Outside Earth’s atmosphere, the timekeeping system that gives structure to life breaks down. When you orbit the Earth in 90 minutes (i.e., 16 sunrises and sunsets every 24 hours), as astronauts do aboard the International Space Station, the words “day” and “night” have fundamentally different meanings.
The human body and its circadian rhythms (sleep and wake patterns regulated by an internal clock) evolved on Earth and are therefore not suited to other environments. In an extraterrestrial, chaotic time world, where astronauts cannot rely on dawn and sunset to maintain their normal schedule, they must follow strict schedules of sleep and work. Any deviation from their natural cycle can quickly lead to Physical and mental health problems.
Lifestyle in space
To ensure that missions run smoothly through disciplined routines, astronauts’ lives in space are planned almost entirely in advance. Activities on the ISS are scheduled down to the five-minute mark, from meals to exercise to maintenance, and all of it must be perfectly synchronized with clocks on Earth.
“You need to be able to tell the time wherever you are to do what you need to do,” says Todd Ely, a senior engineer at NASA’s Jet Propulsion Laboratory.
Astronauts use precise atomic clocks to Coordinated Universal Time (UTC) is the global standard to which all clocks are ultimately set.
of course, Einstein’s theory of relativity the time is do not have Universal: Time passes differently in different situations. If one person is moving faster than another, or is closer to a massive object, time passes slower for that person. These relativistic effects are not significant within the Solar System (and at current spacecraft speeds), but they must be taken into account in time and orbit calculations whenever one goes beyond low Earth orbit.
“Without taking relativity into account, you’re not going to get the right answer,” Ely says.
read more: How astronauts sleep in space
Problems with telling time in space
When close to Earth, the main difficulty will be adjusting to an environment without familiar time cues, but as we get further away, communicating with mission control becomes a bigger problem.
Because messages (in the form of radio waves) can only travel up to the speed of light, it could take up to 14 minutes for news from Houston to reach a spacecraft near Mars, let alone further out in the solar system. This delay poses serious challenges for tasks that require precise timing.
Most of the watches we use in our daily lives crystal — These work well enough for our purposes, but are completely inadequate for astronauts because they don’t measure time consistently, and even the best ones drift apart pretty quickly.
According to NASA:In just six weeks, a quartz clock can become off by one millisecond. That may not seem like a big deal, but it can add up and lead to big navigation errors. Space travel in general, and especially as astronauts begin to venture further from Earth, require even greater precision. Atomic Clock.
Atomic Clock
All clocks rely on a mechanism called a “pendulum,” either literally or figuratively, to keep accurate time. In the case of a quartz clock, that mechanism is a crystal that resonates at a specific frequency and creates an electric current when pressure is applied to it.
But manufacturing errors and environmental factors can cause the performance of crystals to degrade over time. Atoms, on the other hand, are extremely stable: Atoms of the same element resonate at the same frequency every time they absorb or release energy. In other words, atoms are perfect “pendulums.”
Atomic clocks also use crystals, but compare their vibrations to more stable atoms. If the crystal’s frequency is correct, like when an opera singer breaks a wine glass at just the right note, the atom will move into a higher energy state. Any deviation sends an electric shock to the oscillator, signaling it to adjust its frequency.
read more: How NASA is preparing Mars astronauts to deal with isolation and other extreme situations
Navigating deep space
Atomic clocks are used where precision is paramount. Global Positioning System For example, GPS relies on satellites to track our movements every second. Your phone receives signals from the satellites, and those signals are time-stamped with atomic clocks that calculate how long it took for the signal to reach you. Using that information, your phone can pinpoint its location on Earth.
Similar principles apply to navigation in deep space. By measuring how long it takes for radio waves to travel round trip between spacecraft, scientists can calculate their distance from Earth. Continuous measurements of this two-way signal time also reveal their speed and orbit. Combining all this data, they can pinpoint the position of a Mars orbiter to within just a few meters.
Even after more than 20 years at NASA, Elie says, “That never ceases to amaze me.”
read more: Why these 6 items can’t be brought into space
New technology for telling time in space
Since the early 2010s, Ely has been working on designing the next leap in navigation technology: a deep-space atomic clock, an extremely stable device that uses mercury atoms and weighs a fraction of its terrestrial equivalent.
DSAC works so well that a spacecraft can calculate its position and velocity based only on one-way signals from Earth, without having to wait 30 minutes for round-trip communications delays. This enables near real-time navigation, which is useful for high-risk operations like landing on or entering into orbit around another planet.
So far, DSAC has Experimentally testedBut during a year of testing in 2019 and 2020, the prototype’s performance was orders of magnitude better than current space clocks, and it’s possible that the watch may soon become the standard, especially as astronauts begin journeys beyond the Moon to Mars and beyond.
Without highly accurate clocks, “we can’t explore the solar system, we can’t reliably get to our destination,” Eley says.
read more: 4 reasons we should still go to the moon
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Cody Cottier is a contributing writer at Discover who loves exploring big questions about the universe and Earth, the nature of consciousness, the ethical implications of science, and more. He holds a BA in Journalism and Media Production from Washington State University.
