I’ve seen articles about underground water being detected in planets like Mars. I’m assuming it’s detected via satellite (microwaves?), but how does the technology work?
And are we using the satellite that’s orbiting around earth and projecting the (microwaves?) there, or do we send a few satellites specifically to Mars to do these investigations?
In: Technology
I think there is one method we’re you watch something like a meteor slam into and shoots dust up into the atmosphere that we can analyze the spectrum of light going through it from the sun. Different materials give you a different spectrum
On Mars, the Mars Reconnaissance Orbiter (MRO) provides the best evidence yet that liquid water flows intermittently on present-day Mars. MRO uses an imaging spectrometer examine the chemical content of surface rocks. When those rocks are hydrates, then water interacted with them in the past. Following the water down hill can lead to places cold enough that the water would be ice.
There’s a variety of methods, but the most common one is surface penetrating radar.
When you deal with long wavelengths of light in the radio range, the ground actually becomes somewhat transparent. If you think about glass, most of the light goes through but a small amount gets reflected back at you. Whenever light reaches an interface of materials, some light gets reflected back, and how much gets reflected back depends on what the material is made of (specifically the dielectric constant of the material when dealing with radar). By sending a pulse down, you’ll get a small reflection off the surface, but most of the light will continue into the ground. If there is a change in material under the surface, you’ll get another reflection and the properties of the reflection can tell you what the material change was. However, do note that this could be a liquid water aquifer, a solid mass of ice, a region of higher water content in the regular rock, or a totally unrelated mineral formation that just happens to reflect like water does. Usually, when you hear big breakthroughs about water on Mars, it’s actually that last option that gets misinterpreted.
There is at least one Mars orbiter with a surface penetrating radar (SHARAD on MRO).
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