1. VIRTIS STATUS REPORT The VIRTIS Team
Rosetta SWT #28 ESOC May 2010

2. VIRTIS Team Status
VIRTIS Science Team meeting was held May 10th – 12th in Paris (CNES Salle de l’Espace).
Pierre Drossart resigned as French National Team Leader, due to his new duties as director of LESIA, in favour of Stephane Erard.
During the ST we defined working groups mainly to
Prioritized the VIRTIS scientific objectives and verify that these are properly addressed in the Science Theme Table
Provide an observation strategy to achieve the scientific objectives
Publications based on flight data:
Tosi et al. The light curve of asteroid 2867 Šteins measured by VIRTIS-M during the Rosetta fly-by. PSS 2010
Coradini et al., Martian atmosphere as observed by VIRTIS‐M on Rosetta spacecraft, JGR 2010

3. VIRTIS Anomaly Reports (1)
This was the critical one; has been closed by the new S/W upload
The version 4.1 installed has introduced improvements in the data management which makes the data transfer to the S/C faster and thus remove the jam at the exit buffer.
Proper operations have been verified during PC10 and also during the Earth Swing-By#3.

4. VIRTIS Anomaly Report (2)
This was due to a wrong TC sent to the instrument, during PC10
Incorrect window settings for CCD when using a full window acquisition mode
In the future shall be corrected using an automated procedure with parameters consistency verification

5. VIRTIS Anomaly Reports (3)
This loss of synchronisation only happened twice during the two S/W uploads performed so far.
In particular after the instrument entered the Safe Mode and the command EEPROM Status was issued.
Not critical, we shall investigate during the hibernation phase

6. AR Closure VIR-IAS-TN-016
We issued the technote VIR-IAS-TN-016 describing the rationale to close AR-131 and AR-176.
For AR-172 (non critical) we have proposed a workaround solution.

7. PC12 Outcome
During PC12 we performed a verification of alignment of the slit with the Y axis
Repetition of the alignment performed during PC4 when we missed one point
Full scan range
In pitch
Slit size in yaw
VIRTIS did the same operations done in PC4 but…

8. PC04
This was the outcome of PC04
PC04

9. PC12 S/C scan was started with a positive pitch
Misunderstanding probably due to a different axis definition in the OBR
PC12

10. PC12 – Vesta Observation
VIRTIS operated along with Osiris to observe the asteroid Vesta on the 1st of May, in support of the Dawn mission.
Conditions were critical as Vesta distance from Rosetta was 0.28AU equivalent to 1/20th of a VIRTIS pixel and its visual magnitude was 3.9 – 4.
Nevertheless we made an effort to obtain two light curves:
First light curve optimised for IR observation; IRexpo 3sec, CCDexpo 1.3sec
Second light curve optimised for VIS observation; IRexpo 2sec, VISexpo 16sec.
15 lines around WAC Boresight
Only 2-4 DNs in a very limited spectral range of the VIS channel, with the longest integration time, were detected
This means the pointing was correct but the signal level too low to detect a decent spectrum

11. CPCCR Status (RO-SGS-PL-0001_3_a_Rosetta_CPPCR_2010Jan28)
R_VR002 Improvement of the efficiency of the compression S/W routines
It has no impact whatsoever on the operability of the instrument
Would require a relevant S/W development and a full S/W upload;
it will not be implemented and shall be dropped
R_VR007 Check of alignment of VIRTIS-M with S/C y-axis
Although not fully successful during PC12 the data we have collected in PC04 and PC12 are sufficient to achieve the goal of this measurement
R_VR001 (Interference Test), R_VR003 (VR-H boresight calibration refinement), R_VR005 (VR SW patch) all CLOSED

12. Atmosphere Observations VIRTIS-H
CO2 Non-LTE emission observed by VIRTIS-H ROSETTA on Earth (ESB1, ESB2, ESB3), Mars (MSB Feb. 2007) and Venus (Venus Express regular limb observations since Apr. 2006).
We measured abundances as well as limb profile
Radiances in mWm-2sr-1/ mm
Earth (ESB2)
66 km
79 km
89 km
100 km
~10-2 to mbar
Whole CO2 band,
Averaged from 4.2 to 4.4 mm

13. Mars VR03 = S/C scan; start 24/02/2007 at 21:50 ends at 22:10
Longitude coverage 5E to 185E
Latitude coverage: full disk (slit = 1.1 Mars Disk size)
Spatial resolution 30km at Nadir
Radiances in mWm-2sr-1/ mm
~10-3 to 10-9 mbar
Altitudes
73 km
110 km
149 km
188 km
Whole CO2 band,
Averaged from 4.2 to 4.4 mm

14. Venus
Limb observations : regular limb scans at most latitudes and solar zenith angles
Example : observations of 2008/10/29 Orbit 922
Earth, Mars and Venus CO and CO2 Mixing Ratio as well as Kinetic Temperature retrieval
Radiances in mWm-2sr-1/ mm
~10-3 to 10-9 mbar
Altitudes
98 km
107 km
116 km
126 km
Whole CO2 band,
Averaged from 4.2 to 4.4 mm
100 km

15. Earth Observation VIRTIS-M
Fig1. VIS channel; spatial resolution of about 50 km. RGB imaging (0.44, 0.55, 0.7μm).
Fig 2 VIS Channel; contrast enhanced image (0.474μm, 0.785μm, 1.0μm).
Fig 3 VIS Channel; contrast enhancement of chlorophyll absorption feature.
Fig 4 IR Channel; and Radiation emitted from the night side clearly shows up in this image. The cyan spots are high altitude clouds, while Oceans appears in red having a thermal emission and inertia larger than the landforms (in pink).
Fig 5. Thermal emission region at 5.0 μm; the Earth looks fairly uniform on the day and night side. The northern American continent (in the top-left quadrant of the image), mainly at night and during the winter season, appears as the coldest area of this image (in blue).

16. Earth Observation VIRTIS-M
Highest resolution images of the north-west coast of Africa, including Morocco, Gibraltar, Canary Island and the Atlantic ocean.
Top panel VIS true colors,
Bottom panel IR false colours

17. Classification of surface units
VIRTIS-M image capabilities allows to classify different surface units according to certain spectral properties.
LAND MASK: (R707 / R527) ≥ 1.39
OCEAN MASK: : R758 < 0.04
THICK VEGETATION MASK: (R713 / R685) ≥ 1.18
LOW CLOUD MASK: R758 ≤ (after removal of Land, Vegetation and water)
HIGH CLOUD MASK: R758 > (after removal of Land, Vegetation and water)

18. Classification of surface units
Average radiances in the visible region
Average radiances in the infrared region

19. Lutetia Dynamic Rehearsal
VIRTIS goal has been to measure the temperatures level reached several hours after the flip manoeuvre to verify the impact of the sun illumination on VIRTIS radiators.
The obvious impact is on the target thermal emission measurements which will be affected by a large instrument temperature (spurious signal).
The ME and the two PEM have been powered on, to be able to get internal H/K temperatures during the illumination phase.
The ME has been powered on from 19:00 of 14th March 2010 until 01:40 of 15th March 2010.
Rosetta - Sun distance : AU (Lutetia flyby: 2.71 AU)
Rosetta-Earth distance: 0.84 AU (Lutetia flyby: 3.03 AU)
Sun-Spacecraft-Earth Angle: deg (Lutetia flyby: 19.3 deg)

20. VIRTIS-M Temperatures during the dynamic rehearsal
The radiator temperature and the ledge temperature, which is connected by thermally insulated cylindrical rods to the base plate, are the most affected by the Sun exposure

21. VIRTIS-H Temperatures during the dynamic rehearsal
Internal parts of VIRTIS-H have similar behaviour as VIRTIS-M
Fig. 2

22. Extrapolation to Lutetia
If the starting conditions are similar to the Dynamical test the flip will not affect the
VIRTIS measurements during the Lutetia fly-by
Lutetia Dynamic Rehearsal
Lutetia Flyby
Flip
Max(263’) CA
CA +30’
Radiator Temp (M)
137,2
149,2
147,9
147,7
142,1
141,6
Ledge Temp (M)
141,7
152,4
152,8
146,1
146,3
Shutter Temp (M)
139,0
142,2
143,2
143,9
140,3
140,7
141,0
Spect Temp (M)
139,4
145,2
145,7
141,8
142,0
Tele Temp (M)
138,7
142,4
143,3
140,2
140,6
140,8
SU Motor Temp (M)
145,0
141,3
141,4
Temp Prism (H)
138,8
145,6
146,0
Temp Cal S (H)
138,4
144,8
145,3
141,2
Temp Cal T (H)
136,8
142,8
143,7
139,3
139,6
139,7
Temp Shut (H)
136,0
142,3
138,6
Temp Grating (H)
134,7
141,9
137,4
137,7
Temp Obj (H)
138,3
143,0
143,5
139,8
140,4

23. Instrument Thermal environment
It is essential to interact with RMOC/RSOC to have info on S/C orientation and hence S/C internal temperatures during the planning phases.

24. END