If sending data on earth from mars takes e.g 10 min then how do NASA scientists manage to synchronize stuff with Mars rovers ?

Suppose if something goes wrong and it is required to control or guide a rover (from Earth) to perform some immediate tasks to protect itself. So from Earth instructions are sent but it reaches the rover 10 min. later and in those 10 minutes the rover has performed some other actions (which might not be enough to protect itself). So while these things need to be in sync. there should be some technologies or ways to achieve this.

  • $\begingroup$ There's not much that can go wrong on Mars. Its kind of a dead planet. At worst a dust storm can blow up that may potentially damage some sensors or electronics but (and don't quote me on this) I'd be surprised if the rover didn't have the ability to measure current storm levels around it and respond appropriately, without the intervention of us on Earth. $\endgroup$
    – zephyr
    Sep 13, 2016 at 12:26
  • $\begingroup$ @zephyr sending a robot to mars without consideration that anything cant go wrong is not possible !! there must be some mechanism to order or monitor rover at real time. $\endgroup$ Sep 14, 2016 at 5:40
  • $\begingroup$ It can do some thinking on its own recently it turn 18 and can fire its gun on its own - laser drill stuff. With Route, terrain , picture it can be a good robot. $\endgroup$
    – Isrorian
    Oct 4, 2016 at 15:38

1 Answer 1


There is no concept of "immediate" - which leads to situations such as Spirit getting stuck while travelling, and by the time Earth knew about it, the wheels had dug the rover in rather badly.

So "synchronisation" itself really doesn't happen. Instead, routes are risk assessed, and instructions given to the rover to move a distance that should be safe. Some of these have been relatively long journeys, and the computer on board can handle simple instructions, but in general any challenge or any risky route requires the rover to stop, send back position data, image data and so on for analysis, and await new instructions.

Comms is via radio (thanks @PeterErwin) and depending on relative positions of Earth and Mars can be anywhere between 3 and 21 minutes. So there is a lot of sitting and waiting. Some of this time is spent usefully by taking photographs, or "doing science" but sometimes it's just waiting.

Mars exploration is Sloooooow!

  • $\begingroup$ but then what are the technologies are being used to send data to earth from mars ? ;( $\endgroup$
    – Rahul Rabhadiya
    Sep 13, 2016 at 12:24
  • $\begingroup$ mars.nasa.gov/msl/mission/rover/communications $\endgroup$
    – Peter Erwin
    Sep 13, 2016 at 12:28
  • $\begingroup$ Fun fact, a Martian day, or 'sol' is about 37 minutes longer than an Earth day. So at the start of the Curiosity mission, the engineers worked in shifts that were scheduled around a Martian sol rather than an Earth day. $\endgroup$
    – Phiteros
    Sep 22, 2016 at 5:03

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