SRC-555

Satellite Power System: Concept Development and Evaluation Program, Volume VII - Space Transportation; NASA TM-58238; November 1981

Commissioned by National Aeronautics and Space Administration; in-house report, no contract number printed. Who paid for a study is recorded because it bears on how its conclusions should be read, not because it makes them wrong.

Published claims resting on this source

• CLM-1023 The programme's last word on its rockets describes a launcher of about 11,000 tonnes at liftoff flying about once a day, gives fleet sizes and turnaround times, deliberately gives no costs, and ends by recommending a launcher with a quarter to a third of the payload.
• CLM-1025 In 1980 the people building the case set themselves a goal of thirty dollars a kilogram to low orbit, hoped for fifteen later, and said in the same breath that the programme's schedule could not be met.
• CLM-1026 The electric ferry takes half a year to climb to geostationary orbit but burns about an eighth of a kilogram of argon for every kilogram it carries; a chemical stage would burn two kilograms of propellant per kilogram and need almost three hundred trips per satellite. That ratio, not speed, is why the programme chose electric.
• CLM-1027 Getting a crew from low orbit up to the construction site took half a day and a stage the size of a small airliner, refuelled at the top with fuel the slow electric ferry had carried up. Counted fully, moving one worker's year of labour into orbit cost about a million 1977 dollars.
• CLM-1029 In 1980 the programme's own accounting had rockets at roughly one dollar in four of a satellite's cost and nearly one in two of the money needed to develop the system, and it noted that the whole programme through the first satellite cost about what NASA had spent from its founding through Apollo.
• CLM-1031 A launcher a third the size of the reference one would cost about a fifth more per kilogram to fly and need four launches a day instead of one, but would save five billion dollars up front and add only three per cent to the cost of each satellite. By 1981 everyone involved wanted it.
• CLM-1033 At the higher of NASA's two peak figures, the launches would have needed about 6 per cent of US daily hydrogen output and 30 per cent of its oxygen, and making the hydrogen by splitting water would have consumed about half the output of one of the satellites being launched. NASA's own report gives two different figures for how much fuel that is.
• CLM-1034 The programme's transportation workshop said the schedule was probably unrealistic, and the programme's cost reviewer said the launcher fleet was too small for it: about one launch a day on a five-and-a-half-day turnaround with no reserve vehicles, and a fleet of slow electric ferries with no slack for accidents.

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