Boeing spokesman Josh Barrett said the company "closed out" the capsule's structural vulnerability risk when it completed its structural test program in January. While Boeing is working through a number of other issues, they "are not driving any major architectural system changes." "Our numbers show we are exceeding NASA's safety requirements," said Barrett. SpaceX spokesman James Gleeson said the company, working with NASA, has developed "one of the safest, most-advanced human spaceflight systems ever built." "There is nothing more important to SpaceX than safely flying crew," said Gleeson, calling it "core to our company's long-term goal of enabling access for people who dream of flying to space." Founded by Tesla Inc chief executive Elon Musk, SpaceX has cut the cost of rocket launches with its pioneering reusable rocket technology, while Boeing traces its space business back to the first US human space missions of the 1960s and is also the world's largest planemaker. The clock is ticking.