Next-generation ground telescopes received priority designation from a
long-awaited report by the
National Academy of Sciences. They would join
a host of existing ground telescopes and smaller space telescopes
already peering at supernovas,
galaxies and other distant objects in the
starry skies.
Three planned
optical telescopes in the 98-foot (30-meter) range would
house some of the biggest mirrors yet for collecting light from distant
cosmic objects. And proposed
radio telescope would dwarf predecessors by
using many antenna stations to create a total collecting area of a
square kilometer, or 0.4 square miles.
Here's a look at ten of the present and future giants among ground-based
telescopes that provide scientists a glimpse of the past universe
through time and space.
10. Large Synoptic Survey Telescope (LSST)
A new ground-based observatory that would scan the entire available sky
every three nights from Chile could see first light by 2014. The
$465-million Large Synoptic
Survey Telescope would give astronomers
their best view ever of how billions of faint starry-sky objects
change
over time. It could also tackle questions relating to the nature of dark
energy, and perhaps track space rocks that might collide with Earth in
the future.
The
optical telescope would image each region of the sky 1,000 times
over 10 years with an almost 28-foot (8.4-meter) aperture. It
represented a top priority among ground projects slated for the next 10
years in the
Astro2010 Decadal Survey by the National Academy of Sciences.
9. South African Large Telescope (SALT)
This 30-foot (9.2-meter) telescope represents the largest ground-based
optical instrument in the southern hemisphere, and concentrates on
spectroscopic surveys. A main mirror consists of 91 hexagonal mirrors
that join together to form the larger hexagonal primary —not unlike the
Hobby-Eberly Telescope (HET) in Fort Davis, Texas.
Like HET, SALT also has a fixed-angle design that has complicated
observations since it began operation in 2005. But the instrument can
still view about 70 percent of the sky observable from Sutherland, South
Africa.
8. Keck I and II Telescopes
The
twin 33-foot (10-meter) telescopes at the W. M. Keck Observatory
represent the second largest optical telescopes on Earth, located close
to the summit of Hawaii's Mauna Kea. Each instrument's main mirror
consists of 36 hexagonal segments that work together.
Keck I became operational in 1993, followed just a few years later by
Keck II in 1996. The combined observatory has helped astronomers examine
events such as
last year's impact
on Jupiter. It also deployed the first laser guide star adaptive optics
system on a large telescope in 2004, which creates an artificial star
spot as a reference point to correct for atmospheric distortions when
viewing the sky.
7. Gran Telescopio Canarias (GTC)
A 34-foot (10.4-meter) telescope located on La Palma of Spain's Canary
Islands seized the top spot as the world's biggest ground-based optical
telescope in 2009. A main mirror that consists of 36 hexagonal segments
contains some of the smoothest surfaces ever made.
The telescope also has several support instruments such as CanariCam, a
camera capable of examining mid-range infrared light emitted by stars
and planets. The CanariCam also has the unique ability to figure out the
direction of polarized light and use coronagraphy to block out bright
starlight and make fainter planets more visible.
6. Aricebo Observatory
One of the world's most recognizable ground-based telescopes has resided
as a huge 1000-foot (305-meter) radio reflector dish near Aricebo,
Puerto Rico since 1963. The Aricebo radio telescope still represents the
largest single-aperture telescope ever constructed, with its spherical
reflector consisting of 40,000 aluminum panels each 3 feet by 6 feet.
The huge reflector helps make Aricebo an incredibly sensitive radio
telescope, capable of homing in on a faint radio source within just
several minutes of observation. Such radio sources include distant
quasars and galaxies that emit radio waves which only reach Earth 100
million years later.
5. Atacama Large Millimeter/submillimeter Array (ALMA)
One of the largest ground-based astronomy tools comes in the form of the
39-foot (12-meter) radio antennas that will total 66 by 2012, to make
up ALMA's main
array. Each antenna weighs more than 100 tons each and
requires huge crawler vehicles to move it to Chile's Chajnantor plain at
an altitude 3 miles up. This will ultimately help make ALMA the largest
and most sensitive radio telescope ever, at least until a new contender
emerges.
The antenna array can also undergo different configurations by moving
individual antennas around. A compact configuration would place all the
antennas within an area less than 1,000 feet across, or within an
extended configuration with a maximum distance of separation between the
antennas of almost 10 miles. This will allow the array to study
everything from the cosmic "dark ages" billions of years ago to the
processes of star and planet
formation.
4. Giant Magellan Telescope (GMT)
One of the next ground-based optical telescopes will take the form of
the $1.1-billion Giant Magellan Telescope with an 80-foot (24.5-meter)
main
mirror that consists of seven segments. One 8.4-meter segment would
sit in the middle, surrounded by the other six segments that have a
unique curved shape not unlike that of a
potato chip.
The large main mirror would dwarf the current generation of 26 to
33-foot (8 to 10-meter) telescopes and produce images about 10 times
sharper than the Hubble Space Telescope. If fully funded, the telescope
could find a home at the Las Campanas Observatory in La Serena, Chile
and begin full operations by 2024.
3. Thirty Meter Telescope (TMT)
Another of the next-gen contenders for biggest optical telescope on
Earth is the Thirty Meter Telescope. The $1.4-billion telescope's
98-foot (30-meter) aperture would allow for more than 9 times the
collecting area of the largest optical telescopes such as the Keck
Telescopes, and could provide 12 times sharper resolution than the
Hubble Space Telescope.
But TMT and other extremely large optical telescopes would not replace
space telescopes. Hubble's successor, NASA's James Webb Space Telescope,
would find targets for Earth-based giants such as TMT to study in more
detail. The Thirty Meter Telescope is slated to join the Keck Telescopes
and other instruments on Mauna Kea in Hawaii and commence full
operations by 2025-2030.
2. Square Kilometer Array (SKA)
A follow-up to radio telescopes such as ALMA is a telescope capable of
collecting data over one square kilometer. The aptly-named Square
Kilometer Array would become the clear king of radio telescopes, with 50
times the sensitivity of any radio telescope ever built. Such power
could examine signals from the younger universe of 12 billion years ago.
Current plans call for either 30 stations with a collecting area of 656
feet (200 meters) each, or 150 stations each equivalent to a 295-foot
(90-meter) telescope. South Africa and Australia have already begun
jostling in a bid to play host to the $2 billion behemoth, scheduled for
completion around 2020. It co-ranked as the highest priority project in
the European Astronet Decadal Survey, along with the European Extremely
Large Telescope.
1. European Extremely Large Telescope (E-ELT)
No ground-based optical telescope contender can currently match the design proposal for the
European Extremely Large Telescope.
Its 138-foot (42-meter) mirror would put it easily beyond the Thirty
Meter Telescope and Giant Magellan Telescope, with a length reaching
almost half a soccer field. Five mirrors consisting of almost 1,000
hexagonal segments would make up the primary mirror, and give
Earth-bound astronomers the sharpest view ever of the cosmos in the
visual-light spectrum.
Cerro Armazones in Chile will be the future home of the world's largest
optical telescope. The $1.3-billion E-ELT would see first light around
the same time as its smaller next-gen cousins in 2018.
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