VENµS Super-Spectral
Camera
Technical Description
Air & Space IMINT Systems Division
General Concept of VENµS
„ Joint ISA-CNES project for scientific mission
„
„
„
„
„
to evaluate remote sensing applications
12 narrow spectral bands in the VNIR range
Bands for vegetation and water monitoring
GSD 5.3 m
Binning on some bands to achieve high SNR
at the expense of resolution
Swath width 27 km
Air & Space IMINT Systems Division
The VENµS Satellite
„ The satellite is being developed by Israel
Aircraft Industries
„ The VENµS Super-Spectral Camera (VSSC)
is being developed by El-Op Ltd at its
Rehovot, Israel facility.
„ The satellite will also carry an experimental
ion propulsion system being developed by
Rafael, Israel
Air & Space IMINT Systems Division
Venµs Spectral Bands
Band #
Equivalent Central
Wavelength [nm]
FWHM
[nm]
1
2
3
4
5
6
7
8
9
10
11
12
420
443
490
555
638
638
672
702
742
782
865
910
40
40
20
20
24
24
16
16
16
16
20
20
Air & Space IMINT Systems Division
Camera Principles
Camera:
„ Reflective Telescope Objective with field correction lenses
„ Focal plane with 4 detector units, each with three separate
arrays
„ Separate narrow-band spectral filters for each array, giving
12 bands in all (11 different bands, two identical for 3-D info)
„ Camera electronics for amplification and digitization of
signals
Part of satellite:
„ On-board memory to store images until they can be
downloaded to ground station
„ RF Transmitter and antenna
Air & Space IMINT Systems Division
Camera Configuration
Air & Space IMINT Systems Division
Focal Plane Configuration
Detector
C C
Detector
AA
Mirror
Block
45mm
Detector B
Detector D
Air & Space IMINT Systems Division
TriT Detector – Schematic Layout
~ 1.4 mm
Blocking Filter
2.0 mm
Tri5Kx32TDI Detector
Narrow-band Filters
8.0 mm
~68.0 mm
24.0 mm
5200x32TDI; 13x13µm pixel
106.5 mm
125 mm
Air & Space IMINT Systems Division
10 mm
Narrow Band Filters
„ High performance interference filters – high
transmittance, sharp cut-on and cut-off
„ Auxiliary blocking filter to improve out-of-band
rejection
„ Coated directly on detector window before
attachment (3 on each detector unit)
Air & Space IMINT Systems Division
Preliminary Filter Design - example
DSW A w ith Band 1 and Band 4
1
0.9
Transmittance
0.8
0.7
Band 1
0.6
Band 4
0.5
DSW A
0.4
0.3
0.2
0.1
0
350
400
450
500
550
600
650
700
750
800
Wavelength (nm)
Air & Space IMINT Systems Division
850
900
950
1000
1050
1100
1150
Electronics Concept
„ Detector outputs are amplified and digitized (10
bits)
„ Camera controller to manage operation of all 12
channels
„ Power supply converts satellite power to
voltages needed
„ Digital data sent to on-board storage for later
transmission
Air & Space IMINT Systems Division
Thermal Control
„ Temperature of Optics, structure, focal plane
controlled within narrow limits
„ Thermal shield around telescope to isolate from
external effects
„ Thermal interface to satellite bus through two radiator
plates
„ Control allows telescope to point to Earth or space
indefinitely
Air & Space IMINT Systems Division
Interface to Satellite
„ Simple mechanical interface - flexures
„ Simple thermal interface – radiator plates
„ Simple electronic interface – RS422
Air & Space IMINT Systems Division
Calibration Concept
„ No on-board calibration source
„ Accurate pre-launch radiometric and geometric
calibration
„ Design for high stability
„ Vicarious calibration with known ground sites
„ Periodic calibration using the Moon as source
Air & Space IMINT Systems Division