than five million SETI@home volunteers, essentially constitutes one of the
world’s largest supercomputers, and is
an excellent example of how a network
of home computers can be amazingly
efficient by spreading around the processing burden.
Another ongoing citizen science
program, Galaxy Zoo, uses tens of
thousands of home computers, but
in this case the processing power lies
mostly in the human brain. Originally launched in 2007, Galaxy Zoo
is the most massive galaxy classification project ever undertaken. Galaxies come in a mind-boggling variety
of shapes and combinations, making
classifying them extremely difficult.
Galaxy Zoo was tasked with classifying
the nearly one million galaxies swept
up in the Sloan Digital Sky Survey, the
most ambitious survey in the history of
astronomy. Computers and the Internet have been instrumental in circulating images of galaxies to thousands of
volunteers, but the success of Galaxy
Zoo depends on the pattern recognition faculties particular to humans.
“Supercomputers, or even my bat-
tered old laptop, can beat large num-
bers of humans for sheer processing
power,” says Chris Lintott, an astro-
physicist at Oxford University. “The
problem we were facing is one of pat-
tern recognition, and for this task, we
humans have a huge advantage.”
Computerized methods of galaxy
classification have been applied to gal-
axy surveys before, including the Sloan
Digital Sky Survey, but their galaxy clas-
sification is correct about only 80% of
the time, says Lintott. “That may not
sound too bad, but the missing 20%
are often those that are unusual and
thus contain the most information,”
he says. As Galaxy Zoo team members
have discovered, humans are adept at
spotting unusual details. For example,
volunteers noticed some small, round
green objects, now known as “peas,”
in the background of some Galaxy Zoo
images. “They turn out to be the sites of
the most efficient star formation in the
present-day universe, but it was only be-
cause our volunteers spotted them that
we knew to study them,” says Lintott.
A new incarnation of the project,
Galaxy Zoo 2, is now under way and includes a supernova search adjunct. A
veritable flood of data is expected. “In
“exoplanets are
greatly expanding
the planetary
menagerie,” says
Bruce fegley, Jr.
“they provide us
with all sorts of
oddball planets
that one could only
imagine in the past.”
the long run, I think we’ll need a combination of man and machine,” says
Lintott. “This sort of development is
going to be necessary to cope with the
next generation of sky surveys, which
should produce data rates of up to 30
terabytes per night.”
Further Reading
Governato, F., Brook, C., Mayer, L., Brooks, A.,
Rhee, G., Wadsley, J., Jonsson, P., Willman, B.,
Stinson, G., Quinn, T., Madau, P.
Bulgeless dwarf galaxies and dark matter
cores from supernova-driven outflows,
Nature 463, 7278, Jan. 14, 2010.
Benedict, G.F., McArthur, B.E., Forveille, T.,
Delfosse, X., Nelan, E., Butler, R.P., Spiesman,
W., Marcy, G., Goldman, B., Perrier, C.,
Jefferys, W.H., Mayor, M.
A mass for the extrasolar planet Gl 876b
determined from hubble Space Telescope
fine guidance sensor 3 astrometry and
high-precision radial velocities, The
Astrophysical Journal 581, 2, Dec. 20, 2002.
Schaefer, L. and Fegley, B.
Chemistry of silicate atmospheres
of evaporating super-earths, The
Astrophysical Journal 703, 2, June 2, 2009.
Raddick, M. J., Bracey, G., Gay, P.L.,
Lintott, C.J., Murray, P., Schawinski, K.,
Szalay, A.S., Vandenberg, J.
Galaxy Zoo: exploring the motivations of
citizen science volunteers, Astronomy
Education Review 9, 1, Feb. 18, 2010.
Astronomy Education Review Web site
http://aer.aip.org/aer/
based near boulder, co, Jeff Kanipe is a science writer
and author of The Cosmic Connection: How Astronomical
Events Impact Life on Earth.
© 2010 acm 0001-0782/10/0500 $10.00
Information;Retrieval
Data
Deluge
The U.s. Blue ribbon Task Force
on sustainable digital Preservation
and access released its final report,
Sustainable Economics for a
Digital Planet: Ensuring Long-term
Access to Digital Information, a
two-year effort that addressed
the economic challenges of
preserving the world’s ever-increasing amount of digital
information.
“The data deluge is
here,” said Fran Berman,
vice president for research
at rensselaer Polytechnic
institute and co-chair of the
task force. “ensuring that our
most valuable information
is available both today and
tomorrow is not just a matter
of finding sufficient funds. it’s
about creating a ‘data economy’
in which those who care,
those who will pay, and those
who preserve are working in
coordination.”
The Sustainable Economies
report focuses on the
economic aspects of digital
data preservation, such as how
stewards of valuable, digitally
based information can pay for
preservation over the longer
term. The report provides
principles and actions to
support long-term economic
sustainability; context-specific
recommendations tailored to
specific scenarios analyzed in
the report; and an agenda for
priority actions and next steps.
The report also concentrates
on four different scenarios,
each having ever-increasing
amounts of preservation-worthy
digital assets in which there
is a public interest in long-term preservation: scholarly
discourse, research data,
commercially owned cultural
content, such as digital movies
and music, and collectively
produced Web content, such
as blogs.
The report is available at
http://brtf.sdsc.edu/biblio/
BrTF_Final_report.pdf.