Scientist Interview: Giovanni Leone

Giovanni Leone, Director of The Institute of Astrophysics and Planetary Sciences of Atacama (INCT), Chile is a Volcanologist and Planetary Geologist who has been involved in many interdisciplinary, international collaborations to study topics such as the volcanoes of the planet Mars and the satellite Io.  He has been a member of the muography research community since 2019 when he gave the first keynote speech at the first session of the Muographers 2019 General Assembly on “Muographic Interests in Planetary Sciences”. In this interview, he discusses his research on the formation of volcanoes on Mars and how muography could aid researchers of this topic, along with possibilities for incorporating muography into future space missions and his personal vision for the roadmap of muography.

What are the similarities and differences between volcanoes on Earth and on Mars?

Studying the volcanoes of Mars offers a wide choice of volcanic structures and thus an excellent opportunity for comparison with the volcanic structures present on Earth. Earth has nearly double the radius of Mars but Mars is characterized by higher and wider volcanic structures with respect to those present on Earth. For example, Mons Olympus on Mars is around 6.4 times higher than Mount Etna and 2.4 times higher than Mount Everest on Earth, although the latter is not a volcano. Now the question that immediately would arise is why a smaller planet like Mars has higher volcanoes than the Earth. Furthermore, the natural radiogenic sources of heat that remain geologically (and volcanically) active within and on Earth’s surface are still present while on Mars they seem depleted given its evident lack of current volcanic activity. So, such a difference would appear even more striking. A possible answer is that an unusual heat source must have characterized the landscape of Mars in its past. Such an unusual heat source might have been be a giant impact with another large planetary body early in the history of the solar system. The simulations of the Southern Polar Giant Impact (a lunar-sized impactor composed of 80% of iron in its radius that hit the South Pole of Mars) indicated that this event may have provided the additional heat source necessary to justify the shape of the Martian dichotomy (the striking differences between the terrain of the southern and northern hemisphere of Mars), the massive volcanism of its past, and the transient magnetic field that Mars experienced in the first 500 Ma of its history. Actually, even the unusual distribution of the volcanoes in twelve alignments, a unique pattern seen nowhere else in the solar system, was confirmed from images of the surface of Mars exactly as the simulations had predicted they would be positioned.

Did the iron content of the impactor have an important effect on the volcanism of Mars?

Yes, the increasing percentage of iron in the impactor had a more devastating effect on the impact with respect to a mesosiderite (50% of iron in radius) or a stony (10 or 0% of iron) impactor of the same size. In our simulations we obtained the Martian dichotomy and the massive volcanism with an impactor of 1600 km in radius with 80% iron or with a mesosideritic impactor of 2000 km in radius with 50% iron. No dichotomy was obtained with the stony impactor.

Map of Mars showing the Mars dichotomy – the differences between the poles of Mars
(Public Domain image) NASA / JPL / USGS –

For more information about this research, please check the following links:

“Three‐dimensional simulations of the southern polar giant impact hypothesis for the origin of the Martian dichotomy”

“Alignments of volcanic features in the southern hemisphere of Mars produced by migrating mantle plumes”

How can studying the volcanoes of Mars help us to understand volcanoes on Earth? 

Now, regardless of the origin of the heat source that generated the volcanism, the process of magma movement as it rises in the crust is the same both on Earth and on Mars. That’s why the composition of the lavas erupted on Mars is varied (basalts, andesites, even rhyolites) exactly as it occurs on Earth.

How could muography be a part of these studies?

Muography can be a useful tool for estimating the density distribution of the volcanic material on top of the volcanoes of Mars and even the possible presence of magma still clogging the conduits.  This would reveal if magma stalled in the crust or erupted directly from the mantle as a result of plume volcanism.

If you could add a muography experiment to a Martian rover similar in design/cost/size to the Mars Curiosity Rover what geological targets do you think would be most beneficial to study? 

At this point, an obvious target would be the Tharsis region of Mars where plenty of volcanic structures are available but also Elysium would be the next in line as first priorities.

A view of the Tharsis region of Mars
Credit: NASA (
Public Domain Dedication (CC0)
The Tharsis region includes the 3 large volcanoes Arsia Mons, Pavonis Mons, and Ascraeus Mons (and excluding the largest volcano Mons Olympus)
Credit: NASA / JPL-Caltech / Arizona State University –
Elysium region of Mars
Credit: Martin Pauer (Power) – plotted using GMT and gridded MOLA data archive

What do you think would be the minimum capabilities that the muography detector would have to have in order to yield useful scientific information for a Martian rover mission?

Clearly, the technical characteristics of one of the detectors already used on Earth would be perfect for the scope of this project but we are working hard on a possible solution to reduce the muography detector size in order to fit the reduced payload space of the planetary missions.

Please give us your personal opinion about the contribution of muography to solid earth science and engineering.

Like the discovery of X-rays which brought a wealth of applications for human activities, muography can bring exactly the same wealth of applications for human activities (i.e. engineering, mining, archaeology applications, etc. etc.) and for monitoring volcanic hazards in real time.  The most crucial phase to image with the detector is in the week before the eruption when it is possible to monitor eventual magma movement inside the volcanic conduit and thus predict the eruption time with more accuracy. Of course, this would help the authorities to better decide eventual evacuation plans for the population and minimize the impact on flights and other commercial activities. Muon detectors can yield a huge economic reward compared to the small investment required to install and maintain them.

What have been some of the most successful international collaborations you have been involved with? 

One of my most successful international collaborations in terms of scientific results was leading the international (Australia, England, Russia, China, and Italy) group in my research that resulted in a better definition in 3D of the Southern Polar Giant Impact. However, it is also worth mentioning the international collaboration (including NASA) that characterized the research I did on the volcanism of Io during my first PhD at Lancaster University, UK.

What are some of the best ways to foster communication and cohesion in these collaborations?

The best way to foster communication is by communicating. It seems like a game of words but it is not so trivial. Communication is important, it helps everyone to obtain all the information necessary to carry on the work. Often scientists are so focused on their own work that would prefer to climb Mount Everest rather than sending or replying to an email in a timely fashion! But the hard reality is that the work of many others may depend on that email. So, sometimes, saying just a “yes” or a “no” or even “I’m busy but I will respond, say, next week” in an email that would take a few seconds that would not endanger what we are doing and would make the lives of others easier.

As a member of the Muographers community, what do you find most exciting about collaborating with this group?

Good personal relationships are very important in our work. This is a pleasant ingredient that I also found in the Muographers collaboration and what is really exciting is the enormous potential that our research can bring in terms of scientific and economic benefit to humankind. We will make it very clear in all our next publications.