On Dec. 20, 2019, Boeing (NYSE:BA) made its first attempt to send an uncrewed Starliner spacecraft to rendezvous with the International Space Station (ISS). A successful trip would have set up Boeing to conduct another test flight -- this time with a crew aboard -- then to move on to performing a series of lucrative "Commercial Crew" missions under its $4.3 billion contract with NASA.

But the trip did not go well.

Because of a problem with the spaceship's computer, Starliner failed to fire its engines at the correct time, missed its rendezvous with ISS, and was forced to return to Earth, unsuccessful. And as we now know, that was only one of as many as 80 separate problems with Boeing's launch -- problems that NASA now insists Boeing rectify, in a list of recommendations made public in a press briefing last week.

Failure to fix these problems could hamstring Boeing's $26 billion defense, space, and security business (per S&P Global Market Intelligence data), preventing it from competing with SpaceX for future manned spaceflight contracts.

Boeing's Starliner "Calypso" crew capsule, back on Earth after its abortive attempt to reach ISS. Image source: NASA.

Because Boeing failed to complete its first uncrewed Orbital Flight Test successfully in December, the company has agreed to rerun the test flight later this year as uncrewed Orbital Flight Test-2 (OFT-2) -- eating the $410 million cost in the process. To improve the chances that this test will prove successful, NASA has outlined 80 recommendations for Boeing. The agency did not release full details on all the items that need to be fixed last week, saying that "the full list of recommendations is company sensitive and proprietary."

Here's what we do know:

NASA recommended 21 changes to improve simulation and testing of the mission before OFT-2 takes off. In particular, the agency wants to see better integration of hardware and software, and wants Boeing to perform an "end-to-end" test of all hardware prior to the flight. Shockingly, it appears that Boeing did not conduct such a test prior to its failed test flight in December, instead testing software and hardware piecemeal. This may be the reason Boeing failed to notice that Starliner's shipboard computer's clock was 11 hours off from real time, resulting in its failure to fire the engines on time, which in turn resulted in the spacecraft's failure to reach the space station last time around.

The agency has 35 recommendations to make surrounding "process and operational improvements," including bringing in more outside experts to review Boeing's test data, and six recommendations regarding "knowledge capture." In general, NASA will be performing more oversight of Boeing's work this time around.

Seven tweaks to Starliner's software code will be required, seven changes will be made to safety reporting, and at least one hardware change, narrowing the radio frequency band at which Starliner communicates with NASA's Tracking and Data Relay Satellites (so as to filter out interference), will be necessary.

Why so many changes, if only one glitch -- the mistimed onboard clock -- was the primary reason OFT-1 failed? Because as it turns out, in addition to that failure, there were other close calls that could have caused a loss of vehicle.

Notably, a bug in the software controlling the engines in Starliner's service module (which powers the spacecraft on its approach to ISS, but is jettisoned before the spacecraft's "Calypso" space capsule returns to Earth) could have caused the former to collide with the latter after said jettisoning, damaging Calypso to the point that it would not survive reentry into Earth's atmosphere.

Once NASA realized that, they realized how much work remains to be done before Boeing can be allowed to try again with an uncrewed mission -- much less one with astronauts on board.

NASA did not set a launch date for Boeing's OFT-2. Media reports have suggested a second attempt could happen as early as October or November this year, followed by a crewed flight test (CFT) in 2021 if all goes well. Steve Stich, manager of NASA's Commercial Crew Program, confirms that work on the spacecraft "is coming along very well." But even so, the number of software and other fixes that need to be made suggests there's quite a bit of work left to be done before Starliner can try to fly again.

Depending on how quickly Boeing gets this work done, it's likely that before Boeing sends its first batch of astronauts to ISS, its rival SpaceX -- which launched its first uncrewed mission successfully in March 2019, and completed its first crewed flight successfully in May 2020 -- will already be working on its second. As NASASpaceflight.com points out, SpaceX's first "operational crew rotation mission" (Crew-1) is scheduled to fly this fall.

Will that be embarrassing for Boeing? Probably. But at this point, it's actually the company's best-case scenario. As things stand today, SpaceX is the only company (not named Roscosmos) capable of sending U.S. astronauts into space. Until Boeing clears its OFT-2 and CFT hurdles, it will be completely shut out of this market -- and all of NASA's billions of dollars for crewed spaceflight will be SpaceX's for the taking.

More:

What Went Wrong With Boeing's Starliner Crew Capsule Test - Motley Fool