Earth Return Orbiter infographic

The Earth Return Orbiter (ERO) will be the biggest spacecraft to ever orbit Mars. The spacecraft will also be the first interplanetary spacecraft to rendezvous and capture a man-made object launched from another planet and return it to the Earth’s surface, making a full round trip to Mars and back. ERO is a multi-stage modular spacecraft equipped with both chemical and solar electric propulsion. The electric propulsion system will be the most powerful ever flown on any previous planetary mission.  Onboard ERO will be a radiation monitor that will measure the total radiation dose experienced by the spacecraft throughout the entire mission, which in addition to monitoring the health of ERO could provide important information on how to design systems for future human explorers. Launch is planned in 2027, entering into Mars orbit in 2029.