OUR INTERCONNECTED PLANET

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1 OUR INTERCONNECTED PLANET 10 QUESTIONS WITH DR. DELAMERE Exploring the impact of technology on global issues.

2 OUR INTERCONNECTED PLANET Editor s note A fter a 20 year mission, the probe known as Cassini, will take a victory lap and on its final orbit, plunge into Saturn s atmosphere, sending back new and unique data to the very end including valuable insights into Saturn s weather. Dr. Peter Delamere is a Professor of Space Physics at the University of Alaska Fairbanks. His research focuses on comparative magnetospheric physics with an emphasis on the numerical simulation of space Dr. Delamere plasmas using hybrid (kinetic ion, fluid electron) and multi-fluid techniques. Dr. Delamere has studied the solar wind interaction with the giant magnetospheres of Jupiter and Saturn, comets, Pluto, and the plasma interaction at Io. In addition, he has developed models to study the flow of mass and energy through the inner magnetospheres of Jupiter and Saturn to study the internally-driven dynamics of these systems. As part of celebrating this event with the scientific community, we caught up with Dr. Delamere and asked him to share his insights. Saturn: The Basics Adorned with thousands of beautiful ringlets, Saturn is unique among the planets. All four gas giant planets have rings -- made of chunks of ice and rock -- but none are as spectacular or as complicated as Saturn s. Like the other gas giants, Saturn is mostly a massive ball of hydrogen and helium. Download Saturn Fun Facts 2

3 Today Cassini will plunge into Saturn s atmosphere, ending nearly 20 years of ground-breaking scientific exploration and research. What do you think the Cassini project has meant to research on space weather? Cassini has provided over a decade of scientific data through Saturn s equinox and solstice seasons. The duration of this mission has enabled scientists to examine seasonal variations in Saturn s space weather and to explore a physical parameter space that is distinctly different from Earth. For example, Saturn s aurora responds to changes to solar wind dynamic pressure and, unlike Earth, shows little dependence on the orientation of the interplanetary magnetic field. Testing our understanding of basic physical processes in different physical systems is an essential step in validating our terrestrial space weather models. What has supercomputing technology and solutions like Mellanox meant to space weather research in general? Space weather forecasts involve complicated computer simulations and models that assimilate large datasets from numerous space-based missions. Our understanding of space weather requires high-resolution, parallelized computer models with significant memory overhead. Only with access to high performance computing resources is space weather research possible. To boldly go where no spacecraft has gone before, NASA s satellite to Saturn Cassini will finish its 20-year mission by plunging into the planet s atmosphere and sending back never seen before data before it becomes part of Saturn itself. 3

4 Here s one every scientist studying any aspect of space seems to get asked: since finding a form of chemical energy that can support life on Saturn s moon Enceladus, what is your take on the buzz that researchers will soon discover a form of life in our solar system? Saturn s moon, Enceladus, and Jupiter s moon, Europa, are prime targets in the search for life in our solar system. These icy moons harbor water, likely in the form of a subsurface ocean. From our terrestrial experience, water equals life. Studying the chemical processes associated with observed geysers and gas plumes emanating from beneath the icy surfaces could be the key to discovering some type of microbial life, or more Europa is currently the target of NASA s Europa Clipper mission. But Enceladus remains a proposed target for future astrobiology missions. 4

5 By now, everyone reading Our Interconnected Planet knows that the UoA has been using Mellanox InfiniBand solutions across multiple racks to form their HPC system. What has been the most useful aspect of leveraging Mellanox technology in your research efforts? Our parallelized computer codes remain computationally intensive. There is rarely a case where grid resolution is sufficient, or global scope excessive. In other words, our space weather applications are capable is pushing HPC resources to the limit. Access to the latest technology is essential. Saturn s space environment is very different from Earth s. The large, rapidly rotating gas giant has a strong magnetic field that carves out a cavity in interplanetary space. Deep within this magnetospheric cavity is a source of ionized gas, originating from the Enceladus gas plumes. The additional gas pressure inflates the magnetosphere like a balloon and contributes to Saturn s varied auroral forms in a way that is foreign to Earth s magnetosphere. By testing space weather models using Saturn-like parameters, we can test whether behavior varies as predicted, thereby validating our models. Space weather research strives to make accurate predictions that will help mitigate risks to ongoing space activity and human exploration. Where do you see your research making the biggest impact? Our group at UAF studies magnetospheric dynamics, governed by both internal drivers (i.e., planetary rotation) and external drivers (i.e., the solar wind interaction with the magnetosphere). We study fundamental space plasma physics to understand coupling between magnetically connected regions of space. Your work has involved comparative studies of planetary space environments that are crucial for understanding the basic physics that determine space weather conditions. Can you explain how space weather on Saturn impacts Earth and its importance? The coupling involves the transport of mass, momentum, energy (typically through wave propagation and instabilities) between planetary atmospheres and the bounding interplanetary space. It is this coupling that is at the root of space weather. We have found that simple, coarsely resolved models can be useful to understand large-scale (e.g., >10,000s km) behavior; however, much of the interesting physics (e.g., auroral electron acceleration) occurs on small-scales (e.g., 1 km). We specifically study cross-scale coupling using high-resolution computer models that require HPC resources. 5

6 Space weather not the most commonplace area of study, to say the least. How did you first get interested in this field? The answer is simple. I am fascinated by the aurora. I first saw the aurora in Minnesota as an undergraduate physics student and later discovered the field of space weather as a summer student at UAF s Geophysical Institute. I then studied space weather as a graduate student at UAF. Saturn s aurora is, to a large extent, driven by gas originating from Enceladus and caught in the rapidly rotating magnetic field (Saturn s day is only 10 hours 42 minutes!). This stands in stark contrast to Earth where the aurora is driven externally by the solar wind s interaction with Earth s magnetospheric cavity. Saturn s aurora does, however, respond to solar wind variations, but in a manner that is unlike that of Earth. Also, Enceladus generates an auroral spot at the magnetic footpoint in Saturn s upper atmosphere. Imagine the fascination of seeing a moon-generated auroral spot in Earth s atmosphere! Now that Cassini is taking a swan dive into Saturn, what s next for the Lord of the Rings Planet in our solar system? What kind of research do you foresee? I would, of course, like to see a smaller and more focused space weather missions to Saturn. Single-point measurements from one spacecraft have obvious limitations. The next frontier for space weather research in planetary magnetospheres will be multiple spacecraft missions, similar to spacecraft constellations flown at Earth. Where do you see your own research going in the next decade? How does Mellanox technology fit into your plans? Saturn has really interesting weather, including aurora borealis similar to what we see here on earth. What is the most fascinating aspect of Saturn s weather that people wouldn t know? Cassini has returned a superb dataset and the analysis is ongoing. We will continue to leverage Cassini data while testing our computer models. The requirement for cross-scale (i.e., global scale to microphysical scale) resolution is a computational challenge -- a challenge that will require creative computational methods in a massively parallel environment. 6

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