How are the velocity and range of a spacecraft measured from ground based stations? For example we can go on NASA's website and look at the real time data for the mission status of their past spacecrafts, like Voyager. How do they obtain this data?

  • 5
    $\begingroup$ This question exposes essentially zero effort on your part to find answers on your own. There's a lot out there on this. You should do your own research, and then come back here when you have specific questions about it. $\endgroup$
    – Mark Adler
    Oct 18, 2017 at 18:45
  • $\begingroup$ Welcome to stackexchange! Take the tour to learn more about this site, it's a little different than other Q&A sites. If you look around at other questions you'll see that it is normal to do some research first before asking here. In fact, if you search the tags you can read about specific subjects like communications and navigation. $\endgroup$
    – uhoh
    Oct 20, 2017 at 4:08

1 Answer 1


The speed of a spacecraft may be measured from ground using the doppler effect. If the spacecraft sends a signal with a known and very precise frequency, the velocity may be determined by measuring the frequency shift caused by the movement of the spacecraft relative to ground.

Measuring the distance is possible by measuring the delay of a signal from ground to spaceship and back. The known speed of light is used to calculate the distance from the delay time.
See https://en.wikipedia.org/wiki/Doppler_effect and https://en.wikipedia.org/wiki/Radar .

The measurement of distance is done in the same way as using Radar, but when the spacecraft sends a signal back using its transmitter, the method may be used for very long distances too which could not be measured using passive Radar. This way the speed and distance of the Voyager probes may be measured.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.