Sunday, August 26, 2012

Day 90, 8/26/2012 -- Downlink demons

The main issue we've been dealing with here in these last few days of having an integrated experiment is making sure we can downlink data reliably through CSBF hardware. Obviously, while in flight, we can't have any cables connected to the gondola to carry our data down, so we rely on CSBF to provide various sorts of telemetry links (a line-of-sight high-rate 1Mbps transmitter, a 92 kbps TDRSS high-rate transmitter, a 6 kpbs TDRSS low-rate transmitter, and a very slow Iridium system). The challenge for our software is to be able to deal with these data streams whose data rates vary hugely along with a dynamic allocation of which data we want to see over these streams and their update rates, which we plan to vary during the course of the flight (for example, during fridge cycles we want to make sure to downlink all of the fridge-related data, but all of those data are not super important when we're taking science data. So we need to be able to choose which channels to downlink when in order to optimize getting the most relevant data at a given time over our limited data rate connection).

So...this is hard. And it mostly works! But not quite completely. So the order of business for the past few days has been to try and work with this system as much as possible to try and work out the kinks so we (meaning Seth, our resident expert on this software who has left Palestine and is now working remotely) can get working downlinks. Still a work in progress.

Simultaneously, the gondola is slowly being disassembled as much as possible in preparation for the full disassembly. Today, Britt and Michele removed the flight power system and we went back to a scaled-down system so they can take the gondola legs off tomorrow.

Jeff and I also made progress in preparing to repeat a calibration experiment we did a couple days ago. The previous test seems to provide meaningful results, but the signal-to-noise ratio is a little low. We've thought about the experiment a little more and have devised a way to increase the signal in the experiment and have laid the groundwork for making this happen tomorrow first thing.

No pictures today.

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