I am Steven Hauck, a planetary scientist, professor of Earth, Environmental, and Planetary Science at Case Western Reserve University, and the Editor-in-Chief of the American Geophysical Union journal JGR-Planets, which is celebrating its 25th anniversary this year. I have been a member of the Science Team on NASA’s MESSENGER mission to Mercury and I research (primarily solid) planetary bodies from their make-up and processes in their deepest interiors to the geology (e.g., faults and impact craters) on their surfaces.
Exploration of the solar system starting in the 1960s gave rise to a new field of science: planetary science. Robotic and human exploration of moons, planets, asteroids, comets, and other objects in our solar system has provided a whole new family of worlds to discover. Over the past 25 years, multiple nations have sent a multitude of spacecraft throughout the solar system, from the MESSENGER mission to the innermost planet to the New Horizons mission to Pluto and the Kuiper Belt, and missions to the Moon, Mars, Jupiter and Saturn, comets, asteroids and many more places. And there are still so many places in our solar system that we haven't seen enough of yet. My journal, JGR-Planets, publishes new scientific articles seeking to understand the origin, interactions and history of all the objects in our solar system other than the Sun. Check out the JGR-Planets webpage.
I am looking forward to answering many questions about exploring the solar system, what we are learning about the planets, what the planets are made of and how they operate, and more.
I’ll be back at noon EST (9 am PST, 5 pm UTC) to answer your questions, ask me anything!
If you had an unlimited budget and total control, where would you want to see the next few large missions headed towards?
Wow! That’s a heady question. Fortunately, there is a lot of work to build on here. The last Planetary Science Decadal Survey is the result of countless hours of study of where the next steps are in the science. Work toward two of its top “flagship mission” priorities are already underway: Mars2020 and the Europa mission. After that, the recommendations are a Uranus Orbiter and Probe, are an Enceladus Orbiter, and a Venus Climate mission. Uranus has only had a flyby mission by Voyager, Enceladus is one of the most active bodies around and is of interest for its astrobiological potential, and Venus Climate is critical for understanding greenhouse climates on Earth-like planets. If money were unlimited, this is where I would start.
What should a student do in addition to his (or her) university education to get a job as a planetary researcher? For example, to work at NASA/JPL on Opportunity, Curiosity or New Horizons etc.
I personally just finished a BSc in Geology and in Geophysics, and am now doing a Masters of Research in Earth and Planetary Science. My research focus is on remote exploration, and I've started to become more and more interested in planetary exploration... As an Australian however, I'm not sure where my options lie.
Good question. There is no simple recipe, of course. The big thing for a student interested in getting into any area as a researcher, is to get involved in research. For a student completing a masters, the Ph.D. is the next step. It is also important to participate in scholarly communication – especially at conferences and in written publication. Another avenue is to try to take advantage of workshops and summer schools. There are various short programs in astronomy and planetary science that can provide a great entrance to new topics/skills and help develop networks. These range from field camps to impact craters, to short courses around the world. I am not too familiar with the Australian system, but there are researchers interested in planets and exoplanets across the country, from Sydney to Perth and more – find those people and talk to them about opportunities too.
I looked through your research listed on your faculty page and I see you are a specialist in planetary heat transfer and planetary tectonics.
In this light, I am curious about the plate tectonics on the Galilean moons of Jupiter, or planetary bodies in a similar situation. Do these moons have fundamentally different plate tectonics due to their heat source driving from primarily tidal stress rather than solar energy or residual planetary formation heat?
Does a planet need internal energy for plate tectonics? Could a planet like Mercury which gets most of its energy form solar radiation exhibit significant plate tectonics?
Thank you for your time.
This is a really good question! Understanding the origin (or lack thereof) of plate tectonics is really a grand challenge type question in the earth and planetary sciences. At present, Earth is the only known world with plate tectonics (PT). There have been some suggestions of PT like behavior on other Mars and Venus in the past, but they haven’t really gained traction. Recently, however, Kattenhorn and Prockter have argued that one of the key ingredients for PT, a process called subduction where the top rigid layer of the planet/moon dips back down into the deep interior’ is present on Europa.
PT is one manifestation of how a body loses heat. By recycling cold surface material back into the interior, the deep interior can be cooled more efficiently than if that heat is transferred only by conduction across the rigid outer surface layers. The latter method is how most of the bodies in the solar system seem to operate today. Again, this is a frontier level question. But the main issues come down to the strength of the outer layers (does it break easily) and how vigorous solid state mantle convection is in the interior. This heat usually comes from decay of long-lived radiogenic isotopes like those of potassium, uranium, and thorium. However, in the icy moons, tidal heat can be incredibly important, such as at Europa and Enceladus. And it fact it has been suggested that the Tiger Stripes on Enceladus might be a manifestation of a middle ground between a rigid quiescent lid and PT. We have a lot more to learn about plate tectonics.
What are the 'big questions' you are hoping that Juno will or can answer? How do you think Juno can contribute to modern day (technological) advancement?
One of the big things that Juno is doing is measuring the variations in the gravity of Jupiter. This is important because those variations are related to the deep structure of the planet. One of the open questions is whether Jupiter has a solid core or not. This question is important because it will help test hypotheses for how giant planets form - e.g., are they related to gravitational collapse of gas and dust within the solar nebula (akin to how a star forms, but smaller in scale) or is a large planetary body necessary to start accumulating more and more gas (which makes up almost all of Jupiter's mass). Understanding the magnetic field, which Juno is also measuring, will also place important constraints on the structure of the interior, and also magnetic field generation in general.
What was the single biggest surprise you've encountered thus far in your career? I'm talking about things like the brine on mars, or any of the revelations regarding Pluto - you know, thing like that. What has really blown you away and turned out to be something that you did not expect to see?
Usually, it is the next one. We have so much left to learn about the solar system, that everywhere we turn is something unexpected. So I don’t have a single biggest thing. But one of my favorites is the discovery “hollows” on Mercury. These beautiful and unexpected features look like rock is sublimating to space and they are incredibly young. We don’t know how these features work, yet, but just the idea that there is ongoing formation of these features on Mercury is exciting.
What aspect of space exploration is the most important to mankind?
IMHO it is what we learn by exploring that is most important to humans. We learn through the act of exploring, about we can do, what is feasible, what is hard, and why. Importantly, we learn about our place in the universe. Studying the planets is important for understanding our own planet - whether it is the atmosphere, the rocks, how it has evolved, the other planets provide context. For example, there is a limit to how much we can learn about trees, by studying only a single specimen. The same is true for planets, and solar systems, which is why we look beyond to the stars and for exoplanets. So, to me it is about exploring and learning.
Hi Dr. Hauck. I am going to be a freshman this year at Case, and I'd like to know what kinds of things I can get involved with now that will open me up to career opportunities at NASA or other space programs? I'm currently planning on studying mechanical engineering and working for NASA is my dream job.
This is a great question for anyone, especially in college. The best answer is to explore your interests. That includes getting involved in faculty research projects that interest and suit you, participating in related extracurricular activities such as rocketry clubs, geology and astronomy clubs, and finally looking for summer internships at appropriate agencies, like NASA, but also at universities, museums, etc. Best of luck in your first year of college and welcome to Case!
What is without a doubt the most mind blowing fact you can state about another planet?
There are places on Mercury that have double sunrises and double sunsets because of the way that the planet spins on its axis 3 times for every 2 times it orbits the sun. This movie shows a full day at the south pole of Mercury. You see it pause for a bit. That is real, not a video artifact and that is where you would see the sun go down, then slightly come back up, then go down again, and vice versus and sunrise.
Which upcoming missions are you most excited for, and why?
I’m a total space nerd, I get excited for all space missions. I studied aerospace engineering in college and then planetary science in grad school, so I like it all from the nuts and bolts of the rocket and spacecraft, to the science at the end of the tunnel. NASA’s OSIRIS-REx is slated to launch on September 8th to visit asteroid Bennu, study it in unprecedented detail, and return samples. That is exciting. Farther down the line is the European and Japanese mission Bepi-Colombo to Mercury that should arrive in the mid-2020’s. I have spent most of my career studying Mercury and the MESSENGER mission opened whole sets of new questions that Bepi is going to help answer. But truly, I get excited for all of them.
What, in your opinion, would be the most viable planet to start a mining operation, accounting for sheer mineral count, atmospheric conditions, and overall feasibility?
Thanks for doing this AMA, I've always loved the field you work in and I'm very interested to see all the interesting questions/responses!
IMHO the other planets per se are probably not the first best bet for mining operations - at least mining aimed at returning minerals to Earth. If such an activity were to become financially feasible, asteroids are a better bet, and indeed there are companies focused on this idea. The potential advantages are that they are small enough that you don't need large rockets to break the gravity of the body to return the materials. Also, given their primitive nature, asteroids are a reasonable place to think that relatively rare minerals (important for financial feasibility) may be accessible.
I'm sure the journey to becoming a planetary scientist has been a long and interesting one, but what was it that decided this would become your career. Was it a sudden realisation during college or university, or was it a passion and or hobby that you've had since school, which you've made your career.
I have a fascination with space exploration and the planets within and outside of our solar system. I know it's never to late to realise a dream, what science would you suggest for me to study at university, to start me up on my way? I haven't really got a particular job role in mind, as far as that's concerned, I have my options open and want to let my studies lead my decision.
Thank you for reading my question, and have a great day.
Great question. For me it was an accidental realization. I studied aerospace engineering in college – love aircraft and spacecraft. But I did some research in planetary science with a professor at the University of Minnesota and got incredibly wound up in it. At the same time I was taking a few geology classes as electives, and found I enjoyed them more than I thought – a lot. So, when I was finishing school, instead of following my classmates in their search for jobs at aerospace companies, I started applying to grad schools and got into one and my first project was heavily related to the research I did as an undergrad. I have always loved space, but thought it was going to be the hardware side that would be my focus, turned out it didn’t and now I get do science, but use my aerospace interests along the way. I am an accidental planetary scientist of sorts, and feel lucky every day for what I do.
As for what science to study, it is important to follow your interests. Geoscience is at the heart of the kind of planetary science that I focus on. Astronomy is another entrance to planetary science. Observations of many places in the solar system rely on telescopes. And of course, physics and chemistry are good entrances. So it really depends on what you find most interesting.
I'm sure I stand with a lot of people in saying that I'm pretty ignorant to the inner workings of the field of planetary science, so this should be a fun read.
What are your dreams going forward with your research?
Reading your faculty page, I see one of your interests is "iron snow" in Mercury and Ganymede - why doesn't iron snow occur in earth/affect earth's magnetic field?
What are, in your opinion, the "holy grails" of planetary science research?
EDIT: Just so i'm not misunderstood, by holy grail I refer to events or topics that would really shake the field. For instance, I work in vaccines and a universal flu vaccine (one that offers protection from any flu strain, and requires no annual formulation planning) is seen as a holy grail in my industry.
Wow. Big picture. My dreams are pretty simply stated, to explore as much of the solar system as possible. That’s the wide-open-sky view. “Iron snow” is the idea that within the deep metallic core portion of a planetary body that solid iron could start precipitating at or near the top of the core, rather than its middle. The idea is interesting for smaller bodies like Ganymede, Mercury, Mars, etc because the effect of pressure on the melting temperature of one of the likely core composition mixtures (that is iron+sulfur) is such that it would be more likely to crystallize at the top. However, at the much higher pressures in large planets such as Earth, the experiments appear to show that this effect is gone. I think that there are many grand challenge questions. Why does only Earth have plate tectonics? What explains the enormous diversity of planetary magnetic fields in the solar system? Is there evidence for life (past or present, and likely microscopic) anywhere in our solar system? The list goes on. We really are still in the major exploration phase of planetary science.
There's always rumblings of trying to send a submarine to Europa if we could figure out how to get through the crust and into the ocean. How far out is that actually likely to be, if ever? 30 years? 60? Will it have to wait for manned missions that far out?
Brett: I wish that I knew the answer. Yes, concepts like a probe through the ice or a submarine on Europa do exist. How long until that is feasible? I really don't know. However, and important piece of doing that is first knowing how deep through the ice such a mission would have to go. The currently in-development Europa mission is aimed squarely at answering that question. Maybe we'll know that in 15(?) years or so. So that is a start.
I think it is perhaps more likely that a boat or submarine will visit one of the seas on Titan first. A boat was proposed to NASA several years ago, the TiME mission, and was quite exciting, but was not chosen as part of the competitive Discovery mission program. Regardless, those kind of missions could be possible in the future.
Hi Steven, Thanks for the AMA! If the next generation of super heavy-lift launchers (SLS and the rumoured SpaceX BFR) with capacities of 100t to LEO become operational and – dare I say it – in some way affordable, can you think of any missions that could take advantage of that capability? What are the most exciting missions that would then be possible?
SLS scale launchers are exciting to dream about in terms of planetary exploration. Such launchers would open up the kind and size of spacecraft we can send to the outer solar system, perhaps decrease the cruise time to the Kuiper Belt, and vastly increase the complexity of science we can do on other planets – larger rovers, ease sample return missions by carrying more sizeable relaunchers, and even make landing on Mercury more feasible. Costs will always be the sticky wicket there, but if it becomes affordable, there are plenty of places yet to explore.
I'm not sure if this is something you're interested in working on or not, but nevertheless, of the data sets we expect to get from the InSight Mission, which seems most exciting/interesting/relevant to present studies to you?
InSight is a very exciting mission to people who study the physics of planets and their interiors (like me). Really, the seismometer is the major piece of that mission. Being able to measure marsquakes - in order to get a sense of how seismically active Mars is, and to measure the properties of the deeper interior are just two critical questions for any planet really. The seismometer really lets us peer into the deep interior - and seismometers measuring earthquakes on Earth are one of the fundamental tools of earth science. The heat flow sensor is also interesting. The evolution of a planet is governed largely by how it loses heat. Having measurements of the amount of heat that is being lost from the interior helps place constraints on that evolution. I am also looking forward to what we call "tracking data" just measuring where InSight is as a function of time. Those data will give us fundamental information on the deep interior too because how a planet spins, and the slight variations thereof, are dependent on the layering of the interior.
What your favorite planet and why ( Earth doesn't count )?
Always the one that I am working on at the moment. Really they are all fascinating in their own way. Planetary scientists are often continually enamored of the first object they studied (for me that is Venus). Mercury is really at the center of what I have worked on the past decade, from my involvement in the MESSENGER mission. Mercury is such an interesting place because it has this odd resonance where it spins 3 times for every 2 times it orbits the Sun, the, it is a planet that has shrunk by at least 5-7 km in radius over the past 4 billion years, it has the largest fraction of metal among the inner planets, and the list goes on. But I have worked on many other planets, and trust me, they were my favorite at the time too.
What planet would you like to visit yourself?
That’s a question that gets at both the scientific and romantic parts of being a planetary scientist to be sure. In truth: most of them. I’d love to sit on Mercury and see the double sunsets (and double sunrises) that parts of the planet see because of its peculiar resonance where it spins on its axis 3 times for every 2 times it orbits the Sun. The Moon is close enough to be tangible, and it has so many secrets about the history of the solar system. Mars holds a record of geologic history throughout the whole of the solar system. Standing at the edge of Valles Marineris alone would be cool. Titan as the only moon with an atmosphere, and channels, and dunes would be a geologist's dream (seeing Saturn up close too). And after New Horizons’ flyby last summer, Charon, the tectonics on that body are a sight to behold and understand really captured my imagination and thinking last summer, and even though it is distant – Pluto would be in the sky.
Hi Steve, thanks a lot for your AMA and your fantastic job.
I have a couple of questions for you:
what kind of objects could we find in Oort's Cloud? It is possible that there are some Pluto-like objects?
What do you think about Planet 9 theory? Will we find it in the near future?
Thanks a lot beforehand and keep up the good work!
For your first question, we should find objects like long-period comets as that is where they generally appear to come from. So our best, first bet to understanding objects from the Oort cloud is to study comets – in essence letting pieces of the Oort cloud come to us first. Whether there are larger Pluto-like objects remains to be seen.
The work that has gone into inferring the presence of Planet 9 is a bit outside my usual work. However, multiple groups have found indications suggestive of an object deep out there in the Solar System that is perturbing the orbits of icy bodies in the Kuiper belt. Time will tell, but there is clearly a lot of focus in the science community to test this idea and look for confirmation. In truth, I’m waiting just like you.
Has the Chinese space agency been forthcoming with technology, data, and collaborative efforts since their successful Moon landing in 2013? We all know the movie "The Martian" portrayed them as running a successful and highly secretive program, but international space missions practically mandate cross-training in each other's technology, as portrayed in the other movie "Gravity". That conversation must exist in some form; what's it like?
This is an interesting question, though I doubt that I can answer it completely. First, NASA is specifically prohibited from actively collaborating with the Chinese space program by law. This does present a barrier to collaboration, at least between the US and China. However, data from Chinese spacecraft sent to the Moon are publically available.
Hello, Mr. Hauck! I was wondering which moon of Jupiter or Saturn you'd be more interested in getting probe information back from?
What kind of temperatures would you expect in the lower depths of Europa? Do we think it's mostly liquid, or is there some kind of sludge or core in the centre? If you had the chance, would you personally, in a probe, go through the crust of Europa to be the first person to turn the lights on and look around under the 'water'? I find that thought really cool, but terrifying!
Oh my, all of the big four at Jupiter (Io, Europa, Ganymede, and Callisto) are interesting. Ganymede is interesting because it has its own magnetic field and an interesting geological history (not to mention being larger than even Mercury). Io's volcanism and general mode of operation is astounding and would be an incredible opportunity to understand how tidal heating drives planetary evolution when the heating is turned up to 11. But for the Jovian satellites, Europa, which is interesting because of its young surface, plethora of tectonics, possible cryovolcanism, and of course that ocean is the place to go there. Titan and Enceladus are the pplace to go at Saturn. Enceladus is a biggie because of its astrobiological potential, but Titan... it has seas, active surface geology all in materials that are decidedly not rock and liquid water - that is interesting.
I'm not sure if you're the right person to ask but, I'll give it a shot anyway.
I'm a Canadian psychology and neuroscience major in uni right now and I have a personal interest in space, astronomy, robotics, and new technology. Is there any room or position available for someone like me in NASA or CSA? Or should I just stick to trying to get a medical doctor degree and applying to become an astronaut? Do you have any general advice for someone in my situation?
Space exploration is a big melting pot, so I would be surprised if there weren't opportunities. Whether they are as abundant as in other areas related to engineering, aeronautics, and space exploration, I'm not sure. Still, the most important thing is to follow your interests and talents. Choose the things that make you happy. When it comes to making turns like that, don't be afraid to knock on doors and ask questions (like you did of me). I may not have the best answers for your, but others might.
Is it fun being a planetary researcher?
I love it. I like trying to understand how these big planetary bodies operate and why they do, and often do not, seem to behave like each other. I enjoy the kind of work that I do, which is to work on spacecraft mission like MESSENGER, analyze the data and see things that haven't been seen before. I also like to sit in front of my keyboard and write code to make physical models of things work. But there are many ways to be a planetary researcher. I have friends and colleagues who spend significant amounts of time out in the field (from the deserts, to volcanoes, to Antarctica), those who work in labs, and those who observe with telescopes. I also find it fun to share the work we do with other scientists and anyone really. So, the answer is that I find it fun, and feel lucky to be able to do it.
Hi! My son (13) is super into science, I'm a CWRU alum (Graduate School and Law School), and we live in the area. Do you/your department ever do open houses or youth tours?
It has been a while since we have done something like that. The department does support Science Olympiad, and several other more broadly organized programs. Also, many of the faculty and students give presentations at CMNH and other local societies. So, there are other ways to interact too.
Do you think we should keep spending money investigating planets within our solar system that likely don't harbor any extraterrestrial life or should we spend money looking beyond our solar system to more habitable places ?
This is an important question, and I can only speak for myself. However, I think that we have to study the solar system as a whole. The search for life is an important driver of current space exploration policy, and understandably so. However, the study of other bodies is critical for understanding the processes that are fundamental to the operation of planets. We need to study Venus, Mars, and Titan to truly understand climate dynamics and history at fundamental levels. Each of the solid bodies in the solar system give us clues to the history of our neighborhood (important for understanding the conditions early in Earth history, now mostly overprinted by billions of years of erosion, plate tectonics, ice ages, etc), they also are important tests for understanding plate tectonics and its origins – one of the most fundamental questions in all the Earth and Space Sciences. The giant planets are the big kids in the solar system, their influence shepherds the solar system, especially its formation, and they are also the largest repositories of material from the origin of the solar system outside of the Sun. Further, they are similar in size to many of the exoplanets being discovered every year. Responsible allocation of resources is crucially important, but I think the best way to do that is to continually prioritize the areas that are primed for the most important advances and move toward those in thoughtful and responsible ways. Fortunately, in the US we have Decadal Survey process that helps policymakers identify those opportunities.
As a geophysicist, I am familiar with standard methods to study faults and tectonics on earth (e.g. GPS, InSAR, seismology). But none of these exist on other planets, so how do you study tectonics and faults there? Is it just satellite imagery and models?
Related: As a thought exercise, has anyone every applied the same methods for studying the tectonics of other planets to earth, limiting themselves to data similar to what we might have for say Mars, and see what conclusions they could make about Earth? How close would that be to what we actually know about our tectonics?
So, while there isn't GPS elsewhere, we do have some other tools to use. Several of the Apollo missions left seismometers (short and long period) and those data continue to this day to be used to understand the deep interior and to try to understand deep tectonic activity on the Moon. NASA's InSight mission will place a single, modern seismometer on Mars in about 2 years, which will be a great help there. SAR is used at Venus, and any future mission looking at the surface very well may employ inSAR techniques for a variety of reasons.
Still, imagery and topography (either from laser altimeters or from stereo measurements) are important in studying tectonics and faulting on other planetary bodies. At the largest scales, e.g., the relaxation of large impact basins, make use of gravity data. In fact, the very high-resolution gravity data from from the GRAIL mission to the moon have been used to infer the location of subsurface faults (either due to displacements, or later filling, such as in dikes).
As for your second question, I am not quite sure. There is obviously a lot of transference the other way - particularly in models, e.g., finite element, boundary element, etc., and the comparisons with data such as topography and gravity. A good question.
Any plans to explore the asteroid belt?
The asteroids are a great place to study. There have been several missions, for example, the NEAR mission to Eros, the Hayabusa mission that returned some samples, and the Dawn mission has studied the big kids on the block there: Vesta and now Ceres. On Sept 8, NASA will launch the OSIRIS-REx mission to an asteroid. Some asteroid missions are focused on ones closer to Earth, and others farther away, but all are critically important because the asteroids represent some of the most primitive pieces of the solar system that tell us about its history and how the planets were assembled.
Would you like to see a mission to the outermost planets such as Neptune or Uranus to learn more about them and their moons in the late 2020/30's? Or do you think it would be better to focus the funding for a mission like that on something else such as the potential colonization of Mars?
I do think that a mission to Neptune or Uranus is important. The ice giants haven’t yet been studied in detail – they are important parts of the solar system and as we discover more exoplanets with similar sizes around other stars, we need to study the ones in our backyard for important context. I fully believe we can recede from any part of the solar system in terms of exploration.
Does Jupiter have a solid body and ow do we know?
We actually don't know. That is one of the major goals of NASA's Juno mission that recently entered orbit about Jupiter to figure out.
I just re-watched Cosmos again and it got me all fired up about planetary science and space exploration. My question is, as a layman (with a degree in COSC), is there anything I can do to help contribute to the continuing progress of planetary science? I know of the Planetary Society (because who doesn't love Bill Nye?) and was thinking about tossing in a few shekels, but is it worth it? Is there anything else I can do?
This is a great question. Making your thoughts known to policy makers is always a good idea, and regularly important, as governments are the big source of funding for science. Organizations like the Planetary Society and AGU and the American Astronomical Society, etc., are also good at getting their members informed and involved. So, I personally think that is valuable. The other thing is that planetary science and astronomy is, and increasingly so, a great opportunity for citizen science. There are opportunities such as galaxy zoo and Moon Zoo to participate. Citizens have helped find microscopic particles in images of materials returned to space so that they could be studied. There are many ways to be involved. Thanks for being interested and pitching-in!
I'm attending Case next year as a freshman. You seem cool.
Congratulations! Have a wonderful first year!
What is the material composition of Callisto?
The surface materials are largely ice. There are also likely to be rocks and probably some metals mixed with that ice at some depth.
- t3_4w40gl_comments.json 248 KB
Showing 1 Reviews
It is very good tool,so many people convert video to mp3 form help many application,but we have discussed on this web site,how can to convert any video with out any software or applications how to convert youtube videos to mp4 following to this ways,this is best shortcut method,copy video link and paste your choose tool you want to convert video.
This article and its reviews are distributed under the terms of the Creative Commons Attribution 4.0 International License, which permits unrestricted use, distribution, and redistribution in any medium, provided that the original author and source are credited.