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Travelling to New York, Hong Kong or Sydney for meetings can play havoc with your body clock, making it difficult to adjust for days after you get there. Some people feel a little tired but others get serious jet lag. So how much more difficult must it be for those working on Martian time?
Every picture paints a thousand words—especially when that photograph is being relayed back to Earth from Mars. Like Earth, Mars has weather, seasons, volcanoes, canyons and even polar ice caps. So there is huge excitement around the Perseverance rover, which landed on the red planet in February, and has been collecting information since then. The aim is to discover any signs of ancient life, collect rock and sediment samples, get a clear picture of the geology and climate—and pave the way for human exploration beyond the Moon. That will present challenges, not least the fact that a day on Mars is not the same length as one on Earth.
The Martian Calendar
This is something that Dr Niamh Shaw knows all about as she has been on a simulated Mars mission in Utah and a zero gravity flight. Shaw, who is based in the International Space University in Strasbourg, France, is well aware of the complexities involved in space exploration. “A Martian day is not the same length as a day on Earth,” she said. “It’s a bit longer and a Martian year is longer too.”
A Martian day, which is known as a sol, lasts 24 hours, 39 minutes and 35.244 seconds. A Martian year is 687 Earth days or 669 sols. Perseverance’s first Martian day on the surface of the red planet is known as Sol 0. “Mars is farther out than Earth from the Sun. So that’s why it takes it longer to get around to orbit the Sun,” she said.
The rover is working during the Martian day and “sleeping” during the Martian night—as is the Perseverance team back on planet Earth. For about 90 sols, the operations team is working on Mars time, which means they are setting their clocks to the Martian day.
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Working on Martian time
This allows them to respond quickly to any issue the rover may have during its workday. Working on Mars time also means that team members move their start times 40 minutes later each day. Unlike night shifts or unusual working hours, this involves a gradual change of body clock. Eventually, team members will be waking up in the middle of the night to start their shifts. Living on Mars time makes daily life on Earth much more challenging, so the team is doing this only for a limited period.
“I think the body will just adjust to that extra half an hour because it’s almost like delayed jet lag,” said Shaw. “If you go from here to America, the reason we get jet lag is that the time difference is so extreme. Whereas when we go from France to Israel, it’s fine. So I think they’ll be grand.”
The natural instinct that helps us to tell the time will probably be disrupted as the hours shift repeatedly. “It will be like, ‘What time is it?’” she said.
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The Perseverance team
The Perseverance mission was launched from Cape Canaveral in Florida in July 2020 and landed on Mars in February 2021. The core team of engineers and scientists guiding it are based at Nasa’s Jet Propulsion Laboratory (JPL), the hub of operations in Pasadena, California. “If this were an old Western movie, I’d say the descent stage [when the rover landed] was our hero riding slowly into the setting sun, but the heroes are actually back here on Earth,” said Matt Wallace, Mars 2020 project manager at JPL.
Hundreds of others around the world are also working remotely on Martian time, including Professor Nicholas Tosca of the University of Cambridge, who is part of the core science team. As Perseverance crosses the surface of Mars, the professor of mineralogy and petrology in the Department of Earth Sciences is helping to decide which rock samples it collects.
Perseverance’s first images are part of a planned 90-sol initial checkout period. The mission team will perform tests of all the rover’s parts and science instruments to ensure everything—including the team—is ready for surface operations.
The team operating the Pathfinder mission’s rover in 1997 did not take kindly to being required to live indefinitely on Mars time and eventually objected to their bosses at Nasa. Research conducted in 2011 highlighted that people respond differently to working on Martian time. Four out of six team members involved in the experiment saw their sleep patterns change. One participant had moved onto a 25-hour day by the end, which put him out of sync with the others. Every few weeks, it was midnight for him, but midday for the others. “The essential need for humans to maintain sleep–wake activity cycles synchronised to the circadian biology that temporally coordinates human health and behavior appears to be as important on Earth as it will be en route to Mars,” the research team concluded.
For the Curiosity Mars mission in 2012, Nasa put a limit on the number of days any staff member was rostered to work on a mission to 90 days at a time. It also scheduled staff to work no more than four days in a row and started to monitor fatigue levels. These rules have applied to all missions since, including Perseverance, to make working on Martian time less stressful and disruptive for everyone involved.
Much like the experience of the Perseverance team, Shaw’s simulated Mars mission began with video calls with others taking part around the world. “We talked together a lot, but even trying to negotiate that was a challenge, because some of us were in the United States, some in Australia, some in Europe and some in Israel,” she said.
The main mission for the Perseverance rover is one Martian year on the surface. In that time, samples returned from a four-billion-year-old lake deposit on the red planet should give an insight into Earth’s origins. It can also give insight into how man can plan to operate as a bi-planetary species when days are not the same length. “We are going to have to come up with another term. Will we need new time zones? Could Earth be all one time zone, where it’s bright at 3pm in one country but dark in another? These are all questions that need to be answered,” said Shaw.
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