Clocks on Mars tick faster than on Earth by nearly half a millisecond a day, according to new calculations – and the implications for future missions to the Red Planet could be significant.
Neil Ashby and Bijunath Patla at the US National Institute of Standards and Technology calculated that
a clock on Mars ticks 477 microseconds faster per day.
More on Mars
That rate can also shift by 226 microseconds a day, depending on Mars’s distance from the Sun.
The effect comes from general relativity: weaker gravity and orbital motion alter spacetime, changing how time flows.
Surface gravity on Mars is just 38% that of Earth, meaning a second on the Red Planet is slightly shorter than for us on our planet.
Why does it matter? Well, if you’re trying to communicate with a rover using radio waves travelling at the speed of light, microseconds count.
Even the 56-microsecond delay in radio communications between Earth and the Moon means lunar targets could be missed by the length of about 184 football fields – and Mars is much farther away.
Luckily, we already correct for similar effects in GPS satellites, whose clocks run faster than those on Earth – otherwise your phone’s GPS would be misaligned by miles after only a few hours.
But it gets a lot more complicated when you are scaling that solution to deal with interplanetary distances, for worlds with different gravities that are moving closer and further from the Sun’s gravitational influence.
