The highly anticipated launch of the Dream Chaser spaceplane may be delayed yet again as Sierra Space continues to test its experimental vehicle.

The inaugural Dream Chaser, named Tenacity, is slated for a launch date in 2025. However, recent comments by a NASA official revealed that there’s a lot more work to be done before the spaceplane is ready to fly to the International Space Station and that it’s highly unlikely to meet its deadline.

“We still have some of our integrated safety reviews to do, and we’re in the process with updating both of our schedules to try to understand where does that really put us,” Dana Weigel, the program manager for the ISS, said during a recent media briefing, according to Aerospace America. “Sierra’s working on that, and so I need to wait and just get information back from them to see where they think some of that work lines out.”

Dream Chaser has been years in the making. NASA awarded Sierra Space a Commercial Resupply Services 2 (CRS-2) contract in 2016 to provide at least seven cargo deliveries to the ISS. The Colorado-based company originally intended for Dream Chaser’s inaugural flight to take place in 2020, but the spaceplane suffered several delays due to technical issues and certification hurdles. Although its 2025 launch date still appears on NASA’s schedule, Weigel’s recent comments don’t sound too promising.

Dream Chaser is designed to launch to low Earth orbit atop a rocket but survive atmospheric reentry and perform runway landings on the surface upon its return, similar to NASA’s Space Shuttle. The futuristic-looking vehicle has foldable wings that fully unfurl once it’s in flight, generating power through solar arrays. The spaceplane is also equipped with heat shield tiles to protect it from the high temperatures of atmospheric reentry.

“I think everyone really underestimates what it takes to put together a complex spacecraft. I mean, you’re watching it right now with Boeing Starliner, you’re watching it with Sierra, but if we remind ourselves on average it takes eight to 10 years for a spacecraft to get ready and fly,” Weigel told reporters during the briefing.

Apart from SpaceX’s Dragon spacecraft, NASA hasn’t had any luck in moving forward with an alternative means of transportation for its crew and cargo to the ISS. Following lessons learned from Boeing’s Starliner fiasco, which left a crew stranded on the space station for nine months, NASA may be taking extra precaution before launching Tenacity to the ISS.

One of the remaining tasks to be completed before its debut launch is a certification of Dream Chaser’s software. Starliner experienced significant software issues during its first orbital test flight in December 2019, which pointed to problems with the spacecraft’s software certification.

Another hurdle that stands in Dream Chaser’s way to space is its designated launch vehicle. For its debut flight, Tenacity will launch atop United Launch Alliance’s Vulcan Centaur rocket. The 200-foot-tall (61-meter) rocket experienced a booster anomaly during its second flight in October 2024, which delayed its certification process for national security missions. Vulcan is still awaiting certification from the U.S. Space Force and has a backed-up schedule to attend to once it’s ready to fly those missions.

Dream Chaser is the next-generation reincarnation of Space Shuttle that spaceflight enthusiasts have been waiting for, but they may have to wait a little bit longer to see it fly.