Last October 16th was a big day for the Chinese astronomical community. Nearly 200 kilometers northeast of Beijing, at the Xinglong Observing Station of the National Astronomical Observatories of China (NAOC), leaders of the Chinese Academy of Sciences held a ceremony to celebrate the founding of something new and unique: LAMOST, the Large Sky Area Multi-Object Fiber Spectroscopic Telescope.

The LAMOST observatory buildings, aligned on the meridian.

Renjiang Xie

LAMOST is a survey instrument like no other. It was designed for maximum efficiency for one vital purpose: taking spectra of many millions of individually selected, very faint objects. Its designers had to find the best balance for this purpose between aperture, field of view, and many other factors.

The surface shape of LAMOST's 4-meter segmented primary mirror will be actively controlled, allowing the segments to be thin and light.

Renjiang Xie

The instrument's segmented thin mirror, seen above, has an aperture of 4 meters (160 inches), with the segments controlled by active-optics techniques. This aperture will enable LAMOST to obtain spectra of objects as faint as magnitude 20.5 magnitude in a 1.5-hour exposure.

LAMOST's fiber-optic image detector, seen from behind.

Renjiang Xie

That's not remarkable by today's standards — LAMOST's real power comes from its extraordinary field of view. The working focal plane is an immense 1.75 meters in diameter, corresponding to a 5° field on the sky.

As many as 4,000 optical fibers can be automatically positioned onto selected objects in the field, with each fiber feeding light to a spectral analyzer. As a result, the telescope has the highest spectrum-acquiring rate of any in the world.

Being a survey telescope, LAMOST needs to look only near the sky's north-south meridian to catch, in time, a large fraction of the celestial sphere passing across. As a result the telescope occupies special domes that look less like a traditional observatory than like some spaceport from a sci-fi movie.

“LAMOST’s equipment was completely installed by the end of August after four years’ of building," says Yongheng Zhao, the general manager of the project. "We are now in the stage of doing test observations and refining performance, which may take two years.”

With a diameter of some 500 meters (1,600 feet), FAST will be the world's largest radio dish. Click image for cross-section diagram.

NAOC / Chinese Academy of Sciences

FAST Radio Dish

Meanwhile, the ambitious Five hundred-meter Aperture Spherical radio Telescope (FAST) has been allocated government funds of nearly 700 million RMB yuan (nearly US$100 million). FAST will be built in a limestone karst valley in a sparsely populated mountanous area of Guizhou province about 1,800 kilometers southwest of Beijing.

FAST's dish will be composed of about 2,000 active panels, each 15 meters square, that can reshape into a paraboloidal surface for pointing in any direction as much as 40° from the zenith. Construction has begun and should be finished in 2014. FAST is expected to be 10 times as sensitive as the 300-meter dish radio telescope near Arecibo, Puerto Rico, currently the world's largest.
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In the game of astronomy, size matters. To get crisp, clear images of things billions of light years away, a telescope needs to be big.

"The bigger the better," says astronomer Harley Thronson, who leads advanced concept studies in astronomy at the Goddard Space Flight Center. And he thinks "NASA's new Ares V rocket is going to completely change the rules of the game."

Ares V is the rocket that will deliver NASA's next manned lunar lander to the moon as well as all the cargo needed for a lunar base. Its roomy shroud could hold about eight school buses, and the rocket will pack enough power to boost almost 180,000 kg (396,000 lbs -- about 16 or 17 school buses) into low Earth orbit. Ares V can haul six times more mass and three times the volume the space shuttle can.

"Imagine the kind of telescope a rocket like that could launch," says Thronson. "It could revolutionize astronomy."

Right: The roomy shroud of the Ares V could hold about eight school buses. Credit: NASA

Optical engineer Phil Stahl of the Marshall Space Flight Center offers this example: "Ares V could carry an 8-meter diameter monolithic telescope, something that we already have the technology to build. The risk would be relatively low, and there are some big cost advantages in not having to cram a large telescope into a smaller launcher."

For comparison, he points out that Hubble is only 2.4 meters wide.

An 8-meter monolithic telescope would see things more than three times as sharply as Hubble can. More importantly, in the same amount of observing time, the larger mirror would see objects that are about 11 times fainter than Hubble sees because the 8-meter telescope has 11 times the light collecting area.

But Ares V can go yet bigger. It could transport a huge segmented telescope – one with several separate mirror panels that are folded up for transport like the James Webb Space Telescope--but three times the size!

The Space Telescope Science Institute's Marc Postman has been planning a 16-meter segmented optical/ultraviolet telescope called ATLAST, short for Advanced Technology Large-Aperture Space Telescope. The science from an aperture its size would be spectacular.

"ATLAST would be nearly 2000 times more sensitive than the Hubble Telescope and would provide images about seven times sharper than either Hubble or James Webb," says Postman. "It could help us find the long sought answer to a very compelling question -- 'Is there life elsewhere in the galaxy?'"

ATLAST's superior sensitivity would allow astronomers to hugely increase their sample size of stars for observation. Then, discovery of planets hospitable to life could be just around the corner!

"With our space-based telescope, we could obtain the spectrum of Earth-mass planets orbiting a huge number of nearby [60 - 70 light years from Earth] stars," says Postman. "We could detect any oxygen and water in the planets' spectral signatures. ATLAST could also precisely determine the birth dates of stars in nearby galaxies, giving us an accurate description of how galaxies assemble their stars."

This telescope could also probe the link between galaxies and black holes. Scientists know that almost all modern galaxies have supermassive black holes in their centers. "There must be a fundamental relationship between the formation of supermassive black holes and the formation of galaxies," explains Postman, "but we don't understand the nature of that relationship. Do black holes form first and act as seeds for the growth of galaxies around them? Or do galaxies form first and serve as incubators for supermassive black holes? A large UV/optical telescope could answer this question: If our telescope finds ancient galaxies that do not have supermassive black holes in their centers, it will mean galaxies can exist without them."

Dan Lester of the University of Texas at Austin envisions another 16-meter telescope, this one for detecting far-infrared wavelengths.

"The far-infrared telescope is quite different from, and quite complementary to, the optical telescopes of Stahl and Postman," says Lester. "In the far-infrared part of the spectrum, we generally aren't looking at starlight itself, but at the glow of warm dust and gas that surrounds the stars. In the very early stages of star formation, the proto-star is surrounded by layers of dust that visible light can't penetrate. Our telescope will allow us to see down into the innards of these giant dense clouds that are forming stars deep inside."

Observations in the far-infrared are especially challenging. These long wavelengths are hundreds of times larger than visible light, so it's hard to get a clear picture. "A very big telescope is necessary for good clarity at IR wavelengths," notes Lester.


Like the telescopes of Stahl and Postman, Lester's Single Aperture Far-Infrared Telescope ('SAFIR' for short), comes in two flavors for the Ares V: an 8-meter monolithic version and a 16-meter segmented version. Lester realized that, with an Ares V, he could launch an 8-meter telescope that didn't need complicated folding and unfolding. "But on the other hand, if we don't mind adding the complexity and cost of folding and still use an Ares V, we could launch a really mammoth telescope," says Lester.

In addition to all the above telescopes, Ares V could boost an 8-meter-class X-ray telescope into space. NASA's highly-successful Chandra X-ray Observatory has a 1 meter diameter mirror, so just imagine what an 8-meter Chandra might reveal!

Roger Brissenden of the Chandra X-ray Center is excited about the possibility of a future 8-meter-class X-ray telescope called Gen-X.

"Gen-X would be an extraordinarily powerful X-ray observatory that could open up new frontiers in astrophysics," he says. "This telescope will observe the very first black holes, stars and galaxies, born just a few hundred million years after the Big Bang, and help us determine how these evolve with time. Right now, the study of the young universe is almost purely in the realm of theory, but with Gen-X's extreme sensitivity (more than 1000 times that of Chandra) these early objects would be revealed."

Indeed, Ares V flings shutters open wide on our view of the cosmos. It shakes off the shackles of mass and volume constraints from science missions and sweeps us into deep space to view "...a hundred things/ You have not dreamed of."

"We could get incredible astronomy from this big rocket," says Thronson, a professional dreamer. "I can't wait." Read more!

International Year of Astronomy 2009

by the Editors of Sky & Telescope

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IAU

New Year's Day marks the beginning of what will undoubtedly be more than 12 months of celebrating astronomy. The International Astronomical Union (IAU) has designated 2009 as the International Year of Astronomy (IYA2009) to commemorate the 400th anniversary of Galileo's first celestial observations using a telescope. IYA2009 has been endorsed by the United Nations Educational, Scientific, and Cultural Organization (UNESCO) and the U.N. General Assembly.

Much of IYA2009's activities revolve around 11 Cornerstone Projects. While some initiatives are already underway, others still remain under development. The links to their individual sites are listed below. You'll find even more information at U.S. National Node. If you don't live in the U.S., see IYA2009's main site for a link to your country's node.

100 Hours of Astronomy: 400 Years in the Making
The Galileoscope: Millions of People Looking at the Sky
Cosmic Diary: The Life of an Astronomer
Portal to the Universe: A One-stop Universe of News
She Is an Astronomer: Breaking Down Misconceptions
Dark Skies Awareness: Seeing in the Dark
Astronomy and World Heritage: Universal Treasures
Galileo Teacher Training Program: Teaching the Teachers
Universe Awareness: One Place in the Cosmos
From Earth to the Universe: The Beauty of Science
Developing Astronomy Globally: Astronomy for All

And while it's not an official Cornerstone Project, the amateur-led The Earth at Night project is another important element for IYA2009.

Make room on your iPod for the 365 Days of Astronomy Podcast. There's a fact-filled, fun episode every day.

We're happy to provide the article "The Year to Celebrate Astronomy" by organizers Catherine Cesarsky, Pedro Russo, and Lars Lindberg Christensen from the January 2009 issue of Sky & Telescope as a free download in PDF format. (To display PDF files, download and install the free Adobe Reader.)

Be sure to check out the official movie of IYA2009: Eyes on the Skies produced by the European Space Agency and European Southern Observatory.

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