NASA and ESA are currently planning a Mars Sample Return (MSR) Campaign to return samples from Mars safely to Earth for scientific research. The Mars 2020 mission is the first element of this MSR Campaign and has already collected a scientifically return worthy set of samples on Mars. Three of the five guiding principles for the MSR science management are: transparency, scientific maximization and accessibility. Following these principles, NASA and ESA are planning several opportunities for the international scientific community to participate in the planning and execution of MSR science. This Townhall will describe the samples already acquired on Mars, planned research & development activities, and upcoming opportunities for the international science community. The first part of the Townhall is based on presentations by the NASA & ESA MSR Lead Scientists, members of the Mars 2020 Science Team, and members of the MSR Campaign Science Group. The second part of the Townhall is based on open discussions and questions from the audience.