Optical, Spectroscopic, and Infrared Remote Imaging System
OSIRIS is the scientific camera on board of the Rosetta spacecraft. It is a versatile imaging system designed to address key problems of the cosmogeny of comets by investigating the physical and chemical processes that occur in and near the nucleus.
The investigation of the nucleus itself requires high spatial resolution over a wide wavelength range but with modest spectral resolution. The investigation of the innermost dust and gas coma requires a wide field of view with a selection of narrow band interference filters to image the 2-D gas distribution. OSIRIS consists of two cameras:
Two identical full-frame, 2048×2048 pixel CCDs with 14 mm pixels equip both the NAC and the WAC.
- Narrow angle camera (NAC) with a 2.4×2.4° FOV
Wide angle camera (WAC) with a 12×12° FOV
OSIRIS was pre-selected as a PI instrument in April 1996, to be provided by a European consortium under the leadership of Dr U. Keller (MPAe, Lindau, Germany). Following funding difficulties for the original consortium, ESA was asked to participate in the development of the Data Processing Unit (DPU). The Solar System Division accepted this challenge because its participation in OSIRIS is an important step for future scientific expertise in planetary imaging.
The request to provide the OSIRIS DPU was implemented in the design and development phase by a joint venture between the former Technical and Operational Support Directorate (Payload Systems Division) and the Science Directorate (Solar System Division). This partnership provided the opportunity to direct the development of an onboard payload data processor within the ESA Technological Research programme (TRP) to a specific, real application, thus providing a cost-effective contribution to the Rosetta instrumentation.
OSIRIS DPU Flight model, board level test at EADS/ Astrium
Stiffener plate for DSP circuit board, needed for improved mechanical stability
The DPU consists of two Digital Signal Processors (DSP) modules, a solid state mass memory, and spacecraft and camera interfaces. It facilitates image acquisition from both cameras, image compression and autonomous control of the entire instrument.
OSIRIS DPU flight model, pre- integration
The Solar System Division provided a total of 3 fully-equipped "elegant breadboards" for system testing during the development phase. Furthermore, one qualification and 2 flight models were produced and delivered to the PI institute.
The hardware was delivered with an industry-standard real time operating system (VIRTUOSO) and specific low level device drivers.
- Power consumption: 8W (compressing and transferring data at max. rate) 3.5W (low power mode)
- Total mass: 1.4 kg (electronic boards, excl. housing)
||Rad-hard Temic processor TSC21020, 20 MHz, 60 MFLOPS, data transfer speed from DSP memory to mass memory > 38 Mbps continuous |
||4 Gbit netto DRAM- based |
- 8 kByte (8 bit) PROM (Bootstrap Kernel)
- 256 kword (48 bit) EEPROM (OS, Task Specific Program Modules)
- 256 kword (48 bit) Program SRAM (zero wait state)
- All program memory is latch up and SEU immune
|Local Data Memory
- 4 Mwords (32 bit) fast SRAM image store, latch up and (almost) SEU immune
- 128 kword (32 bit) fast SRAM variables + stack, latch up and SEU immune
- 128 kByte Non-Volatile EEPROM
- Serial command I/F to NAC and WAC
- Serial data I/F to NAC and WAC
- Serial command and data I/F to mechanism controller
- Serial command and data I/F to power converter
- OBDH spacecraft I/F
||DSP board, S/C-interface: Dual cold redundancy|
Mass memory board: Graceful Degradation
|Protection Against Single Event Radiation Effects
- SEL: Latchup detectors for mass memory, else LU immune components
- SEU: Memory Error Correction (SSCDSD)
- DSP Watchdog (two stage)
||Low-Power Mode (program SRAM de-select, partial clock disabling) |
||Standard Real Time Operating System (Virtuoso)|
- The electronic boards of the DPUs were designed and manufactured under the responsibility of Astrium GmbH, Ottobrunn, Germany
- Rosetta was launched in March 2004. First OSIRIS images were received during the commissioning phase in May 2004. They demonstrate the flawless performance of cameras and DPU.
- Key SCI-SO personnel: P. Wenzel (lead, 'double- CoI'), U. Telljohann (technical manager), D. Koschny (deputy), B. Johlander (components procurement)
Last Update: 19 Apr 2011