Spaceflight Now

Risk of solar radiation to aircraft fliers to be studied PPARC NEWS RELEASE Posted: October 9, 2000

An EU directive, which came into force in May 2000, required member states to assess the exposure of aircrew to cosmic radiation inside aircraft, yet surprisingly little is known about the causes and effects of this hazard. The risk, which also affects frequent flyers, is expected to increase as the Sun becomes more active and emits more radiation in the approach to Solar Maximum this year. In addition there is a trend for passenger aircraft to fly at higher altitudes where protection from the Earth's atmosphere is less.

Mullard Space Science Laboratory (MSSL) and Virgin Atlantic Airways have teamed up with the Civil Aviation Authority and the National Physical Laboratory to study in detail the cause and nature of the radiation. The project is funded by the Particle Physics and Astronomy Research Council, the UK's strategic science investment agency. It is part of a programme at MSSL to investigate the effects of space weather on the Earth. It is an excellent example of how academia can work with industry.

The team will measure the radiation in aircraft cabins, assess the potential risk, determine the cause and provide predictions of hazardous events.

MSSL's Dr Bob Bentley, project scientist, says 'We know that cosmic radiation at aircraft altitudes is several orders of magnitude more intense than that experienced at ground level, because there is less protection from our atmosphere at high altitude. But the extent and nature of the risk to aircraft and aircrew is poorly understood. MSSL are world experts in space weather, cosmic radiation and solar activity and it is exciting for us to work on a project that will directly benefit aircrew and frequent flyers.'

Sir Richard Branson, Virgin Atlantic's Chairman, explains 'All aircraft, but in particular future generations of aircraft, may be affected by this and it is surprising how little is known. We are very fortunate to have Bryn Jones, a Virgin Atlantic pilot, working as part of the study team. Through our involvement with the scientific community Virgin is doing everything it can to provide the best duty of care to its passengers and crew.'

Bryn Jones says 'This is an excellent opportunity for Virgin to be involved at the cutting edge of space science research into what causes the radiation.'

The radiation has three potential sources: galactic cosmic rays, solar energetic particles and magnetospheric particles. Each of these cause secondary particles on the edge of space, which shower down into the denser atmosphere below. The main aim of the project is to determine the relative importance of the three sources at aircraft altitudes.

The new study combines MSSL's expertise in solar and space plasma physics, Virgin's ability to fly the detectors, the CAA's expertise in air regulation, safety and medicine and NPL's radiation measurement experience.

The study team will make methodical measurements over a range of latitudes, longitudes and times, and analyse the results. One important aspect has been the capability for rapid response. Dr Andrew Coates, head of MSSL's space plasma group, says 'During the very active space weather conditions in mid-July we noticed that the solar activity had increased significantly at lunchtime on 14 July. We rushed the detector along the M25 and by that evening the detector was gathering unique data on a Virgin flight to Hong Kong. Events like this, combined with the methodical study, will allow us to build up a picture of the complex chain of events affecting radiation levels in aircraft cabins'.

Drs David Thomas and Graeme Taylor of the National Physical Laboratory are involved in the calibration of the instrument, and in providing guidance on interpretation of its readings in terms of signals produced by various types of radiation. Expertise in this area is important as radiation doses and effects are not simply a product of the amount of radiation absorbed, the type of radiation is also important.

Medical doctor Robert Hunter, from the Civil Aviation Authority, originally set up the study, at first joining forces with MSSL and then bringing in the other team members. He says, 'We need a better understanding of the factors that may cause the radiation dose rates in aircraft to vary. In particular we need to determine the influence of solar activity. The radiation dose from a transatlantic flight is similar to the dose from a chest x-ray. For frequent fliers and aircrew the accumulated dose may be significant, indeed aircrew are amongst the most highly exposed occupational groups to radiation.'

With the purchase of new detectors, the study team are now aiming to have detectors flying almost continuously.

The study will last for three years.

-- Rachel Gibson (rgibson@hotmail.com), October 11, 2000