United Launch Alliance was selected officially as launch service provider for first two space missions of Sierra Nevada Dream Chaser space plane. Two flights are planned for 2020 and 2021 under CRS-2 contract signed between NASA and Sierra Nevada in January 2016.
On July 22, 2017 Sierra Nevada and United Launch Alliance announced about signing contract for delivering Dream Chaser for first two resupply missions covered with CRS-2 contract. Vehicle will be probably launched in 2020 and 2021 (NASA will confirm flight schedule in following months) on the top of the Atlas 5 in 552 configuration. In this version Atlas 5 is supported with five SRB solid rocket boosters, it has five meter wide payload fairing to cover Dream Chaser and is equipped with two RL-10 engines installed in Centaur upper stage.
Dream Chaser which will fly under CRS-2 contract was modified to meet demands of NASA, as originally vehicle was designed for manned flights. Instead equipment necessary for crewed flights, it will be equipped with deployable cargo compartment in the tail section (jettisoned before reentry), there will be no cockpit windows. Deployable solar panels were added along with avionics and onboard computers necessary for automated flight.
CRS-2 contract covers delivering supplies for the International Space Station during 18 missions from 2019 to 2024. Each from three companies (Sierra Nevada, SpaceX and Orbital ATK) were awarded with 6 missions.