Bethany Ehlmann is a professor in planetary science at the California Institute of Science (Caltech) and NASA’s Jet Propulsion Laboratory (JPL). She gave a plenary talk on Monday about, “Mars: Geochemical Cycling on a Once Habitable World.” The summary of the plenary talk, written by Dr. Eleanor Berryman, can be found here. I had an opportunity (pun intended) to talk with professor Ehlmann about Mars, the future of space exploration, and on women in science.

Note: If you missed out on the plenary talk by professor Ehlmann, please check out the video: https://www.youtube.com/watch?v=e0yU1vlkEE0

“I explore planets to try to figure out their history and how they came to be.”

“I’ve always been interested in space exploration. I was fortunate when I was an undergraduate student, I had the opportunity to work on the Spirit and Opportunity rovers. That was just incredibly exciting to work at JPL, day to day, with very senior scientists. I was just a little undergrad! It was amazing to get new data from another planet.”

“A lot of it goes to hard work but also thinking strategically about what kinds of problems to work on, and who to work on them with. I think it is a mixture of picking problems that are interesting and exciting, but are also tractable; the key is to work on the best problems that are still solvable. Also, surrounding yourself with good people is also very important, because science is something that very few of us are experts in everything. I certainly am not! I really learn a lot from my colleagues. And then it is really work!”

“Anything athletic and outdoorsy. I play tennis, go on hikes, go sailing, or go scuba diving. Also, I have been doing a lot of native plant gardening in California!”

“We certainly are not there yet! Although, the graduate student population is starting to approach 50:50; not there yet, but it is approaching it. So I think there is progress… It’ll just take time and also some conscientious effort to make sure that the graduate population is reflected as the hiring decisions made for the next generation of faculty.”

“To be clear, I was not saying that obliquity controls loss of water. Obliquity controls the availability of liquid water. That’s a key distinction. The loss of water is mainly controlled by how fast it is lost to space, and how quickly it is locked into hydrated minerals into the crust. But for the water that remains as solid ice, or as vapor in the atmosphere, whether or not either of those exchange in the liquid form, depends on the radiative transfer among other things; and that is, of course, is determined by obliquity, in terms of where the volatiles are stable on the planet. That is important, along with occasionally other things, like volcanoes or impacts changing the composition of the atmosphere, which I did not have too much time to get to.”

“We have a really good sense from the meteorite collection as well as measurements in situ. Primary mineral includes various types of pyroxenes, olivines, feldspars, iron oxides, ilmenites, and magnetites. There is also [few percent] of sulfides and phosphates. Secondary minerals include smectite clays, chlorites, illites, kaolinite, serpentines, prehnite, silica, zeolites, sulfates, alunite-jarosite family minerals, carbonates, chlorides, perchlorates, akaganeite, and various iron oxides. It’s really quite a long list. You typically have igneous minerals as primary minerals. But then you can also get both secondary minerals transformed from weathering or primary precipitates, as well. Those are slightly different things.”

“That is a loaded question! I think we need to pay attention to Mars as Mars. We can reason by analogy with Earth, but that only goes so far. It is because the physics and chemistry are the same, but the starting conditions and the conditions often are not. You can’t make 1:1 comparison on weathering systems. It’s not that Mars is just a basaltic planet, it’s a basaltic planet with more iron in the system. I think we’re now at the level where we have so much data, that we need to think carefully, and think about Mars as Mars and develop a system in its rights, separate from Earth.”

“One of the challenges doing this from the orbital scale… You know that when you are looking at a rock, you have upwards of [around] 5 minerals. What you see from the orbiter typically is the most dominant minerals, so only around one to two minerals. It is very challenging to do whole-rock identifications of all of the phases. But…Sometimes, it’s the phases present in small amounts that are the ones that matter the most (even if they aren’t infrared spectrally dominant). The challenge is always keeping in mind, not only what you know is present (because you are able to positively identify in the spectra), but also what you don’t know. [Essentially], keeping in mind the full parameter space. You can [always] see fingerprints of few minerals, but then it’s always a question of what else is there, what is plausible based on the surroundings. Certain things are not readily detectable from Mars orbit. For example, some anhydrous form of calcium sulfate, which we detected with XRD with the rover… It’s very flat in the highest spatial resolution short wave infrared datasets. So, one always have to keep in mind, what is less detectable.”

“Fortunately, I get to work on the dream projects! We’re currently designing instruments and missions to go to other planets and planetary bodies. For the near term future, I am working on a proposal to send an imaging spectrometer to the moon to look at water ice. I am working on a proposal with colleagues at JPL to send the imaging spectrometer to the surface of Europa! And then… I really do mean what I say in my talk, in that, I think it is important to get back to the surface of Mars. I would love to help lead a new paradigm of exploration where we can continually send rovers, but more of them, so that we get to explore this amazing diversity of environments in time and space. I would love to lead a multi-rover mission to Mars and help enable that!”