Methane rockets are easier to fuel than hydrogen ones

For decades, the most powerful rockets relied on liquid hydrogen to reach the stars. While hydrogen is incredibly light and efficient, it is a nightmare to manage on the ground. To keep it in liquid form, engineers must chill it to a staggering minus 400 degrees Fahrenheit. At these temperatures, the tiny hydrogen molecules become escape artists, seeping through the microscopic pores of metal fuel tanks and requiring expensive, specialized materials to contain them.