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NASA Planetary Scientists released a video that says they have confirmed that there is an underground ocean in Europa and that Titan has liquid oceans made of hydrocarbons.

I myself am an aspiring planetary geologist and current student, the only instrument I have seen them using is the spacecrafts orbiting these moons.

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    $\begingroup$ Note that the satellite is not an instrument, but rather a platform that hosts many instruments. The NASA website should list the instrument suites on each satellite somewhere on its website. $\endgroup$ – casey Nov 27 '14 at 22:50
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    $\begingroup$ Evidence for a subsurface ocean on Europa includes visual data (instrument:camera), and magnetic patterns. I don't know what you call a thing to measure magnetism, but it's not a camera - so that's at least one more instrument. They also use spectroscopes/spectrometers, I'm sure. $\endgroup$ – FumbleFingers Nov 28 '14 at 19:58
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    $\begingroup$ A magnetometer (who'da thunk it?). $\endgroup$ – naught101 Nov 29 '14 at 12:15
  • $\begingroup$ You might have a better chance for an answer if you as "What evidence do scientist have for oceans on Titan, and how do they interpret it?" That question will lead on to discussion of what tools are needed to detect that evidence. I mean, there's no such thing as an oceanoscope. You take data (imagery, etc.) and add interpretation (e.g. "These ridges look like they're caused by icesheets crashing together"), and keep gathering evidence like that until one hypothesis (i.e. there is an ocean on Titan) seems more likely than any other. $\endgroup$ – naught101 Nov 29 '14 at 12:21
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As casey said, the satellite isn't an instrument in itself, it is a platform hosting many instruments. What you're talking about the discovery of oceans on Titan and Europa, you're referring to the the Cassini-Huygens mission aimed at, among other things :

  • Determine the composition of the satellites surfaces (such as Titan)
  • Prove or disprove the existence of oceans or water on those satellites.
  • Characterize Titan's surface on a regional scale

In order to establish the existence of oceans or water on those satellites, scientists use:

  • Spectroscopy

More precisely, absorption spectroscopy. AS is an analytical chemistry tool used to determine the presence of a substance in a sample. Thanks to a spectrometer, you'll be able to gather a lot of information about the elements on this Moon, and by further analysis, determine if there's water or no.

N.B : I am not talking about liquid water, but about water. Science now establishes the validity of certain signatures, but liquid water is to be confirmed.

What about Cassini?

Cassini used a lot of spectrometers : the VIMS (Visible and Infrared Mapping Spectrometer) was used on the satellite to gather information on the surface.

"Our instrument measures the characteristic colors of the many materials that make up planetary surfaces and atmospheres: rocks, ices -- such as water, ammonia, methane -- and organic compounds," says Dr. Bonnie J. Buratti, VIMS Investigation Scientist. "VIMS data makes it possible to know what surfaces and atmospheres are made up of."

Image taken from the spectrometer

  • Volcanic observation

Indicators such as Geysers can be used to support the theory of water presence in subsoil. If by any radars, such as the ISS from Cassini (Imaging Science Subsystem), you can see geysers, then you can search about the possibility of water. Why? Because as you may know, water is pressurized in subsoil. Then, when water is heated by the heat of rocks, and it will tend to result in a geyser.

enter image description here

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  • $\begingroup$ Fantastic answer (+1), there are many great analogies with Earth-based observations. $\endgroup$ – user889 Nov 29 '14 at 15:53
  • $\begingroup$ Related: earthscience.stackexchange.com/q/448/725 $\endgroup$ – Gimelist Nov 30 '14 at 6:41

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