Once again, NASA can expect even more delays and budget increases for its Space Launch System (or SLS) — the behemoth rocket the space agency is building to take humans to the Moon and Mars.

Today, NASA’s inspector general, which performs periodic audits of the space agency’s programs, released a scathing report on the current status of the Space Launch System’s development — and things look bleak. The rocket, which has already suffered from numerous cost overruns and budget delays, is projected to cost billions of dollars more than expected. The vehicle also probably won’t be ready to fly by June 2020, the current target date for the rocket’s first launch.

The report blames many of the issues on Boeing, the main contractor of the SLS. Boeing has been struggling with the development of the SLS core stage — the main body of the rocket that contains the primary engines and most of the propellant. The first core stage, meant to be used on the SLS’s inaugural test flight, was supposed to be delivered in June of 2017. It’s now expected to be ready by December 2019, and chances are it will probably come even later than that. The inspector general argues that these delays can be blamed on “poor performance” on the part of Boeing. The company has consistently given bad estimates for how much work is required for the core stage, as well as how many people are needed to complete it, the report says.

As these delays build up, NASA can expect to unload a whole lot more money to complete the development of the SLS. Given current estimates, the space agency is expected to spend $8.9 billion through 2021 just so that Boeing can complete the first core stage and work on additional stages for upcoming flights; that’s twice the amount NASA had expected. Also that number is in addition to all of the other contracts NASA has to complete the SLS. For instance, the main engines for the rocket, which were also used to power the Space Shuttle, are being built by Aerojet Rocketdyne. And that contract has cost upward of $2 billion so far.

Delays and bloated costs have been a common problem for the SLS program. The rocket was originally supposed to have its first launch last year, but its debut has been continually pushed back as its budget expands. NASA has now spent nearly $12 billion on SLS development, which has been ongoing since 2010. And that number is only expected to grow. Since November 2017, NASA has been targeting the first test flight of SLS for 2019, but that has now shifted to 2020. And the inspector general report doubts that new date will hold either.

Boeing has chalked up many of the delays to a lack of funding, but NASA officials told the inspector general that money isn’t to blame. Bad estimates by Boeing have contributed to many of these problems, the report argues. Not only has Boeing failed to understand the scope of its tasks, but the contractor has failed to give NASA good approximations for budget and timelines. Boeing has struggled with work efficiency, too: only about half of Boeing’s scheduled tasks are finished on time. Contamination of tubing hardware and the misalignment of a large robotic welding tool have also slowed down development, and then there’s been just some bad luck. A tornado damaged NASA’s Michoud Assembly Facility in New Orleans, where the SLS pieces are being built, and that delayed production for two months.

The report also calls out NASA for bad management. NASA doesn’t require Boeing to give detailed information on how much it costs to develop the stages for SLS, which makes it hard for NASA to track Boeing’s spending. As a result, the space agency doesn’t really know if the company is meeting its target goals. Additionally, NASA has been giving Boeing a lot of award fees — bonuses that companies can make on top of their original contracts when they do great work. The report says these fees are odd given how badly Boeing has been performing. For instance, Boeing spent $600 million more than it was supposed to between 2014 and 2018 and is running two years behind schedule — but NASA awarded the company an extra $323 million in award fees anyway.

The inspector general provided seven recommendations for NASA about how to move forward and fix these issues. These include telling Boeing to come up with more accurate timelines and renegotiating the current contract so that NASA knows exactly how much this rocket is going to cost. Otherwise, the way the contract is laid out now is not sustainable, the report argues.

In the meantime, this report provides ample ammunition to those who are critical of the SLS program, arguing that it costs too much money and that there are other comparable, less-expensive rockets in development that NASA could use. NASA has countered these arguments by saying that the SLS will be the most powerful rocket in the world when it is finished, capable of putting nearly 290,000 pounds into low Earth orbit.

The only problem is the true strength of the SLS may not be realized for some time, as NASA is building two versions of the vehicle — Block 1 and Block 1B. Block 1B, the more powerful version, won’t be ready to fly until 2024 at the very earliest, and that’s likely to change given all these delays. Meanwhile Block 1 can only loft a little more than 200,000 pounds into orbit. That’s not much more than the capability of current vehicles like the Falcon Heavy, which can put about 140,000 pounds into the same orbit. And the Falcon Heavy costs anywhere between $90 million to $150 million to launch — a small cost compared to SLS development.

Perhaps the biggest thing keeping SLS alive at this point is its strong backing in Congress. Much of SLS development takes place in Alabama, and the state’s representative, Sen. Richard Shelby (R-AL), has been the rocket’s biggest advocate. Shelby ensures that the vehicle gets adequate funding every year, and it seems likely he will continue to fight for the program. Additionally, many jobs supporting the SLS program are spread throughout the US, giving the vehicle extra support in Congress.

However, this report is not good news for SLS supporters. NASA will need to make some big changes in how the program is run, or this rocket is likely to stay on the ground.