Earth Return Orbiter (ERO)

The Earth Return Orbiter (ERO) will be the biggest spacecraft to ever orbit Mars. 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. The objective of the mission is to capture a capsule full of Mars soil samples collected by the U.S. Mars 2020 rover (Perseverance) and then launch the capsule to Earth so that the samples can be studied.