<p>1977, Arecibo: <a href="http://www.sciencemag.org/content/196/4290/650.abstract" rel="noreferrer">Galilean Satellites of Jupiter: 12.6-Centimeter Radar Observations</a> Radar echoes.</p>

<p>1973, 12.6 cm: <a href="http://www.sciencedirect.com/science/article/pii/001910357390002X" rel="noreferrer">Radar Observations of the rings of Saturn</a> Content is hidden behind Elsevier's paywall, so this might not be radar echoes.</p>

<p><a href="http://www.nasa.gov/vision/universe/solarsystem/asteroid-20061219.html" rel="noreferrer">NASA, 2006 implies</a> the limit for radar echoes is at the moons of Saturn: </p>

<blockquote>
  <p>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. </p>
</blockquote>

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

CC BY-SA 3.0
2014-08-24T02:21:13.490Z
2014-08-24T02:21:13.490Z
Wayfaring Stranger
<p>I know people bounced lasers off of Venus and Mercury in 1960s in order to test the <a href="http://en.wikipedia.org/wiki/Shapiro_delay" rel="noreferrer">Shapiro delay</a>. Since then, we've developed higher power lasers and radio transmitters (<a href="http://en.wikipedia.org/wiki/Bolshakovo_transmitter" rel="noreferrer">Bolshakovo transmitter</a>). </p>

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

CC BY-SA 3.0
2014-06-26T03:55:00.373Z
In some extent, the Voyagers, it depends on your definition or curiosity purposes.
Py-ser
CC BY-SA 3.0
2014-06-26T05:14:39.403Z
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.
questionhang
CC BY-SA 3.0
2014-06-26T14:32:16.887Z
https://en.wikipedia.org/wiki/Radar_astronomy
Florin Andrei
CC BY-SA 3.0
2014-06-27T01:58:11.523Z
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.
questionhang
<distances>
What is the farthest object we've been able to bounce signals off of to date?
questionhang
# What is the farthest object we've been able to bounce signals off of to date?

(Asked by: username_0 on 2014-06-26)

I know people bounced lasers off of Venus and Mercury in 1960s in order to test the [Shapiro delay](http://en.wikipedia.org/wiki/Shapiro_delay). Since then, we've developed higher power lasers and radio transmitters ([Bolshakovo transmitter](http://en.wikipedia.org/wiki/Bolshakovo_transmitter)).

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

**Tags:** distances
> **Comments:**
> **username_1**: In some extent, the Voyagers, it depends on your definition or curiosity purposes.  
> **username_0**: 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.  
> **username_2**: https://en.wikipedia.org/wiki/Radar_astronomy  
> **username_0**: 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.  

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## 1 answers

### Answer by username_3 on 2014-08-24. Score: 7 | Accepted answer

1977, Arecibo: [Galilean Satellites of Jupiter: 12.6-Centimeter Radar Observations](http://www.sciencemag.org/content/196/4290/650.abstract) Radar echoes.

1973, 12.6 cm: [Radar Observations of the rings of Saturn](http://www.sciencedirect.com/science/article/pii/001910357390002X) Content is hidden behind Elsevier's paywall, so this might not be radar echoes.

[NASA, 2006 implies](http://www.nasa.gov/vision/universe/solarsystem/asteroid-20061219.html) 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.


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