I trained SpaceX astronauts for a NASA mission. Being responsible for their safety was stressful, but preparing my friends for space was an honor.

• Laura Crabtree worked at SpaceX as an astronaut trainer and engineer for over 10 years.
• She told Insider she trained the NASA astronauts for SpaceX's first crewed mission to the ISS.
• Crabtree spoke about developing close friendships with the crew and testing the training herself.

This as-told-to essay is based on a conversation with Laura Crabtree, a former SpaceX employee and current CEO and cofounder of aerospace-software firm Epsilon3. It has been edited for length and clarity.

I've been passionate about sending humans into space since I was eight years old, so becoming a mission operations engineer at SpaceX in 2009 was a lifetime achievement for me.

Over the 11 years I worked there, I lived and breathed space. I even dreamed about launches, training, and the tasks I needed to do — it was a lifestyle, not a job.

Out of the 20 employees in the mission operations team, I was the only trainer. My role involved writing, training, preparing astronauts, testing software, analyzing data, and more. 

It was my responsibility to ensure the astronauts were as safe as possible when launching into space. It was stressful and I worried about everything, but I loved it.

Training for NASA missions

In 2014, I wrote SpaceX's proposal for NASA's Commercial Crew Program, which is a partnership with private firms that sends cargo and humans to the International Space Station (ISS).

The proposal included information about how SpaceX would train astronauts for the trip and for scenarios such as launch escapes. I also wrote the training for the ground operations team.

NASA selected SpaceX as one of the partners for the program, and six years later, SpaceX sent its first crewed mission to the ISS.

Two NASA astronauts, Bob Behnken and Doug Hurley, launched on the Crew Dragon spaceship — and I had the privilege of training them for the flight.

Putting myself in the astronaut's shoes

The astronauts couldn't stay at SpaceX's headquarters in Hawthorne, California, for multiple weeks at a time, as they had to travel around for ISS training. That meant I developed a set of different lesson plans that each lasted a week.

One week, the training would be focused on the spacecraft's power system, another week it would be on launch escapes, and the next I'd train the crew on emergencies.

The astronauts had to experience being inside the cockpit simulator or capsule simulator and react to different in-flight situations.

They were tested in extreme scenarios, including depressurization and fires in the capsule, which were more than likely not going to happen.

I tried out the trainings and simulators myself — I couldn't have sent my friends to space in the vehicle if I wasn't comfortable flying in it.

Sending my friends to space

I developed close friendships with the crew, and it was an honor to see my friends fly to space while helping the US launch humans again.

I always joked that I would take their suit and go instead of them — I would definitely fly to space if I had the chance. 

Working for Elon Musk

Before I was offered the job, I was interviewed by Musk, who used to interview every applicant vying for a position at SpaceX. I often saw him in the office but we didn't speak directly.

Musk brought a vision to the company that I liked — that's why I stayed there for 11 years. He had a way of getting staff excited about the future and they would always be invigorated after an all-hands meeting.

But by 2020, I wanted a new challenge.

I developed aerospace software for a startup I cofounded called Epsilon3, which was inspired by my time at SpaceX, where I built software for the training and operations and saw how the space industry could progress faster with the right tools.

SpaceX has been ambitious since its inception 20 years ago, and the same can be said for its employees. You have to feel very passionate about the company's mission, humanity, and the space industry.

If you don't, you probably won't stay at SpaceX for long.