In the classic television series “Star Trek” the star ship Enterprise powered by blue light beams, speeds from planet to planet orbiting different worlds before zooming off to do more exploration.
These are current real life adventures of NASA’s Dawn spacecraft launched from Cape Canaveral in 2007 now making discoveries announced this week about planetary and solar system evolution.
Dawn is flying into history as an ion powered spacecraft with its own blue light beams to travel 1.5 billion mi. to orbit one body, then depart and fly another billion miles to orbit a second body—just like the fictional star ship Enterprise.
As it orbits two unexplored worlds, first the 330 mi. dia. Vesta and later the 600 mi. wide Ceres, both designated asteroids when discovered more than 100 yr. ago, Dawn is finding rather than being a traditional asteroid Vesta is highly differentiated. Dawn will depart for Ceres in July and arrive in Feb. 2015.
This makes Vesta a round baby planet—a 4.5 billion yr. old protoplanet whose structure, unlike asteroids, could not be shattered by the cataclysmic bombardment that occurred 4.1-3.8 billion years ago from leftover chunks of solar system formation.
“Dawn’s ambitious exploration of Vesta has been going beautifully,” said Marc Rayman, Dawn chief engineer at the Jet Propulsion Laboratory in Pasadena, Calif. “As we continue to gather a bounty of data, it is thrilling to reveal fascinating alien landscapes.”
New images and data highlight the diversity of Vesta’s surface and reveal unusual geologic features, some of which were never previously seen on asteroids.
These results were revealed this week at the 43rd Annual Lunar and Planetary Science Conference near the Johnson Space Center, Houston.
Vesta is one of the brightest objects in the solar system. Dawn has found that
some areas on Vesta can be nearly twice
as bright as others. “Our analysis finds this bright material originates from Vesta and has undergone little change since the formation of Vesta over 4 billion years ago,” said Jian-Yang Li, a Dawn participating scientist at the University of Maryland, College Park.
Bright areas appear everywhere on Vesta but are most predominant in and around craters. The areas vary from several hundred feet to around 10 miles across. Rocks crashing into the surface of Vesta seem to have exposed and spread bright material. This impact process may have mixed the bright material with darker surface material.
“One of the surprises was the dark material is not randomly distributed,” said David Williams, a Dawn participating scientist at Arizona State University, Tempe. “This suggests underlying geology determines where it occurs.”
The dark materials seem to be related to impacts and their aftermath. Scientists theorize carbon-rich asteroids could have hit Vesta at speeds low enough to produce some of the smaller deposits without blasting away the surface.
Higher-speed asteroids also could have hit Vesta’s surface and melted the volcanic basaltic crust, darkening existing surface material. That melted conglomeration appears in the walls and floors of impact craters, on hills and ridges, and underneath brighter, more recent ejecta.
Vesta’s dark materials as shown below suggest the body may preserve ancient materials from the birth of the solar system 4.5 billion years ago.