The most accurate means to tell the time is being used to improve space travel.
This week, NASA launched a miniature atomic clock into orbit with the help of a Falcon heavy rocket in Florida. The clock is said to be 50 times more stable than others of it’s kind in orbit, such as the clocks used in GPS satellites. Exciting stuff, but what is an atomic clock?
Simply put, it is the most accurate way we have of telling the time.
Normal, everyday clocks keep track of time by counting the number of times an object they’re connected to “resonates”. For example, a clock can have a pendulum which swings back and forth, which acts as the “resonator” and is counted by the clock every time it moves. In the case of digital clocks, a quartz crystal is used as it’s microscopic movements can be counted. The clock does this electronically, counting them using an assigned number of cycles, which us humans have established as the means to measure them. The more accurate the resonator, the more accurate the clock.
Atomic clocks take this a step further and use the microscopic movements of an atom to tell the time. Specifically, the energy that is contained within an atom. What makes this accurate is that some atoms resonate at a very exact frequency, meaning that its energy can be consistently tracked and measured. To do this, an atomic clock uses the atom of a chemical element called cesium (Atomic number 55 on the periodic table). Cesium-133 resonates at 9,192,631,770 cycles per second, which is tracked by how much energy the atom is absorbing or emitting. That is a microscopic method to measure time, and much more accurate than something like quartz crystals, which are made to keep time at a standard frequency around the world.
The atomic clock that NASA has launched, which uses mercury-ion to tell the time, serves to improve the way in which the agency communicates with deep-space probes. By carrying their own clocks, the probes can make navigational calculations based on the signals that are sent to them. It can make course corrections in real time and won’t be effected by time delays that can happen when in communication with Earth.