Thursday, November 29, 2012

Hang Test (and preparing for it): November 28 and 29, 2012

Wednesday morning we got to work on the final preparations for our Hang Test. I spent most of the day making and modifying our map of the locations of all of the temperature sensors located throughout the instrument. Kenichi updated our internal monitoring website with the maps that I had made and also made it possible to click on a sensor's location on the map and see the history of the readings it put out. This lets us track how hot and cold various parts of the detector are getting, and make sure that things aren't getting too cold or overheating. Makoto continued working with his monitoring and initial analysis software, while Dana and Frank sealed up the last parts of the insulation layer. After lunch, JohnE and I got to work looking at in-flight calibration of the instrument and where to set certain parameters. 

Thursday morning, we were told that the weather forecast called for some wind early in the morning that was expected to die down after a few hours, at which point we would do our Hang Test. The Hang Test is an important milestone, since a successful one means that a balloon payload is basically ready for launch. The tricky thing with the Super-TIGER Hang Test was balancing what we needed with what had to happen with BLAST. Right now, Super-TIGER occupies the back half of our payload building, while BLAST is in the front, closer to the door. Since BLAST uses liquid helium to cool down various parts of their instrument, and the Super-TIGER PMTs can be damaged if exposed to helium, BLAST has to do the filling of its helium tanks outside, so they need to be in front.

Luckily, BLAST has a number of tests that they need to carry out outside, so they are able to do those while our payload needs to be outside, minimizing the amount of re-arranging that needs to happen. The downside is that BLAST has very large shields to keep the sun out of their telescope, and these shields act as a giant sail if the wind picks up. Once the wind started dying down, BLAST got picked up by the CSBF launch vehicle, The Boss, and driven out to their "dance floor" deck a few hundred feet away from the building for their tests.

Once BLAST was out of the building, we got to work getting Super-TIGER ready to be lifted out onto our deck. We had to set ourselves down on the deck in order to be picked up by The Boss, and then moved about five feet off of the deck and set down on jack stands. This allowed the CSBF crew easy access underneath the instrument to install the Ballast Hopper, which will control the ballast that we will carry with us during flight, and drop if we need to maintain altitude. This was also when we deployed all of the solar panels that are used to power both our instrument and all of the CSBF equipment that is flying with us.

The Boss then drove us out a bit and arranged itself so that the Super-TIGER instrument solar panels were pointed directly at the sun, which was then almost above Mount Erebus. In the direct Antarctic sunlight, we were able to get more than twice as much power as we actually needed out of the panels. We then took some quick group photos and went inside to run through out test.

Essentially, the Hang Test was where we did everything we would need to do to launch the payload without actually attaching a balloon to it. We also pretended that we were in flight while hanging on The Boss, and sent commands via the fast Line-Of-Sight (LOS) antennas, as well as the TDRSS (fast) and Iridium (super slow) satellite links. We were able to verify that everything we needed worked fine, but when we got into the part of the checklist where we were doing some higher-level commands (that worked on Tuesday, during our pre-hang test test), we were told that the winds looked like they were picking up and we had to come inside.

We quickly sent several commands to the instrument to try to get as much testing as possible done, and then The Boss brought us back to the payload building and went to get BLAST. At this point, the wind was gusting up to 14 knots, so getting BLAST and their giant sun-shields inside was important. They got inside without any problems, so everything worked out ok.

We then went over the data we took during the Hang Test and made sure that everything was working. Everything looked good, so the plan for the next couple of days is to finalize our calibration, decide on priority thresholds and make sure our monitoring software is good to go. We'll also get to work training everyone on how to use the command software and making a personnel schedule for the flight monitoring.

It sounds like the vortex over Antarctica in the upper atmosphere that needs to set up before we launch is basically set up. The plan we heard yesterday was for the CSBF folks to launch a "Pathfinder" balloon on December 1 to verify that the vortex is indeed working properly. Otherwise, there is some paperwork and an approval process from higher-ups at NASA that CSBF needs to go through before launching, which is expected to finish up on December 4th. Otherwise, things look good for us going for the first launch opportunity that presents itself after the 5th. 

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