Launching rockets into space is a dangerous, risky job for anyone. Doing so with a crew pod sitting on top complicates things even more, so NASA has some pretty strict guidelines on how launch-day preparations are handled when its own astronauts are the ones headed into space.

One of the big rules NASA has is that the rockets doing the pushing have to be topped off with fuel before the astronauts climb aboard. It’s a safety precaution to prevent any mishaps during the fueling process that could lead to injury or even death, so NASA takes it very seriously. Now, for the first time ever, NASA might loosen its requirements just a little bit, and it’s doing so because of SpaceX.

In a new blog post, NASA reveals that it has reached an understanding with SpaceX that would allow for the company’s rockets to be fueled with the crew already on board. SpaceX has been doing things this way for some time, and the company’s rockets are usually fueled up less than an hour before they actually launch into space. That normally wouldn’t sit well with NASA, but the administration is giving SpaceX a chance to prove that it’s safe to do so.

Here’s how NASA sees the whole thing unfolding:

If all goes according to plan, on launch day, the Falcon 9 composite overwrap pressure vessels, known as COPVs, will be loaded with helium and verified to be in a stable configuration prior to astronaut arrival at the launch pad. The astronauts then will board the spacecraft about two hours before launch, when the launch system is in a quiescent state. After the ground crews depart the launch pad, the launch escape systems will be activated approximately 38 minutes before liftoff, just before fueling begins. SpaceX launch controllers then will begin loading rocket grade kerosene and densified liquid oxygen approximately 35 minutes before launch.

However, NASA isn’t ready to just give SpaceX the option to do things this way without proving that it can. The tentative agreement is based on the ability of SpaceX to demonstrate that fueling the rocket after crew loading is safe, and it’s going to have to perform five test runs of the process before NASA will allow its astronauts to be involved.

Of course, the first order of business for SpaceX is actually getting its manned rocket configuration finished, and that’s taking some time.