Space Environment and Protection Group

Overview

Designing electronic systems for space is more complex than designing equivalent systems for terrestrial use. Space poses some unique challenges - the environment is very hostile and space systems need to work in little or no atmosphere, across a wide temperature range, and under continuous attack by radiation in the form of protons, heavy ions, and electrons from the sun. Fault tolerance and operation under these conditions can be particularly tricky. Understanding ‘where’ and ‘when’ a satellite will operate will form the beginnings of an effective design.

Missions

It is possible to perform environmental tests such total ionising dose experiments in space. The STRaND mission, run jointly by our Centre and Surrey Satellite Technology Ltd (SSTL), includes a number of tasks ranging from Android programming to systems design to radiation testing.

For the last 10 years, SSTL has been operating the retired European Space Agency (ESA) pathfinder satellite GIOVE-A. The satellite was the first European satellite to be launched into the demanding MEO radiation environment and is now providing valuable in-orbit data from an altitude of 23,300km. The Merlin radiation monitor on board has collected a 10-year record for the MEO orbit and data analysis at the Surrey Space Centre, supported by ESA.

Collaborative projects

We were involved in collaborative projects in space radiation research including:

The Rad-X project

The Rad-X mission aims to obtain crucial additional data to better characterise the interactions of cosmic rays and solar particles with the upper atmosphere. In this region neutrons and other particles are generated (think of the large hadron collider)  which can pose a hazard for modern aircraft control systems located at lower altitude where they also give passengers and crew doses of radiation, especially during certain space weather events.

In future aircraft engineers want to  design aircraft to fly significantly higher than they do currently, where conditions are much more ‘space-like’ and hence we need better data and models for this region of the atmosphere.

An experiment to measure radiation levels high in the stratosphere was successfully carried aloft to an altitude of 125,000ft (38km) as part of the NASA Rad-X stratospheric balloon payload. This is more than three times higher than commercial flight altitudes, and twice the cruising altitude of the famous Concorde.

The balloon was launched from the NASA Columbia Scientific Balloon Facility, New Mexico, USA, and spent about 24 hours afloat taking measurements. The payload remained at 125,000 feet for about eight hours and then it descended to about 80,000ft for the remainder of the time to collect data at different altitudes. The payload was successfully recovered in order to analyse the data collected.

We have been funded by NASA to participate in this mission.

Please visit the Rad-X project website or contact Keith Ryden and Dr Alex Hands for further information. Read our news piece on reaching the stratosphere on the NASA Rad-X balloon.

SPACESTORM

SPACESTORM is a collaborative project funded by the European Union's 7th Framework Programme to assess the impact of an extreme space weather event on satellite systems and components, model space weather events and mitigate adverse effects on satellites. The project builds on the forecasting of space weather started by the FP7 SPACECAST project.

Other SPACESTORM partners include the British Antarctic Survey, ONERA, Finnish Meteorological Institute and DH Consultancy.

Research areas

GEO radiation dose analysis

The GEO long-term dose analysis study investigates the effects of space radiation released through extreme events.

GEO and MEO data (charging and dose of radiation) are gathered. The experimental data is analysed at the SSC and the findings are used to develop and validate new models such as:

• The MOB-DIC electron belt model for internal charging
• Development of real-time risk indicators for charging (from in-orbit data)
• Loss of electrons from the inner belt.

Using the Geant4 toolkit

Geant4 tools used by SSC include MULASSIS and GRAS.

The multilayered shielding simulation software tool (MULASSIS) was developed as part of the European Space Agency (ESA) activities in the Geant4 collaboration. It is based on the Geant4 M-C simulation toolkit developed by a large international collaboration lead by CERN. The software is used for radiation fluence, dose, and effects analysis.

Geant4 radiation analysis for space (GRAS) is a Geant4-based tool that deals with common radiation analyses types (TID, NIEL, fluence, SEE, path length, charge deposit, dose equivalent, equivalent dose and more in generic 3D geometry models.

Atmospheric radiation measurement

In-flight measurements include the new MAIRE model (with RadMod Ltd) and validation using flight data.

SEE research for avionics include:

• Contributing to IEC standards (extreme events)
• Risk assessment for nuclear industry
• Public heath extreme case assessments
• Chip-IR collaborations.