"The elephant in the room."

[exoscientist]

How Pure Is the Comet? <br />August 4, 2006<br />"...when a team led by Carey Lisse (University of Maryland) aimed the infrared Spitzer Space Telescope at the cloud of ice and dust that erupted from the collision, they were surprised. The team reports in the August 4th Science that the Tempel 1 debris was laced with carbonates and clays: two classes of minerals that, on Earth, usually form in the presence of liquid water."<br />http://skytonight.com/news/3491846.html<br /><br /> Given the observation of eruptions of liquid water on Enceladus, and the widespread speculation they may be due in part to radiogenic heating you would think it would at least be mentioned the prior theories that radiogenic heating might have allowed liquid water in comet interiors early in the Solar Systems history <b>AND</b> that this may have allowed conditions conducive to life within comets.<br /> Just as importantly is the fact the theories of radiogenic heating in comets were not introduced arbitrarily but because carbonates and clays had <b>ALREADY</b> been observed in carbonaceous meteorites, some if not all of which are believed to stem from comets.<br /><br /><br /> Bob Clark <br /><br /> <div class="Discussion_UserSignature"> </div>

 

[JonClarke]

There is many forms of heating available to comets and small asteroids, radiogenic is just one of them. Collisions, perhelion heating are also important. Radiogenic heating from short half like elements like Al26 has considered been a possible source of some (not all) early heating for decades. So your point is?<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>