Struggling through final bottleneck

I quickly calculate that we are now at at least 99.9% of the YES2 project effort... Some of the last 0.1% these days reminds me of the tough times of construction and test last Winter.

Not everything in a project as challenging as YES2 works out everyday as you´d want it, and more often even, not WHEN you want it. Today we performed the close-out operations in the Baikonur Cosmodrome, which includes a short test, checking that all pyro's are in safe configuration and all internal mechanical latches are switched off. It also plans the final upload of the mission parameter file. These mission parameters bring all design, analysis, test and simulation results of the project together in about twenty numbers and three tables, that tell the YES2 computer how to deploy the tether successfully, what are the timings of the contingency cases (so-called time-out settings), how the deployer friction will behave etcetera. These parameters depend on many tests we have performed in the past, but also on the final confirmation on nominal landing site, orbital parameters and ground stations planned, updates on center of mass and moments of inertia (determined from test and analysis) etc., and must take into account many details and trade-offs, such as particular characteristics during the first seconds of deployment: 30 ms tension peaks we expect, pitch-off rate from the ejection springs etc. We need to prepare for all such anomalies and contingencies by choosing the right deployment control and for example the initial brake position. It is a nice job to do, it is what YES2 is all about: well-controlled deployment of the tether. And it is fun to identify all the details that may have big effects, and take them into account. Yet after this year's hard work on first the hardware and afterwards the software of the satellite, we needed a rest, a bit release of tension. Therefore attention shifted to the implications of test results and design updates on the deployment, honestly, some weeks too late.

Before I left to Baikonur Erik and I went through the deployment test data and determined most, but not all, friction parameters. Then Marco and me worked on the design of the final deployment profile for the last 3 nights (during the day mostly we have to be in tests in the launch preparation facility). We eventually uploaded a file, but doing analyzing the verification tests we performed on the engineering model, we discovered we had overlooked some details, leading to a ~1 km potential error in deployment. This would significantly impact the mission success, so we contacted Paul Williams at RMIT, a YES2 tether deployment expert and he spent his night in Australia supporting us. In this way we did manage to have a new file ready and verified during the day. Unfortunately the 5-minute window we had planned for its upload had unexpectedly been shifted to earlier in the day, and thus we missed that opportunity.

So far we have managed to stick to the tight Foton schedule very well throughout the course of the project. We can be proud of that, it has been not an easy task for our team: we got the go-ahead for construction and launch only a year ago and there have been plenty of late problems that were overcome only just in time. That makes it painful to actually miss a deadline this short before launch. Still, there is no reason to panic :) we have requested another and obviously final upload opportunity on Monday, as part of our pyro-arming session. The pyro arming is the last action on YES2 before it lifts off to a less hospitable place.