[templar]

We may have found a covered layer of liquid slightly below the dust.

Tar. Like in the La Brea Tar Pits.

[e_engineer]

Tar. Like in the La Brea Tar Pits.

Maybe not exactly like La Brea. It's -90 degrees C on Mars, so long chain hydrocarbons (tar) would be really viscous like a rubber ball.

Shorter chains might behave like slush, and hydrocarbons would explain the neutron spectrometer readings from last year.