1. OSIRIS Solar System Simulator
Contributed by:
Ivano Bertini and Walter Sabolo
15 November 2005
Agay, OSIRIS Team Meeting

2. Agay, OSIRIS Team Meeting
Summary - 1
The OSIRIS Solar System Simulator (OSSS) is a collection of IDL and Matlab programs to determine which Solar System (SS) objects (at present Sun, planets and known asteroids) are detectable by the cameras during the different mission scenarios, and to analyse the geometry of the flyby phases.
OSSS computes the geometry of the Solar System as seen by OSIRIS at the date of interest, giving as output all useful geometric and photometric data.
15 November 2005
Agay, OSIRIS Team Meeting

3. Agay, OSIRIS Team Meeting
Summary - 2
The knowledge of the stellar background (e.g. by using the USNO catalog) where the asteroids are projected during the approaching and leaving fly-by phases is of vital importance in order to achieve the scientific objectives of OSIRIS instrument.
It will help the identification of the targets and their astrometry and photometry, determining a priori which standard stars have to be used to calibrate the data.
Another important point is determining the presence of known Solar System small bodies inside the field of view (FoV) of the instrument. In case of an object detection which is not a star, we have to check if it is a new asteroid (or comet) or an already known one.
15 November 2005
Agay, OSIRIS Team Meeting

4. Agay, OSIRIS Team Meeting
Summary - 3
Moreover, the knowledge of every known SS object in the FoV of OSIRIS images helps in studying the camera performances using the in-flight images, and it is therefore useful for calibration purposes.
The software package allows also to study in detail the geometry of the flyby phases helping in planning the observational campaign. It is also possible to investigate the various mission phases for small objects that are close to the S/,C providing important hints for target opportunities and redefinition of the mission operation plan.
More details can be found in the OSSS User Manual, in I. Bertini’s PhD thesis, and in W. Sabolo Master Thesis.
15 November 2005
Agay, OSIRIS Team Meeting

5. Excerpt from Bertini’s Thesis
The following slides are taken from Bertini PhD Thesis
15 November 2005
Agay, OSIRIS Team Meeting

6. A new model of cometary dust and the Wide Angle Camera of the Rosetta mission
Bertini Ivano
Supervisor: Prof. Cesare Barbieri
Co-Supervisor: Prof. Nicolas Thomas
15 November 2005
Agay, OSIRIS Team Meeting

7. Rosetta mission and OSIRIS
Rosetta = ESA cometary mission
Study origin of comets, relation between comets and IS material, implications origin of the SS. Study of Asteroids.
Reach and escort (~1yr) comet 67P/C-G, flyby with 2875 Steins & 21 Lutetia (MB asteroids).
OSIRIS = main camera system on-board
WAC: ~ 12o X 13o, ~ 21’’/px
NAC: ~ 2o X 2o, ~ 4’’/px
15 November 2005
Agay, OSIRIS Team Meeting

8. The Calibrations of the WAC using in-flight images
Calibrate the instrument with
in-flight data
Limiting Magnitude of the WAC (Green, Red)
WAC Geometric Distortion (correction algorithm determination) – Identification of stars on the frame, future studies of real 3D shape of the targets reconstruction
15 November 2005
Agay, OSIRIS Team Meeting

9. The limiting m of the WAC
Determination of the WAC limiting m (Green and Red filters) using in-flight images (S/N~5)
Identification of stars on sub-frames close to the WAC boresight (1002px) with commercial software Astrometrica
Comparison with theoretical limiting m
Green: ~ 11 (30s) ~ 13 (120s)
Red: ~ 12 (5s) ~ 13 (15s) ~ 14 (30s) ~ 14 (60s)
15 November 2005
Agay, OSIRIS Team Meeting

10. Agay, OSIRIS Team Meeting
Geometric Distortion
x’m-xt
(α,δ)cat  (x,y)frame
x=A+Bα+Cδ y=A‘+B‘α+C‘δ
Step1: (x,y) = g(α,δ) (identification 6 stars)
Step2: (xm,ym)=f1,2(x,y)
f1,2є O(3) found with identification 1420 stars
Results: allows identification of bright stars in the FoV
y’m-yt
15 November 2005
Agay, OSIRIS Team Meeting

11. Conclusions & Perspectives
STILL ON-GOING
OSIRIS
CALIBRATIONS
PERSONAL
CONTRIBUTION
FINAL CALIBRATION REPORT ENTIRE OSIRIS TEAM
15 November 2005
Agay, OSIRIS Team Meeting

12. Agay, OSIRIS Team Meeting
The OSIRIS Simulator
Orbital Propagator re-building the geometry of the SS in a S/C-centred RF at the date of interest (asteroids, planets, Sun)
Scientific Purposes:
Calibrations (stellar background determination)
Fast identification of the targets
Search for small satellites of target asteroids (OSIRIS scientific goal)
Observational strategy for Asteroid Flybys
Mission operation plan definition
15 November 2005
Agay, OSIRIS Team Meeting

13. ASTEROIDS Orbital Elements (MPC Orbital Database) T0
SUN and PLANETS positions
(JPL DE2000) Ti
Orbital Propagation
Cowell Method
S/C position
(FDG) Ti
Asteroids+Sun+Planets
S/C-centred positions Ti
ASTEROIDS positions Ti
Geometric and Photometric data:
m, (α,δ), PA, SEA
WHAT IS DETECTABLE & WHERE IT IS
Definition Mission
Operation Plan
FLYBYs
Observing Strategy
15 November 2005
Agay, OSIRIS Team Meeting

14. Results Simulator: asteroid flybys
Detailed analysis flyby geometry
Observations during approaching phase (leaving phase - straylight)
Definition observing strategy searching for asteroid satellites (Hill’s sphere analysis ~ 24h before flyby)
Determination known asteroids and planets perspectively in the FoV
Determination close asteroids beside mission targets (new mission operation plan?)
15 November 2005
Agay, OSIRIS Team Meeting

15. Conclusions and Perspectives
Software package to analyse Rosetta mission phases (personal application to asteroid flybys – supervision Sabolo, Master CISAS student: application first Earth gravitational assist) and help calibrations has been realized
Perspectives:
application to future mission phases (planetary gravity assists, comet approach, search for close targets during active phase: eventual opportunity targets)
easy to update with new trajectory and orbital elements data
15 November 2005
Agay, OSIRIS Team Meeting

16. Simulator + GD Correction
Hunting for asteroids in OSIRIS images
15 November 2005
Agay, OSIRIS Team Meeting

17. Agay, OSIRIS Team Meeting
Recent Additions
Recently a sub-program has been added that reads some results from the Asteroids main version and the Asteroid-flyby version and produces a list of asteroids close to the S/C, independently of the viewing direction, at the date of interest. This can be useful in the search of target opportunities during the mission phases with the consequent redefinition of the mission operation plan.
A preliminary User Manual has been written (October 2004).
15 November 2005
Agay, OSIRIS Team Meeting

18. A graphics display from Sabolo Thesis
(actually, it is a frame of a movie)
15 November 2005
Agay, OSIRIS Team Meeting