Instrument Overview                                                       
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 Overview and accommodation                                                   
 The VMC consists of one unit that houses the optics, CCD and readout         
electronics (CRE), digital processing unit (DPU), and the power converter     
(POC). A Peltier element connected to the bottom of the CCD will be           
used to cool the detector. In order to avoid moving parts (filter wheel) the  
camera is designed so that four objectives (channels) share a single CCD. The 
stray light protection is provided by external and internal baffles. The VMC  
is mounted on the +Y wall inside the spacecraft.                              
The image data from CCD are read out by CRE and sent to the 1 Gbit mass       
memory integrated within the DPU. This DPU has a so-called 'system-on a chip' 
(SoC) approach, which integrates all DPU functions into a single chip and     
therefore results in a miniaturised implementation. The processor is based on 
a SPARC V8 compatible core, implemented in a radiation                        
hardened Xilinx Virtex FPGA. Before image data is sent to spacecraft via high 
speed IEEE 1355 interface, different image processing functions (e.g.         
flat-fielding or JPEG2000 compression) can be done in real time or offline.   
All VMC internal functions can be configured by the build-in On-board         
Command Language OCL, which allows the execution of user definable            
scripts in parallel working virtual machines.                                 
                                                                              
                                                                              
 Science Observations in Orbit                                                
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 In flight the VMC will have several operation modes to cover all possible    
observation goals and conditions. The modes are: pericentre, transmission,    
monitoring, and limb.                                                         
 Pericenter mode                                                              
 The pericenter mode will be used to study small scale dynamics and the fine  
cloud structure with high spatial resolution. It will be used when the        
spacecraft is within 250-10,000 km from the planet. At such short distance    
VMC will be the only imaging instrument. The images collected during a        
pericentre pass will be stored in the VMC internal memory and send to the     
spacecraft afterwards in transmission mode.                                   
 Monitoring mode                                                              
 The monitoring mode will be used to study the global atmospheric dynamics    
from distance for relatively long time: ~8 hours in ascending arc of the      
orbit or ~2 hours in the vicinity of pericentre.                              
 Limb sounding mode                                                           
 In the Limb mode, VMC will study vertical structure of atmospheric hazes     
above the clouds.                                                             
                                                                              
                                                                              
    Investigators and Other Key Personnel                                     
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    Principal Investigator:  W. Markiewicz, MPS Lindau, Germany               
                                                                              
    Data Processing Manager: T. Roatsch, DLR Berlin, Germany