Training for an asteroid landing at the Neemo undersea base (pictures)

For astronauts floating hundreds of miles above the Earth in an airless, weightless atmosphere, even the simplest tasks need to be thought out in detail, planning for every step. Thousands of man hours and millions of dollars go into space exploration, and once the rocket has reached the silent depths of space, things absolutely must go as planned. There's no room for error.

The only frontier left on Earth, it is said, is the oceans, and for astronauts of NASA and the European Space Agency, these deep terrestrial environments provide the conditions needed to simulate space missions. It's the perfect place to test the techniques and instrument performance for the future of space exploration, and now NASA is looking at asteroids as their next great space destination.

The NASA Extreme Environment Mission Operations program (NEEMO) project 16 allowed astronauts the chance to train for a manned mission to an asteroid, something NASA has outlined as a core goal, hoping to land a man on a speeding space rock by 2025.

European Space Agency astronaut Tim Peake and his Neemo crewmates, including NASA astronauts, resurfaced last week after spending 12 days underwater. The aquanauts tested equipment and techniques for future space exploration and worked with students above on educational experiments studying the effects of pressurized environments.

The training session off Florida’s Atlantic coast gathered together about 100 European Space Agency astronauts and support crew at the underwater base named Neemo, where the agency ran through the technical aspects of life in space, practicing communications, living in cramped conditions, performing "waterwalks," and engaging in team problem solving.

Here, a European Space Agency aquanaut practices moving through a weightless environment with a jet pack.

For these Neemo aquanauts, diving underwater is one of the best ways of simulating weightlessness on Earth. The aquanauts spent hours on "spacewalks," exploring potential methods of retrieving samples from an asteroid, as well as testing tools and techniques.

European Space Agency astronaut Tim Peake talks with students as part of the project's "science under pressure" educational experiments, which involved collaboration with students on science experiments in the underwater habitat.

Educators and scientists from NASA, the European Space Agency, and the Japan Aerospace Exploration Agency proposed science experiments that evaluate whether simple, everyday tasks, such as blowing a bubble or operating a remote controlled device, will be more difficult at a higher pressure environment.

NASA astronaut Dottie Metcalf-Lindenburger (@AstroDot) anchoring a mock-up of Geo-Physical Array into the sea bottom simulating the surface of an asteroid. Metcalf-Lindenburger is secured with her feet locked into a Portable Foot Restraint carried by a mini Sub that's role-playing a Space Exploration Vehicle.

Aquanaut Steve Squyres from Cornell University has been blogging about his adventure beneath the surface. "Just like any other field scientists, we started with reconnaissance, flying above the surface with jet packs and reporting back to Mission Control what we discovered. On the spot, they came up with a science plan for us, just as would happen with a crew at an asteroid. And then it was up to us to use all the tools we had at our disposal, in whatever way we thought best, to carry out that science plan."

Here we see a submersible transporting a Neemo aquanaut to a simulated asteroid. In space, chipping off a piece of asteroid would require that an astronaut hold on to something, otherwise he would float away. The submersible was tested underwater as a means of getting to asteroids as well offering a stable platform for astronauts to work on.

During Neemo missions, aquanauts employ a technique known as saturation diving to live and work in the Aquarius Reef Base underwater habitat for weeks at a time. Aquarius is an ambient pressure habitat, meaning its atmospheric pressure is equal to the surrounding water pressure -- about 2.5 times that of surface level at the habitat’s depth.

Aquarius is an underwater ocean laboratory located in the Florida Keys National Marine Sanctuary. The laboratory is deployed three and a half miles offshore, at a depth of 60 feet, next to spectacular coral reefs. Scientists live in Aquarius during 10–day missions using saturation diving to study and explore our coastal ocean. Aquarius is owned by NOAA and is operated by the University of North Carolina Wilmington.

NASA is actively planning to expand the horizons of human space exploration, and with the Space Launch System and the Orion crew vehicle, humans will soon have the ability to travel beyond low Earth orbit. That opens up a solar system of possibilities, and NASA’s goal is to send humans to explore an asteroid by 2025. But, they say, to accomplish that goal, the planning, experimenting, and training must start now.