Assembly of the first NuSTAR optics module (FM0). NuSTAR flies two optics units, each with 133 layers of grazing incidence optics. Using epoxy and graphite spacers, the layers were built up, approximately one layer per day, on a CNC (computed numerically controlled) lathe assembly machine at Columbia Universitys Nevis Laboratory. The inner 66 layers are comprised of 6 segments with 12 pieces of glass per layer, while the outer 67 layers are comprised of 12 segments with 24 pieces of glass per layer. Each completed unit is 47.2 cm (18.6 inches) long, 19.1 (7.5 inches) cm in diameter and weighs 31 kg (69 pounds). This picture, taken on 2010 May 16, shows 82 layers. The 100th layer was laid on June 9th, and FM0 was completed on 2010 August 5.