Solar electric propulsion systems had been successfully used in several space exploration missions and were well-suited for deep space missions where long-duration operation and high specific impulse were important. SEPs had to play an important role in future space exploration missions, particularly for missions to destinations beyond the inner solar system.
Are there any upcoming space exploration missions that will utilize solar electric propulsion systems?
Solar electric propulsion systems had been successfully used in several space exploration missions and were well-suited for deep space missions where long-duration operation and high specific impulse were important.
That's a bit incorrect due to the inverse square law, which makes solar power be about 4% of the value near Earth at Jupiter's orbital distance. Beyond Jupiter, solar power becomes even more useless. Where solar electric propulsion has been most useful is objects orbiting the Earth. While there have been a small number of space exploration missions that used solar electric power, these pale in comparison to the huge number of commercial spacecraft in low Earth orbit and in geosynchronous orbit that utilize SEP.
Wikipedia has a list of spacecraft with electric propulsion, but it is terribly out of date. It lists SpaceX's Starlink satellites as "planned" (they're operational), but since those are LEO satellites, they don't quite count as space exploration missions. The linked page includes NASA's Gateway and Brazil's ASTER as planned spacecraft that will use solar electric power. (The Wikipedia page lists ASTER as having a launch date in 2021. That has been delayed until 2025.) Both Gateway and ASTER qualify as space exploration missions.
