launch vehicles for new astronomy missions. The committee recognizes that some important missions, such as the ASTRO telescope, the HST second-generation instruments, and the High-Energy Transient Experiment (HETE), are dependent on the Shuttle for either launching or servicing. While this report was in its final stages of preparation, ASTRO had a successful nine-day mission producing x-ray, extreme-UV, and UV spectra; UV polarization measurements; and UV images of a wide range of astronomical objects. A preliminary inspection of those data suggests that many discoveries will follow from the full analysis of the dataset.
An imaginative, innovative program of technology development is a prerequisite for the missions of the next century. Current programs such as the NICMOS instrument for HST and the entire SIRTF mission benefited from NASA's investment in advanced detector technologies. AXAF benefited from the application of bolometers (developed in infrared astronomy) and charge-coupled devices (CCDs; developed in optical astronomy) to x-ray astronomy. Future submillimeter and far-infrared telescopes as large as 10 m may use technology being developed by NASA for lightweight optics with surface accuracies around 1 µm.
Technology development set in motion long before critical mission milestones is cost-effective. The committee concurs with the strong support given by the Committee on Space Policy (the “Stever Report ”; NAS-NAE, 1988) for vigorous technology development across NASA's entire space astronomy program. Chapter 1 recommends new technology initiatives in support of a generation of telescopes beyond the Great Observatories. As discussed in Chapter 6, “Astronomy from the Moon,” the committee strongly favors phased technology-development efforts that progress from laboratory test beds, to modest instruments and precursor missions with significant scientific goals, and finally, to large sophisticated observatories.
Theory provides the paradigms within which observations are planned and interpreted, and it must also respond to unexpected observational discoveries. A strong theoretical community also makes motivating, and often surprising, predictions about what might be seen. This predictive capability is often crucial in designing new instruments: for example, the characteristics of the Cosmic Background Imager recommended in Chapter 1 are determined by theoretical calculations of fluctuations in the microwave background, and the proposed gamma-ray-spectroscopy Explorer mission is designed to detect theoretically predicted lines from supernovae in other galaxies. Solar neutrino experiments