Short Term Scientific Missions are institutional visits aimed at supporting individual mobility, fostering collaboration between individuals. They allow scientists to go to an institution or laboratory in another COST country to foster collaboration, to learn a new technique or to take measurements using instruments and/or methods not available in their own institution/laboratory. They are particularly intended for young scientists. For this year, 4 STSMs will be advertised soon after the end of the COVID-19 pandemic period. You can learn more for the available Institutions from Prof Oliver Karanfilski the STSM chair. You can also learn more about STSMs from section 8 of the COST Vademecum.
For the current grant period (until April 2021), you can get information here.