Having landed on the moon, humankind’s next greatest challenge is to send astronauts to Mars. And as you probably already realize, this task is made difficult by how much further away Mars is from Earth (I highly recommend clicking on that link). Therefore, any manned mission to Mars has to take into account long-term food storage, fuel capacity, waste disposal, making sure the astronauts don’t go crazy from boredom, etc. However, there’s one more issue that is quite interesting really, and one that you may not have heard about yet.

Time.

See, time passes differently on Mars. In fact, a Martian day, or “sol”, lasts 40 minutes longer than a day on Earth. By 90 sols, Martian time ends up 2.5 days behind Earth time. Now, as Tom Chmielewski of The Atlantic reports, this has proven difficult for the people in control of Curiosity rover, who have to constantly be on Martian time. In fact, they’ve even recruited their families into helping them adjust to Mars time by having them adapt alongside them (a true test of marriage, am I right?).Though the rover controllers eventually adjusted better, the time difference still took a toll on them.

Truth is, there’s a good reason why they had a hard time adjusting. The human body has its own “molecular clock” inside its cells that runs on a 24-hour cycle known as the “circadian rhythm”. Circadian rhythms are naturally maintained by the rise and fall in levels of different cellular proteins throughout the day and night. Back when the Pathfinder rover was on Mars, Harvard professor Charles Czeisler was simultaneously working on an experiment to see how well people could adjust to a longer day. He went all out with this experiment too, isolating the test subjects from any outside influence that could affect their perception of time.The result: no one adjusted well. Their circadian rhythms remained on the body’s natural 24-hour cycle.

Fortunately, Czeisler’s group later found the secret to altering a person’s circadian rhythm was actually not in the length of time exposed to light, but the wavelength (or color) of light exposed to. Though they haven’t found the specific wavelength that works best for adjusting to Martian time, they have at least discovered that blue light decreases your body’s level of melatonin, a hormone released around bedtime to promote sleeping (this is why Facebook-ing right before bed is a bad idea). Current plans are underway to experiment with astronauts aboard the International Space Station to see if altering exposure time to blue light at night can effectively push them onto Martian time.