NASA awarded $20.7 million to a Rockledge, Fla., construction company to modify a mobile launcher at Kennedy Space Center for the Space Launch System (SLS) heavy-lift rocket the agency is building to launch the Orion crew capsule on deep-space missions.

Under the firm, fixed-price contract announced May 8, J.P. Donavon Construction Inc. is expected to begin work at NASAโ€™s Florida launch site in June and finish by the end of 2014. Midwest Steel Inc. of Detroit is a major subcontractor on the project. 

SLS is slated to make its first launch in 2017, lofting an unmanned Orion toward the Moon. A crewed repeat of the circumlunar mission is targeted for 2021.