FULL NAME panoramic Survey Telescope & rapid response System
MIRRORS 1.8 m each PROJECTED COST $100 million
TIMELINE one (above) of four planned systems is built
MISSION 1.4 gigapixel cameras to image sky, find “killer” asteroids
LOCATION pan-STArrS 1 sits atop haleakala on maui in hawaii
ing. We’ve had ideas about what happened back then.” At last,
she says, “we’ll get to witness this directly.”
Big telescopes peer deeply into space but can see only a tiny
portion of the heavens at once. While an instrument gazes
intently at a speck of sky, spectral fireworks may be break-ing out elsewhere. To spot such drama, a new class of survey
telescopes is rolling out.
The first to debut is Pan-STARRS, the Panoramic Survey
Telescope & Rapid Response System, with a modest 1.8-meter
telescope. This facility atop Haleakala on the Hawaiian island
of Maui should enter full-scale operation this spring, notes
Nick Kaiser, a principal scientist with the project.
Pixels, the discrete elements that make up an image, are a
measure of resolution, and Pan-STARRS will capture pixels
in abundance. The field of view will be vast — 7 square degrees
for each mirror in its four planned telescopes. Each will have
a 1.4-gigapixel camera, so even this wide view will encompass
a high resolution. The telescope will train its eye on a patch
of sky for about 30 seconds and then move to another. By
photographing 1,000 segments nightly, “we’ll image the entire
sky once a week,” Kaiser predicts.
One high priority “is being able to detect 90 percent of all
killer asteroids, near-Earth asteroids bigger than 300 meters,”
he says. “That should take us about 10 years,” which is the projected duration of the mission.
Right now, Pan-STARRS relies on a single telescope. If
funds hold out, it should get three clones. Each of the four
telescopes would simultaneously view the same patch of sky.
Sometimes a digital detector registers a false positive, perhaps from a stray cosmic ray, Kaiser says. With four images
of the same spot, he says, three will veto any false report.
The far more ambitious Large Synoptic Survey Telescope
is scheduled to see first light in 2014 from a Chilean mountaintop. Its 8.4-meter mirror is in production, and the completed system would use the world’s largest digital camera to
get a resolution of 3.2 gigapixels. By 2016, LSST is expected
to be scanning not only for asteroids and supernovas but
also for details of dark matter — the majority of the universe’s mass, now unseen — and the dark energy serving as
a mysterious, accelerating force (SN: 2/2/08, p. 74).
Compared with the recently completed set of data from
the ongoing Sloan Digital Sky Survey, even the smaller Pan-STARRS will offer “a lot more pixels,” Kaiser observes. “So
we’ll see a lot fainter objects.”
Other new missions will put communities of stars in perspective — literally.
“At the moment we don’t know the distances to most stars
in the Milky Way,” observes Ellis, “so we don’t have a three-dimensional map of even the galaxy that we inhabit.” But
Gaia, a European Space Agency project due to launch in 2011,
will correct that, he predicts.
The mission will carry two telescopes into orbit, each
focused at a different angle to provide the equivalent of
binocular vision. And the spacecraft itself will spin slowly to
scan the entire celestial sphere. Over several years, its precision measurements — its accuracy is expected to be the
equivalent of measuring the diameter of a human hair at a
distance of 1,000 kilometers — should provide a 3-D map of
all the stars within 30,000 light-years of the sun.
During its five-year mission, Gaia should map about a
billion stars and other objects roughly 70 times — each time
charting their position, distance and brightness, with unprecedented precision, to track changes over time.
Another mission will offer a historical perspective on
stars, what’s being called “galactic archaeology,” notes Mike
Irwin of the University of Cambridge in England. Its data
will be the chemical fingerprints of stars as read by a new
Wide-Field Multi-Object Spectrograph, or WF-MOS. This
instrument is being designed for use, perhaps by 2014, with
Japan’s refurbished 8.2-meter Subaru telescope atop Hawaii’s
Star trajectories can become jostled, as passing galaxies kidnap stars or as maturing stars take up relationships
with strangers. But wherever it goes, a star carries the
chemical fingerprint unique to its nursery environment,
Irwin explains. By analyzing a star’s spectral, or chemical,
fingerprint, he says, astronomers hope to identify which stars
in a throng are related, and which trace back to other regions
of the galaxy. Similarly, he says, “as our galaxy cannibalizes