These are some of the questions I am interested in and that I have in some ways worked on - which usually lead to new questions...
Planetary Magnetic Fields
Magnetic fields are ubiquitous in our Solar System and beyond! Some planets generate their own internal dynamo fields (e.g., Earth and Mercury) , some used to do that (e.g., Moon and Mars) for some we are just not sure (e.g. Venus). Dynamo fields can magnetize crustal rock under certain thermal or environmental conditions and by studying those rock we can learn about the time this rock was emplaced. Planets also sit in time-varying external magnetic fields, driven by the Sun. Those fields interact with internal fields and are for example linked to the way a planet loses its atmosphere. External fields also induce eddy currents in the interior of a planet and allow studying the internal structure of a planet. Are you convinced that magnetic fields are extremely powerful and any planetary scientists can benefit from what we do? If not make sure to contact me!
When and how did planetary dynamos operate for individual planets?
Dynamo Fields are linked to interior conditions and thermal as well as material properties. Ancient dynamos tell us about a time their host planets must have been able to sustain a dynamo. For Mars for example, these conditions might have been linked to the presence of a thicker early atmosphere.
High resolution MAVEN satellite data allowed us to detect crustal magnetization in terrain that is 4.5 and 3.7 billion years old - constraining the timing of the martian dynamo. We also found that the strength of the dynamo at 3.7 Ga could have been very similar to today's Earth dynamo.
What was the mechanism that powered this dynamo? Did it operate continuously? When did it cease and why? Is it linked to the changing climate on Mars?
What is the current interior state of planetary bodies?
I already talked about planetary dynamos which are an indicator for the internal state of a planet. However I also mentioned that external fields can probe planetary interiors and we can magnetically sound a planet. This allows us to investigate electrical conductivity which is linked to volatile content (yes water!), temperature and material properties.
Learning about the interior of planets is hard, but InSight has done an amazing job - mostly using the seismometer, but the magnetometer has been doing a pretty good job too (see below)!
Because the Moon has a very simply defined geometry when it is in the geomagnetic tail, we were able to describe the inducing field using a single set of spherical harmonic coefficients (l=m=1). This allowed us to derive a transfer function and invert for electrical conductivity in the lunar mantle. This study shows that we can magnetically sound the Moon with just a single station. What's next? There are 3 Apollo stations that carried a magnetometer and so much is happening and planned for the Moon, so stay tuned.
Does the nature of local mantle structure reflect surface variations in crustal magnetization? Is compositional heterogeneity acquired during accretion and differentiation preserved?
How does the Sun interact with individual planets?
These time-varying fields I talked about are driven by the Sun and depending on the individual magnetic field environments of a planet or Moon they will interact with it differently. Interaction with the Sun is important and e.g., solar storms have the power to impact navigational systems we rely on heavily on Earth. They also have to power to remove large amounts of atmosphere.
InSight’s magnetometer provides the first surface recordings of the Martian magnetic field environment over 1241 sols. We observe transient and periodic external fields with time scales of minutes up to a year and discuss their origins. The find that time variations in the surface magnetic field are primarily driven by the ionosphere and are thus strongly affected by atmospheric seasonal variations. We discuss limitations of such observations due to the single point measurement and possibilities future missions will provide.
What are the long-term trends? What would we observe in a different location, i.e., what is the influence of crustal magnetic field? What about solar storms? InSight operated during a very quiet time period in terms of solar activity ...