This first cut in one of these frames marked the spot where the upper sill beam of the telescope cavity will be placed, running along the top edge of the cavity opening. All the beams along the perimeter of the outer cavity need to be pre-installed as a way of tying the structure together along the edge of the opening. Once that's done, the cut in the aircraft's exterior, or fuselage, can begin. Cutting of the exterior fuselage skin, which promises to be a unique milestone, is scheduled for the end of this year.
Gratings are an integral part of many astronomy instruments.
Just as prisms spread wavelengths apart by bending them, with light passing right through the prism, gratings spread different wavelengths apart by diffraction and reflection, with the light waves typically bouncing off the grating surface. The great thing about gratings is that the best of them can separate out, or disperse, wavelengths so far that scientists can get very precise information about what's going on in any particular wavelength region. That's where Hyperfine comes in. The former is now being tested and is scheduled for delivery soon, and the latter was delivered last year. They're creating the outer skin of the section of the aircraft's fuselage around the exterior cuts for the telescope cavity.