PROBA-3 is a mission devoted to the in-orbit demonstration (IOD) of precise formation flying (F²) techniques and technologies for future ESA missions. It is part of the overall ESA IOD strategy and it is implemented by the Directorate of Technical and Quality management (D/TEC) under a dedicated element of the General Support Technology Programme (GSTP).
PROBA-3 will fly ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun) as primary payload, which makes use of the formation flying technique to form a giant coronagraph capable of producing a nearly perfect eclipse allowing to observe the sun corona closer to the rim than ever before. The coronagraph system is distributed over two satellites flying in formation (approx. 150m apart). The so called Coronagraph Satellite (CSC) carries the camera and the so called Occulter Satellite (OSC) carries the sun occulter disc.
A secondary payload will be embarked on the occulter satellite; it consists of the DARA solar radiometer.
The proposed PROBA-3 Coronagraph System (ASPIICS) will be the first space coronagraph to cover the range of radial distances between 1.08 and 3 solar radii where the magnetic field plays a crucial role in the coronal dynamics, thus providing continuous observational conditions very close to those during a total solar eclipse, but without the effects of the Earth’s atmosphere. ASPIICS will combine observations of the corona in white light and polarization brightness with images of prominences in the He I 5876 Å line.
ASPIICS will provide novel solar observations to achieve the two major solar physics science objectives: to understand physical processes that govern the quiescent solar corona, and to understand physical processes that lead to coronal mass ejections (CMEs) and determine space weather.
The PROBA-3 coronagraph optical design follows the general principles of a classical externally occulted Lyot coronagraph. The external occulter (EO), hosted by the Occulter Spacecraft (OSC), blocks the light from the solar disc while the coronal light passes through the circular entrance aperture of the Coronagraph Optical Box (COB), accommodated on the Coronagraph Spacecraft (CSC).
ASPIICS is built by a European consortium led by CSL, including more than twenty partners from seven countries (Belgium, Poland, Romania, Italy, Ireland, Greece, and The Czech Republic) under the auspices of the European Space Agency’s General Support Technology Programme (GSTP) and the Czech Prodex Programme. The expected launch date is in 2018.
The Image Data Compressor (IDC) is implemented in the RTAX2000 FPGA which is a subassembly of the Data Processing Unit (DPU) of the Coronagraph Control Box (CCB) of the ASPIICS Coronagraph System, which is designed to compress blocks of raw coronagraph image data (64 x 64 pixels) based on CCSDS 121.0-B-2 algorithm enhanced with a) 2D second-order predictor, and b) variable bit-scraping capability.
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