Showing posts with label ASTEROID TEMPERATURES. Show all posts
Showing posts with label ASTEROID TEMPERATURES. Show all posts

Tuesday, May 1, 2012

WHAT IS AN ASTEROID REALLY LIKE ONCE YOU GET TO KNOW THEM

FROM: NASA
WASHINGTON -- Findings from NASA's Dawn spacecraft reveal new details 
about the giant asteroid Vesta, including its varied surface 
composition, sharp temperature changes and clues to its internal 
structure. The findings were presented today at the European 
Geosciences Union meeting in Vienna, Austria and will help scientists 
better understand the early solar system and processes that dominated 
its formation. 

Spacecraft images, taken 420 miles (680 kilometers) and 130 miles (210 
kilometers) above the surface of the asteroid, show a variety of 
surface mineral and rock patterns. Coded false-color images help 
scientists better understand Vesta's composition and enable them to 
identify material that was once molten below the asteroid's surface. 

Researchers also see breccias, which are rocks fused during impacts 
from space debris. Many of the materials seen by Dawn are composed of 
iron- and magnesium-rich minerals, which often are found in Earth's 
volcanic rocks. Images also reveal smooth pond-like deposits, which 
might have formed as fine dust created during impacts settled into 
low regions. 

"Dawn now enables us to study the variety of rock mixtures making up 
Vesta's surface in great detail," said Harald Hiesinger, a Dawn 
participating scientist at Münster University in Germany. "The images 
suggest an amazing variety of processes that paint Vesta's surface." 

At the Tarpeia crater near the south pole of the asteroid, Dawn 
revealed bands of minerals that appear as brilliant layers on the 
crater's steep slopes. The exposed layering allows scientists to see 
farther back into the geological history of the giant asteroid. 

The layers closer to the surface bear evidence of contamination from 
space rocks bombarding Vesta's surface. Layers below preserve more of 
their original characteristics. Frequent landslides on the slopes of 
the craters also have revealed other hidden mineral patterns. 

"These results from Dawn suggest Vesta's 'skin' is constantly 
renewing," said Maria Cristina De Sanctis, lead of the visible and 
infrared mapping spectrometer team based at Italy's National 
Institute for Astrophysics in Rome. 

Dawn has given scientists a near 3-D view into Vesta's internal 
structure. By making ultrasensitive measurements of the asteroid's 
gravitational tug on the spacecraft, Dawn can detect unusual 
densities within its outer layers. Data now show an anomalous area 
near Vesta's south pole, suggesting denser material from a lower 
layer of Vesta has been exposed by the impact that created a feature 
called the Rheasilvia basin. The lighter, younger layers coating 
other parts of Vesta's surface have been blasted away in the basin. 

Dawn obtained the highest-resolution surface temperature maps of any 
asteroid visited by a spacecraft. Data reveal temperatures can vary 
from as warm as -10 degrees Fahrenheit (-23 degrees Celsius) in the 
sunniest spots to as cold as -150 degrees Fahrenheit (-100 degrees 
Celsius) in the shadows. This is the lowest temperature measurable by 
Dawn. These findings show the surface responds quickly to 
illumination with no mitigating effect of an atmosphere. 

"After more than nine months at Vesta, Dawn's suite of instruments has 
enabled us to peel back the layers of mystery that have surrounded 
this giant asteroid since humankind first saw it as just a bright 
spot in the night sky," said Carol Raymond, Dawn deputy principal 
investigator at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, 
Calif. "We are closing in on the giant asteroid's secrets." 

Launched in 2007, Dawn began its exploration of the approximately 
330-mile- (530-kilometer-) wide asteroid in mid-2011. The 
spacecraft's next assignment will be to study the dwarf planet Ceres 
in 2015. These two icons of the asteroid belt have been witness to 
much of our solar system's history. 

Dawn's mission is managed by JPL for NASA's Science Mission 
Directorate in Washington. Dawn is a project of the directorate's 
Discovery Program, managed by NASA's Marshall Space Flight Center in 
Huntsville, Ala. UCLA is responsible for overall Dawn mission 
science. Orbital Sciences Corp. in Dulles, Va., designed and built 
the spacecraft. The German Aerospace Center, the Max Planck Institute 
for Solar System Research, the Italian Space Agency and the Italian 
National Astrophysical Institute are international partners on the 
mission team. 

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