UVVis Design and Integration at CASA

Before shipping out to APL (Applied Physics Laboratory) to be integrated with the rest of the BRRISON payload, the UVVis bench and everything DayStar related had to get put together at Boulder’s own CASA (Center for Astrophysics and Space Astronomy).

Just 10 weeks after being brought onto the project, integration of DayStar designed hardware and software into the optical bench began. Talk about a sprint, this was one of the fastest integration deadlines anyone on the UVVis team had ever seen. Half of the physical components were still raw blocks of aluminum/titanium, waiting to be manufactured when moved to CASA. The electronics system was, shall we say, a little immature to begin powering the entire payload (as many defunct motherboards can attest to). The software was barely in a stage where it could demonstrate functionality, let alone perform mission-like tasks. But the schedule reigns supreme! So starting on June 1st, everything started to come together.

Lets step back first. Before the DayStar team was alerted to our roll in the project, the rest of the UVVis engineers and scientists had been working for a few short months on everything not involving electrons. As usual, the insane schedule made designing a complex optical path a formidable challenge. Due to the short time line, a lot of design decisions were driven by part availability. In a field where most mirrors and optical components you might require will take months to be fabricated, polished, and coated, almost everything they had to work with had to be COTS. Luckily, we were not a part of this process, and it was all finished by the time we were brought on board. Here are some of the early plans for the bench (early being February, just 3 months before the whole bench had to be delivered).

Over the next month, mechanical and optical designs were fleshed out by the highly skilled senior mechanical engineers at SwRI, CASA, and HPD.  The guys at HPD did a remarkable job with the Filter Wheel and Fold Mirror mechanisms, as well as all of the other supporting hardware.

About this time, the DayStar crew was brought in. Our first team briefing on our rolls re-spawned the unofficial slogan of the mission “You want us to do what?” Our original thought was that we would be a part of a bigger team of software/electronics experts and would have the manageable roll of image acquisition in a pre-defined system. Not so! It turned out we would be responsible for everything to do with the flight and ground software, payload electronics, computer hardware, and the bench’s sole Project-Level Requirement: proof-of-concept of a Fine-Steering-Mirror control system. In essence, we were given optical bench with mirrors, motors, and cameras in place, and tasked with making a mission out of it. Kevin, Nick, and Zach were still students at the time. Kevin and Zach with another job already, and Jed was supposed to be working full time on a different SwRI project. So when we realized the scope of our involvement, it was a rude awakening. But we were excited to get started! At the time, we were participating in the 2013 IEEE conference in Big Sky, MT. Say goodbye to powder days, hello to huge design decisions made in the resort dining area.

Between the commandeered dinner table and the drive home, we became fully functioning members of the team. Jed started modeling the Fine-Steering-Mirror control law, Nick began the design and component choices for the power system, Zach made models of a pressure vessel to house the yet undefined computer and power systems, and Kevin took the stripped-down DayStar CDH code base and started designing the software architecture. We had a long way to go, and everything was just starting to ramp up , but we were rolling!

We had a little over two months to then procure all electronics and hardware and get a functional system in place for integration at CASA. By that time, Nick had round one of the electronics stack complete (AMAZING considering he did the whole design himself), and was put in charge of defining the wiring for the whole system. Kevin and Zach had written about 30K of the 60K lines of code that would comprise the flight system and had worked out (most of the) kinks with the cameras and electronics. Jed had demonstrable models of the Fine-Steering-Mirror control system in hand, and had preliminary thermal analysis of the easy-bake oven that is our electronics pressure vessel. While we were working on all that, the CASA scientists and engineers were setting up a clean tent environment, and began the unnervingly delicate task of assembling and aligning the bench components starting with a raw, untouched bench on June 1st.

Most of the time components, software, power, and cabling are all conceptualized and built at the same time.  We were beyond relieved to have the professionals at CASA to make us flight-quality (or float-quality, as it were) wiring harnesses. It was one more thing off our plates, and a highly skilled, tedious task at that.

For the DayStar crew, one of the biggest challenges was just fitting all of the system’s electronics into the pressure vessel. What was normally spread across 12 feet of desk space now had to fit inside a box about as big as bathroom trash can. It all ended up fitting in the end, but through no easy feat of electronics Feng Shui! The compact mass of computer and power electronics squeaks when put into the pressure vessel. Who said we need margin anyways?

Many many sleepless nights and end-of-shift sunrises later, we were ready to ship. It was stressful at times, but overall a very exciting month. I can’t say how rewarding it was to be involved as deeply as we were on a NASA mission like this. We never thought we’d have this kind of responsibility until decades after we got our diplomas, let alone while still pursuing them.

On June 21st, we wrapped up the whole bench like a big static-proof Christmas present and sent if off to APL. We would meet it a few days later and begin the next blisteringly fast paced segment of pre-flight activities.

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