The activities of the Soyuz 30 crew, however, were severely curtailed so as not to interfere with the Soyuz 29 crew. On the Soyuz 29 crew's rest day, the international crew had to stay in their Soyuz to perform their experiments. Nevertheless, Hermaszewski conducted many experiments. One was crystallization experiments which produced 47 grams of cadmium tellurium mercury semiconductors for use by infra-red detectors on board the station. The yield was far greater - 50% compared to 15% - than ground-based experiments.