September 6, 2013
Late Friday night, NASA plans to launch its Lunar Atmosphere and Dust Environment Explorer (LADEE) on a 100-day mission to study dust and gas molecules floating around the moon.
You might not expect it, but this is an important event for astrobiology. Why? Because the moon, particularly icy craters on the moon, function in some ways as the Earth’s attic, storing treasures from our past.
Due to the weathering and churning of Earth’s crust, it’s nearly impossible to find evidence from the time when life originated on our planet more than 3.5 billion years ago. The moon still has plenty of material from that period, however. Asteroid and cometary impacts were common in early Solar System history, and most of the large lunar craters originated billions of years ago.
During that time, whenever a major asteroid hit Earth, it would cause crustal material to be ejected from the planet, some of it containing organic material and perhaps even simple unicellular life. Some of that material may have been re-deposited on the moon, where it would still lie under chunks of ice and rock, protected from cosmic radiation and frozen in place. It’s the only place where we might find the type of organic macromolecules and polymeric substances involved in the origin of life on Earth. Perhaps we would even learn what the first living cells were like.
The moon also holds interest for astrobiologists because of its exceptionally large size compared to its host planet, which results in strong ocean tides. Early in Solar System history the moon was closer to Earth, and the tides were even stronger. Tidal forces acting on the interior of the planet might have triggered the start of plate tectonics—the Earth’s universal recycling mechanism. They would also have created tidal flats, with cycles of wet and dry, and salt-rich and salt-poor conditions—a boundary environment that some scientists, including myself, consider a suitable place for the origin of life (among other places such as hydrothermal vents).
Finally, LADEE should give us useful knowledge about the complex interactions between the space environment and the “dead rock” we call the moon. Nobody expects to find active life there, but data from the mission could be important for understanding life on the Blue Planet.
Note: The LADEE launch is scheduled for 11:27 p.m. Eastern time Friday from Wallops Island, Virginia, and should be visible along the U.S. East coast. Here’s how to watch.
Dirk Schulze-Makuch is a professor of astrobiology at Washington State University, and has authored or co-authored seven books related to the possibility of life in the solar system and beyond.
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