With the advent of the space shuttle era, increasing rocket activity is expected in the Earth's upper atmosphere. The space shuttle solid-fuelled booster rockets emit ∼150 tonnes of alumina (Al2O3) particles per launch, much of which spreads throughout the upper troposphere and stratosphere1. Such particles can seed aerosols and clouds, and might therefore cause changes in the terrestrial radiation balance and climate2. Estimates are made here showing that average ice nuclei concentrations in the upper troposphere could increase by a factor of 2, and that an aluminium dust layer weighing up to 1,000 tonnes might eventually form in the lower stratosphere. © 1982 Nature Publishing Group.