
The prospect of a new haul of exoplanets with K2 is
exciting, but even if Kepler’s exoplanet-hunting days
are over, its legacy is far from fi nished. The Kepler team
and the astronomical community are swamped with its
exquisite light curves and still has nearly one year of data
waiting to be fully analyzed. Planet Hunters has barely
scratched the surface of the Kepler data. There will be
many more discoveries yet to come with your help.
The Future Is with the Machines
Astronomical surveys in the coming decade will enter
the petabyte era with new instruments and observatories
currently being planned and built, such as the Large
Synoptic Survey Telescope (LSST) and the Square Kilo-
meter Array (SKA). LSST is an 8.4-meter optical telescope
currently being constructed in northern Chile that will
survey about 18,000 square degrees of the Southern skies
in fi ve fi lters. Once LSST opens its eyes to the sky in
around 2022, it will produce the largest public dataset in
the world, generating 15 terabytes worth of image data
each night!
The SKA will be the largest radio telescope ever built
when it comes online in the next decade. Radio dishes
will be constructed in Australia and South Africa and
combined to produce an eff ective collecting area of 1
square kilometer. The SKA will generate roughly 11 tera-
bytes of raw data per second with sensitivity unmatched
by present-day radio arrays.
Astronomers will use both LSST and the SKA to study
everything from dark matter and dark energy to small bod-EXPLORE MARS Mars Reconnaissance Orbiter’s HiRISE cam-
era captured these images of fans and blotches on the southern
polar ice cap. By visiting planetfour.org, you can explore Mars
from your home and help scientists monitor these features as
the ice cap thaws in the southern spring.NASA / JPL-CALTECH / UNIVERSITY OF ARIZONA (3)Planet Hunters2.indd 22 12/24/13 11:45 AM