The
space agency is launching these missions at a time when decades of
observations from the ground, air, and
space have
revealed signs of change in Earth's ice sheets, sea ice, glaciers, snow cover and permafrost.
New high - resolution
observations of Vesta by the DAWN mission
reveal that the creatr is part of an even larger impact basin that was created by two massive overlapping impacts roughly around one and two billion years ago, which scooped out around one percent of the asteroid's estimated volume and blasted it into
space (more
from NASA's DAWN Mission and NEO Program; 1997 NASA / Hubble news release; Cornell University; Thomas et al, 1997; Kelley et al, 2003; and Jerry Coffrey, Universe Today, June 15 2009; and Russell et al, 2012; Jaumann et al, 2012; Marchi et al, 2012; and Schenk et al, 2012).