December 7, 2012
Did Dawn Mission Find Water-Carved Gullies On Vesta Asteroid
Michael Harper for redOrbit.com — Your Universe Online
In 2007, NASA launched the Dawn Mission to study the asteroid Vesta and dwarf planet Ceres. Carrying a visible camera, a visible and infrared mapping spectrometer, and a gamma ray and neutron spectrometer, Dawn set out on an 8 year mission to gather a wealth of data from these two celestial bodies.Dawn arrived at the first stop in its journey, the asteroid Vesta, in June 2011 and recently departed for Ceres this September.
Now, NASA is busy pouring over the images and other data collected by Dawn during its time spent with Vesta.
As researchers began analyzing these images, they noticed some intriguing gullies on the side of very young craters on the surface of Vesta. Now, Jennifer Scully, a Dawn team member at the University of California, Los Angeles (UCLA), has been charged to lead a team to discover how these gullies were formed.
According to Scully, some of gullies look like straight chutes which run across the crates. Others appear more sinuous and end in what has been described as “lobe-shaped deposits.”
Scully and her team will explain how these gullies were formed on Vesta in a presentation at this year´s American Geophysical Union conference in San Francisco. Other Dawn team members will also be presenting their findings and research about other aspects of the asteroid Vesta.
"The straight gullies we see on Vesta are textbook examples of flows of dry material, like sand, that we've seen on Earth's moon and we expected to see on Vesta," explained Scully, according to a report at NASA. “But these sinuous gullies are an exciting, unexpected find that we are still trying to understand."
According to Scully, the aforementioned sinuous gullies are longer, narrower and feature more curves than the shorter and straighter gullies. These winding gullies start from V-shaped regions referred to as “alcoves,” then move on to merge with other gullies.
So far, NASA scientists have 2 theories on how these gullies have been formed and have begun looking at examples on Earth and Mars to find more clues.
“On Earth, similar features - seen at places like Meteor Crater in Arizona -- are carved by liquid water," said Dawn´s principal investigator, Christopher Russell. "On Mars, there is still a debate about what has caused them. We need to analyze the Vesta gullies very carefully before definitively specifying their source."
Though the scientists are suggesting liquid erosion could be responsible for carving these gullies, they aren´t yet ready to make such a definitive claim.
"We want to hear what other people's opinions are," said Scully in an interview with the BBC. "We're just putting it out there to the community; we're not suggesting anything hard and fast at this stage."
Russell agrees, saying the scientists should be very careful in their interpretations of these gullies.
"We want to be very, very sure on any statement or pronouncement we make about the gullies or water or anything like that, because it turns out that there are a lot of different interpretations - we have to work our way through them," he said, speaking to the BBC.
"That's exactly how the scientific method works - we have an idea; we have to test it against the available evidence, and a lot of people are shareholders in that evidence and they will talk to us about what their evidence is,” he concluded.