Boeing is set to begin detailed wind tunnel tests of its Crew Space Transportation (CST-100) spacecraft following a successful preliminary design review of the launch vehicle adapter structure.

The CST-100 is designed to carry crews to the International Space Station as well as take space tourists to the Bigelow Aerospace orbital space complex, and could make its first test flight as early as 2016.

Completion of the review marks a key milestone for Boeing, which is developing the CST-100 under a Commercial Crew Integrated Capability (CCiCap) agreement with NASA. Boeing, along with competitors SpaceX and Sierra Nevada, was awarded a contract for this follow-on phase to the Commercial Crew Development 2 (CCDev-2) program last August.

The Launch Vehicle Adapter is being designed by United Launch Alliance (ULA), maker of the Atlas V rocket that will deliver CST-100 to orbit. Boeing says detailed engineering of the adapter can now begin as it continues to progress toward the first of two planned test flights of the CST-100.

John Mulholland, vice president and program manager of Boeing Commercial Crew Programs, says the review also “sets the baseline for us to proceed to wind tunnel testing and the launch segment review in June.”

Boeing says that two additional CCiCap milestones were also completed earlier this year. These included the engineering 2.0 software release, which “lays the groundwork for spacecraft control and communications,” the company says. The second was the Landing and Recovery Ground Systems and Ground Communications design review, which establishes a plan for the equipment and infrastructure needed for ground communications and landing and recovery operations.