To the red planet

NASA’s top doc: DO oversees the health of astronauts, preps for Mars mission

J.D. Polk, DO, shares how his background in aerospace medicine led to his new post as NASA’s chief health and medical officer.


In his new role as NASA’s chief health and medical officer, J.D. Polk, DO, is among those working to ensure astronauts’ safety as NASA prepares for its first human journey to Mars.

“The crew can’t just come home whenever they want. We need to ensure the astronauts are trained to deal with routine medical care as well as emergency medical issues when they embark on exploration missions,” says Dr. Polk.

In this edited interview, Dr. Polk discusses his NASA career and the health challenges astronauts might encounter on the first human journey to Mars.

What does your job entail?

I wear a couple of different hats. I concentrate on the medical needs of NASA astronauts and aviators and also oversee occupational health for the agency employees. We must ensure that the crews both in space and on the ground are healthy to decrease mission risk. I also oversee the technical requirements that impact the astronauts’ health, such as how a vehicle will be built, whether radiation can be mitigated, how much exercise a crew can do on board, and their food and water needs during a mission.

J.D. Polk, DO (left), and Shannon Moynihan, MD, work the console during a space shuttle mission.

As chief health and medical officer, I need to know the systems and International Space Station by heart. I can appreciate the concerns flight surgeons and crews face in their roles. Without this operational knowledge, I might write a policy that has unintended consequences.

NASA also monitors all astronauts for the rest of their lives. We look at the long-term health consequences of going into space and the impacts that space exposures have on the quality and quantity of astronaut life.

As NASA prepares for its first human journey to Mars, what are some of the health challenges astronauts on that mission might face?

Because of the time delay in transmission of communication between Earth and Mars, astronauts need training on dealing with an emergency medical issue while awaiting instructions from the flight surgeon.

The loss of gravity will cause bone loss as well as visual impairment. Exposure to radiation also is a concern as it affects their immune system and increases their cancer risk. Otherwise, the astronauts will face the same health issues we have here on Earth, such as getting a virus or suffering injuries from a vehicle crash.

What are the steps you took in your career that led you to NASA and this role?

When I was in the Air Force Reserve, I supported space shuttle launches and landings. When a NASA flight surgeon position opened up in Houston, one of the NASA flight surgeons asked if I was interested, and I applied.

I returned to NASA a year ago after taking some years to work for the Department of Homeland Security and serve as dean of the Des Moines (Iowa) University College of Osteopathic Medicine.

This job—NASA’s chief health and medical officer—requires a specialized skill set with board certification in aerospace medicine and experience with space medicine. The eight years I previously spent at NASA coupled with the policy and leadership experience I gained in my other positions give me an advantage in this role.

What advice would you give to DOs and students who are interested in aerospace medicine?

Be sure to get a broad breadth of medical experience. Most flight surgeons are dually trained in a primary care specialty as well as aerospace medicine. Do additional residency training in aerospace medicine in a civilian residency or in the military. One of the best ways to get involved is to do a rotation at NASA as a medical student.


  1. Jessica Grover

    Hello, I’m a third year osteopathic medical student at Michigan State University. Since I was little I’ve been intrigued and captivated by the work of NASA and had dreams of working for this program. I am VERY interested in doing a rotation through NASA and would love to get some more information on how I would go about setting this up. Thank you so much for posting this article!

    1. Dr. J.D. Polk- NASA

      Hi Jessica
      The NASA Johnson Space Center has a one month rotation in Houston for fourth year medical students. Look for “NASA Medical Student Clerkship” on your search and you should find the entry point. Or alternatively, you can always contact me.

  2. Robert S. Juhasz, DO

    Thank you JD for allowing us to live vicariously through your amazing life journey. Thank you also for your service to our nation and the osteopathic medical profession. On a day when we honor another Ohioan American hero born not far from where you were, I say…God’s speed JD…

    1. Dr. J.D. Polk- NASA

      Thank you Bob, but let’s give credit where it is due. I had many good mentors and teachers while I was a medical student and resident, including a young internal medicine attending named Bob Juhasz, DO. Growing the next generation of osteopathic leaders is one of the most important things we do. Thank you for your service to the profession!

  3. Ed Johnson

    Lost track of most of our AMP (aerospace medicine primary) class 1999, Brooks AFB. I still have the black T-shirt you designed (Sierra Hotel). You were always a fast burner. The Space Medicine program is in good hands. Thank you for taking on such a daunting task…Mars. I am still doing my small part here on earth in the USAF Reserve.
    Col (Dr.) Edward G. Johnson
    Travis AFB

  4. Mali Schneiter

    Hi Dr. Polk!

    I’m not sure if you remember me but I was one of your former students at DMU. I’ve been meaning to reach out to touch base and give you updates as well as I have a good friend from residency that I would like to put in touch with you.


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