Living in a Giant Clean Room – Our Testing and Integration at APL

With the UVVis bench on it’s way to MD, Kevin, Zach, and Steve-O prepared to fly out to meet it at APL just days later. Upon arriving they moved our giant Christmas present into another clean tent where we would be able to ensure it survived the trip and continue working on it. We took two big trips out to APL. On the first trip Kevin and Zach were sent to get the instrument up and running and continue the mad dash development of the flight and ground software.  Jed followed a week later to focus on getting the control law to work for the first time. Nick came out near the end of the second week to fix a few power issues and his time spanned the two main trips.

A large part of our first push at APL was preparing for an altitude chamber test that would prove our hardware would survive the cold, near vacuum flight environment of 120,000 ft. It was a test to verify the custom pressure vessels, to make sure the heaters did their jobs, and to ensure that our mechanism and electronics did not get too cold or hot and stop working correctly.

At the end of Nick’s solo time we integrated the UVVis instrument onto the telescope and moved all of our operations into the high bay, a huge room specially built for the assembly of aerospace hardware like satellites and balloon payloads (but mostly satellites). While in the high bay we had to wear smocks, hair nets, masks, and gloves almost all the time (especially when near the payload). After Nick’s shift, Jed came back to get the control law working with light actually going through the telescope for the first time. The motion we are trying to correct for is so small that testing the control law was done by someone leaning on a optics table. You could in no way feel the table move but we saw lots of motion on the cameras through the telescope. The simulated star (a tiny light seen through a special backwards telescope called a collimator) moved all over the place as we pushed on the table. As it so happened the movement was almost exactly what we expect to see during flight. The development of the flight software, ground software, and control law testing pressed on at break neck speed for another two weeks after Kevin and Zach rejoined Jed for round two. Being in the high bay was quite an experience but I don’t think any of us miss having to wear the clean room garb and listen to the non-stop rush of air all day every day.

Looking at those pictures you might have some questions like:

Why do you have to wear that stuff? Contrary to what you might think, we aren’t in a dangerous environment. Instead we are trying to keep human junk off all the sensitive hardware. One of the features that makes a clean room or tent “clean” is a constant filtered airflow preventing dust and particles from collecting. Clean room procedures prevent outside contaminants from getting in and smocks and other garb keep us (skin cells, sneezes, etc.) from contaminating the instruments while we work on them.

How big is the telescope mirror and why is it gold? It’s 0.8 meters in diameter and it is painted gold because that gives APL’s IR Instrument more light and does the opposite for the UVVis instrument. This telescope is actually being reused from a former mission called STO. It was resurfaced (precisely grinding the glass into a parabolic shape) and coated specifically for this mission.

What’s that bag covering the telescope? It’s a special material made of polyethylene terephthalate with a metallic film that gives it that silvery appearance. It is an anti-static material that prevents you from accidentally shocking and destroying electronics you might touch. If you ever buy electronics that are not already encased for consumers, they will likely come in a bag made of the same stuff. This material is also what we wrapped our instrument in before shipping it to APL. In the case of the telescope it is really just an expensive dust cover.

What’s that janky blue Home Depot foam about? That is a low outgassing foam for insulation that happens to be available at common hardware stores. To keep the optics in focus we have to keep the optics bench within a temperature range and we do that using heaters and by isolating the bench from the environment as much as possible. On top of having to worry about the temperature we have to worry about what materials do when they are subject to very low pressures. If you have a foam with a bunch of bubbles in it, in low pressure they will explode and fling little bits of foam all over the optics you have worked so hard to keep clean. Materials that are low outgassing mean they don’t do that. If the hardware store foam offends your sense of what constitutes (near) space worthy technology don’t worry, the foam is covered by shiny gold mylar before flight.

During our weeks in MD we became regulars (favorites) at the sushi place by our hotel. The waitresses there loved to give us a hard time about our apparent lack of Sake ordering manners and grew fond of smacking Kevin upside the head. While working 12 hours a day every day we were able sneak away for a few evenings and afternoons to visit the surrounding area. We visited the Air and Space Museum on the DC Mall where we were cumulatively children in a candy store. We had one especially interesting moment while looking at a full scale model of the Hubble Space Telescope and some of the amazing pictures it has taken on a wall. We remembered why we were putting ourselves through all this. If we succeed, we will be one step closer to getting Hubble quality pictures from balloon. It won’t be this mission but if we do well this time we will still be on our way to building The Hubble Killer, a balloon borne telescope capable of Hubble quality images at a fraction of the cost.

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