Courtesy of Sierra Space
- Tom Marshburn worked at NASA from 1994 to 2022. He spent 18 years in the astronaut corps.In 2022, he joined Sierra Space, a commercial space company. He now primarily works at a desk.Astronaut life was exciting but demanding. He told BI he has no regrets about the career transition.
This as-told-to essay is based on a transcribed conversation with Marshburn, a 64-year-old former NASA astronaut who is now a VP at Sierra Space. The following has been edited for length and clarity.
I've spent a total of 337 days in space.
During that time, I completed five spacewalks. Stepping out of the hatch, there was just this wide universe ahead of me and Earth 250 miles below.
The spacewalks were daunting — some would say terrifying — but I felt privileged to be able to do them. While they were a great experience, I'm more than OK with not doing them anymore.
These days, I work a desk job in the private sector instead.
Becoming an astronaut
I fell in love with space in high school.
I majored in physics at college, and got a graduate degree in engineering. I dreamed of working with NASA building spaceships.
After completing a college thesis in biomedical engineering, I realized my strengths were more rooted in the medical world. I trained in emergency medicine and practiced for about 10 years.
During that time, NASA was accepting applicants from outside physicians for flight surgeon roles, whose jobs would be to take care of astronauts.
The NASA selection process varies depending on the role and the makeup of the corps.
In my view, they look for people with technical expertise in something, a wide skill set, and the ability to communicate well on technical and non-technical topics. NASA is also interested in how candidates have pushed themselves outside of work and the calculated risks they've taken.
When I applied in 1994, I looked at what accepted astronauts had done, made a list of what resonated, and started checking off the boxes. That's how I did it — but there's not one way to become an astronaut.
NASA
I joined NASA in 1994. During that time, I spent three months learning Russian before heading to Star City, the cosmonaut training center outside Moscow.
There are events in training, particularly in Russia, where there was absolute exhaustion, both physical and mental.
I've never been as hyperthermic or hypothermic as I was in Russia for both winter survival and summer water survival training. At one point, during water survival training, I had a core body temperature of 104°F.
Another challenge was being away from my family. My wife and I have one daughter. We communicated every day that we could, even if I was exhausted, they were tired, or we just didn't feel like it. We did it anyway, because then you get used to it and it becomes a habit.
I spent the next decade as a flight surgeon. I supported one crew, then various crews, before supporting NASA's entire medical program for the International Space Station.
I was selected to become an astronaut in 2004 and spent 18 years in the NASA Astronaut Corps.
An emergency spacewalk taught me about preparation
My first flight was in 2009 — a 15-day space shuttle mission to the International Space Station, or ISS. At the launchpad, there's a huge sense of excitement.
At your first launch, there's some trepidation. It's like you're about to take the biggest final exam of your life. Typically, you don't get a lot of sleep, but there's a lot of laughter and anticipation. On that mission, I did three spacewalks.
My second flight was in late 2012. I flew to the ISS aboard a Russian Soyuz. I had no spacewalks planned, but about three days before I was set to come back, in May 2013, there was an emergency — a leak of ammonia coolant.
If you lose the coolant, the power system can overheat, and then you have to shut it down, which is a really big deal. Preparing for a spacewalk typically takes nine weeks, and we had a matter of hours.
It taught me that preparation matters.
Mission control had the plan. We just followed their lead, step by step. It was one of the best examples of teamwork I've ever had the privilege of being a part of.
All the years of training and experience meant we were prepared and had the confidence to handle that situation.
Transition to the private sector
From 2021 to 2022, I was part of the SpaceX Crew-3 mission for about six months. It was my final mission, and the first for my crewmate, Kayla Barron.
Once it was over, I knew I was ready to leave the astronaut corps. I was in my sixties. There were a lot of new, good people who needed to fly, and I didn't want to take their spots.
In 2022, I entered the private sector when an opportunity at Sierra Space came up. I wanted to do work that would allow others to fly into space. The company has invested a lot of money in transportation to and from space and platforms for living in space.
Courtesy of Sierra Space
I enjoy the variety in my work days. I'm involved in business development and human-factor requirements, which help ensure that a space vehicle for humans keeps them safe and able to do their job without injury or undue physiological stress.
Astronaut life took its toll, but I have no regrets
This job is a little more sedate in the sense that I'm usually at a desk.
I miss some of the more physical aspects of being an astronaut, but it did take its toll on me. I'm OK with being able to figure out what my body can endure on my own, rather than being told I'm going to spend three nights in freezing conditions in the Russian Siberian Outback.
Any regret about no longer being an astronaut is extremely momentary. It's a fleeting feeling when I see my former colleagues and hear what they're up to.
I've been able to bring a lot of lessons from NASA to my current role: leadership, team building, and the technical parts of humans in space.
A desk job at Sierra Space is the right place at the right time for me.
