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.

A few weeks ago Jonathan was asked to make a mini website for YES2. He absorbed loads of information from many of us and now there is a nice YES2 corner at ESA: www.esa.int/yes2

YES2 will complete today the checkout operations and then the only remaning action will be on the 10th the arming of the system.

After a rather stressful 3 days, we have successfully implemented and tested the two additional safety measures for YES2: a late request for design change from the Russian partners: a slip-knot and autonomous cut function, both to activate in case of early accidental tether jam and release tether and Fotino from Foton such that the tether cannot wrap around Foton. The team and YES2 showed great flexibility to implement such a change at this time without opening (much of) the satellite. In parallel we made sure that the OBC receives data from the UHF (a left-over open issue) and that the important length sensors of YES2 are fully functional. After successful functional test, the YES2 hardware can be said to be 100% in good shape now.

YES2 is being removed from its big brother Foton, as it will be fitted with extra safety measures, that were required to be allowed to deploy the tether. With those measures, YES2 received the final go ahead for flight, 3 weeks from now!!

 

http://www.findu.com/cgi-bin/find.cgi?call=sq5fnq-11&units=metric 

we could live follow the Polish-executed high altitude balloon test, which will be followed by a Fotino drop test. Marcin Stolarski and team were there in the fields and practised working with the Fotino release system, data recording and... successful recovery of the balloon among the wild forest and lakes of Poland, so recovery of Fotino could be well possible!

YES2 is on the battery pack of FOTON and SOYUZ is already waiting for us ....almost done... :)

We received this amazingly accurate drawing from a 6 year old, Alex, who according to Alma, his mother, shows and explains the YES2 animation to all his classmates. It seems Alex really likes the action-packed YES2 mission and has a clear image of what it will look like ;)

0. Fotino, MASS and FLOYD. 1-YES2 on Foton orienting towards the Earth. 2-Tether deploying. 3-Fotino release. 4-Fotino and MASS coasting towards the atmosphere. 5-Fotino re-entry over Africa. 6-Fotino descent on parachute.

What is this chaotic scene then about? Well, it is rather hard to visualize software doing a good job!

This is the Delta-Utec tether deployment test rig, simulating space dynamics in a real-time, hardware-in-the-loop test of the YES2 tether deployment. The hardware present are engineering models (flight replica's) of YES2 tether, barberpole brake system (hidden behind tether), optical loop detection system, on-board computer (on table), stepper driver (in shiny box). The real thing under test however is Mathieu & Fernando's On-Board Computer software's deployment control: how robust and accurate can we control the deployment when problems occur? YES2 deployment control effectiveness was already tested with simulated hardware, and with real hardware but a breadboard computer and earlier software version. This is the first time flight software and hardware come together in a closed-loop deployment test. Due to the enormous time pressure this is done while the rest of the YES2 team is moving to Baikonur, the launch site.

ESA included YES2 in the kids section, worth a look if you like puzzles:
http://www.esa.int/esaKIDSen/SEM1329OY2F_ga.html