Human spaceflight isn’t just a matter of making sure you have enough food, water, and oxygen to keep you going for as long as the mission lasts. You also need to stay fit. The zero-gravity or microgravity environment can wreak havoc on the body over time, so astronauts spending weeks or months aboard the International Space Station and other vehicles are required to spend several hours a day exercising.

Which begs the question: What the hell does exercise in space look like?

NASA has just posted a pair of videos on YouTube that provides some illustration. The space agency reveals that the March 22 Cygnus resupply mission for the ISS carried the brand new Miniature Exercise Device (MED-2) up to the ISS. MED-2 is a new apparatus that uses small robotic actuators to apply and modify motion and resistance required for different kinds of workouts.

Fernando Zumbado, the project manager for the MED-2 at the Johnson Space Center, explains in the video that the current exercise device ISS astronauts use weighs several-thousand pounds and is about as big as a large phone booth. MED-2, on the other hand, is an incredibly small 65 pounds, and is basically as big as a backpack. “We’re really pushing the engineering on this,” he says. “You can change the load just by pushing a button.”

If we’re serious about traveling longer distances in space — like to Mars — we’re going to have to get astronauts attuned to smaller spaces. “Having a big exercise device,” says Zumbado, “is not conducive, since it uses a lot more power [and] uses a lot more mass.” The MED-2 actually combines the two main exercise devices used on the ISS into one, reducing both power and mass.

MED-2 won’t be replacing the current ISS exercise devices — at least not yet. NASA is still just testing it out to get feedback from the crew in space and see how they can improve upon it. But this is just another sign that NASA is pretty serious about hitting that 2040 deadline for sending astronauts to the red planet. It’s never too early to start preparing.