Mars Time



The Martian day, called a “sol” is 24 hours and 39 minutes, making it 39 minutes longer than an Earth day. In order to properly monitor a Mars rover‘s mission, many of the scientists and engineers involved switch to Mars time, at least for the first three months. A forty minute longer day may not seem like much of an adjustment, but that daily forty minutes adds up and before too long you are out of sync with Earth’s day and night. Here is the story from AP about a whole family that is trying the adjustment out.

Since the landing of NASA’s newest Mars rover, flight director David Oh’s family has taken the unusual step of tagging along as he leaves Earth time behind and syncs his body clock with the red planet.

Every mission to Mars, a small army of scientists and engineers reports to duty on “Mars time” for the first three months. But it’s almost unheard of for an entire family to flip their orderly lives upside down, shifting to what amounts to a time zone change a day.

Intrigued about abiding by extraterrestrial time, Oh’s wife, Bryn, could not pass up the chance to take their kids – 13-year-old Braden, 10-year-old Ashlyn and 8-year-old Devyn – on a Martian adventure from their home near the NASA Jet Propulsion Laboratory where the Curiosity rover was built.

“We all feel a little sleepy, a little jet-lagged all day long, but everyone is doing great,” Bryn Oh said, two weeks into the experiment.

Days on Mars last a tad longer. Earth rotates on its axis once every 24 hours – the definition of a day. Neighbor Mars spins more lazily. Days there – known as sols – last 39 minutes and 35 seconds longer than on Earth. The difference may not seem like much each day, but it adds up.

To stay in lockstep, nearly 800 people on the $2.5 billion project have surrendered to the Martian cycle of light and dark. In the simplest sense, each day slides forward 40 minutes. That results in wacky work, sleep and eating schedules. Many say it feels like perpetual jet lag.

The Oh family broke in slowly. A sign on their front door warns: “On Mars Time: Flight Director Asleep. Come Back Later.”

Days before Curiosity’s Aug. 5 touchdown, the children stayed up until 11:30 p.m. and slept in until 10 a.m. In the beginning, it wasn’t much different from a typical day on summer vacation. As the days wore on, they stayed up later and later, waking up in the afternoon and evening.

One day last week, the family ate a 3 p.m. breakfast, 8 p.m. lunch, 2:30 a.m. dinner and 5 a.m. dessert before heading off to bed.

To sleep when the sun is out, their bedroom windows are covered with aluminum foil or cloth to keep out any sliver of light. In the hallway, a handmade calendar keeps track of the days and schedules are written on an oversized mirror. A digital clock in the master bedroom is set to Mars time.

The article goes on about the various troubles the family has in essentially rotating their day and nights forward about a time zone every day. I wonder what effect the slightly longer Martian day might have on any colonists. They wouldn’t have the trouble of having to contend with Earthly time cues, such as sunrise and sunset, or with human activities, which on Mars would be in accord with the Martian day. I don’t think the extra forty minutes would be too hard to adjust to, if everyone in the colony were on the same time.

They would have to do something about their clocks. Would they divided a Martian day into 24 slightly longer Martian hours? What about minutes and seconds? The Martian year is about 687 Earth days. Would Martian colonists measure time by Earth years or Mars years? If I lived on Mars, would I be able to get away with saying I am 20 (Martian) years old?

It will be interesting to see how they figure these sorts of things out. I hope I live to see a colony on Mars.



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