Earlier this month, MTS spoke one-on-one with Dr. Kathryn Sullivan - the only person to have walked in space and descend to the deepest point in the oceans, The Challenger Deep – about her experience diving to the deepest point on Earth; some  of the challenges and opportunities she has faced along the way, and  her thoughts about the future of scientific exploration and discovery.

MTS: What were some of the most interesting things you saw or experienced in making the dive to the bottom of the Challenger Deep?

Kathryn Sullivan (KS):  The submersible itself is a fascinating one-off, specially-designed craft. It is the first and only one to successfully dive multiple times to such depths. The Bathyscape Trieste and (filmmaker/explorer) James Cameron's Deep Sea Challenger only went to full ocean depth once. We did three dives in the span of seven days, which is a real testament to the radical step forward in design this submersible is. And, as a nerd and engineer in my own right, that was fascinating. 

The bottom was composed of light-tan, fine silt, but with many small mounds and pock marks, which tell you that there is a fair number of critters burrowing, living, and feeding on the upper few centimeters of thet sediment. There were some sea cucumbers on the bottom that were being pushed along by some combination of our thrusters and the ambient current. I also saw clear signs of current sculpting of the sediment in a couple of places, as well as a couple of linear tracks that told me some organism had crawled along the bottom. I would love to have a chance to go back and do a closer observation of the mechanical properties of the sediment.

MTS: Were there any parallels with respect to how you prepared – mentally and physically – for space flight aboard the Space Shuttle Discovery and the descent to the Challenger Deep?

KS: There were more contrasts than similarities. This really all comes down to the fact that I had much greater responsibilities on the shuttle. 

The submersible is  a rated single-pilot craft and was piloted by  Victor Vescoco. I needed to know where my own spare air bottle was, how to don the emergency breathing hood, how to communicate with the surface, and how to drop the surfacing weights just in case the pilot keels over.  And I had to be athletic enough to climb down through the trunk and sit still and stay alert for the 12 hours we expected to be in the sub.

Another difference is that one (Space Shuttle launch) is an explosive start and one is an exceedingly calm, serene dissent. In one, you’ve got a thousand-mile field of view. In the other, you've got a 30-foot field of view. In one, the capsule needs to protect you from the utter lack of atmosphere outside. And in the other, it needs to shield you from 1100 atmospheres worth of pressure outside.

MTS:  In the one image of you inside the submersible, you are pretty bundled up. Was it terribly cold inside? 

KS: When you do a deep dive like this, you're sitting inside a metal sphere and going down into water that's basically freezing. So, the temperature inside the sphere is going to continue to drop as you spend time on the bottom. At one point, I think temperature in the sphere fell to 22- or 23-degrees Fahrenheit. This is quite a contrast to the tropical temperatures on the surface. So, you pack gloves or a warm cap in advance. I also borrowed some big down mountaineering booties from the expedition leader to keep my feet warm. There is a heating circuit inside the cabin. However, you have a finite number of electrons in the batteries, and you want to allocate them to the lights and thrusters and not spend them on heating the inside of the vessel. 

MTS: With the advances in remotely operated and autonomous vehicles, why is it important to send people to such a deep and dangerous place as the Challenger Deep?

KS: To borrow a phrase from Don Walsh “no little kid ever wants to be a robot when they grow up .” There is something quintessentially human, inspirational, attractive, and appealing about watching others go to the unexplored places. This creates a  contagious sense of adventure and is a beacon to younger generations.

Truth be told, I tend to see this relationship between manned and autonomous vehicles as working hand in glove rather than as a binary choice. If you already know what data you need to collect, then using a robotic or autonomous device that can retrieve that information is sensible. But when you're going into a profoundly unknown environment, I think it’s pivotal to keep a human frame of reference that says: “I know some information. I'm after some questions. But I also don't know everything about this environment. And I’m curious.” The full sensory awareness of human crewed submersibles is key to gathering peripheral, unexpected information in an environment that may not be fully known.

MTS: Can you talk about the importance of both success and failure and how those shaped you into the person you become personally and professionally?

KS: While we all like to celebrate accomplishments, I’ve found throughout my career you learn more and your character develops more intensely when you have to deal with a setback, rather than when you're just cruising along from success to success. I am quite fortunate in that I've never had any big physical injury or issue that’s knocked me totally off course. But I've done my bits of misdirection. In my book, Handprints on Hubble, I write about one of my  more glorious breakdowns when I threw the wrong switch inside a space shuttle on the launch pad and set off every alarm in the cabin. The saving grace was that it was completely reversible, and it didn't hold up the next day’s launch. At the time, I was a freshly minted astronaut who had not yet flown in space, and I spent the rest of that night and quite a time thereafter pretty sure I had just upended my entire career, as the stakes and performance expectation were high. In this case, fatigue was the main factor not incompetence. Regardless, NASA expects the best out of you and that was clearly a miss. Period. Full stop, a big miss. All you can do is to move forward, learn, and grow from experiences like these.

MTS: What would you want to tell aspiring oceanographers and astronauts who might want to follow your footsteps?

KS: I would say that you shouldn’t try to replicate my professional path. I followed one road to these opportunities, but there is more than one way to get there. Looking ahead, it’s likely that the number of possible pathways is likely to widen and expand in the future. On the Ring of Fire expedition, for example, the gentleman in charge of the six-man sub team grew up in rural Northern British Columbia. He had a high school education and did a stint as an ice road trucker. The two women in charge of the multi-beam echo sounding mapping both had master's degrees from the University of New Hampshire. Another crew member was a champion swimmer from Australia who went to a maritime college and then worked as a scuba diving instructor. Only one person on that ship, me, had a Ph.D., but all were essential to the operation.

Furthermore, as commercial opportunities continue to evolve and new companies come online, I think you will find that organizations are looking for people with a more diverse set of skills. If you’re laser focused on becoming an aquanaut in a sub or an astronaut aboard a spacecraft, then intense academic preparation will probably still be  a must. However, across all missions – be they at sea or in space – there is a team of people with diverse backgrounds and talents that make each operation successful. And it is incredibly gratifying and fun to be a part of those things, whether you get the window seat or not.

MTS: Finally, you have travelled 200 miles up, and 7 miles down. What is the next frontier for human exploration? More specifically, what is your next frontier for exploration?

KS: I've actually traveled 334 nautical miles up! The conventional definition of exploration is about physically going somewhere, observing a phenomenon not seen before, and contributing new knowledge to the scientific enterprise. I have done a lot of that, but I've come to view that description as too narrow. Exploring is simply curiosity and action. It doesn't have to involve getting on a ship or into airplane and traveling great distances. There are countless things to continue exploring – whether that is through the lens of a microscope or in the pages of a book. That’s still exploring in my book. Personally, I know that I won't run out of things to learn. Having said that, if someone wants to offer me one more trip to space, I will undoubtedly say “Yes!” and would be extra happy if that was to the moon or Mars.

Listen to Dr. Sullivan's August 19, 2020 webinar discussion, "Challenger Deep Dive: From the Heights to the Depth," with MTS President Zdenka Willis here.