Pieces of Ancient Earth May Be Hidden On the Moon

swestcott brings us a story from Space.com about the possibility of finding evidence for ancient Earth life on the moon. A team of scientists has published work confirming that meteorites originating from Earth could have remained sufficiently intact while colliding with the moon to allow the survival of biological evidence for life. Quoting: "Crawford and Baldwin's group simulated their meteors as cubes, and calculated pressures at 500 points on the surface of the cube as it impacted the lunar surface at a wide range of impact angles and velocities. In the most extreme case they tested (vertical impact at a speed of some 11,180 mph, or 5 kilometers per second), Crawford reports that 'some portions' of the simulated meteorite would have melted, but 'the bulk of the projectile, and especially the trailing half, was subjected to much lower pressures.'"

Comments

Looking for a reason...

[Ceriel Nosforit]

Here's a good reason to go back to the moon if there ever was one. Or at the very least a better excuse than we've had so far.

Though the survival of the species is always a good reason...

Re:Let's start with the obvious

[Anonymous Coward]

A cube is pretty much the worst shape possible when it comes to distributing the force of an impact evenly across the entire object. So simulations show that cubes can survive crashing into the moon, then its fairly safe to say that other shapes can survive too.

The next planetary scandal

[heroine]

Can just see the reaction to this. Life can't survive elsewhere in the solar system. It's all pieces of Earth that got blown out.

Re:The next planetary scandal

[Tablizer]

Can just see the reaction to this. Life can't survive elsewhere in the solar system. It's all pieces of Earth that got blown out.

That's why a study of the DNA etc. is important if life is found on another body. If the basic "alphabet" of the newly-discovered life matches that of Earth's, then most likely its a form of contamination from a central source.

We wouldn't necessarily be able to tell where the original source is if such was the case. Other bodies in the solar system were stable while Earth was still smoldering such that perhaps life formed on a different body that cooled faster and then spread to Earth after it cooled. Identifying the original "seed body" may be tricky.

Re:The next planetary scandal

[jd]

Given there are multiple solutions to the DNA unwinding problem (but on Earth only one was used) and given that life on Earth has tended to convert symbiotic organisms into organelles with minimal DNA (or nothing) and migrate the rest into the nucleus (ie: a monolithic design, which isn't necessarly the only design nature could have opted for), and given there are other factors that probably became selected because of the specific prevailing conditions on Earth, if the contamination was far enough back, we'd be able to tell by the divergence. Earth had very specific conditions, and there are multiple solutions to many microbiological problems. Organisms on Earth may have tried several and adopted the one that suited Earth conditions best, or Earth conditions may have made multiple experiments impossible.

(The cell itself probably post-dates the first 'true' life by a few hundred million years - long enough for any Earth fragments to be blasted onto nearby worlds - and the cell is only one way of building structured life. Assuming you have structured life. Pre-cellular life might be fine for some worlds, and mono-cellular life could potentially do much better than multi-cellular life in the atmosphere of a gas giant. You don't want complexity under harsh conditions.)

However, this leads to a major problem. Given that the bases that exist on Earth probably are the bases that would be used elsewhere, anything that is too simple cannot be distinguished from a parallel line of evolution. Given the level of sophistication you can pack onto a tiny space probe, the level of sophistication you can distinguish at in practical terms is far greater than the level that you could distinguish at in textbook theory.