Kennedy Space Center, Fla. - Boeing's CST-100 Starliner is set to make history as it carries astronauts for the first time, marking the inaugural crewed launch of the Atlas 5 rocket. The highly anticipated Crew Flight Test (CFT) mission remains on schedule for launch at 10:34 p.m. Eastern on May 6.

The Starliner spacecraft was successfully transported to the launch pad on May 4, with no reported technical issues and favorable weather conditions forecasted for the launch.

This mission not only signifies the 100th flight of the Atlas 5 rocket since its debut in 2002 but also represents the first time it will carry astronauts. United Launch Alliance (ULA), the manufacturer of the Atlas 5 rocket, has introduced several modifications to support crewed flights. Among these modifications is the addition of an emergency detection system, which continuously monitors the launch vehicle's systems and provides crucial data to Starliner, enabling it to activate its abort system in the event of any rocket malfunctions.

The crewed Atlas 5 rocket also incorporates a Centaur upper stage equipped with two RL10 engines, a configuration similar to previous Centaur versions flown on other launch vehicles and currently adopted by ULA's upcoming Vulcan rocket.

Despite these changes, the rocket largely adheres to the standard procedures and processes utilized in satellite launches, according to Gary Wentz, Vice President of Government and Commercial Programs at ULA.

To certify the Atlas 5 for NASA's crewed missions, extensive evaluation and verification processes were performed. Ian Kappes, Deputy Manager of the Launch Vehicle Systems Office for NASA's Commercial Crew program, revealed that between 11,000 and 12,000 individual verifications were conducted on various vehicle components and processes. This involved digging into paperwork from the rocket's developmental stage dating back two decades, including hand calculations.

One of the significant challenges faced during the assessment was obtaining adequate data on the Russian-built RD-180 engines that power the Atlas booster. Despite limited insight, the Launch Vehicle Office deemed the risks acceptable but also aimed to minimize them by working closely with ULA to find ways to improve safety.

Following the Crew Flight Test, Boeing has a contract with NASA for an additional six operational Starliner flights, all of which are planned to launch on the Atlas 5 rocket. However, ULA has stopped selling the Atlas 5 as it transitions to the Vulcan Centaur. This means that any future Starliner missions, whether for NASA or other customers, would have to relocate to other rockets like the Vulcan.

While preparations for the transition are underway, ULA is collaborating with Boeing to human-rate the Vulcan Centaur for Starliner missions. Mark Nappi, Vice President and Program Manager of Boeing's Commercial Crew program, expressed confidence in their progress, stating that they now have a good understanding of the requirements.

Looking ahead, NASA's Launch Vehicle Systems Office is already contemplating the certification process for launching crewed missions on future vehicles like Blue Origin's New Glenn. Taking into account lessons learned from both the Atlas 5 and Falcon 9 projects, the team is interested in acquiring additional data from these vehicles.

As the countdown to the historic crewed launch of the CST-100 Starliner on the Atlas 5 rocket continues, the collaboration between Boeing, ULA, and NASA marks another significant milestone in the ongoing development of human spaceflight capabilities.

By Jeff Foust