Spirit Finds Carbonates...

The Spirit rover has found clear evidence of carbonate rocks on Mars.  Carbonate rocks form only in neutral or alkaline water, in conditions conducive to life-as-we-know-it.  Actually, Spirit recorded the evidence for the carbonate rocks way back in 2005 – but the evidence was recorded on a sensor that was covered in dust, and the dust distorted the readings.  Just recently scientists figured out how to remove the distortion computationally, and thereby found the carbonate rock's “signature”.  The same instrument has collected data for about six years, and the same computational technique means that much of that data can now be “cleaned up”, quite likely leading to other “new” discoveries with old data...