Normally, NASA has its focus entirely on the heavens above — but the agency is going an entirely different direction with its latest mission. NASA will be sending astronauts deep beneath the surface of the ocean for an all-new mission that will focus on preparing astronauts for the extreme environments they’ll encounter when they had to Mars sometime in the 2030s — hopefully.

A group of astronauts, engineers and scientists will head to the bottom of the Atlantic Ocean this summer to prepare for future deep space missions and a journey to the Red Planet, according to a NASA statement.

The expedition, called NASA Extreme Environment Mission Operations 21, or NEEMO, involves isolating crew members at the bottom of the ocean, simulating what astronauts will experience in microgravity environments — such as the International Space Station or distant asteroids and planets.

It will be a 16-day mission that started July 21. The crew will test out tools and techniques for future space exploration. They will also test a telemedicine device and, while they’re down there anyway, collect a few samples for marine biology and geology studies.

“NEEMO 21 astronauts and crew will pioneer complex tasks on the seafloor utilizing the most advanced underwater navigation and science tools which are methodically choreographed to mimic a Mars exploration traverse,” NEEMO Project Lead Bill Todd said in the statement. “Equipment can fail, communication can be challenging and tasks can take longer than expected. Other tasks go just as planned. All cases are equally beneficial. It’s how we learn and how we are able to assemble all of this together so that someday we’re prepared for the unexpected when we are living on and traversing the Martian surface.”

The statement added: “The NEEMO crew and two professional habitat technicians will live 60 feet below the surface of the Atlantic Ocean in Florida International University’s Aquarius Reef Base undersea research habitat 6.2 miles off the coast of Key Largo, Florida. NEEMO 21 is supported by the Human Health and Performance Directorate at NASA’s Johnson Space Center with funding from ESA and partnerships with the Naval Postgraduate School, Embry Riddle Aeronautical University, Vega Telehealth, TeloRegen, and Johns Hopkins.”