Abstract. One approach to beamed energy propulsion uses a solid heat exchanger to absorb energy from a distant source and transfer it to a working fluid. Systems of this type can be designed using either microwave or laser sources. In general, microwave sources have been expected to be less expensive than lasers for a given power, but to be more limited in range and/or energy density. With the development of high power millimeter-wave sources and low-cost diode laser arrays, both assumptions are open to question. In this paper, we compare current and projected microwave and laser source technologies for a 100-kilogram-class ground-to-orbit launch system and identify key issues affecting the system-level trade between the two approaches.
We describe the design and construction of a new search for supernovae, based on the use of current computer and detector technology. This search uses a computer-controlled telescope and charge coupled device (CCD) detector to collect images of hundreds of galaxies per night of observation, and a dedicated minicomputer to process these images in real time. The search system has a detection threshold of 17th visual magnitude, discovered its first supernova on 18 May 1986, and at this writing has found three additional supernovae. The system currently is being upgraded with an improved detector and a more powerful computer. At full speed and sensitivity, the system will be able to search 2500 galaxies per night with a limiting magnitude of 19 or fainter.
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