NASA’s next big space observatory — the James Webb Space Telescope — probably won’t launch in March 2021, potentially creating added costs for the long-delayed and over-budget program. Unforeseen technical problems are prolonging the process of finishing up the telescope, making it increasingly likely that the spacecraft will have to launch at a later date.

The grim news is detailed in the latest report from the Government Accountability Office (GAO), which performs audits of federally run programs. The GAO, which has been keeping a watchful eye on the telescope’s development for years, claims that there is only a 12 percent chance the agency will meet its March 2021 goal, thanks to a recent analysis done in October by those working on the program. NASA will figure out a new date in the spring of this year, according to the audit.

A delay would be just the latest hiccup in a long, troubled history

A delay would be just the latest hiccup in a long, troubled history for the James Webb Space Telescope, or JWST. When it was first being conceived in the 1990s, JWST was thought to cost somewhere between $1 billion and $3.5 billion, and scientists expected it to launch between 2007 and 2011. Since then, the costs skyrocketed, shooting up by 95 percent as the launch date has slipped further (and further) into the future. NASA now expects the total development and operational costs of JWST to run $9.66 billion.

The GAO claims that Northrop Grumman, the main contractor on JWST, has come a long way over the last year, and made significant milestones as it readies the observatory for launch. However, Northrop has eaten up most of the reserve schedule it had budgeted when planning out the timeline for the next couple of years, and now only has less than a quarter of that buffer time left. The contractor has done some work to get that schedule reserve back, but there’s very little margin for error.

Technical issues are to blame for eating up all this precious time, a long-standing problem for Northrop Grumman as it’s been piecing together JWST. Testing in 2018 caused some screws and washers to come lose on the spacecraft, and Northrop Grumman accidentally caused tears in the vehicle’s sun shield, a delicate piece of hardware needed to keep the telescope cool in space. Most recently in 2019, testing revealed powering issues with two important spacecraft components. The contractors have addressed the failures, but these mounting technical challenges have caused the workforce to work longer than expected, which may lead to increased costs for the program.

Technical issues are to blame for eating up all this precious time

It’s unclear exactly how much a delay will run NASA at this point. NASA indicated to the GAO that it has enough funding to support a delay of three to four months beyond the March 2021 date. However, the extra work required of Northrop Grumman’s workforce may lead to significant cost overruns.

The GAO isn’t making any recommendations with its report, so it’s possible there may not be much that NASA can do at this point to keep things on track. In response to the audit, NASA argued that the telescope has met a lot of milestones in 2019, and that the year ahead will be extremely busy, too. In 2020, the observatory will go through a series of environmental testing to ensure it can survive in the harsh vacuum of space. That testing should last until November, according to the space agency.

“We’ve reduced a lot of risk, but there are still technical challenges ahead to prepare this very complex observatory for launch,” Gregory Robinson, the program director for the James Webb Space Telescope, said in a statement to The Verge. “While the schedule for the March 2021 launch readiness date is tight, we are still planning toward that, without any changes to the budget. The schedule will be reviewed again in May 2020.”

Despite the turmoil it’s been through, JWST is still a massive priority for the astronomy community. Once complete and launched, it’ll garner the title of the most powerful space observatory ever built. The telescope, which will be situated 1 million miles from Earth, sports a giant gold mirror that spans 21 feet (6.5 meters) across, allowing the observatory to see some of the oldest, most distant objects in the Universe. It will essentially allow astronomers to peer back in time to when the Universe first burst into being 13.8 billion years ago. So while the delays have been frustrating, NASA and the astronomy community still want to see the project through.

Update January 29th, 1:40PM ET: This article was updated to include additional information and a statement from NASA.