1Scientific mission scenarios as of January 2010

Scientific mission : feasibility, scenarios

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Scientific proposals■Following the call for proposal of 2006 by our PIs, about 80

scientists have submitted a request■Today : 148 requests from the scientific community■Some considerations :

Reminder : An “image” corresponds to a piece on earth of 27 kms * 27 kms a site is a piece on earth, of at least one image, with, when any, a required

scan angle. Those which are longer than 2 images (54 kms long) are called “composite sites”

Some scientists have submitted many sites For instance : a scientist proposes 26 sites

Some geographic places are requested with different scan angles by the scientist

For instance : TAPAJOS, in South America, is requested at Nadir, forward, and backward -> counts for 3 sites

Some sites are requested by different scientists For instance : ARCACHON is requested by two different scientists

Composite sites were created to scan close sites For instance; SLOVENIA 2 and SLOVENIA 3 were gathered in a single

composite site : SLOVENIA 23

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Statistics■The request :

Number of original request registered since the 2006’s call for proposal :148

Programming artifacts (composite sites gathering scientists’ requests) : 1 -> number of sites registered in the system : 149

Number of duplications : -12 -> number of sites to be processed : 137 Note : number of geographic places concerned : 126

■ Actually achieved (17th iteration) Number of scanned sites : 95 (reminder : mission spec : 50 sites, system spec :70 sites) Out of reach : 19 Discarded because cinematic conflict : 21 Discarded because simulator anomaly 2 Total : 137

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DistributionSites processed vs scanned

0

10

20

30

40

50

60

70

processed 3 17 11 30 11 62 3

scanned 2 11 8 24 6 41 3

Oceania Asia AfricaNorth

America

South

AmericaEurope Israel

3 composite sites -> 26 images

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Main constraint applying : satellite agility

■ Most significant example : rev 17 : too many sites to scan

Example of cinematics conflictExamples of cinematics conflict resolutions

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Concerns to be worked out■Rev 17 still too loaded wrt to the size of the auxiliary data

buffer on board-> no work around possible. A few (4 or 5) sites will have to be discarded

■Poor S-band coverage to upload the telecommands (2 passes (+2 as back up) per week). Work around to discuss : number of passes to be increased

■Note : if the orbit is 666 kms high (3 day repetitivity) : many more (25%) scans possible. Only one site scanned at 720 km (2 day repetitivity) cannot be scanned at 666 kms.

■ final selection of the sites : end of 2010 (launch – 18 months). Pre-requisite :

Orbit choice (depends on the launcher) Real constraints applying on the use of the system given by MBT

(see here-over)

7Scientific mission scenarios as of January 2010

Additional slides

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Also sprach Zarathustra :« use the system as designed, not as

specified »

■ Essential : the system will be used as designed, not as specified, according to the actual constraints captured in the MOCD :

■ Constraints identified today :1. Satellite agility2. Max duration per orbit in camera « hot » modes3. Max ON/OFF number of the focal plane electronics4. OBR size5. Auxiliary buffer size6. Command file size7. Command upload max duration8. Max tilt (for image quality purpose)9. Power balance10.Thermal balance

■ Caution : this rationale leads to have more images per orbit and per cycle than originately specified in the System Requirement Document.

System spec System design ConstraintsCaptured in user manual(s) and/or MOCD

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The regular ASD in VM1 : findings

■ Departing point : the SiteDefinitionSet file

■ Inhibition of non "S" sites

■ Inhibition of Tsukuba and Uzbekistan to work around anomaly # 42 on VESTALE

■ 3 kinematic conflicts found : On rev 2 (Central Europe). Kinematic conflict solved by discarding : Gilching

Free scan angle, Gilching at +10°, Gilching at -10°, Bily Kriz at +10°, Bily Kriz at -10°, San Rossore at +10°, San Rossore at -10°

On rev 7 (South-West USA). Conflict solved by discarding : STSfree, Gray Ranch

On rev 17 (Western Europe). Conflict solved by discarding : Geldersse at +10°, Geldersee at -10°, Hasselt, Brabant, Hesse, Grand Morin, Laegern, Dombes, Castella, Arcachon, Sauterne, Le Bray

On rev 19 (South America). Conflict solved by discarding : Tapajos at free scan angle

■ ASD REGULAR for VM1 : VE_VM01_MPL_ASDEFN_R_REGULAR_NMNL_0017.EEF

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Compliance with the constraints

Constraints Compliance of the mission profile at CDR

Satellite agility See SRDS Compliant. Use of VESTALE guarantees that the satellite’s agility capacity is taken into account

Max duration in hot modes

Max 4 mn Compliant. Max is : 228 sec on rev 17

Max ON/OFF on the FPE

15 000 per year, total of 45000 compliant :- about 14500 ON/OFFs per year in VM1 (150 scientific cycles * 94 ON/OFFs per cycle)- Total estimated for the overall mission : 40000

OBR size 108 GBytes + 12 GBytes margin compliant

Auxiliary buffer size

400 KBytes per orbit for the scientific mission :500 – 50 (allocated for IHET) – 50 (allocated

for housekeeping)

not compliant on rev 17 : 485 Kbytes recorded on rev 17

Scientific command file size

200 Kbytes compliant

Command file upload time

7.3 mn for upload (rev 9, which is a back up of rev8))

Regular ASD : compliant. Not compliant if we want to have a 24 hrs overlap in the upload and two uploads per week

Max tilt Recommended to keep a max cone angle of 40° Compliant

Power balance Average Depth of Discharge (DOD) shall be less than 15%

Nominally the Battery momentary Depth of Discharge (DOD) shall not exceed 30%.

In exceptional cases the DOD shall not exceed 50%.

The battery should be fully charged at intervals of least once every 24 hours.

Analysis was done for VM3.Considering sequences of 3 orbits with 4 mn imaging followed by 1 rev with IHET over 40

mn, the EPS is stable.The power is balanced in VM1 (poor probability to be unbalanced)

Thermal balance   Thermal is balanced

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Present scientific profile versus original specification

Number of scans/images

Specified in the SRD Present scientific profile

per rev Max 12 scans of max 2 images each

SRD not respected on :-Rev 2 (Central Europe) : 18 scans-Rev 17 (Western Europe) : 22 scans-Other revs are compliant with SRD

per day Max 80 images (one image is : 27 kms * 27 kms)

Regular scientific mission is compliant

per 2 day cycle Max 70 scansMax 140 images

Regular ASD : 95 scans, xxx images

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The regular ASD in VM3 : findings

■ Departing point : the SiteDefinitionSet file

■ Inhibition of the sites accessed from revs : 4, 8, 12, 16, 20, 24, 28, 31, as thse revs are used or orbit maintenance by the electric thrusters IHET

■ 2 conflicts found : On rev 2 (Central Europe). Conflict solved by inhibition of : Bugac On rev 18 (Western Europe). Conflict solved by inhibition of : Hesse, Laegern,

Dombes, Grand Morin, Brabant, Hasselt, Valdala, Camargue

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VM3 orbitzoom on Europe

Rev 2Rev 18