Looking beyond Dawson again – way beyond – two groups of scientists viewing the sky from Hawaii have discovered a thin layer of ice around asteroid 24 Themis. The separate research teams have measured proof of the ice, and of organic matter, using the NASA Infrared Telescope on Mauna Kea.
24 Themis, about 120 miles in diameter, is part of the Themis Asteroid Family in the outer portion of the main asteroid belt, between the orbits of Mars and Jupiter.
And the reason this particular ice matters? It bolsters theories that Earth’s original water source may have been icy asteroids, crashing into our planet and bringing H2O to our locale.
Wired magazine offers this explanation of the possible link between the ice discovery on 24 Themis and that beautiful blue water many of us will be boating on/swimming in this summer:
“What we’ve found suggests that an asteroid like this one may have hit Earth and brought our planet its water,” said astronomer Humberto Campins of the University of Central Florida, the lead of one of the two separate teams that reported similar findings April 28 in [the scientific journal] Nature.
While there is plenty of debate around how Earth got its oceans, this new evidence suggests some of the water came from extraterrestrial sources. Here’s how it may have happened: More than four billion years ago, after a massive collision between Earth and another large object created the moon, our planet was completely dessicated. Then, during the Late Heavy Bombardment period that followed, during which lots of asteroids hit Earth, the ice that the objects carried became our store of water.
“The more we find in our asteroid belt objects that do have water, the more convinced we are that that was a possible process to rehydrate the earth,” said NASA astrobiologist Mary Voytek.
NASA’s own press release emphasizes that 24 Themis, the largest asteroid in the family, must have an ice core because surface ice doesn’t last when asteroids are so close to the sun (“close” taking on a whole new sense of distance when we’re talking about space, of course).
“Finding widespread water ice on an asteroid so close to the sun was a completely surprising result. We expect ice to evaporate quickly into space from the surfaces of asteroids,” said Noemi Pinilla-Alonso, a research scientist at NASA’s Ames Research Center, Moffett Field, Calif. Pinilla-Alonso is the co-author of a research paper titled, “Water ice and organics on the surface of the asteroid 24 Themis,” published this week in the British-American scientific journal Nature.
On a clear night in January 2008 … for the first time, the infrared measurements taken at the IRTF showed the characteristics of frozen water on Themis.
Although the frozen water on asteroid 24 Themis should have disappeared into space more than a billion years ago, it is still seen uniformly covering the surface. “This discovery tells us that water vapor is slowly leaking out of the inside of the asteroid at the present time and freezing on the surface in a paper-thin layer that we can measure with our telescope,” observed Pinilla-Alonso. “We also see the signs of the organic materials that are necessary for the formation of life on Earth.”
Intriguing stuff, asteroids acting almost like time machines for us.
Also intriguing – it seems that numerous “artist’s rendition” images of 24 Themis (and of asteroids in orbit generally speaking) are available online, but not photographs. And most of the artistic dream-images are just that, dreamy and a bit corny – d’oh! So the photo above is of the Mauna Kea telescope, instead, taken from http://www.astr.ua.edu/keel/telescopes/irtfmoonlitbig.jpg.