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Broadcasters and telecommunications companies now depend so heavily on
satellites that they keep spare ones on the ground or parked in orbit as
back-ups. But different firms use different satellites and frequencies, so one
firm鈥檚 spare is no use to another. Now the Californian company AssureSat Inc
wants to offer a universal replacement (WO 01/3310) by launching a satellite
with transmitters that can be set to work on any frequency. While conventional
satellites only have enough spare fuel to keep them steady in orbit, or to move
very slowly, the new spare is designed for at least four fast moves into
different orbits. So it can replace a failed satellite within days.