EChO will be launched into a direct transfer orbit on a Soyuz-MT Fregat launch vehicle that will lift off from Europe's spaceport in Kourou, French Guiana. Launch is anticipated in the 2020-2022 time frame.
The final orbit for EChO will be an eclipse-free, large-amplitude quasi-halo orbit around the Sun-Earth L2 Lagrange point. This will provide an environment that is benign with regard to radiation exposure and, critically for the photometric stability of EChO, is also thermally stable. The proposed orbit has the added benefits of being eclipse-free (Earth and Moon), and of offering instantaneous visibility of a large number of EChO targets at any one time.
The science data volume of EChO will be very modest ( ≈ 1 Gigabit per day) and ground contact will only be required for 2 hours, twice per week.