Source of UV is believed to be Earth albedo. Team is addressing question of whether any surfaces that did not see UV Earth albedo were contaminated. Team is addressing issue of whether deposition occurred in HST bay during 3.5 years in space or during the Servicing Mission. Additional samples from the High Speed Photometer exterior are being collected and are expected to help resolve these issues. Based on existing data, scientific instruments currently in HST appear to have minimal UV degradation.
Work is underway to assure future instruments are also minimally affected.