Innovative Interstellar Explorer

This study focused on measuring the interstellar medium, the region outside the influence of the nearest star, the Sun.

[3] As a concept study, a number of technologies, configurations, and mission goals were considered, leading to the choice of a spacecraft propelled with ion engines powered by a radioisotope thermoelectric generator (RTG).

[5] A variety of strategies were assessed, including using launch windows (not counting backups) for a Jupiter assist in 2014, 2026, 2038, and 2050—about every 12 years.

[3] The launch opportunity for the 2014 window passed,[6] but for example it could have resulted in a Jupiter flyby by early 2016 and then go on to reach 200 astronomical units (AU) by 2044.

[4] In 2011, the study's primary author gave an update to website Centauri Dreams, giving a retrospective on the mission and its feasibility since its publication in 2003.