1.5Bil BP-1Bil BP在火星上,这是Hesper

1.5Bil BP-1Bil BP在火星上,这是Hesperian时期,地表水已经干dried,但仍大量沉积在地表以下。
原文:1.5Bil BP-1Bil BP    On Mars this is the Hesperian period when surface waters had dried up but still lay in large quantities below the surface.