Space Weather causes years of radiation damage to satellites using electric propulsion

Van Allen belts
The Van Allen belts. Credit: NASA / Van Allen Probes / Goddard Flight Center

The use of electric propulsion for raising satellites into geostationary orbit can result in significant solar cell degradation according to a new study. The extended journey time results in greater exposure to the damaging effects of space weather. Understanding the size of this risk is essential for commercial operators to take steps to mitigate the effects and protect their assets.

The new research by British Antarctic Survey, University of Cambridge, and DH Consultancy – published this month in the journal Space Weather – is being presented at the Royal Astronomical Society’s National Astronomy Meeting today (1 July 2019).

The study concludes that after a radiation storm, maximum solar cell output power could be reduced by up to 8% by the time satellites reach their target destination using electric orbit raising. This is equivalent to the level of damage that would be expected after spending around 15 years at geostationary orbit.

During a radiation storm, charged particles released by the Sun become trapped within Earth’s magnetic field, forming the Van Allen radiation belts which encircle Earth, and collisions with these charged particles causes damage to the solar cells. This degradation is up to 8% of output power in a worst-case scenario, but even in a quiet environment, the study predicts a 1-3% reduction in output.Lead author Alexander Lozinski, a space weather scientist at the British Antarctic Survey (BAS), comments

“Now we understand the level of damage caused by a slower journey into geostationary orbit, commercial satellite operators can plan optimal routes during the mission design and planning phases to ensure the best lifespan for their products”.

In the last four years commercial satellite missions have begun to employ the use of electric propulsion for orbit raising. Without the need to carry chemical propellant onboard, satellite size and mass can be reduced, resulting in significant cost savings. Reducing the size of satellites could make it possible to launch two spacecraft on the same rocket (almost halving the cost of launch). Alternatively, the savings in mass could be used to accommodate additional/larger payloads, enabling increased revenue or greater technical capability.

In a conventional launch the satellite is placed into a geostationary transfer orbit by the launch vehicle and uses chemical propellants to reach geosynchronous orbit. This orbital transfer manoeuvre typically takes a few days. However, when (solely) electric propulsion is used, it can take up to 200 days to reach the target orbit due to lower thrust. This results in satellites spending a longer in the Van Allen belts, where they are exposed to the harmful effects of space radiation.

“We studied three different types of orbit raising and found that although 8% degradation is very high, careful choice of orbit and shielding can reduce this to an acceptable level,” says Lozinski.

“For example, transfer orbits with a high initial apogee (maximum altitude) allow satellites to pass through regions where trapped protons are present, at greater speed, reducing the level of damage from radiation.”

“Commercial satellites with all-electric propulsion were first introduced in 2015” says Professor Richard Horne, Head of the Space Weather team at BAS. “We never expected such a large reduction in power from a radiation storm. The good thing is that this study will help the satellite industry to plan the best orbit which reduces radiation damage”.

Media contacts

NAM2019 Press Office
01524 595 245 or 01524 592 120

Robert Massey
Royal Astronomical Society
Mob: +44 (0)7802 877699
nam-press@ras.ac.uk

Anita Heward
Royal Astronomical Society
Mob: +44 (0)7756 034243
nam-press@ras.ac.uk

Kate Arkless Gray
Royal Astronomical Society
nam-press@ras.ac.uk

Science contacts

Alexander Lozinksi
British Antarctic Survey/University of Cambridge
alezin33@bas.ac.uk

Interview facilities

Media representatives are cordially invited to attend the meeting and can register at no cost. Press room facilities will be available in Faraday Seminar Room 2 for the duration of the conference – from 0900 BST on Monday 1 July to 1500 BST on Thursday 4 July. For free registration for the meeting, please contact the press team via nam-press@ras.ac.uk

Scientists at the conference are also available for interview via both a radio studio and TV studio at Lancaster University; the Globelynx TV network offers broadcast quality HD video to the world’s leading broadcasters and an ISDN line for interviews in a radio booth.

Please book these via the Lancaster University Press Office on +44(0)1524 592612.
 


Notes for editors

Alexander Lozinski will deliver his talk “Evaluation of Solar Cell Radiation Damage during Electric Orbit Raising” on Monday 1 July at 17:45, at the National Astronomy Meeting in Lancaster. More info can be found on the conference website.

“Solar Cell Degradation due to Proton Belt Enhancements During Electric Orbit Raising to GEO” by Alexander R. Lozinski, Richard B. Horne, Sarah A. Glauert, Giulio Del Zanna, Daniel Heynderickx and Hugh D. R. Evans is published this month in the journal Space Weather DOI: 10.1029/2019SW002213.

NAM 2019

The RAS National Astronomy Meeting (NAM 2019) is taking place at the University of Lancaster from 30 June to 4 July 2019. It includes the annual meetings of the UK Solar Physics (UKSP) and Magnetosphere Ionosphere Solar-Terrestrial (MIST) groups. The conference is principally sponsored by the Royal Astronomical Society (RAS), the Science and Technology Facilities Council (STFC) and Lancaster University. Full details are visible on the dedicated conference website. Access credentials for embargoed press materials are available on request from the NAM press team via nam-press@ras.ac.uk.

About the Royal Astronomical Society

The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organises scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 4,000 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.

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The Science and Technology Facilities Council is part of UK Research and Innovation – the UK body which works in partnership with universities, research organisations, businesses, charities, and government to create the best possible environment for research and innovation to flourish. STFC funds and supports research in particle and nuclear physics, astronomy, gravitational research and astrophysics, and space science and also operates a network of five national laboratories as well as supporting UK research at a number of international research facilities including CERN, FERMILAB and the ESO telescopes in Chile. STFC is keeping the UK at the forefront of international science and has a broad science portfolio and works with the academic and industrial communities to share its expertise in materials science, space and ground-based astronomy technologies, laser science, microelectronics, wafer scale manufacturing, particle and nuclear physics, alternative energy production, radio communications and radar.

STFC's Astronomy and Space Science programme provides support for a wide range of facilities, research groups and individuals in order to investigate some of the highest priority questions in astrophysics, cosmology and solar system science. STFC's astronomy and space science programme is delivered through grant funding for research activities, and also through support of technical activities at STFC's UK Astronomy Technology Centre and RAL Space at the Rutherford Appleton Laboratory. STFC also supports UK astronomy through the international European Southern Observatory.

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