Congratulations everybody! 

I find it unbelievable but true. It's been already one year since the YES2 deployment, perhaps the most ambitious student space project ever. Time raced by, as I was studying the data from many many angles. And as it turns out from my analysis performed over the last 12 months, it was a highly successful tether experiment. There are so many sources of complementary and highly detailed data that analysis will continue for at least one more year. But many essential results have already been obtained, first rough ones early this year, then improved/detailed during the Summer months.    ----    The YES2 students have moved on and can be found working at ESA, in responsible positions at EADS, or with new start-up companies in Poland, Greece and other countries. Our great sponsor Emxys is now a significant player in Spanish space industry. In SSAU and other universities in Russia research on tethers is continuing full throttle inspired by YES2. Myself I am amending my PhD work on tethers with the YES2 results. Flight data is a great addition to a thesis.    ----    It may be hard to understand for an outsider what it means to have been part of YES2. Was it just a student project? Was it just an industrial project without real education? When the quiet waters of everyday business are stirred and things are really made to happen by people that are focussed and frantic, if not fanatic, some envy and misunderstanding may appear here and there in the suspension, and rumors are born, inaccurate images created. But every team member knows he (or she) was part of something very special that will not easily be described or repeated. A fantastic and warm atmosphere, 100s of new friends, great hands-on work and learning, a level of professionalism rarely seen in student projects, incredible challenges - yet eventually they were all overcome. From the beginning till the end we were surrounded by supporters and by skeptics, and the skeptics may now wonder what they can learn themselves from the unlikely success of the YES2 team.

• The ESA Education Office
• ESA HME
• ESA Technical Support
• TsSKB Foton Team
• Centers of Expertise
• The Students

Because of many requests, please find the Thank You poster attached.

Prof Belokonov announces the 5-th Russian-Eurpean Samara Space Summer School from 20-30 August 2008:

The program reveals interesting topics from YES2 to Earth observation satellites: www.volgaspace.ru/school.

Prof Belokonov says:"Wellcome for all students. New projects are waiting them."

In the days to follow (2-5 September) there will be a conference in Samara (just keep hanging around). There is a call for papers-deadline May 15th and topics like YES2 and flight opportunities for next Bion missions should interest you: http://volgaspace.ru/SPEXP2008/en/index.html

This colorful picture shows a fit of YES2 rate date (dark blue, loops per second vs. deployment time in the second stage, peaking at 65 Hz at deployment completion), as derived previously, vs. a recent spectrograph from RedShift's DIMAC accelerometers (green, yellow, red). Amazingly, the rattling of the tether (with a mass density of only 0.2 gram per meter) as it unwinds inside FLOYD [those who have been at the deployment tests know the sound of it!] is visible as accelerations on the 7000 kg Foton spacecraft, and shows up as a curve of high intensity in this plot of frequency vs. time . The match of the two independently determined curves provides direct evidence of the correctness of the deployment reconstruction by the YES2 team, as the overlay is near perfect, and confirms once more the full deployment of 31.7 km tether.

The fate of Fotino is better understood today. Based on deployment simulations including the MASS/Fotino attitude behavior, matched to DIMAC data, it seems likely that Fotino went through a rather nominal release and re-entry, and there is no reason to believe it would not survive:

- At the end of deployment, the shock was small enough not to induce full rotation of MASS/Fotino so the Fotino was probably not entangled in the tether.

- At the time of Fotino release, the Fotino was properly oriented and tether forces were optimal for separating Fotino effectively from MASS (similar to best case parabolic flight tests)

YES2, the tallest vertical structure ever made by mankind... As tall as 100 Eiffeltowers or nearly 4 times Mount Everest.

The long awaited DIMAC data sheds new light on YES2 and the workings and influence of the Foton attitude thruster. It is now confirmed that the tether deployment stopped at 8625 s, as suspected earlier. New is that it is now certain that the tether REMAINED attached when deployment completed and a swing back to the vertical was started! At the proper time the tether was cut. It also seems that Fotino was released at the right moment and deorbited into Kazakhstan. Features such as the stepper driver/barberpole activity can be clearly recognized, as well as the hold phase (gravity gradient tension), including longitudinal tether oscillations. During the swing, jerks such as those predicted are visible (see separate article below).

The DIMAC data shows accelerations of Foton resulting from disturbing forces. During the YES2 mission, one of the major disturbances is the YES2 tether tension. So in a way, the DIMAC was also a tether tension sensor. The data is high quality and very rich in information for YES2. It will keep us busy for months. A first glance tells us:

• The tether deployment stopped abruptly at 8625 s, as expected. The DIMAC derived tension profile is generally consistent with the 31.7 km best fit deployment case reported in the YES2 data analysis report. Although it must be admitted that presently sensor drift makes it difficult to distinguish between deviations and drift effects (this will be improved in the near future) the swing behavior and bouncing, deployment angle and Foton orbit raising all match the best-fit 31.7 km scenario and together provide a very strong case.
• A large shock (~30 N) followed, higher than expected.
• The tether remained attached to Foton, so the piece of tape at the end did NOT come lose.
• The tether was cut from Foton according to the timeline (9364 s).
• It seems that the release of Fotino can also be confirmed from the data, there is a sharp drop in tension visible some seconds after Fotino release time (9344 s).

This could mean that the entire SpaceMail mission was completed, and Fotino was sent into a trajectory towards Kazakhstan, and must have landed upstream (roughly between Baikonur and the nominal landing point near Astana), case G in the report, possibly towards case J.

A public version of the post flight data analysis is now available, see attachment. It does not yet include the GPS and accelerometer data. Analysis of this data could lead to a significant improvement of the estimate of Fotino's fate and potential landing site. Also we are currently analyzing the exact cause of the failure of the OLD signal registration in the second stage (*).

(*) It was so far demonstrated that the problem was present in the flight model at time of delivery, but NOT in the engineering model, so it is probably related to an electronical patch that was installed shortly before delivery on the flight model only and tested due to time constraints only till 4 m/s compared to the max. velocity of 13 m/s in YES2 flight. Ilias has performed some breadboard testing suggesting that thermal (heating) effects related to this patch may be to blame, but this is yet unconfirmed. IMTsrl is testing the electrical interface on the OBC board. A test will yet be performed at Delta-Utec to make demonstrate the software was indeed able to deal with the velocity (as it was in the engineering model) so that the problem can be narrowed down to the electrical interface hardware.