Solar Orbiter

Solar Orbiter

Development of the Data Processing Unit for the Solar Wind Plasma Analyser instrument, part of the Solar Orbiter mission.

LAUNCH DAY: Sunday 9 February 2020 h 11,15 p.m. from Cape Canaveral, Florida (h 05,15 a.m. - CET, Monday 10 February). To learn more and follow the lauch visit the offial ESA Website

The Sun and its extended atmosphere, the heliosphere, is a very complex system. The inner planets of the Solar System, including the Earth, lie within the heliosphere and its influence can sometimes be clearly detected by researchers and scientists during phases of high solar activity.

The Solar Orbiter mission, part of the European Space Agency’s Cosmic Vision program, is a new mission  intended to explore the Sun and its heliosphere to improve our understanding of Space weather and its effects on Earth. It will observe the Sun and collect measures in an orbit ranging from 0.28 (closer than Mercury) to 1.4 AU (the Earth is at 1 AU). In addition, this mission will provide with a natural laboratory to study processes in fundamental physics, astrophysics and plasma physics that cannot be studied elsewhere in such detail.

Ten sensors on-board

The scientific payload of Solar Orbiter is composed of ten experiments. Among the instruments, the Solar Wind Plasma Analyser suite (SWA) will provide comprehensive in-situ measurements with very high temporal resolution of solar wind’s particles composition (ions, protons and electrons) and velocity distributions. The final goal is to establish the fundamental physical links between the highly dynamic magnetised atmosphere of the Sun and the solar wind in all its quiet and disturbed states.

SWA is in turn composed of four sensors devoted to the analysis of particles at different energy levels. Two of the instruments measure electrons (Electron Analyser Sensor, or EAS), one measures protons and alpha particles (Proton Analyser Sensor, or PAS) and one measures heavy ions which are a minor constituent of the solar wind (Heavy Ion Sensor, or HIS). The instruments will independently measure 3D velocity distribution functions, evaluate density, speed, temperature and thermal flux of the plasma composing solar wind.

Europe and Italy cooperated at the SWA experiment providing the Data Processing Unit (DPU) through a project having Roberto Bruno of INAF Institute for Space Astrophysics and Planetology (IAPS) as the scientific responsible and SWA Co-Principal Investigator.

The SWA DPU project has:

  • Provided single interfaces to the spacecraft for power, telemetry, tele-commands and power management;
  • Provided commands management, data handling and data compression for the four instruments;
  • Provided the Electrical Ground Support Equipment (EGSE) for the instrument suite;
  • Contributed to the on-board data compression SW definition.
  • Contributed to the implementation of the Mechanical Ground Support Equipment (MGSE);
  • Contributed to sensor definition;

The role of Planetek Hellas

Planetek Hellas personel worked in this activity in the premises of Planetek Italia in Bari, where  they had the opportunity to gain the know how related with  on-board software design and development.

In specific the personel of Planetek Hellas focused on  the EGSE SW layer and on the on-board software for scientific data processing.

They were involved in two main roles: the first was the development of the scientific software on-board (including scientific data processing and compression, as already mentioned) and the second is the design and development of software sub-system in the Electrical Ground Support Equipment (EGSE).

Both these aspects inherit from SpacePDP experience: modules already developed have been customised in order to accommodate for the SWA suite specific needs. The Data Processing Unit on-board is based on a LEON2 processor module (as SpacePDP), and includes as well the Space Wire interfaces (again part of SpacePDP). The EGSE itself on the other hand is aimed to the DPU verification and thus includes a customisation of the FPGA module implementing Space Wire core. It has to simulate in fact DPU’s external interfaces which the interaction with the DPU pass for.

SWA sensors collect the particles composing the wind; one of the main task in the on-board data handling is the evaluation of “moments” in phase space, i.e. mathematical expressions able to characterise wind considered as a plasma flux. However, as evidenced by the scientific team, such a calculation needs of a significant percentage of total computational resources, so we are developing optimal implementation custimised to the specific data involved. The same approch has been adopted in order to define which is the compression techniques best fitting to data.

project information

NASA, ESA and Italian Space Agency
Application fields:

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