Spaceflight Insider

Take the plunge: Former astronaut talks about NASA’s NBL

NASA astronaut Jessica Meir descends into the space agency's Neutral Buoyancy Laboratory in late November 2016.

NASA astronaut Jessica Meir descends into the space agency’s Neutral Buoyancy Laboratory in late November 2016. The facility has been critical in training astronauts for their upcoming missions since the mid-1990s. Photo Credit: Jason Rhian / SpaceFlight Insider

JOHNSON SPACE CENTER, Texas — NASA continues to use one of its Texas-based assets to provide astronauts with training essential to the missions they conduct on-orbit. The Sonny Carter Neutral Buoyancy Laboratory (NBL) is home to the massive pool where astronauts go underwater to simulate the microgravity environment in space.

Divers at the NBL prepare for a training session. Photo Credit: Juan Diego Delagarza / SpaceFlight Insider

Safety divers accompany astronauts whenever they train in the NBL. Photo Credit: Juan Diego Delagarza / SpaceFlight Insider

The NBL measures an expansive 202 feet (61.5 meters) long, 102 feet (31 meters) wide, 40 feet (12.1 meters) deep, and contains some 6.2 million U.S. gallons (23,469,550 liters) of water. By comparison, an Olympic-sized pool contains a ‘mere’ 253,000 U.S. gallons (957,700 liters).

NASA purchased the structure that contains the NBL from McDonnell Douglas in the early ’90s and refurbished it to support the agency’s training objectives in 1995.

Pool usage

To gain a better understanding of how the pool is used, SpaceFlight Insider reached out to one of our technical consultants, former NASA astronaut Nicole P. Stott. She provided an overview of the specifics involved in training at the facility for extra-vehicular activities (EVAs).

“For shuttle EVAs, we used to do approximately 7–10 runs in the pool for the timeline of whatever tasks we were planning for on-orbit. For ISS EVAs, since there are fewer planned EVAs for particular crew members in a given mission, they have gone to more of a skills-based approach to training in the pool. In other words, the ISS crews are trained to perform a variety of tasks across the ISS that represent the skills needed to perform most tasks that might come up,” Stott told SpaceFlight Insider.

Crews that train at the NBL have their work cut out for them. Not only do that have to prepare for EVA tasks pre-assigned for their mission, they also must train for dealing with potential anomalies that may occur within a wide range of unplanned scenarios.

Before astronauts even get into the pool, they have to complete classes meant to familiarize them with the highly specialized tools and hardware they will utilize both in the NBL and when they are on EVA. As is the case with occupations around the world, one of the first steps in training is familiarization.

“This class is called a ‘1g’ – a run through the tasks (procedures and hardware) in a classroom or pool deck before getting in the pool. The day of the actual run starts with a physical exam by the flight docs and then a briefing with the entire test team to review the plan for the run and the different support needed (this includes the ops control team, the divers, the training team, and also an IV astronaut). Like the actual EVAs in space, the time in the pool is usually around six hours, with the bulk of the morning preparing the suits and conducting safety checks on the pool deck,” Stott said.

NASA astronaut Jessica Meir prepares to train at the Sonny Carter Neutral Buoyancy Lab near Johnson Space Center in Houston.

The Sonny Carter Neutral Buoyancy Lab is located near the space agency’s Johnson Space Center located in Houston, Texas. Photo Credit: Jason Rhian / SpaceFlight Insider

She went on to add that the astronauts must work closely with the other divers present, as they are focused on safety, tech support, and photography. In short, the emphasis is on teamwork.

“These are very talented and experienced professionals who can be very helpful with advice and feedback, and, like any diving situation, these dive buddies are there to give support if something goes wrong with the suit or operation,” Stott told SpaceFlight Insider.

Stott noted that she is not privy to the modifications either to the NBL itself or the training that will be carried out there in support of deep space missions. However, she believes that the requirements and situations anticipated for these missions can be effectively simulated within the facility.

“Like other operations outside of LEO, we are going to have to prepare for more local ops control versus dependence on MCC.  This includes both nominal and off-nominal ops.  The local communication and operations protocol will have to be modified pretty significantly to manage this,” Stott told SpaceFlight Insider. 

The Orion spacecraft

While SpaceFlight Insider was at the NBL, a mockup of the Orion spacecraft was moved via overhead crane into the pool at the NBL. Moreover, in subsequent interviews conducted at JSC, engineers and officials with the space agency discussed the latest plans for Orion and SLS to conduct their first integrated flight as early as late 2018.

“This is a mission that truly will do what hasn’t been done and learn what isn’t known,” said Mike Sarafin, EM-1 mission manager via a page on NASA’s website. “It will blaze a trail that people will follow on the next Orion flight, pushing the edges of the envelope to prepare for that mission.”

The first crewed flight of NASA’s new human-rated spacecraft, Orion, is currently scheduled to lift off from Kennedy Space Center’s Launch Complex 39B in the early to mid-2020s. Dubbed Exploration Mission 2, the mission could herald flights of Orion and the super heavy-lift Space Launch System rocket as much as 1–2 times per year.

Stay tuned all this week as SpaceFlight Insider brings you exclusive content from our tours of NASA’s Johnson Space Center and Space Center Houston.



Jason Rhian spent several years honing his skills with internships at NASA, the National Space Society and other organizations. He has provided content for outlets such as: Aviation Week & Space Technology,, The Mars Society and Universe Today.

Reader Comments

The astronaut you have pictured is Jessica “Meir”, not “Weir”. Just thought you’d like to know.

And btw, I’m the guy (safety diver) in the photo giving the “Hang Lose” sign, so I’ve worked with Jessica just “a few” times.

Jan. 31, 2017

Thanks Bill!

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