Could you tell us a little bit about yourself?
I am a Professor of Planetary Geophysics at University of Paris Diderot and Institut de Physique du Globe de Paris. I have a physics and seismology background, and started planetary seismology as Principal Investigator of the Mars 96 Mission. I then continued to promote the seismic exploration of planets with various projects, until the selection of InSight by NASA, which will deploy a seismic station on Mars in September 2016.
What are the most important recent developments in the field of research discussed in your chapter?
Planetary seismology had a new birth in 2000, with the re-analysis of the Apollo seismic data, made by several groups. This has led to new seismic models of the Moon, to the discovery of the lunar core, and to a much better understanding of the seismic data generated by impacts. The second major development is currently in the making, and will be related to the InSight mission, with long-awaiting data: the last mission providing seismic data on another telluric body than Earth was indeed Viking, 40 years before InSight!
How can other seismologists, planetary scientists and astrophysicists learn from this area of research?
A wonderful example of fruitful exchanges of idea is associated with the continuous excitation of the Sun and planets by convection or continuous acting sources, the so called hum… This came from helioseismology and is now used for Earth seismology. Another example is the development of Earth ionospheric seismology, and of new techniques enabling remote sensing seismology. Both examples have shown that theories and tools of astrophysics can also be used to study planets and even the Earth.
Could you recommend one or two of your key research papers related to your book chapter? Could you tell us a bit more about the research?
Lognonné P. and C. Johnson, Planetary Seismology, in « Treatise in Geophysics, 10, Planets and Moons », editor G.Shubert, chapter 4, 69-122, Elsevier, 2007, doi : 10.1016/B978-044452748-6.00154-1,
Lognonné, P., M. Le Feuvre, C. L. Johnson, and R. C. Weber (2009), Moon meteoritic seismic hum: steady state prediction, J. Geophys. Res., 114, E12003, doi:10.1029/2008JE003294
Both papers are related to planetary seismology of telluric planets in depth. The first one is a general review, whereas the second one is a more oriented research papers, showing that the continuous fall of small meteorites is generating a continuous excitation of the Moon. So even atmosphere-less planets do have a continuous hum…
How important is it for you to be involved in international, collaborative, interdisciplinary research linked to seismology?
International collaboration is key in seismology: waves ignore countries' borders and propagate freely, and long-term observations from Earth, planets and stars require observatories to be located all over the spherical and rotating Earth. This collaboration is also required to build future missions with landing on planets and deployment of seismic stations.
Do you have any other messages to our readers?
Important dreams demand long-term efforts to realize them… It will have taken the community 40 years to put a seismic station on Mars, and we now need to put seismic stations once again on the Moon before the 50th anniversary of the end of the Apollo seismometer operations in 1977.