Boeing defends Starliner space capsule ground tests after problematic debut flight

Boeing engineers examine the Starliner spacecraft that flew on the Orbital Flight Test mission in December 2019.  (Image credit: Boeing)

After Boeing's CST-100 Starliner failed to reach the International Space Station in an uncrewed test flight in December, NASA has raised some serious questions about the company's ability to safely launch astronauts into space. 

A joint NASA-Boeing independent review team identified two major software glitches that arose during the Orbital Flight Test (OFT) mission: an incorrect timer that prevented Starliner from reaching the correct orbit to dock with the space station, and a valve-mapping error with the spacecraft's thrusters that could have caused an in-space collision

On Wednesday (Feb. 26), the Orlando Sentinel reported that members of NASA's safety advisory panel were surprised to learn that Boeing "did not perform a full, end-to-end integrated test of Starliner in a Systems Integration Lab" with its Atlas V rocket, and that doing such a test "could potentially have caught the issues Boeing later experienced in the mission."  

Related: Boeing's 1st Starliner flight test in photos

John Mulholland, vice president and program manager of Boeing's Starliner program, sought to set the record straight about this alleged lack of testing in a teleconference with reporters on Friday (Feb. 28). 

"I don't think that report was characterized exactly right," Mulholland said. "We did an extensive amount of testing integrated with the launch vehicle both in the lab in Denver and also in the lab of Houston." But rather than running a test of the entire mission, Boeing broke the flight test into "chunks" that were tested separately, he explained.

Boeing engineers thought that it would be "more logical to break the mission phases into chunks and do a lot of testing in those smaller chunks," he said. "When you do a single run from launch to docking, that's a 25-plus hour single run on the computer." If the team had decided to run this simulated test from the launch all the way to the spacecraft's docking, which happens two or three days after liftoff, "the length of that run would be incredibly long," he said, so the team "decided that they would rather run multiple tests of different chunks of the mission." 

Mulholland added that Boeing deemed these fragmented qualification tests to be "adequate and comprehensive" at the time, and that Boeing's staff was not "taking any shortcuts" by opting not to run the full, end-to-end test. "It was not a matter at all of the team consciously shortcutting or not doing what they believed was appropriate," Mulholland added.

However, he acknowledged that such a test could have been helpful in identifying critical software defects that were missed. "From a hindsight standpoint, I think it's very easy to see what we should have done, because we uncovered an error," Mulholland said. "At the time, that sensitivity wasn't wasn't recognized."

Having learned from its past mistakes, Boeing now plans to implement the longer, more complete tests before Starliner flies again. 

"The one improvement that we're going to make going forward is to make sure that before each flight, we will run the launch-to-docking phase of the mission, and then we'll run the docking-to-landing phase of the mission completely."

NASA, which commissioned Boeing (and SpaceX) to build spacecraft that will launch astronauts from American soil for the first time in nearly a decade, has expressed concerns over the company's development and testing procedures for Starliner, particularly when it comes to software issues. The agency has not yet publicly said whether it will require Boeing to repeat the uncrewed OFT mission before the first crewed Starliner mission, which has been scheduled to launch to the International Space Station in mid-2020. 

The independent review team has completed its investigation of Starliner's hardware and mission data and has found no new problems with the spacecraft. However, they're still working to audit more than 1 million lines of code to look for any other possible software defects. Mulholland said it would be at least a few more weeks before that audit is complete. 

Email Hanneke Weitering at or follow her @hannekescience. Follow us on Twitter @Spacedotcom and on Facebook.


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Hanneke Weitering
Contributing expert

Hanneke Weitering is a multimedia journalist in the Pacific Northwest reporting on the future of aviation at and Aviation International News and was previously the Editor for Spaceflight and Astronomy news here at As an editor with over 10 years of experience in science journalism she has previously written for Scholastic Classroom Magazines, MedPage Today and The Joint Institute for Computational Sciences at Oak Ridge National Laboratory. After studying physics at the University of Tennessee in her hometown of Knoxville, she earned her graduate degree in Science, Health and Environmental Reporting (SHERP) from New York University. Hanneke joined the team in 2016 as a staff writer and producer, covering topics including spaceflight and astronomy. She currently lives in Seattle, home of the Space Needle, with her cat and two snakes. In her spare time, Hanneke enjoys exploring the Rocky Mountains, basking in nature and looking for dark skies to gaze at the cosmos. 

  • Leftyricardo55
    Part of me wants to be very judgmental of Boeing not to even have done the software testing before launch. (Boggles the mind), but going forward I gotta just hope they get it together next time. growing up watching Gemini launches-they all made it to orbit.
  • Hari
    I'm wondering if 'Mad' Mike Hughes ever asked Boeing for advice.
  • JTG
    "Boeing engineers thought that it would be "more logical to break the mission phases into chunks and do a lot of testing in those smaller chunks," he said. "When you do a single run from launch to docking, that's a 25-plus hour single run on the computer." "

    That's a dubious statement at best. Boeing Engineers didn't think it was more logical to break up the testing - sounds more like upper management thought it would be more financially viable.

    Two things wrong with breaking it up into "smaller chunks".

    1. Who checks for overall integration between the "smaller chunks"? When simulated conditions are fragmented, this doesn't follow the actual flight environment.

    2. By testing through "smaller chunks", Boeing isn't looking at problematic issues that may arise early on in any portion of the launch/flight segments. Using a fragmented approach, how can engineers determine anomalies that may CASCADE throughout the entire flight profile? "Smaller chunks" doesn't fit the tried and true approach of test as you fly and fly as you test. What Boeing is doing is spend as little as possible because extra testing to them has little value if their narrow-minded thinking perceives it as such.

    Let's see if Boeing business executives think it was worth bypassing a 25-plus hour single run on a computer. It's time to bring back Boeing Engineers into the decision-making process, not the shills for upper management execs.