Climate change in drylands

Approximately 40 percent of the earth's surface is covered by drylands in which average annual precipitation is lower than evaporation. The changes projected to unfold in these areas in the course of climate ...

Nov 19, 2014
4.4 / 5 (18) 1

How to land on a comet

Generally speaking, space missions fall into one of three categories:  difficult, more difficult, and ridiculously difficult.

Nov 04, 2014
4.9 / 5 (16) 7