9.25 The next section of track is one kilometer long, and provides fine adjustment of the payload velocity before release. The bucket is accelerated at 1 m/sec 2 , along a track accurate to within 25 microns. Residence time within this track section is 40 milliseconds, and upon exit the payload velocity must be accurate to within 1 mm/sec, measured by laser doppler which is also accurate to within 1 mm/sec. The final vernier adjustment takes place in the third track segment, also 1 kilometer long. The payload and bucket is allowed to drift through this track segment, being slightly decelerated by electromagnetic drag on the order of 1 cm/sec 2 . This track must have the same alignment tolerances as the previous section, and payload residence time is similarly short. At the end of this section, the payload is released from the bucket, and rises away from the Moon due to its high velocity, which must be accurate to within .1 mm/sec downrange and 1 mm/sec crossrange, in order to have a circular error probability of 100 meters at Lagrange point L2. The final 3 kilometers of track is the deceleration section, where the now-empty buckets are slowed at the rate of 1000 m/sec 2 . At the end of the straightaway, the buckets follow the 180 degree curve in the track, and return to the initial point along a 15 kilometer track parallel to the acceleration track. The return trip is made at the rate of 180 m/sec. The TLA is designed to throw the payload masses at the rate of 3 to 4 per second, and 75 buckets are on the track at any one time. Since acceleration is not provided by mass expulsion, but instead by electrical energy, the TLA offers the promise of being a highmass-flow-rate, low-cost launcher for the bulk of the material needed to construct the colony. However, it has several serious problem areas that will demand much closer analysis and testing before such a system may be baselined for an actual colony construction program. lunong these areas are fatigue failure in the buckets and track elements due to high amplitude, high frequency cyclic loading; maintenance of track accuracies on the order of microns over a length of 15 kilometers, complicated by 280 degree (Centigrade) variations in lunar surface temperatures with the lunar day-night cycle; and guidance and control adequate for the task of launching several
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