The X-ray Telescope (XRT) of the Hinode mission provides an unprecedented combination of spatial and temporal resolution in solar coronal studies. The high sensitivity and broad dynamic range of XRT, coupled with the spacecraft’s onboard memory capacity and the planned downlink capability will permit a broad range of coronal studies over an\ud extended period of time, for targets ranging from quiet Sun to X-flares. This paper discusses in detail the design, calibration, and measured performance of the XRT instrument up to the focal plane. The CCD camera and data handling are discussed separately in a companion paper

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The paper analyzes the use of spaceborne spinning tethers for a reusable system to transfer payloads with a mass up to 4000 kg from low orbits to geostationary. The study indicates that a two-stage system is lighter than a single-stage tethered system with present day tether materials. A first stage in low orbit and a second stage in medium Earth orbit provide the required velocity increments for injecting the payload into geotransfer orbit with the final orbit circularization provided by the satellite kick motor.The orbits of the stages are resonant in order to provide periodic encounters and are optimized with the goal of reducing the overall system mass. The close-approach dynamics between the second stage and the payload released from the first stage is simulated to demonstrate the salient features of the rendezvous process. A total of 10 transfers over two years of operation without refueling is adopted for computing the propellant needed to reboost the stages. A preliminary analysis leads to the conclusion that a two-stage tethered system is more competitive, on a mass basis, than a chemical upper stage after two transfers.

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