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ALEXIS [AeroAstro]

ALEXIS (Array of Low-Energy X-Ray Imaging Sensors) was a small satellite which carried an ultrasoft X-ray telescope array for astronomy studies and a high-speed VHF receiver/digitizer (Blackbeard) for studying the effect of lightning and electromagnetic impulse from exploding nuclear devices on the ionospheric transmission.

The spacecraft is spin-stabilized with a period of 2 rpm and the axis points sunward. The Blackbeard experiment operated successfully. The astronomy data needed a full pointing and aspect solution in order to be interpreted.

It was launched on a Pegasus booster from the wing of a B-52, but a solar paddle was damaged during the flight. No contact with the satellite was established until three months after launch. New attitude control techniques were developed and the satellite was brought under control. The telemetry system performed nominally.

ALEXIS operated successfully for 12 years and it exceeded all expectations in spite of the serious solar array incident. It was decommissioned on 29 April 2005.

Nation: USA
Type / Application: Experimental
Operator: USAF STP (Space Test Program)
Contractors: AeroAstro
Equipment: Ultrasoft X-ray monitor (6 compact normal-incidence telescopes, 66, 71, and 93 eV), Blackbeard
Configuration: Spin stabilized, 4 solar panels
Propulsion: ?
Power: 4 deployable fixed solar arrays, batteries
Lifetime: 1 year (design); 12 years (reached=
Mass: 115 kg
Orbit: 741 km × 746 km, 69.8
Satellite COSPAR Date LS Launch Vehicle Remarks
ALEXIS (P89-1B) 1993-026A 25.04.1993 Ed, B-52, RW04/22 Pegasus with Orbcomm-CDS 2


Further STP missions: