The International Space Station (ISS) is the ultimate triumph of collaboration in science and space exploration. Since its inception 25 years ago, over 280 astronauts from 26 different countries have visited it and performed a plethora of science experiments to advance our knowledge of space and the universe.

Now, however, the International Space Station is running on a skeleton crew: four astronauts returned home last month in the first medical evacuation in ISS history. For privacy reasons, neither NASA nor the astronauts have revealed the nature of the medical issue or which astronaut was affected.

The only three astronauts remaining on the space station are NASA’s Chris Williams and Russian cosmonauts Sergey Mikaev and Sergey Kud-Sverchov.

NASA has moved up the launch of the four-person Crew 12 to as early as the morning of February 11. This is slightly complicated by the already planned Artemis 2 mission, which will orbit the moon in preparation for an Artemis 3 moon landing. Artemis 2 is critical for potential Mars missions, so it takes priority over sending reinforcements to the ISS.

I had the opportunity to correspond with Chris Williams, the only NASA astronaut left on the space station, over text (yes, texts send to space!). Williams is on his first mission after being selected to join the astronaut class in 2021. He received a bachelor’s degree in physics from Stanford University then a doctorate in physics at MIT, where he conducted research in astrophysics. He is a medical physicist by training and completed his residency training at Harvard Medical School. Below is our conversation, edited for length and clarity:

What made you want to become an astronaut – have you always known what you wanted to do, or did you decide later in life?

I always wanted to be an astronaut, ever since I was little! I think the idea of exploration and discovery has always fascinated me, and being an astronaut seemed like the ultimate way to be an explorer.

What was your experience training to go up to space and launching?

It was a lot of work, but extremely interesting. One of the things I like most about this job is that you need to learn a lot about many different areas – on the space station we not only need to know how to do different scientific experiments, but we also need to understand how to fix all of the different systems and equipment onboard as well as how to do spacewalks to fix things outside. It is about a two-year training period once you get assigned to a mission, and you spend that time learning both about the International Space Station and the spacecraft you will launch on.

What is the most challenging part of living on the International Space Station?

The hardest part is being away from your family for a long time. It is really fun being up here but hard to be away.

Do you have any hobbies or facts about yourself that you’d like to share?

I have always liked traveling and visiting new places, and having the chance to see the Earth from space has only made me more excited to try to see and visit as much of our beautiful planet as I am able!

What advice would you give to a high schooler interested in a science career?

Keep being curious and following your curiosity! My career as a scientist took a path that I could not have imagined when I was in high school, but it came about by continuing to keep an open mind about things I was interested in and not being afraid to try new directions!