Which big telescope should the US build?

Science : For the past 5 years, Jerry Nelson and his colleagues at University of California have been working on plans for the Thirty Meter Telescope (TMT)—whose primary mirror will be a glinting mosaic of 492 hexagonal segments . Meanwhile, Roger Angel and his collaborators have set their sights on building the Giant Magellan Telescope (GMTO)—whose seven monolithic 8.4-meter mirrors, arranged like flower petals, will function as a primary mirror 24.5 meters in diameter. If the telescopes are built—TMT on Mauna Kea in Hawaii, GMT at Las Campanas—each will capture images up to 10 times sharper than today’s best ground-based telescopes.Both will shoot for the same scientific goals, looking at the first stars and galaxies , studying the formation of planets and stars , the growth of black holes , and probe the nature of dark matter and dark energy . And both will cost between $700 million and $1 billion.So far, neither telescope has come close to securing the total funding it needs, and if they are built with little federal support, the National Science Foundation would be hard pressed to provide the operating and maintenance costs.Given the funding challenges, some astronomers say the two sides should join forces to build one telescope to rival the European Southern Observatory ‘s proposed 42-meter segmented-mirror telescope, the European Extremely Large Telescope .