Lockheed Martin [LMT] completed the critical design review (CDR) for the application software of its Iridium Next constellation of global communication satellites, according to a company statement.

The company said the CDR shows the design is at a high level of maturity and keeps the program on schedule for a first launch in 2015. Lockheed Martin spokeswoman Suzanne Smith said in an email the application software provides a core telecommunications function that enables satellite calls to occur around the world.

During the review, the design for the application software, which performs the primary role in supporting subscriber services to user terminals, was examined by teams from Iridium, Thales Alenia Space and Lockheed Martin to ensure it will support all the functions needed for Iridium Next satellites.

Smith said the company will begin building the software now that its design has been approved and software coding will be completed in 2014.

“The new software supports all capabilities currently available to Iridium subscribers and its modular design will allow 3G services to be seamlessly implemented into the new constellation,” Bob Kramer, vice president of operational systems and services for Lockheed Martin information systems and global solutions-defense, said in a statement.

The Iridium Next satellites are slated to replace those currently in the Iridium constellation of 66 cross-linked, low-Earth orbiting satellites. Iridium Next will provide continuous coverage over 100 percent of the Earth’s surface as well as enhance Iridium mobile communications services.

Smith said the Iridium Next communications satellite constellation is a “pure” commercial contract with no Defense Department funding for development, but DoD purchases satellite bandwidth as a commercial purchaser, enabling troops to make satellite communications calls and supplementing DoD satellite communications links.