Friday, July 19, 2013By:
This week we held the NASA Goddard tour for the other SPS interns, and I made major progress on my project. Early in the week I decided to replace the hodgepodge of bits from the parts-without-a-home cabinet that had been simulating the central component of my model with a proper part. The actual component will be copper, but for my purposes, aluminum is easier to work, so I turned an aluminum rod to the right profile and added the holes for the suspension threads. As I disassembled the old model, it occurred to me I could also use actual Kevlar instead of the nylon stand-in as before. Once the bobbin was suspended in place with the Kevlar, and all the strings were tight, I tentatively prodded the bobbin to test its range of motion. It moved so little that if I closed my eyes, I couldn’t tell it wasn’t just bolted to the frame! Furthermore, my previous tests concluded the Kevlar has a working load of 31 newtons; when I measured the tension in my model, it came to 26 newtons. This is ideal because it means we are using the full available strength of the Kevlar to provide stiffness to the bobbin, and thus we are using the minimum cross-section for the stiffness. Reducing the cross-section is important because it improves the thermal isolation of the heated source and bobbin from the refrigerated base. I also realized that I would need to add an additional piece between the mounting plate and the waveguide it attaches to, which will provide another place to implement an innovation which the existing unit does not employ: placing an insulating layer of plastic between the metal parts. Now my design has two insulated breaks in addition to the Kevlar, which on its own is a 55% improvement over the existing design. I have yet to estimate the gain from the breaks, but it should be significant.
On Wednesday we brought the other ten interns to NASA Goddard for a tour and town hall with the Center Director and the Administrator of NASA. We looked around the visitor center, enjoyed a fun and science-heavy presentation with the Science on a Sphere visualization system, and then attended the Administrator’s talk. Afterwards, we met up with Dr. John Mather, Goddard’s own Nobel laureate and friend of SPS interns everywhere for a tour of the cleanroom, integration and vacuum test facilities where they’re building the James Webb Space Telescope and a number of other projects. He gave us an insider’s view of the progression of the project, delivered while we all had our noses glued to the second-story windows of the largest cleanroom in the world. Exploring the myriad spaces and running across while fleets of satellites or equipment returned from space (HST WFC2!) is an amazing way to discover how incredible our capabilities are when we put our minds to work.