How do you prepare astronauts for the challenging task of working on asteroids? By sending them to the bottom of the ocean.


And how do you prepare the public for the excitement of future space-exploration missions? By live-tweeting, webcasting and blogging about the whole experience.


On June 11, a team of four international astronauts went not into outer space but 63 feet below the ocean surface off of Key Largo, Fla. The astronauts will spend a total of 12 days at the National Oceanic and Atmospheric Administration's Aquarius Reef Base undersea research habitat. According to NASA, the isolation and microgravity environment of working on the ocean floor will allow the crew to simulate and test concepts for future missions to explore asteroids.


The first human mission to an asteroid is planned for 2025.


This is the 16th excursion of the NASA Extreme Environment Mission Operations (NEEMO), which has been sending astronauts into the ocean since 2001.


While underwater, the crew — who have spent the last several months training for the mission — will focus on three areas related to asteroid missions: communication delays, optimum crew size and how to operate in environments will little to no gravity.


The four-person team includes NASA Commander Dottie Metcalf-Lindenburger (a former space shuttle pilot), astronaut Timothy Peake from the European Space Agency, astronaut Kimiya Yui from the Japan Aerospace Exploration Agency and Steven W. Squyres, the Goldwin Smith professor of astronomy at Cornell University and chairman of the NASA Advisory Council. Squyres is the principal investigator for the two Mars rover projects and is monitoring their progress while he is underwater.


Although they will be operating this mission in physical isolation from other humans, the crew will be documenting everything they do online, using Twitter, blog posts and live webcams to interact with the public. Two video cameras will capture all of the action from inside the laboratory and outside in the water. Another live feed will come directly from the astronauts' helmets when they are underwater so the public can see exactly what they see and listen in on their communications.


So what do the astronauts hope to learn while underwater? "These are some of the big questions we're trying to answer," Peake told BBC News. They team will be testing foot plates that would allow future astronauts to attach themselves to and explore asteroids without falling into space in a zero- or low-gravity environment. They are also testing robotic arms and other equipment that would be used to collect rock samples from asteroids. "NASA also wants to know what sort of team compositions are required," Peake said. "Is it better with one SEV [space exploration vehicle] or two SEVs, working in pairs or as individuals? We'll be coming up with all sorts of data that will shape NASA's asteroid mission."


The team is already deep into their mission and working hard. Squyres tweeted Monday night, "I have to remember not to get so wrapped up in the work that I lose sight of just how cool this stuff is."


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