Disastrous debut

As the Athena I lifted off for its inaugural launch on 15 August 1995 from SLC-6 at Vandenberg, looking diminutive among the pad facilities built for much larger rockets, the programme was some nine months behind schedule.53 The vehicle was carrying the 150-kilogram GEMstar data-relay satellite for CTA Space Systems. It was to put the satellite into a polar orbit at an altitude of 680 kilometres, but at T+160 seconds it veered off course and the range safety officer destroyed it some 466 kilometres downrange, at an altitude of 148 kilometres.54^5 The tracking camera footage indicated that an anomalous pitch excursion started at T + 79 seconds. The investigation focused on the 500 telemetry channels from T + 65 seconds to the shutdown of the first stage at T+82 seconds. After the first stage had been jettisoned, the vehicle coasted (as planned) until the second stage ignited at T+150 seconds, but at T+121 seconds the 'coning' motion it had

The inaugural launch of the Athena I on 15 August 1995.

inherited dislodged the shroud 24 seconds before it was to have been shed. Although the second stage rapidly stabilised itself, the range safety officer destroyed it because it was not on the desired trajectory.56^7 In fact, two independent failures were found, either of which would have led to the loss of the vehicle.58 The thrust-vectoring system had induced the attitude excursion shortly prior to first stage shutdown. The inertial measurement unit had failed while coasting, at T+127 seconds. The Castor 120 was a modified missile booster with a carbon-epoxy casing and a 'submerged' flexible nozzle bearing that was driven through 5.5 degrees of deflection by cold-gas-pressurised hydraulic actuators to vector the thrust to steer the vehicle. The spent hydraulic fluid was vented, but it caused a fire that eroded the insulation of the cable with the signal from the sensors that measured the orientation of the nozzle, causing a short circuit that made the control system deflect the nozzle - which induced the attitude excursion. The thrust-vectoring system was similar to that of the Peacekeeper, except that the hydraulic fluid in that case had not been vented. The solution was to install a reservoir to collect the spent hydraulic fluid, thereby forming a closed system. The subsequent inertial measurement unit fault resulted from corona arcing in its power supply. Litton, the manufacturer, had tested the unsealed package for this phenomenon, but only to the 70,000-foot limit of its vacuum chamber. A test by Lockheed Martin for the investigation established that it began to arc at 86,000 feet! The solution was to apply a compound to protect the components that were susceptible to arcing, and to seal the package. It was an object lesson in favour of high-fidelity testing. The Castor 120 had been adopted for several other 'lightweight' launch vehicles, but this was its first flight. In light of this failure, the development of the Athena III was put on hold.59 Despite this setback, Lockheed Martin was confident that in June and July 1996 it would be able to launch the Lewis and Clark satellites that NASA had initially booked with OSC's Pegasus and later reassigned to the Athena, but this optimism was to prove unfounded.60,61,62 After two years of redevelopment, it was hoped to launch an Athena I in May 1997, but this was slipped to provide more time to analyse a test of the revised thrust-vectoring system.63 An Athena I from Vandenberg finally placed Lewis into orbit on 22 August 1997, but the satellite immediately malfunctioned, leading NASA initially to postpone and later to cancel the second satellite.

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