<p>Using an icebox-like instrument nicknamed Himalaya, an Indian-origin researcher-led team has revealed that fluffy ice on the surface of a comet would crystallise and harden as the comet heads toward the Sun and warms up.</p>.<p><br />As the water-ice crystals form, becoming denser and more ordered, other molecules containing carbon would be expelled to the comet's surface.<br /><br />The result is a crunchy comet crust sprinkled with organic dust, NASA said in a statement.<br />"A comet is like deep fried ice cream. The crust is made of crystalline ice, while the interior is colder and more porous. The organics are like a final layer of chocolate on top," explained Murthy Gudipati of NASA's Jet Propulsion Laboratory in Pasadena, California.</p>.<p><br />Researchers already know that comets have soft interiors and seemingly hard crusts.<br />In the new study, Gudipati and Antti Lignell, post-doctoral scholar at the California Institute of Technology, put together a model of crystallising comet crust.</p>.<p><br />The experiments began with amorphous or porous ice -- the proposed composition of the chilliest of comets and icy moons.</p>.<p><br />In this state, water vapour molecules are flash-frozen at extremely cold temperatures of around minus 243 degrees Celsius.<br /><br />Gudipati and team used their Himalaya instrument to slowly warm their amorphous ice mixtures to minus 123 degrees Celsius, mimicking conditions a comet would experience as it journeys toward the sun.<br /><br />The ice had been infused with a type of organics called polycyclic aromatic hydrocarbons (PAHs) which are seen everywhere in deep space.<br /><br />"What we saw in the lab - a crystalline comet crust with organics on top - matches what has been suggested from observations in space," Gudipati noted.</p>.<p><br />"Deep-fried ice cream is really the perfect analogy, because the interior of the comets should still be very cold and contain the more porous, amorphous ice," he pointed out.<br />The composition of comets is important to understanding how they might have delivered water and organics to our nascent, bubbling-hot Earth.</p>.<p><br />New results from the Rosetta mission show that asteroids may have been the primary carriers of life's ingredients.<br /><br />For Gudipati, comets are capsules containing clues not only to our planet's history but to the birth of our entire solar system.<br />The study appeared in the Journal of Physical Chemistry.<br /></p>
<p>Using an icebox-like instrument nicknamed Himalaya, an Indian-origin researcher-led team has revealed that fluffy ice on the surface of a comet would crystallise and harden as the comet heads toward the Sun and warms up.</p>.<p><br />As the water-ice crystals form, becoming denser and more ordered, other molecules containing carbon would be expelled to the comet's surface.<br /><br />The result is a crunchy comet crust sprinkled with organic dust, NASA said in a statement.<br />"A comet is like deep fried ice cream. The crust is made of crystalline ice, while the interior is colder and more porous. The organics are like a final layer of chocolate on top," explained Murthy Gudipati of NASA's Jet Propulsion Laboratory in Pasadena, California.</p>.<p><br />Researchers already know that comets have soft interiors and seemingly hard crusts.<br />In the new study, Gudipati and Antti Lignell, post-doctoral scholar at the California Institute of Technology, put together a model of crystallising comet crust.</p>.<p><br />The experiments began with amorphous or porous ice -- the proposed composition of the chilliest of comets and icy moons.</p>.<p><br />In this state, water vapour molecules are flash-frozen at extremely cold temperatures of around minus 243 degrees Celsius.<br /><br />Gudipati and team used their Himalaya instrument to slowly warm their amorphous ice mixtures to minus 123 degrees Celsius, mimicking conditions a comet would experience as it journeys toward the sun.<br /><br />The ice had been infused with a type of organics called polycyclic aromatic hydrocarbons (PAHs) which are seen everywhere in deep space.<br /><br />"What we saw in the lab - a crystalline comet crust with organics on top - matches what has been suggested from observations in space," Gudipati noted.</p>.<p><br />"Deep-fried ice cream is really the perfect analogy, because the interior of the comets should still be very cold and contain the more porous, amorphous ice," he pointed out.<br />The composition of comets is important to understanding how they might have delivered water and organics to our nascent, bubbling-hot Earth.</p>.<p><br />New results from the Rosetta mission show that asteroids may have been the primary carriers of life's ingredients.<br /><br />For Gudipati, comets are capsules containing clues not only to our planet's history but to the birth of our entire solar system.<br />The study appeared in the Journal of Physical Chemistry.<br /></p>