CAPE CANAVERAL, Fla. — Today’s Atlas rockets bear little resemblance to those used to launch John Glenn, Scott Carpenter, Wally Schirra and Gordon Cooper into space in 1962 and 1963, but the boosters, now built by United Launch Alliance (ULA), once again are being prepared to carry humans into orbit.

The company, a joint venture of Boeing and Lockheed Martin, is working for two firms developing commercial space taxis, with an eye toward flying NASA astronauts to the international space station within about four years. Another potential customer is privately owned Bigelow Aerospace, which is developing free-flying orbital outposts that would be staffed by company astronauts and available for lease by researchers, businesses, educational institutes, agencies and tourists. 

ULA plans to demonstrate its commercial human spaceflight service in 2016, a date that is driving development of several rocket upgrades and a crew access tower for its Cape Canaveral launch complex. 

“We had a preliminary design review of the crew access tower design, heading toward critical design review later this year to make sure that all of the safety and accommodation features are included,” said John Mulholland, vice president and program manager of commercial programs and space exploration for Boeing, one of the two firms developing human spaceships that would fly on Atlas rockets.

ULA currently flies its Atlas 5 rockets from Launch Complex 41 at Cape Canaveral Air Force Station, located just south of the Kennedy Space Center.

“We have a clean launch pad concept, where we process the vehicle  in the Vertical Integration Facility a couple of thousand feet from the pad, then the day before launch roll the rocket and the spacecraft or the capsule out to the launch pad,” said Jim Sponnick, the ULA vice president who oversees the Atlas and Delta rocket programs. 

“On the day of launch after we check out the systems and fuel the rocket, then we load the crew into the capsule, so the addition of the crew access tower is a major part of that,” he said.

The company recently completed two wind tunnel tests, one to study aerodynamics and loads on an Atlas 5 rocket flying with a Boeing CST-100 capsule and the other to understand how the crew access tower would change the ground wind conditions to the rocket itself. 

Construction of the crew access tower would begin with the next phase of the NASA-backed Commercial Crew Program awards, expected next year. In addition to Boeing, NASA currently has partnership agreements with Space Exploration Technologies Corp., which would use its Falcon 9 rockets to launch a crewed variant of the Dragon cargo capsule, and Sierra Nevada Corp., which, like Boeing, intends to fly on Atlas boosters.

NASA has requested $821 million for its Commercial Crew Program for the fiscal year beginning Oct. 1 but has been making due with roughly half that amount. A draft request for proposals for the program’s next phase is expected to be released this summer, with a final solicitation released in early fall. A contract award is expected in July 2014.

“There will definitely be less than three [awards]. One or more is what we’re thinking. I’d like to keep all three, but you need funding for that,” said Ed Mango, NASA’s Commercial Crew program manager at the Kennedy Space Center.

Among the planned upgrades to the Atlas rocket itself, the most important change will be largely invisible. Engineers are designing an emergency detection system to automatically monitor systems on the rocket and determine if anything is amiss so the flight could be aborted.

“But almost as important is to make sure that you don’t leave a perfectly good rocket,” Mulholland said, referring to a scenario where a false alarm triggers a crew escape system.

ULA already is collecting flight data during its Atlas satellite launches to characterize parameters for planned human missions. 

“We haven’t yet flown the emergency detection system, but we’re collecting all of the data that’s going to serve to define those boundaries for normal and abnormal,” Sponnick said. 

“We’ll fly it with launches starting in  2016, and probably with some demonstration missions before that,” he added.

Prototype testing is expected to begin later this year.

Also under development is a launch vehicle adapter, which will be the interface between the rocket and the crew capsule. A second round of wind tunnel tests is under way and slated to wrap up in August, Mulholland said.