1. ESA UNCLASSIFIED – For Official Use Presentation to INAF on Formation Acquisition and Error Contributions 21/01/2016

2. Proba-3 INAF Update | 21/01/2016 | Slide 2 ESA UNCLASSIFIED – For Official Use Nominal Orbit 1.Orbit period 19h38m 2.DTM1: a.Perform V CSC propulsion b.Align s/c, acquire CLS & FLLS c.Perform V CG correction d.Re-aquire FLLS e.Achieve Sun-Pointing 3.DTM2: a.Align s/c, acquire CLS & FLLS b.Perform V HPGP 4.FAQ: a.Align s/c, acquire CLS & FLLS b.Formation coarse & fine acquisition using CG

3. Proba-3 INAF Update | 21/01/2016 | Slide 3 ESA UNCLASSIFIED – For Official Use Position Errors induced by STR errors 1.In both cases, FLLS gives the same reading. a.STR error not directly observable 2.All attitude errors are multiplied by the distance (150m) 3.Other major error sources: a.Thermoelastic deformation of optical bench b.CCR error c.FLLS meas. error 4.Calibration can remove some of this error Assumed Nominal position Actual position due to STR error

4. Proba-3 INAF Update | 21/01/2016 | Slide 4 ESA UNCLASSIFIED – For Official Use Calibration of FLLS on OSC

5. Proba-3 INAF Update | 21/01/2016 | Slide 5 ESA UNCLASSIFIED – For Official Use Acquire VBS

6. Proba-3 INAF Update | 21/01/2016 | Slide 6 ESA UNCLASSIFIED – For Official Use Acquire FLLS

7. Proba-3 INAF Update | 21/01/2016 | Slide 7 ESA UNCLASSIFIED – For Official Use Move to correct apriori position 1.Incorrect STR-FLLS bias will cause incorrect position

8. Proba-3 INAF Update | 21/01/2016 | Slide 8 ESA UNCLASSIFIED – For Official Use Reduce ISD 1.Calibrate CI-STR 2.Reduce ISD to acquire shadow. 3.Acquire OPSE

9. Proba-3 INAF Update | 21/01/2016 | Slide 9 ESA UNCLASSIFIED – For Official Use Get into approximate correct position 1.Using OPSE to get into approximately correct position 2.May require rotation of OSC 3.Acquire SPS

10. Proba-3 INAF Update | 21/01/2016 | Slide 10 ESA UNCLASSIFIED – For Official Use Calibrate FLLS 1.Once SPS acquired, calibrate FLLS 2.Calibrate at different distances using the OPSE

11. Proba-3 INAF Update | 21/01/2016 | Slide 11 ESA UNCLASSIFIED – For Official Use SPS calibration 1.SPS is expected to be the most accurate lateral position sensor for Coronagraphy 2.SPS is insensitive to attitude errors 3.Without SPS, the FF system is not able to know the position with respect to the umbra with an accuracy better than ~5 mm 4.This has to be taken into account in the SPS error budget and the SPS in- flight calibration approach 5.Maybe the transition umbra-penumbra could be used to calibrate or validate the penumbra intensity profile (based on the knowledge of the distance between the SPS

12. Proba-3 INAF Update | 21/01/2016 | Slide 12 ESA UNCLASSIFIED – For Official Use Are velocity-only measurements useful? 1.Thruster pulse every 20 seconds a.Each pulse introduces acceleration errors due to thruster uncertainty b.Between pulses, there is very little acceleration (on the order of 1e-7 m/s 2 ) 2.Measurement error from HAMS ~700m 3.However, attitude control loop is at 1Hz a.Attitude errors will distort HAMS position measurements (multiplying by distance => 1-2 arcsec = ~1mm error) b.Control loop reacts to STR measurements each second c.=> Noise on HAMS measurements not simply Gaussian Noise 4.Simulation velocity errors ~ 2e-6 m/s a.this is using older PDR simulator b.updated simulator with more realistic models will be worse

13. Proba-3 INAF Update | 21/01/2016 | Slide 13 ESA UNCLASSIFIED – For Official Use Retargeting Manoeuvres 1.Retargeting Manoeuvre a.Rotate target line up to 30 b.Rotate about CSC CoM c.1 metre deflection of OSC = 0.38 degrees rotation of OSC 2.Resize manoeuvre