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

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.

From DIMAC also the deployment angle could be determined (with about 5 degrees accuracy), and compared to the YES2 reconstruction. A clear confirmation was obtained from phase and amplitude of the swing during the hold phase (between first and second stage), as well as the angle during most of the second stage. Amazingly, the complex lateral (sideways) waves in the tether during the swing back to the vertical could be resolved as oscillations on the tether angle at Foton, both in DIMAC data as in YES2 simulations of the mission that were meant to match the flight data. The match is uncanning and shows how the YES2 mission data is already providing a yet unseen understanding of tether behavior in space. The data confirms the YES2 reconstruction, namely that the Fotino was released nearly exactly at the vertical, which would have sent it towards the Uzbeki-Kazakhi border (see earlier story on this site).

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)

- At the time of Fotino release, Fotino's angular motion was less than 30 deg/s [See image below]

- In the worst case of a 30 deg/s rotation at atmospheric entry, simulations show that Fotino stabilizes in time at 105 km altitude, and oscillates around the nominal stagnation point by about 50 degrees, which is still within margin. The simulated heat flux is still significantly less than that tested in the plasma chamber. [See image below]

Based on matching of the deployment/re-entry simulation to the YES2 deployment and DIMAC data, the red ellipse in the map provides an indication of the currently suspected Fotino landing area.

Did Fotino land in the Aral Sea? Fotino floats, but could not be made waterproof. It would explain why the beacon signal was never received as it would not survive for the 2 hours required to be picked up by ARGOS. However, Fotino would likely have floated to a shore, so that is where it may be found. Remember, there is a financial reward for those who find it :)

The indicated zone is NOT FINAL, because the simulations have not been completed yet. It is expected the estimate can be significantly improved based on future results. The red zone is for the case of successful or slightly delayed release of Fotino from MASS at the end of the swing. The orange zone includes also the case of release failure. Originally intended landing point (Tasty Taldy) and launch site (Baikonur), as well as the Russian Center of Expertise (Samara) are indicated.

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).

Above picture compares the YES2 measured tension after ejection to that derived from DIMAC Foton accelerometer data. An amazing fit!

The DIMAC data shows a clear tension component that indicates significant deviations (up to 30 degrees) of Foton attitude from the vertical. From this it could be understood what was the Foton attitude control algorithm, which turns out to be quite different from the one expected. The new understanding resolves some apparent contradictions in our earlier analysis (see also 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.

We still need to study when exactly Fotino came lose from the belts to determine where in between these cases Fotino ended up.

• The delay between Fotino release time at one end of the tether and tension drop at the Foton end would be valuable information on the speed of sound in the tether, and seems to be consistent with expectations (several kilometers per second).
• The proper performance of the stepper driver and barberpole brake can be confirmed, as the tension signature due to braking is clearly recognizable. This data allows for separating several types of oscillation observed in the tether during the first stage deployment so we can learn about details of deployment dynamics that do not show up in ground tests.
• The tension during hold phase is as expected, and shows oscillations which will tell us about stiffness (EA = 120 N at 0.2 N tension, matching ground measurements) and damping of the tether, allowing us to improve simulations. 
• The bouncing of the tether after deployment (picture on left) matches well the preliminary deployment reconstruction simulation (see insert and image on right), the difference in timing tells us more about the tether stiffness and thus in a next iteration we can better simulate the bounce and learn about the dynamics of Fotino at time of release (was it stable or spinning?).
• The DIMAC measurements shortly after ejection can be overlayed well with the YES2 tensiometer data, and demonstrate the DIMAC data is a good representation of tether tension. (See separate article).
• The tether angle with respect to Foton could be derived from the direction of the acceleration in Foton body frame. Combined with the YES2 deployment reconstruction performed earlier, a detailed coherent picture appears on the Foton attitude during the deployment and swing. See picture below. For the second stage this conclusion was already confirmed to several degrees precision from DIMAC magnetometer data.
• Foton attitude control thrust could be filtered from the data and it was shown that Foton Attitude Control System (ACS) maintained an angle with the vertical of about 30 degrees while the tether climbed to its swing angle. The Foton torque followed well the tether-tension induced torque during this time. See picture below. While the tether was at lower angles, it appears Foton attempted to follow the tether direction, minimizing the control torque requirement.

Potentially critical open issues are still:

• uncertainties due to sensor drift over time, which will be estimated by RedShift at a later stage.
• There is possibly a deviation of about 10 degrees in the hold phase swing angle between RedShift magnetometer data and YES2 deployment reconstruction which may indicate a slightly different first stage deployment from so far assumed. Further work into the first stage deployment reconstruction is necessary.

OTHER NEWS 

Further analysis of earlier ejection data shows that the pitch-off rate measured by the gyro was about 4 degrees per second, and maximum amplitude just after ejection would then be about 30 degrees. This information should allow for improved subsatellite simulations.

(*) 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.

Today we received the first results from SSAU GPS data, displaying the altitude as function of time. The yellow vertical lines indicate the important events Ejection, Start Second Stage, Cut Tether, from which can be seen that most of the First Stage and the full Second Stage are covered by the available data. Also post cut data is available to study the new orbit of Foton after tether release. The Hold Phase (just before Second Stage) is covered by a large number of data points, even if there are some holes in the data, it should be sufficient to filter out the exact motion and tether deployment behavior: by detailed analysis of the GPS data and determining deviations of the Foton orbit with respect to the expected motion of the center of mass, the tether dynamics can be derived.

In addition to this important mission result, DIMAC accelerometer data is expected early February. 

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I WISH EVERYBODY A SUUUUUUUPER CHRISTMAS!!!!!!!!.....full of joy and satisfactions!!!!!!!!!

I hope to see you veryvery soon!!!!!!

Hugs and kisses

Cristina (3)

C'MOOOOOOOOOOOOOOOOONNNNNNNNNNNNNNNNNNNNNNN

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Hi,

I wish you all nice Christmas holidays and a happy new year 2008!

Greetings from Germany!
Patrick

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Hello my friends,

I want to wish you too a Merry Christmas and a Happy New Year from Spain.

Best wishes for 2008!!

Hugs,

Isabel

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Hi everyone!

Same here: Merry Christmas and a happy new year to all you YES2 veterans
out there!

See you again some time,
Gerrit

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My dear YES2 friends,
 
I wish you all to pass a nice Christmas and to have a superb end and begin of year.
 
Hoping to see you all as soon as possible
 
God bless us
 
Angelo

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Buon Natale e Felice Anno Nuovo da IMT srl
Merry Christmas and Happy New Year from IMT srl.
Massimo Perelli - Giovanni Cucinella

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On 24/12/2007, Maurizio Burla <maurizio.burla@gmail.com> wrote:
Hi all!!!

Greetings from Italy as well!
If I make a balance of the year, I have a very very big positive on the YES2 period... I don't know if I will have a similar opportunity anytime in the future! That was really a great present, so thanks you all guys ;)

Ciao & buon Natale & happy new year!!! :)

Maurizio

On Dec 23, 2007 11:34 PM, Fernando Apesteguía < fernando.apesteguia@gmail.com > wrote:

Hello everybody.

I just want to wish all of you Merry Christmas and the best wishes for 2008.

Enjoy with the family / friends and take care. :)

Greetings from Spain.

On Nov 28, 2007 2:47 PM, Moisés Navalón Bernabéu

< moises.navalon@emxys.com> wrote:
>
>
>
> Hi everybody!!
>
> Congratulations for your work and for the success of the mission. It was
> very hard but...We did it!! A 30 Km tether deployment in space. Awesome!!
>
> Unfortunately, I still have exams on December so I will not be at the party
> with you. Maybe next time. I hope to see you soon.
>
> Have a great party!!!
>
> Best wishes,
> Moisés Navalón

----------------

Should I begin this memo with the words "dear colleagues", you would probably
start worrying for I might come with requesting something to you.  As a
matter of fact I do so, but  requiring a rather small effort.   All I am
asking is to share with me a brief thought at the end of this year.
Admittedly, I look at December 31st and January 1st as two numbers, two
consecutive days, two dates in the calendar.  Nothing more.  However, for a
moment let me deviate from my "arithmetical" conception of the year end and
stick to tradition of doing a balance summary of 2007 and what filled most of
its months.  I actually recollect and think of the time and the experience
that we shared this year with the Foton-M3 project and the goals that we
achieved as a team.  I am frankly and openly grateful to all of you for the
shy way you'd brought about the success of this project and its scientific
aims, for the honest and positive manner you'd always approach the
difficulties and problems met on the path, for the solutions you'd finally
been able to find,  for the faithful and bald strength you'd conducted all
the project phases with, and, last but not least, for the friendly and
cooperative attitude you'd always kept with all colleagues and partners in
this challenge.  It has been a pleasure sharing this workload with you and
feeling that I could always rely on a great team backing me up.  It has been
a pleasure enjoying the completion of the project stages and the deserved
"celebrations".  I carry forward to next year this wealth of feelings looking
ahead for a new joint endeavour with you and your team mates.   You probably
realised that our business is a small world and, irrespective of new
commitments and assignments, I am pretty sure that our professional roads
will cross again and manyfold.  Till then, my very best wishes for your
future projects with the kindest  invite to extend them to all your
colleagues and co-workers in the team, which I could not reach directly with
this message of mine.

Antonio 

The YES2 project was a success: a 31.7 km space tether, great technology and science, great experiences and friendships. From the first YES2 students in January 2001 to the data analysis today. The drink on December 1st became a worthy and happy project closure. More pics, click on "read more". Also you can go to: http://fotki.com/fiabo/parties/yes2-party/ . To add your own pics, ask Fabio! The YES2 project is pretty much closed, but data analysis and results refinement will continue. Also we are looking for opportunities to keep the team together and build on the developed technology with a successor experiment.

Do you recognize our Configuration Items 5815 and 5816? Retrieved from the outside of the Foton capsule after re-entry.

More than just having deployed completely, we can now explain why YES2 has been a major success not just in terms of education, but also technically - especially from a development and tether mission point of view:

The SpaceMail strategy's most challenging objectives were achieved

• controlled deployment of the tether to a stable position 3.4 km below Foton. This 'First Stage' is a key ingredient of SpaceMail, not tried before, and intended to obtain a sufficiently precise continuation of the deployment
• successful holding phase, release and initiation of the second stage, nominal to 2/3rd of deployment time
• 30+ km tether deployment in space (strong indications exist for the 31.7 km case)
• delivery of the capsule into an immediate re-entry trajectory 

YES2 has been a technical and scientific success

• The data from YES2 and YES2 SSAU (OLD's, GPS), DIMAC (accelerometers) and NORAD (TLE) allow to recontruct in high detail the full YES2 deployment (see pictures below for current status). 
• The tether deployer controller system has functioned fully according to plan, friction on the barberpole was close to that predicted. The system is mature for a follow-on mission.
• The tether spool performance can be analyzed thanks to the large amount of data. It has already been demonstrated that the tension required to remove the tether from the spool was several times higher than expected, but not too high, and the spool's friction did show a nominal dependency on deployment velocity (the second major performance parameter)
• Plentiful data exists to recreate the mission in detail and study differences between ground tests and space performance, such as stiffness effects, oscillations, shock waves etc.
• The data allows also to investigate what went wrong (length measurement signals intermittently failed to arrive -at least with proper time tag- in the on-board computer) and make the next effort a full success.
• The YES2 satellite, safety systems, staging systems and on-board software have all worked very well

Not bad for a bunch of students. Congratulations!

PARTY PARTY PARTY

A YES2 reunion & champagne party will be organized at Delta-Utec premises to celebrate this great outcome on Saturday December 1st, 1600-1900. Everybody who reads this sentence is automatically invited.

Also, in the party we will try to convertness our sadness about having not heard about Fotino into proudness that also this capsule's technology was properly qualified and from that we can derive hope that someone one day will find Fotino in Siberia or on Russia's Pacific beaches.

Till then!

Above picture shows the YES2 tether deployment trajectory (side view with Foton in 0,0 moving left, and Earth downward) as it was preliminarily reconstructed using the raw data. The left image is a zoom on the first stage (3.4 km), the right is the full view. The black line is a simple integration of tether dynamics using the raw length data from the OLD (and length rate after 6300 s). After that, Delta-Utec's advanced tether simulator YESsim was used to reconstruct the hardware's particular performance during the flight and to investigate oscillations and bouncing effects, as can be seen in the orange curve.

YES2 second stage reconstructed deployment speed versus nominal. A maximum of 16 m/s was reached, and deployment completed with about 13 m/s some 6 minutes early.

The deployment versus nominal deployment would have looked in space like this:

It can be seen that a larger swing was achieved, which would have resulted in a more effective re-entry trajectory than nominal. The nominal deployment did not aim for such an angle, as it was conservatively designed to include some margin in case friction in space would be very high. The result is a clear indication that the YES2 system could have easily performed the nominal deployment would the computer not be confused about the length and given up on decelerating the deployment near the end. Note that most likely the tether released at the deployment completion (red dot), so the swing to the Fotino release (pink dot) was probably not made. Future data analysis will clarify this point.

So how could the deployment be reconstructed, if the length data was corrupted after t=6300 s? A complex story, and many data sources were used. However, mostly, the loop rate (or number of tether loops that are unwound from the spool every second) could be determined as a function of time from the raw mission data. The curve is plotted below. From integration of this loop rate, the loops unwound at any point in time could be calculated and therefore also the speed. Integrating tether dynamics leads to the deployment plot side-view shown above.

The brown dots are considered higher quality data than the black. From 8000 seconds only sparse data is available with lesser reliability. A statistical analysis of the available data (not shown) has demonstrated that the deployment did continue, and that the loop rate was rising steeper. This seems also to be indicated by the few remaining loop rate data points. Finally, it could be determined that the deployment was completed around 8622 s (last OLD and after this time DIMAC measured no more disturbing accelerations of Foton, indicating tether was slack or released) and was most likely fully deployed (31705 m) at this time. Most likely, because Foton orbit change (measured by NORAD) indicates that the tether was released from the spool at this time. In order for deployment to complete, looprate between 8000 and 8622 s would have had to continue as indicated by the orange line. Note that this line (determined independently from the looprate data) matches quite well the sparse remaining data points. Quite neat, no? Soon we will have more data (DIMAC, GPS) to further refine this result.

With the deployment known, we can calculate the tension level required to follow this trajectory and compare it with the nominal profile, based on pre-flight measurements of the spool. It can be seen from below plot that the YES2 deployment (silver curve, Maximum Speed) follows well the nominal curve (dotted red line) as long as the velocity is close to nominal. As soon as velocity gets higher than nominal (due to lack of braking), friction in the canister increases as a result of unwinding physics, and which can be seen in the plot because the silver curve diverges from the red dotted line. It can be concluded that the friction behavior during YES2 deployment Stage 2 was fully nominal and could have well been controlled had the computer not been confused since t=6300 s.