Large-scale, large-aperture space astronomy - Beyond the next generation

Over the next decade two major technologies will be introduced in spacebased astronomy: large aperture optics and spaceborne optical interferometry. In a recent study for NASA we proposed the use of space telescopes at each of Jupiter's Lagrange points L4 and L5 for cooperative, ultra-long-baseline astronomical observations. The system would be comprised of one or more platforms placed at each of these points, robotically maintained and designed for long life and extensibility. Synthesis imaging using separated telescopes across baselines at least 1000 times longer than any currently under consideration will be possible, and will utilize the natural orbital motion of spacecraft in halo orbits about the Lagrange points. Other science applications supported by this concept include long-baseline paral lactic astrometry, solar system exploration, and exosolar planet studies. The use of the Jovian Lagrange points as astronomical "sites" will provide measurement baselines across planetarysized scales of space and time but will also require very advanced space systems. Key technologies needed include: very large aperture lightweight space optics, precision metrology across extreme distances, and advanced space robotics. Although the requirements are stressing, all of the required technologies are currently under development, and many of the advances needed to support the concept will be developed as a result of currently planned or proposed programs.