1. Fly-By Working Group Meeting
OSIRIS
Fly-By Working Group Meeting
Padova
February 4/5, 2010
Holger Sierks
Max-Planck-Institut für Sonnensystemforschung

2. Osiris Fly-By Working Group - Agenda
Thursday, Feb 4 Lutetia fly-by preparations
09: Welcome
09:10 Lutetia in a nutshell; wrap-up by Colin Snodgrass and by UPD
09:20 'Lutetia cratering history' by Simone Marchi
09:30 Fly-by geometry and timeline, break points – latest updates by Michael Kueppers
09:50 Discussion of current input to Lutetia science planning
Basis: spreadsheets and comments distributed by Olivier and Laurent
exposure time comments by Uwe, comments by Sonia
Observations overview/wrap-up by Richard Moissl
Lutetia early light curve
Satellite search
Shape determination
Phase function
High-res imaging
Adjourn
Conversion to timeline, exposure time guidance, imaging cadence
11:00 Coffee break

3. Osiris Fly-By Working Group - Agenda
11:30 Hardware insert (due to presence of mechanism team)
NAC Shutter brake test plan overview by Richard Moissl
Brake commissioning
Light tightness analysis
Friction determination
A/B point selection/optimization
SHM MRB close out readiness
WAC shutter parameters
13:00 Lunch break
14:30 Discussion and distribution of work packages for data processing and evaluation
Lutetia light curve
Shape by light curve inversion
Satellite search
Dust
Global shape reconstruction

4. Osiris Fly-By Working Group - Agenda
Stereo, elevation maps
Photometric properties, surface regolith properties
Surface geomorphology
Age determination
Surface composition
Space weathering
Physical properties
Context with VIRTIS
16:00 Coffee break
16:30 Calibration status wrt Lutetia data analysis, overview by Cecila Tubiana
Data reduction
ESB3 results as relevant for Lutetia
WAC straylight
Open issues
17:30 Wrap-up discussion of current planning status
(=> telecon /w LAM and others)
18:30 Adjourn
19:45 Dinner (ristorante Ai Navigli)

5. Osiris Fly-By Working Group - Agenda
Friday, Feb Lutetia fly-by preparations cont’d
OSIRIS hardware as relevant for Lutetia planning cont’d
09:00 Discussion of Lutetia planning cont’d
10:00 Status WAC reference camera
WAC FS shutter rework
WAC filter wheel
WAC front door wiring
WAC return to Osiris Reference System
Status of OSIRIS power converter issue
Short status report
Risk assessment (preliminary)
Impact for Lutetia sequence planning
11:00 AOB
11:30 Adjourn

6. Lutetia Working Groups
Package
Theme
Osiris Working Group 1
Lutetia light curve
S. Mottola, C. Tubiana, LAM 2
Shape by light curve inversion
LAM, S. Lowry (tbc), C. Snodgrass, J.B. Vincent 3
Satellite search, dust
P. Gutierrez, I. Bertini, R. Moissl, S. Schroeder, C. Snodgrass, F. Marzari,
W. Sabolo 4
Exosphere (Na, OH)
C. Grava, M. Kueppers, C. Snodgrass, F. Ferri 5
Global shape reconstruction
LAM, S. Casotto, E. Simioni, W. Sabolo, P. Gutierrez 6
Stereo, elevation maps
C. Snodgrass, R. Moissl, G. Cremonese, E. Simioni, LAM 7
Photometric properties, surface regolith properties, Space weathering
L. Lara, J. de Leon, A. Barucci, S. Spjuth, M. Lazzarin, S. Magrin, F. Ferri, I. Bertini, S. Schroeder, P. Vernazza, C. Lerat, R. Brunetto, S. Fornasier, B. Carry, S. Marchi, Wing Ip, P. Vernazza, LAM 8A
Surface geomorphology
S. Marchi, M. Massironi, F. Ferri, S. Besse 8B
Surface features (the unknown)
S. Besse, LAM 10
Age determination
S. Marchi, F. Marzari, M. Massironi, S. Mottola, M. Kueppers 11
Surface composition
C. Snodgrass, S. Marchi, M. Lazzarin, S. Magrin, A. Migliorini, L. Lara, J. de Leon, A. Barucci 12
Moved to WP7 13
Physical properties
L. Lara, J. de Leon, M. Lazzarin, S. Magrin, F. Ferri, A. Barucci, Wing Ip, LAM 14
Context with VIRTIS
C. Tubiana, L. Lara, J. de Leon, F. Ferri, A. Migliorini, A. Barucci (VIRTIS Co-I), M. Lazzarin, LAM

7. Power Converter Issue
In July, 2009, a high power event was detected during validation of sequences for ESB #3 on the Osiris reference system at MPS
No immediate thread was found (inspection, logs review)
ESB #3 validation runs continued after power cycle
NAC shutter issue was detected, we swapped in QM shutter
Inspection revealed that the NAC shutter was in fail safe (blocked in half open position), as was the WAC front door (permanent open position)
High power event was a failed reset of power converter consumer switches (heaters, s/s, fail-safe mechanisms)
Side bar: failed to readout NAC CCD in fail-safe mode

8. Power Converter Issue

9. Power Converter Issue Root cause:
Flight spare PCB on Osiris reference system used a ceramics and a tantalum capacitor to control main and redundant wake-up timing (different temperature slopes)
2 degC elevated temperature in clean room plus high level of activities with a number of power cycles created perfect match for crash on FS
Crash on data and address bus during initial wakeup of main and redundant controllers cause lack of zeros at time of switch reset
Sequence of latches to reset determines uncontrolled fail safe activations: NAC shutter, WAC FD, NAC FD, WAC shutter
Timing is sharp: need min. 50 usec gap, have 300us on flight Osiris
Flight Osiris PCB used tantalum caps on main and redundant side
First temperature tests with flight lot tantalum caps reveals a give or take ~100 usec/10deg -> 20 degC leeway around RT

10. Power Converter Issue

11. Power Converter Issue
AFT (flight temperature range) is -30 to +40 degC
-> no way to go to low temperatures !
Flight rule in place now for +20 +/- 20degC at switch on, goal +-15
Characterization of a Rosetta s/c heater (5W) on EBox will help, but not suffice
May need to tilt comet approach (s/c is cold) to warm up +Y-panel (violation of s/c flight rules wrt solar panel sun incidence angle)
Investigation on board/component level is ongoing
Procured 300 pcs of flight identical capacitors from Vishay (manufacturer)
Started temperature tests to investigate statistical spread of capacity decrease versus temperature within a fabrication lot
Caps are excellent, to spec (+/- 10%), we are looking for half a per cent deviation!
ESA project is informed, meeting at ESTEC held in January 2010
MRB with ESA to come in March/April 2010 (end of temp tests)

12. Power Converter Issue Conclusions (preliminary):
In principle, risk is limited if temp at switch-on is close to +20C (reduce turn-on temperature range)
In principle, risk is limited if temp at switch-on was already seen in flight (and close in time)
However, capacitors age. As do DC/DC converters. So safe T-regime today might not be safe after 10 yrs in flight (or after 5 yrs – today)
Further reduction in temperature range is requ’d
Risk will remain throughout the mission
Iteration with ESA/MOC, ESA QA/parts; MRB ongoing
For Lutetia (and PC12 and others):
Ensure turn-on temperature is ok (hard requirement)
Limit number of switch-ons, best to 1 per campaign
If power cycle is unavoidable, wait min. 1 h for thermal equilibrium on power converter board (avoid gradients on converter board)