The ALEXIS Project: EUV Astrophysics on a Rollercoaster

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Session 113 -- HST, UIT and UV Instruments, UV Processing and Archives
Display presentation, Saturday, January 15, 9:30-6:45, Salons I/II Room (Crystal Gateway)

[113.10] The ALEXIS Project: EUV Astrophysics on a Rollercoaster

J. Bloch, B. Edwards, W. Priedhorsky, D. Roussel-Dupr\'{e}, B.W. Smith (LANL), O.H.W. Siegmund, T. Carone, S. Cully, T. Rodriguez-Bell, J. Warren, J. Vallerga (UCB-SSL)

The Array of Low Energy X-ray Imaging Sensors (ALEXIS) satellite is Los Alamos' first attempt at building and flying a low cost, rapid development, technology demonstration and scientific space mission. The ALEXIS satellite contains the two experiments: the ALEXIS telescope array, (which consists of six EUV/ultrasoft x-ray telescopes utilizing multilayer mirrors, each with a 33 degree field-of-view), and a VHF ionospheric experiment called Blackbeard. The spacecraft is controlled exclusively from a ground station located at Los Alamos.

The 250 lb. ALEXIS satellite was launched by a Pegasus booster into a 400 nautical mile, 70 degree inclination orbit on April 25, 1993. Images from a video system on the rocket seemed to indicate that ALEXIS had been severely damaged during launch with one of the 4 solar panels breaking away from its mounting. (It later turned out that the solar paddle was still attached to the spacecraft but only through some cable bundles.) Attempts at communicating with the satellite were unsuccessful until a surprised ground crew received a short transmission on on June 2. By mid July, ground station operators had regained full control of the satellite and scientific operations were initiated at that time. However, the damage to the spacecraft has rendered unusable the original scheme for obtaining spacecraft attitude solutions. In order to fully analyze the telescope data, a new algorithm implemenation to determine telescope pointing information is under development. Scientific results from data already in hand and those to be collected will not be possible until this task is complete.

This poster will summarize the current status of the ALEXIS project, its scientific goals, and the prospects for full mission recovery. This work was supported by the Department of Energy.

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