The Parker Solar Probe is already considered one of NASA’s most ambitious missions, but the agency isn’t taking chances when it comes to potential glitches. Minutes before the Parker Solar Probe was scheduled for liftoff, NASA called off the launch, postponing the high-stakes operation for at least another day.

The probe has seen prior delays but this was the first rescheduling to take place at the last minute. In the weeks leading up to liftoff, the agency remained confident in the August 11 launch date, especially after NASA revealed its new and improved heat shield, or Thermal Protection System. However, rather than problems with the heat shield, NASA announced on Saturday that the launch was postponed due to a glitch in the spacecraft’s Delta IV Heavy rocket.

Parker Solar Probe launch
The Parker Solar Probe while the countdown was still underway

“As we picked up the count and got into t-minus 4 minutes, the team received a gaseous helium red pressure alarm,” Mic Woltman from the NASA Launch Services Program said during NASA’s live coverage. “That kicked them out and now the team is looking and evaluating that but unfortunately there wasn’t enough time this evening to troubleshoot that for a launch.”

The anomaly in helium pressure from the Delta IV Heavy was a violation of the launch limit, resulting in a hold. Once the problem was addressed, NASA said there wasn’t enough time remaining in the window to restart the launch.

Woltman predicts a quick turn-around before NASA tries again, however. The launch is now planned for August 12 from Space Launch Complex-37 at Cape Canaveral Air Force Station at 3:31 a.m. Eastern.

Once launched, the Parker Solar Probe will use Venus’ gravitational pull to shrink its orbit around the sun. These flybys will take roughly seven years, eventually bringing the probe as close as 3.7 million miles from the center of the solar system and making it the first spacecraft to enter the sun’s corona, or outer atmosphere. It’s still history in the making, just a few hours late.