Flight Anomaly Investigation Closer look at the flight video showed slight shadow movement of ISS #2 (MAA Lightband) one frame  before ISS #1 movement was noticed. T he theory was that when ISS #1 separated it pushed the Avionics  Deck back against the MAA Cylinder causing the halves of ISS #2 to temporarily contact. Eventually it  was believed that one of the roller separation springs on the Avionics Deck re-contacted MAA. This  imparted a torque on the Avionics Deck, but since the spring force’s line of action bisects the center of  MAA, the MAA/Cylinder received very little torque. This explain s why the Avionics Deck spun-up and the  MAA Cylinder did not. Several ideas were also speculated in the days imme diately following. Perhaps the MAA jammed on the  spin-up snubber during ejection. MAA may have seized against the Avionics Deck snubbers when it attempted to rotate out. The o-ring stiction may have been so high that the springs could not overcome  the force. The Lightband separation systems may not have separated cleanly.  Using dynamic simulation software, Matthew Eby of The Aerospace Corporation was able to model many  variations of the separation event. This included simultaneous ISS separation and staggers of varying  delay. He also adjusted the o-ring preload. In the end, the analysis confirmed the initial assumptions that  ISS #2 separated 0.01 to 0.02 second before ISS #1. The halves of ISS #2 temporarily re-contacted and a roller separation spring re-contacted MAA, imparting the observed rotation on the Avionics Deck.  Since FCal ejected quickly it received far less scrutiny in the post flight investigation, however its anomaly  is just as important to understand. FCal contained two antennas secured in a groove around its equator.  These were to deploy several seconds after the magnetic inhibit was removed and the satellite ejected.  These wires were noticed during assembly to slightly bulge out past the spherical surface  near their root  and initial bend into the groove. Also, the upper rings of the ISS Lightbands attached to the ends of the  cylinders. The socket head cap screws used to attach them were secured with lock-wire. Great care was  taken to keep the lock-wire close to the ring and out of FCal’s deployment path and staked to remain in  place. It can only be assumed that one or a combination of the fo llowing occurred. First, FCal may have  come off the inhibit during flight, causing FCal to power on and release the antennae. This scenario is  unlikely since two snubbers pen etrate the surface of the satell ite. Second, the antennae could have  broken free or come loose, bulging out of the groove. The antennae could then have temporarily snagged  on the lock wire of the upper ring. Lastly, a section of lock wire may have broke and stuck out into the  deployment path of FCal, forcing it to bend out of the way as FCal passed by.   History Leading to the Anomaly  Late in the design phase of the ICU it was determined that the ICU Lid lacked the required stiffness to  prevent the ICU from contacting CAPE’s inner wall during launc h. The designers lacked the necessary  software to maximize the part’s specific stiffnes s. Thus as time was critical and the mass margin was high  a design was made to simply “throw mass at the problem” to increase stiffness of the ICU Lid. The impact  of this change to other aspects of the design was not fully understood until later in the test phase.  The unique design of the ICU makes it nearly impossible to test the flight separation event. The only  possibility was to test on a KC-135 “vomit comet”. However the logistics and safety concerns of deploying  and then restraining five separate bodies with a combined mass of 185 kg on a plane make it a difficult  task. The program budget and schedule also did not allow for this. At the time, detailed dynamic analysis  software was not available to the ICU designers. Therefore, an inexpensive 2D separation test was  designed to simulate the flight event as closely as possible. The test consisted of 2D steel mock-ups of the 5 separable ICU components mounted on near frictionless planar air bearings (Figure 9). The masses  150