The idea of LCROSS

My grandfather has been able to do many things during his astrophysics tenure. I attribute my love of physics and astronomy to him. I remember wanting to wear one of his rocket missions-into-the-aurora borealis t-shirts for a week straight (I don’t remember if my mother allowed her crazy son to actually do it!). He has had a lot of impact on what I’ve chosen to do, even with very sporadic communication. Regardless, my head still turns when I hear about things that he has contributed to.

One thing that he was very excited about was his involvement in pitching the idea of LCROSS. He said it took about 25 years for the idea to come to fruition, but it finally did in 2009 when—if you recall—a spacecraft was hurdled into the depths of a crater on the south pole of the moon. A large series of figures and pictures are included here. One of the purposes of smashing into the moon was to find water (in the form of ice) at the base of the craters, where the water hasn’t been sublimated by the sun. Well, it turns out, my grandfather and his co-workers were correct.

They did indeed find water at the base of the craters. However, LCROSS also found a number of volatiles, including methane, ammonia, and hydrogen gas. A debate has begun on where or how those volatiles got into that crater. One of the most common thoughts is that comets or asteroids composed of those materials crashed into the moon and delivered those materials; this is a very viable option considering the number of impacts the moon has absorbed. The other thought is that the lunar ice is able to react with high-energy cosmic rays (that are not shielded by an atmosphere or magnetic field) over millions of years.

This idea was published by Crites et al. (2013). They state that these cosmic rays (because of their constant, high-energy bombardment of simple ices) have the ability to “stimulate organic synthesis.” This means that the growth of more complex molecules can happen anywhere that has volatile ices and exposure to high-energy cosmic rays. This would include many of the smaller planets and moons in our solar system (Mercury, Pluto, Jupiter’s moons, etc.).

An example of their modeling and experimental results are found above, which is Table 3 from their published paper. The important things to note are the starting compounds (column 1), the product resulting from cosmic ray bombardment (column 2), and the resulting mass of the product from a mass of 1kg of the starting compounds (column 5). So, just by starting from different combinations and ratios of water, carbon dioxide, methane, and carbon monoxide, they were able to get molecules of methanol (CH3OH), ethanol (C2H5OH), and many others.

To me, this shows the impact (no pun intended) and progression of ideas: (1) a group of scientists had a thought to create a plume of material from the base of a lunar crater; (2) that turned into a mission at NASA; (3) the discovery of water AND volatiles present on the moon’s surface; (4) theories of the origination of these materials concludes this conversion process could be occurring all over the solar system.

In other words: keep the ideas/thoughts/questions/hypotheses coming!