Aerospace Engineering Department

1. SD2: Status and On Comet ScienceP. Di Lizia, F. Malnati, P. Francesconi, A. Ercoli Finzi, F. Bernelli-Zazzera Aerospace Engineering Department

2. Agenda • SD2 Status • SD2 Open points • Cruise phase • Post Hibernation phase • Comet phase • First Science Sequence (FSS) • Requirements • Proposed sequence • Long Term Mission (LTM) • SD2 Facility • Perforation Strategy • Test campaign • Preliminary Results

3. (switch on SD2) OK (4 rotations) OK (2 movements) OK (20 rotations) OK (4 movements) OK • (2 movements) OK OK OK OK OK SD2 Status • In flight tests performed: • Commissioning (4 blocks) • Electronic behaviour tests • Carousel movements • Volume Checker movements • Active checkout ( 3 checkouts) • Carousel movements • Drill rotation • Drill translation • EEPROM refresh • Passive Checkout ( 6 checkouts) • EEPROM content check • Electronics switch on • Position resolvers switch on Results

4. SD2 Status • Fully commissioned: • All mechanical items of SD2 have been tested during cruise phase Mechanical unit (including Drill) Electronic unit Carousel SD2 is ready for comet phase

5. SD2 OPEN POINTS: Cruise phase • Required (or desired) activities for next active checkouts: • Carousel movements • Drill rotation • Drill translation • EEPROM Refresh (during PC#12)

6. SD2 OPEN POINTS: Post hibernation phase • Test definition • Complete test of SD2 is recommended after hibernation • Carousel movements • Drill rotation movement • Drill translation movements • EEPROM refresh (Mandatory) • Constraints about • Power budget • Data rate • Access to Rosetta (RF link) • Other subsystems and experiments activities • No activities foreseen during SDL phase

7. SD2 OPEN POINTS: Comet phase • Decisions for both phases: First Science Sequence • How many holes • How many samples from each hole • Which ovens shall be used to release samples • Use of Volume Checker Long Term Mission • Use of SD2 to perform qualitative analysis of mechanical characteristics of comet soil

8. SD2 FSS: Requests (1/2) • Reference Documents: • Philae Science Objectives [RO-LAN-L1-1000; Issue 1.1 Draft; January, 02, 2009] • Requests:

9. SD2 FSS: Requests (2/2)

10. SD2 FSS: # of holes - # of samples

11. SD2 FSS: Proposed Sequence • Low Drill translation velocity (2 mm/min) for H1S1 and H2S1, and during drilling to maximum depth • Duration and consumption do not include stand-by phases

12. SD2 FSS: Mission Plans; HK, SC Packets • Necessary mission plans: 30 • House-keeping (HK) and Science (SC) Packets

13. How to sample the comet Sampling tube Drill bite Comet soil Oven Drilling phase Sampling phase Discharge phase

14. SD2 Scientific Instrument Tool SD2 Scientific Instrument Correlation analysis between drill telemetry data and the mechanical characteristics of the perforated material ? (material parameters) = f (telemetry data) Experimental approach

15. SD2 DIA Facility(Laboratory) SD2 DIA Facility • Strain gauge equipped with an amplifier and the conditioning system • Current sensor • DC Power Supply • Low-pass digital filter • Data Acquisition device • Labview Software • MATLAB

16. SD2 Facility - Specimen Simulation of different sampling scenarios, according to different on comet surface conditions. • GASBETON • MULTI-LAYER • GRAPHITIC-FOAM

17. Perforation strategy - Material Characteristics • GASBETON • Fragile material • Low density (~500 kg/m3) • Porous composition • GRAPHITIC-FOAM • Fragile material • Low density (560 kg/m3) • Porous composition

18. Test campaign - Inclined surface Simulation of SD2 operation on irregular cometary surface • Test 20° • Test 60° F The contact between cutting and surface is asymmetrical, with an asymmetrical distribution of cutting stress FL C

19. Test campaign- Multi-layers specimen First layer: mix of concrete material Second layer: gasbeton Goal: Drill behaviour analysis (discontinuity of force and torque)

20. Test campaign- Multi-layers specimen First layer: dry graphitic-foam Second layer: frozen graphitic-foam Goal: Drill behaviour analysis (discontinuity of force and torque)

21. Perforation strategy - Experimental Approach Experimental campaign with different specimen categories: • Imposition of decreasing drill rotation speed values • Identification of the minimum rotation speed required to drill the specimen without stepper motor stop Creation of a DATABASE of correlations between minimum speed value and the material characteristics Minimum Rotation Speed

22. Test campaign- Gasbeton Gasbeton drilling: Ct = 4 Vt = 10 Cr = 1 Vr = 18

23. Test campaign- Gasbeton Drill Rotation speed levels Drill Translation speed levels

24. Preliminary Results • SD2 could be used as a scientific instrument in order to retrieve qualitative mechanical information about comet soil • The procedure about the soil analysis is both time and power consuming • Several mission plans need to be uploaded • Several laboratory tests must be implemented: • The database about different soil mechanical characteristics • The correct sequence of drilling test in order to perform the test in best way without risk • It could be useful in case of some failure of other experiments (backup solution)

25. SD2: Status and On Comet ScienceP. Di Lizia, F. Malnati, P. Francesconi, A. Ercoli Finzi, F. Bernelli-Zazzera Aerospace Engineering Department