How exactly can one prepare for the weightless “microgravity” experienced during spaceflight here on Earth, where gravity is very much a part of everyday life?
Generally speaking, there are 3 options.
Lunar gravity simulator. (Image courtesy of NASA.)
The second involves fitting a would-be astronaut into a harness and getting them to walk along an inclined slope with 5/6 of their weight supported by the harness, thus simulating lunar gravity.
The third and most commonly used technique is known as neutral buoyancy training. This involves putting an astronaut into a spacesuit, submerging them in a swimming pool and pumping/bleeding enough air into the suit to allow them to “float” at a desired static depth in the pool. Neutral buoyancy is the backbone of scuba diving practices—the whole point of diving is to control your depth, rather than floating to the top or sinking to the bottom.
Option one is limited in terms of time. 20 seconds isn’t a lot and both the first and second options are limited in terms of how much mass can be tested. It’s fine for people, but not so great for spaceships.
This is where neutral buoyancy pools come in. They offer unlimited test time and for any size of payload, be it human-sized or spacecraft-sized.
This is important for a number of reasons. Extravehicular activities can last for many hours and the use of a pool like this can allow astronauts to train for procedures with the benefit of having a full support team to guide them and assist if anything goes wrong. They do not have the luxury of a physical rescue if something should go wrong while working outside the International Space Station.
So these pools have to be pretty big, right? Right. The Neutral Buoyancy Laboratory in Houston measures 62 m (203 ft) by 31 m (102 ft) and is 12 m (39 ft) deep. It has a mockup of the ISS inside, as well as various spacecraft including the SpaceX Dragon, JAXA HTV and ESA ATV. It is currently the world’s largest indoor swimming pool.
But it looks like that is all about to change. UK-based company Blue Abyss is planning to build an even bigger pool, dedicated to commercial space exploration, diving and human physiological research.
This new pool will be located on the Knowledge Gateway site at the University of Essex and will measure a whopping 50 m (164 ft) by 40 m (131 ft) by 50 m (164 ft) deep. These dimensions will make it not only the largest by volume but also the deepest pool on the planet.
Rendering of spacecraft being lowered into the deep shaft. (Image courtesy of Blue Abyss.)
Spacecraft need to be tested for water ingress and must be made water-tight in case of an ocean-based splash landing. When astronauts land in water, they need to be prepared to escape the vessel in case of emergency and this is where astronaut egress training comes in handy.
The Blue Abyss pool will feature a custom-built 20-ton crane, which will allow the loading of spacecraft modules into the water. It will feature wet belts and other apparatuses typically found on dive support vessels that dispatch underwater rovers into the ocean.
The pool will require massive filtration capabilities. According to John Vickers, CEO of Blue Abyss, the pool will filter “between 2,500-3,000 m³ per hour—that’s almost the same volume (3,700 m³) as Nemo 33 in its entirety!” This will likely be a custom build.
In addition to the neutral buoyancy tasks associated with such a pool, the facility will have some innovative features in terms of the facility’s architecture.
The pool will be heated by geothermal energy, which will be achieved by harnessing low-grade thermal energy (heat) from large boreholes within the facility grounds. A ground source heap pump will then elevate that heat from the boreholes and utilize it to heat the pool.
The ventilation system will involve high-efficiency heat recovery, which will heat the air during cold seasons (which, in England, is most of the time) and will cool the exhaust air via adibiatic processes to help keep the temperature of the facility down in the summer months.
Any ventilated air will be sucked back into the system to allow for heat reclamation, ensuring that the system is as closed-looped as possible. This translates to higher efficiency and a higher level of sustainability.
Sustainability is the key here. Solar panels on the roof of the building will provide power and light to the facility and will ensure that environmental and financial costs are kept to manageable levels.
“I want the building to have a real ‘wow’ factor to it—not only in terms of the recognition we hope the building will garner for what it represents and what is going on within it, but that the design, use of materials, shape, energy usage and sustainability are equally at the heart of this project,” said Vickers.
“Often businesses seem to compromise what they do with where they do it and I wanted both of these elements to be in harmony,” Vickers continued. “I want to create a genuinely world-class facility that has merit, looks and longevity.”
Blue Abyss is tentatively scheduled to become operational in mid-2018.