Using NASA ’s OSIRIS - REx , researchers have determine the first grounds of thermal tension brave on an airless body . The squad are currently analyse asteroid Bennu in detail in preparation for its descent toward the surfacelater this year . In doing so , they found that rock on the asteroid crack due to the dispute in temperature from night to day .
As report inNature Communications , the spacecraft is orbiting 600 meters ( 0.4 knot ) from the surface of the asteroid , which is the closest - ever orbit around a celestial object . This has permit for high - resolution observations of bowlder on the surface .
“ This is the first sentence grounds for thermal fracturing has been definitively observed on an object without an atmosphere , ” lead author Jamie Molaro , from the Planetary Science Institute , said in astatement . “ It is one man of a puzzler that tells us what the surface used to be like , and what it will be like jillion of years from now . ”
The temperature difference on Bennu is quite striking . During the day , temperature can value a sear 127 ° C ( 260 ° F ) and at Nox a icy -73 ° C ( -100 ° F ) . This alteration is somewhat rapid as the asteroid spins on its axis every 4 minute and 18 minute . Despite the constant and important thermal excursion , the team were unsure whether or not they would observe thermal stress weathering .
“ On Earth , there are chemical weathering processes that help make thermic fracturing more effective , " Molaro explained . " The presence of atmosphere and wet within cracks makes them easier to grow , and so on Earth this event really can not be decouple from the consequence of the thermal stresses themselves . We ’ve observed evidence of thermal fracturing on Earth and on Mars , both surroundings where chemical weathering may recreate a persona . Therefore , while it was theoretically possible for thermal fracturing on an airless body to pass alone , it was not decipherable whether or not the stresses would be strong enough to cause crack ontogeny in absence seizure of the chemical effects . "
OSIRIS - REx has show that Bennu is , basically , a orotund chunk of detritus generally held together by sombreness . The spacecraft will aviate down tothe aerofoil in Octoberto collect a sample before institute it back to Earth in a few years .
scale features on a cliff expression ( a ) and on boulders ( b - f ) with varying size and locating . The bright dome on the view of gore ( a ) is a boulder behind the exfoliating cliff . NASA / Goddard / University of Arizona
