As part of the fellowship, Jesse-Lee Dimech will investigate what new information can be gained about moonquakes.
Between 1969 and 1972, five of the Apollo missions successfully placed seismometers at landing sites on the Moon, which recorded ground motion and radioed this information back to Earth. Contained in this dataset are more than 13,000 moonquakes that were recorded up until 1977, when the devices were turned off.
“Seismic energy such as earthquakes, or in this case, moonquakes, is useful for looking inside a planet without having to dig it up. Using their energy, we can gain insight into the composition and structure of the Moon,” says Jesse-Lee.
“The data set I will be working with has been processed several times already, but by applying new techniques we may be able to get new information.”
One of those new techniques is shear wave splitting analysis, a key research interest of Professor Martha Savage from Victoria’s School of Geography, Environment and Earth Sciences, who has collaborated with Jesse-Lee to undertake the first shear wave splitting analysis off-world.
“When seismic waves travel through layers of rock they split in much the same way light does when it hits a crystal. By measuring how much splitting occurs, we can learn a lot about subsurface conditions.”
Another technique Jesse-Lee will be using is a statistical method of examining the faults responsible for the moonquakes. This method of analysis was developed by Associate Professor Richard Arnold, from Victoria’s School of Mathematics and Statistics, and Associate Professor John Townend of the School of Geography, Environment and Earth Sciences.
“I applied this technique in my PhD to earthquakes we found in the upper mantle—the layer beneath the crust—which was able to tell us what type of faults produced them. We plan to use a modified version of this code to understand the type of faulting associated with ‘deep’ moonquakes, which are situated about halfway between the Moon’s surface and its core.
“I will be continuing to work with Professor Savage and Associate Professor Arnold while I’m at NASA. New Zealand has great scientific minds and I’m excited about maintaining and building relationships with people here.”
Some of the techniques Jesse-Lee plans to use on the Moon may also be useful in helping NASA learn about the composition of Mars when they land a seismometer there in two years’ time as part of the InSight mission to Mars.
Australian-born Jesse-Lee says he has loved space since he was a child, and a post-doctoral role at NASA is the culmination of a lifelong ambition.
“I was actually pen pals with Australia’s first astronaut Andrew Thomas. We exchanged several letters when I was a kid, and I even talked to him on the phone once, as well as fellow astronaut John Glenn who just happened to be in the office at the time. They definitely inspired me. I was also the youngest member of an astronomy club. I’ve always been fascinated by NASA.”