MarCO or Mars Cube One is an experimental mission that is sending two tiny spacecraft along with InSight to Mars. If successful, they will relay real-time telemetry from InSight to Earth during the landing.
Three launches to the Moon and one each to Mercury and Mars; two arrivals at near-Earth asteroids; and an approach to an encounter with a distant Kuiper belt object are highlights we anticipate in 2018.
NASA has decided to move forward with the InSight mission after its delay last December, setting a new launch date of May 5, 2018. That will put the landing on Mars on November 26, 2018. In order to launch in two years, one of its two science instruments must be redesigned.
2015 has seen few deep-space-craft launches, but 2016 is shaping up to be a banner year with three launches, followed quickly by a fourth in early 2017. All of the missions under development have reported significant milestones recently.
Dawn has successfully entered orbit at Ceres, becoming the first mission to orbit a dwarf planet and the first to orbit two different bodies beyond Earth. I also have updates on Curiosity, Rosetta, Mars Express, Hayabusa2, the Chang'e program, InSIGHT, and OSIRIS-REx.