Future trends: Hypersonic missions and cosmic radiation exposure
Since 2011, Bauhaus Luftfahrt is concerned with the growing relevance of cosmic radiation exposure in aviation as well as with technical synergy potentials for sustainable and low-radiation flying.
Travel time reduction is a key driver for air traffic development. Hypersonic concepts promise direct connections over the largest intercontinental distances within a few hours. Elevated speeds go along with higher flight altitudes and typically with transpolar routes. Up to 20–25 kilometres above ground, radiation intensities strongly grow and are maximal at the poles. Simultaneously, shorter flight durations imply smaller irradiation times.
While flying at high altitudes generally increases annual doses of aircrews with fixed block hours, shorter flight duration may reduce passengers’ radiation burden. In a recent journal article1, an intricate dependence of route dose on the phase in the sun’s 11-year cycle and on flight trajectory was revealed. In periods of low solar activity, for passengers on transpolar hypersonic routes, similar or higher values emerged as on the present ones. In times of high solar activity, counterintuitively, the growth of radiation rates with altitude and latitude is less severe. Here, the shorter exposure on hypersonic missions allowed for lower doses than today. Yet, during occasionally occurring solar storms with order of magnitude increased dose rates, hypersonic routes may not be served, leading to economic penalties.
Important co-benefits for radiation protection were found in previous works2, 3 for nanocomposites as novel structural materials and hydrogen as fuel. Exploiting these synergy potentials may allow for low-radiation flying at high altitudes irrespective of solar activity.
1L. Koops, “Cosmic Radiation Exposure of Future Hypersonic Flight Missions”, Radiation Protection Dosimetry (2016)
2A. Sizmann, L. Schrempp-Koops, “Shielding Cosmic Radiation in Air Traffic”, ICAS 2012, Brisbane, Australia (2012)
3L. Schrempp-Koops, “Size Effects on the Efficiency of Neutron Shielding in Nanocomposites – a full-range analysis”, International Journal of Nanoscience, 12 3 (2013)
- Flight routes in comparison: Envisaged, representative (partly) hypersonic routes a), b), d) and corresponding present-day references c), e). In order to avoid noise pollution, hypersonic trajectories typically precede over large water expanses with low/no population density, often close to the poles (see a) and d)). LAPCAT (Long-term Advanced Propulsion Concepts and Technologies), European Commission, 6th framework (2008)
- Route dose – trade-off between higher altitudes and shorter flight time: 1) Variation of effective dose rate with altitude, geographical position, and solar activity; 2) Flight time of trajectories a) and c) (compare above); 3) Accumulated dose along flight trajectories a) and c), respectively for low and high solar activity