Next Generation Space Telescope and future missions

The infrared band (1 μm-1 mm), largely unobservable from the ground, is one of the outstanding frontiers of space astronomy. Rapid progress in detector technology, lightweight cold mirrors, deep space missions, and new concepts in instrumentation continues to open this frontier. Planned missions include the SIRTF, SOFIA, NGST, FIRST, Planck, and ASTRO-F. Proposed missions include the Japanese H II/L2 mission, several forms of imaging interferometers to search for planets and resolve detailed structures, and a far IR interferometer called SPECS. We review the scientific objectives and technical progress that enable each of these missions, and discuss the ultimate limits that might be achieved. The prospect of achieving HST-like sensitivity and angular resolution over the entire range of infrared wavelengths is real and scientifically exciting. The technical innovation required is difficult but not impossible. Continuing revolutions in manufacturing and engineering processes can enable scientific breakthroughs of immense importance.