A scientist’s simple animation shows why there won’t be a way to communicate with astronauts on Mars in real time

An artist’s rendering of astronauts and human habitats on Mars. JPL/NASA
  • NASA plans to send humans back to the moon and, eventually, to Mars.

  • Communicating with Mars astronauts 42 million miles away would require patience: Even at the speed of light, it takes three minutes to send a signal from Earth to Mars.

  • A planetary scientist’s simple animation shows why we probably won’t be able to video chat any Mars astronauts.

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NASA and its commercial partners are working to develop the launch systems and mission technologies the agency will need to send astronauts back to the moon, build a base there, and eventually springboard humans to Mars.

One of the most difficult things about a crewed Mars mission, of course, is the 42-million-mile distance — not just traveling that far, but communicating planet-to-planet.

Light speed is the fastest that any object can travel through space. In a perfectly empty vacuum, a photon (a particle of light) can travel 186,282 miles per second (299,792 kilometers per second).

That’s incredibly fast; however, light speed can be frustratingly slow if you’re trying to communicate with or reach other planets — even the one next door.

James O’Donoghue, a planetary scientist at the Japan Aerospace Exploration Agency (JAXA), made a simple animation to demonstrate the communications delay that future Mars mission controllers would face.

“Light-speed radio communication between Earth and the moon isn’t so bad, but using it to video chat with Martian astronauts is going to be tough, even when Mars is closest to Earth,” O’Donoghue wrote on Twitter when he shared the animation below.

All in all, it takes three minutes and two seconds to send a signal from Earth to Mars at light speed.

How NASA communicates with Mars robots

The light-speed radio waves beaming through space in O’Donoghue’s animation are exactly how NASA communicates with its Mars robots. But that could change by the time it launches astronauts to the red planet.

For now, rovers and landers on the Martian surface beam radio signals up to spacecraft that orbit Mars, which then relay the radio waves to Earth. Here, a global system of radio antennas called the Deep Space Network (DSN) pick up the signals.

nasa deep space network antenna
An antenna at the Goldstone Deep Space Communications Complex, located in the Mojave Desert in California. NASA/JPL-Caltech

If mission controllers want to send a command to a robot on Mars, the signal follows the same path: DSN antenna beam it across space to Mars-orbiting satellites, which then send it down to the surface.

That’s how NASA will manage its newest rover, Perseverance, which launched in July and is currently en route to Mars.

NASA has communicated across space via these radio waves — and nothing else — since it began launching humans in the 1950s.

But the agency plans to upgrade to space-laser communication by the time it launches its first astronauts to Mars.

nasa laser communications mars space lasers
Illustration of a spacecraft using laser communications to relay data from Mars to Earth. NASA’s Goddard Space Flight Center

Though lasers also travel at the speed of light, they can transmit data at 10 to 100 times the rate of radio waves, using far less hardware. NASA estimates it would take nine weeks to laser-beam a map of Mars back to Earth, but the process would take nine years with current radio communications. 

NASA first tested the technology when it laser-beamed an image of the Mona Lisa to a satellite circling the moon in 2013. It’s set to launch a new satellite to try out space-laser communications in Earth’s orbit in 2021.

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