instrumentation. The committee recommends an immediate start for the technology development needed to reduce the cost of construction and to develop the adaptive optics. The cost of technology development and construction is estimated to be about $400 million. It is assumed that half of these costs and half of the operations costs will be borne by private and/or international partners; the cost estimates in Tables 1.1 and 1.2 are therefore based on a federal capital cost of $200 million. Open access to GSMT by the U.S. astronomical community should be directly proportional to the investment by the NSF.

Constellation-X Observatory. The premier instrument to probe the formation and evolution of black holes—both stellar black holes in our galaxy and supermassive black holes in the nuclei of other galaxies—Constellation-X will also measure the physical conditions in the first clusters of galaxies, study quasars at high redshift, contribute to nuclear physics by measuring the radii of neutron stars, and trace the formation of the chemical elements. To achieve the sensitivity needed to meet these goals, Constellation-X will consist of four x-ray telescopes in separate spacecraft. Each telescope will have high spectral resolution over a broad energy range, ~ 0.25 to 40 keV. Constellation-X has been under active study for more than 5 years, and the technology issues are well in hand for a start in the middle of the decade.

Expanded Very Large Array. The VLA is currently the premier centimeter-wavelength radio telescope in the world, despite being based on the technology of 20 to 30 years ago. Replacing key components with modern technology will provide an order-of-magnitude increase in sensitivity with unprecedented image quality and a 1,000-fold increase in spectroscopic capability, all at a fraction of the cost of constructing a new facility. The addition of eight new antennas will provide an order-of-magnitude increase in angular resolution, making it comparable to that of ALMA and NGST. The EVLA will be a powerful instrument for studying the formation of protoplanetary disks and stars, as well as the formation and evolution of the first galaxies.

Large-aperture Synoptic Survey Telescope. By surveying the visible sky every week to a much fainter level than can be achieved with existing optical surveys, LSST will open a new frontier in addressing time-variable phenomena in astronomy. This 6.5-m-class optical telescope will detect 90 percent of the near-Earth objects larger than 300 m in diameter within