I know people bounced lasers off of Venus and Mercury in 1960s in order to test the Shapiro delay. Since then, we've developed higher power lasers and radio transmitters (Bolshakovo transmitter).

Are there any farther objects where we've been able to detect the reflected wave?

  • 1
    $\begingroup$ In some extent, the Voyagers, it depends on your definition or curiosity purposes. $\endgroup$
    – Py-ser
    Commented Jun 26, 2014 at 3:55
  • 1
    $\begingroup$ So far, we are able to communicate with Voyagers. However that is not what I wanted. I mean direct reflection of laser or radio signal, which is totally different with communicating with Voyagers. $\endgroup$ Commented Jun 26, 2014 at 5:14
  • 1
    $\begingroup$ en.wikipedia.org/wiki/Radar_astronomy $\endgroup$ Commented Jun 26, 2014 at 14:32
  • $\begingroup$ Very useful wiki link. At least we have got the signal bounced off by asteroids between Mars and Jupiter. However it seems we are able to do it further, because we still have good resolution at that distance. $\endgroup$ Commented Jun 27, 2014 at 1:58

1 Answer 1


1977, Arecibo: Galilean Satellites of Jupiter: 12.6-Centimeter Radar Observations Radar echoes.

1973, 12.6 cm: Radar Observations of the rings of Saturn Content is hidden behind Elsevier's paywall, so this might not be radar echoes.

NASA, 2006 implies the limit for radar echoes is at the moons of Saturn:

Radar astronomy employs the world's most massive dish-shaped antennas, which beam directed microwave signals at their targets, which can be as close as our moon and as far away as the moons of Saturn.

Looked for studies w radar echoes from moons of Uranus and Neptune, as well as Pluto/Charon, none found. The data may be out there.


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .