Nasa’s tracking and data relay satellite (TDRS) K-L programme has completed its system-level critical design review (CDR) and production readiness review (PRR).

TDRS K and L satellites are the 11th and 12th satellites being built for the TDRS system.

The TDRS system relay system provides voice, data and communications relay services to Earth-orbiting spacecraft, the International Space Station, launch vehicles and the Hubble Space Telescope.

The two new Boeing-built satellites will replenish the aging TDRS constellation established in 1983 to replace Nasa’s worldwide network of ground tracking stations.

Reviews confirm that the TDRS K-L system design will meet Nasa’s requirements and operate effectively to pave the way for Boeing to begin assembling the satellites.

TDRS K and L are scheduled for launch in 2012 and 2013.