Let me know if I can explain it more clearly.
Multi-part MIME containing inline images is actually what you're looking for and it's fairly easy to implement.
Here's an example. They handwave over the html section that actually refers to the inline images that they embed, but that's the basic layout you need.
Right now, conditions are not right for liquid water to exist on the surface of Mars. Atmospheric pressure is too low, water goes from ice directly to vapour with no liquid phase in between. "Life as we know it" requires liquid water as a medium. Possibly at the bottom of the deepest valleys on Mars or deep (like km) underneath the surface we might still find remnants of life.
What we will most likely find on Mars with our rovers is a history of life once existing. Life, from a billion years ago when it was warmer and wetter and plate tectonics still worked and essential chemicals weren't locked up in rocks.