As NASA’s next flagship space telescope is riddled with delays, the space agency is giving scientists some hard limits on how much money can be spent on future astrophysics missions. Last week, NASA announced that scientists proposing ideas for new space telescopes must limit their budgets to between $3 billion and $5 billion for the missions. The cost cap may force scientists to alter the designs of the missions they’ve been working on.

Right now, four teams of scientists are designing ambitious space telescope concepts in preparation for an upcoming report to NASA known as the 2020 Decadal Survey for Astrophysics. It’s an enormous review compiled by the National Academy of Sciences every 10 years that lists what kinds of missions the astrophysics community thinks NASA should work on in the decade ahead. These missions are designed to answer the biggest open science questions, like whether we can look for black holes and young galaxies with X-rays. Many researchers also want to know if we can directly image an Earth-like planet outside our Solar System. And if so, can we peer into its atmosphere to see if it hosts life?

“The writing was on the wall for a lot of people because it’s very clear that there is this overall trend of conservatism.”

In 2016, NASA commissioned teams to work on four different telescope designs — HabEx, LUVOIR, Lynx, and OST — that could help answer these questions. Up until now, the teams didn’t have to design their missions with any cost caps in mind, and a couple have been working on concepts that might exceed $5 billion. (One might even reach close to $20 billion.) Granted, these designs aren’t meant to be final blueprints but to serve as references for NASA when the agency does invest in its next big telescope. Still, NASA tries to follow these concepts as best it can, and now the agency wants to make sure that the missions can be made within a reasonable budget. And that means certain teams will have to limit the scope of their ideas — something that a few researchers saw coming.

“We were telling people we were considering cheaper options,” Scott Gaudi, an astronomer at Ohio State University and co-community chair for the HabEx study, tells The Verge. “The writing was on the wall for a lot of people because it’s very clear that there is this overall trend of conservatism.”

NASA is mainly worried that there won’t be much money to spend on future big-budget astrophysics missions. The space agency’s next flagship space observatory, the James Webb Space Telescope, or JWST, is delayed and over budget, meaning it will eat up more of NASA’s astrophysics money than expected in the years ahead. Meanwhile, the Trump administration recently proposed canceling another major astrophysics mission, the WFIRST telescope, arguing that the spacecraft design was too costly. The move indicates that the administration may not want to fund big-budget astrophysics missions in the future, as it focuses on a human return to the Moon.

“We need to ensure we can accomplish breakthrough science while adhering to a realistic, executable scope and budget for the next decade,” Paul Hertz, the director of the astrophysics division at NASA, said in a statement.

Things might have been different if JWST hadn’t been delayed yet again this year. In March, NASA announced that JWST would not launch in spring 2019 as expected, but it would probably fly in May 2020. The delay is due in large part to a number of mistakes that have been made during the telescope’s construction. Right now, JWST is being pieced together at the California facilities of Northrop Grumman, the main contractor of the telescope, and teams there have had accidents while handling the hardware. For instance, the contractor caused tears in JWST’s sunshield — a key component that protects the telescope from the Sun. Meanwhile, “screws and washers” have been coming off of JWST during testing, according to Space News.

Not only has all of this pushed back the launch date, but it also means that NASA is definitely going to exceed its development budget for JWST, which was capped at $8 billion by Congress. NASA has not announced how much more money it needs for the project now, but it plans to release those details later this month. JWST has dominated the astrophysics budget at NASA for the last two decades. Once it launches, the cost of operating the telescope will be much less than the cost of building it. But NASA must continue to fund the spacecraft’s construction for the next couple of years, which means it won’t have the extra funds for other projects.

“It’s an environment of cold feet.”

Plus, proposing another huge space telescope right now may not be the best look given what happened to JWST. When it was first proposed in 1996, the telescope was supposed to cost between $1 billion to $3.5 billion, with a launch happening sometime between 2007 and 2011, according to the Government Accountability Office. More than 20 years later, the entire cost of the project will exceed $8.8 billion, and its launch date may be pushed back even further; NASA is only 70 percent confident it can meet the May 2020 deadline.

“JWST has literally nuts and bolts falling off it, and here we are proposing $20 billion missions when you have an enormously delayed [probably] $10 billion telescope that still isn’t working,” Grant Tremblay, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics who is working on the Lynx team, tells The Verge. “Originally, it was supposed to be $1 billion and launch in the 2000s. It’s an environment of cold feet.”

NASA’s next big astrophysics mission has also been on thin ice due to costs overruns. The WFIRST telescope, meant to scope out dark matter in the Universe, is still in its development phase, with an expected launch in the mid-2020s. However, a review of WFIRST in October found that the project’s estimated budget had grown to $3.9 billion when the telescope was originally supposed to cost less than $2 billion. The Trump administration tried to cut the mission altogether in the recent budget request for fiscal year 2019. The mission is still funded through 2018, and it’s possible Congress will keep the mission alive in finalized spending bills for next year. But the future of the telescope is unclear.

The significant delay of JWST and the uncertainty surrounding WFIRST had many wondering if NASA should delay the upcoming decadal survey since it’ll be difficult to focus on other projects in the 2020s. But after speaking with many within the astrophysics community, NASA decided to move forward with the decadal, which will be finalized over the next two years. These new cost caps are a consequence of moving forward. “We as a community need to reconcile our vision for the next generation of space telescopes with this reality imposed by funding,” says Tremblay. “And the senior officials at NASA think that a very large — meaning greater than $5 billion — astrophysics mission is basically a political non-starter at this point.”

For now, the four teams are pushing forward with their designs, due to NASA by June 2019. LUVOIR, which is proposing a massive space telescope with a mirror more than twice as wide as that of JWST, says it is exempt from the cost cap. That may be because the study was always aimed at thinking big. But the other three teams will have to check their budget. Tremblay says the Lynx team has been anticipating budget constraints and has already been trying to work toward a mission less than $5 billion. The HabEx team isn’t too stressed, either. They were considering incorporating a starshade — a massive spacecraft that would fly a great distance from the actual telescope to block out the light of stars. And Gaudi says they have been working on new designs that should fit into the cap. “We were focusing on mission designs that were less expensive,” says Gaudi. “For us, it doesn’t really change things very much.”

Still, limiting the scope of astrophysics missions can be frustrating, since getting comprehensive results often requires big budgets. “JWST, when it launches, will do transformational science,” says Tremblay. “We’re in a regime right now where the questions that we ask the Universe require ambitious facilities to answer. Our telescopes are getting very expensive because they need to be even more powerful.”

Correction June 5th, 3:23PM ET: This article originally stated that the decadal was put together by the National Academies of Arts and Sciences, but it is the National Academies of Sciences.