Being in space is like being Superman every day, says Clay Anderson, a NASA astronaut from Omaha, Nebraska. At the international space station, where he spent five months last year, he flew to breakfast, work and the bathroom.

But floating around in zero-G can have some serious consequences for the human body, NASA’s experts have learned, including the weakening of bones. In fact, studies have shown that space travelers can lose 1 to 2 percent of their bone mass each month on average, according to NASA.

One way that astronauts have been fighting bone loss is through strength training. And they’re getting some help with a new machine delivered this week by the shuttle Endeavour, which docked with the international space station on Sunday.