Planetary Physics

Planetary Physics

Planetary Physicists study the Solar System and its constituents as well as exoplanetary sytems. Many are astronomers, too, in the sense that studies are conducted remotely. However, by employing spacecraft as probes, planetary physicists can reach out and touch many bodies in the Solar System, and thereby conduct astrochemical and astrogeological studies not possible in other astronomical disciplines. A major thrust of planetary research is to identify environments suitable for the development of life and, in turn, to detect evidence of life in the Solar System and beyond.

Here are the researchers in Planetary Physics who are able to supervise graduate students. To see a detailed profile of anyone, including contact information, click on the title bar or portrait. To see a personal research website (if available), click on the research picture.

Supernovae and their remnants; Pulsars; Active Galactic Nuclei; Observational tests of general relativity; Radio continuum astronomy; Very Long Baseline Interferometry.

I study galactic and extragalactic compact, celestial sources of radio waves such as supernovae, pulsars, black hole candidates, radio stars and the powerful cores of radio galaxies and quasars. With the technique of very-long-baseline interferometry (VLBI) and a network of several large radio telescopes girdling the globe, it is possible to image the areas of activity of these sources and determine their positions with an angular resolution 1,000 times better than with any optical telescope on Earth. In particular, this allows us to make sequences of images of young, rapidly expanding supernovae, study the interaction of their shock fronts with the circumstellar medium, search for pulsars in their centres and compose the results in a "movie of an exploding star." As a spin-off, we obtain vital information for determining the distance to the host galaxy, which helps to anchor the extragalactic distance scale. We have developed a novel data acquisition system for phase-coherent baseband recording of pulsars to complement our VLBI observations and extend our studies to searches for new millisecond pulsars and their possible companion planets and black holes. Also, we investigate the cosmological jets of energetic particles which emanate from the active centers of so-called superluminal radio galaxies and quasars with speeds that appear to be faster than the speed of light. These studies help us to understand the physics of the immediate environment of these centres which are believed to be supermassive black holes.

Applications of Global Navigation Satellite Systems (GNSS), especially to positioning and navigation.

My research interests centre on the use of Global Navigation Satellite Systems (GNSSs), most notably GPS, for a multitude of precise positioning and navigation applications. Specific application areas include crustal deformation monitoring, precise orbit determination, and precise positioning of offshore platforms. This research requires development of positioning algorithms, which include filters, functional models, stochastic models, and prediction models to mitigate physical affects. Recent algorithm research has focused on improving the robustness of precise point positioning, and extending the range of single-baseline, real-time kinematic (RTK) GPS.

Modeling and forecasting of weather and climate.

I am an active developer of advanced numerical modeling and data assimilation systems for studying weather and climate. I utilize state-of-the-art numerical models and ensemble-based data assimilation techniques to improve weather forecasts, regional climate predictions, and air-quality forecasts. Particularly, I am interested in mesoscale dynamics and severe weather.

Scientific instrumentation and techniques for missions to planets, moons and asteroids.

I am interested in optical instrumentation, including LiDAR, for planetary mapping and imaging. For example, I led the development of the meteorology instruments aboard the Phoenix lander on Mars, Canada’s first instruments on another planet. Most recently, I have been the lead scientist for the Laser Altimeter (OLA) for the Origins Spectral Interpretation Resource Identification Security Regolith Explorer (OSIRIS-REx). OSIRIS-REx is now on its way to Asteroid 1999RQ36 (Bennu), where it will collect samples and return them to Earth. Besides its value to identifying a sampling site, the OLA data will provide us with new insights into the structure and composition of the surface of one of the most primitive bodies in the solar system. As well, we will be using the data to calibrate observations of asteroids that are made using telescopes on Earth. Separately, I am experimenting with Raman spectroscopy as a tool for measuring constituents of planetary atmospheres. One objective is to develop a rover-based instrument to localize methane, a gas which is a signature of biological activity.

Atmospheric emissions; Air quality; Turbulent processes.

I study the emission, deposition, and transport of chemicals, pollutants, aerosols, and particles to and from various sources, including petroleum production facilities, road traffic, forests, and arctic environments. Prior to coming to York, I worked for 5 years as a physical scientist and post-doctoral researcher in the Air Quality department of Environment Canada. Current studies include emissions and mixing of pollutants from highway traffic, emissions from oil sands production facilities, and the interaction of pollutants with forest environments and mixing within the forest canopy. Previously, I have worked on wind-induced transport of sand particles and blowing snow in the Arctic.

Nanosatellite technology development, including micro-propulsion, sensors, and actuators; Remote sensing.

I develop efficient systems and infrastructure for space flight, and direct the Communications and Operations Laboratory. My research interests centre on nanosatellite technology development. Nanosatellites are, in general, spacecraft with a mass less than 10 kg. They have been increasingly recognized as valuable tools for demonstrating new technologies in space as well as an effective means to educate space engineering professionals due to their relatively low cost. My focus has been to develop a series of space technologies that will lead to scientific nanosatellite missions in the near future. Currently, I am investigating several areas including micro- propulsion system design, MEMS-based attitude sensor and actuator design and algorithms to incorporate their low-grade characteristics, and subsystems based upon field-programmable gate arrays. I am a Canadian participant for the QB50 Mission to develop nanosatellites for an Earth Observation experiment.

I have a passion to engage youth from non-science, non-academic backgrounds, and young women in particular, to discover their potential through scientific problem solving and in turn enrich the diversity of ideas and perspectives within the engineering field. To this end, I am a part of many progressive initiatives, including Space Junk, a youth-at-risk workshop with Big Brothers Big Sisters of Toronto, and Go Eng Girl, introducing girls in secondary school to engineering. Also, I initiated and subsequently guided the York University Rover Team, which has won major international awards each year since 2007.

Micro- and nano-structuring of polymer material systems; Bio-based and smart multifunctional materials; Advanced thermal management materials.

My research is focussed on micro- and nano-structuring of polymer material systems, with the emphasis on tailoring and optimizing their multifunctional properties for a wide spectrum of applications (e.g., energy storage and harvesting, sensing and actuation, biomedical devices, thermal management, and environmentally benign packaging). This highly interdisciplinary research area requires integrating the principles and techniques of advanced manufacturing, materials science, fluid mechanics, thermodynamics, and rheological sciences.

Space-based remote sensing of Earth's atmosphere, especially stratospheric ozone; Spectroscopic instrumentation and techniques.

My primary research focus is space-based remote sensing of the Earth’s atmosphere. I am especially interested in monitoring atmospheric constituents, such as ozone, and I develop and deploy instrumentation for that purpose. Ozone is a particularly important gas because it shields us from much of the ultraviolet (UV) radiation from the Sun. To monitor UV radiation and the levels of ozone and sulphur dioxide in the atmosphere, I co-invented the Brewer Ozone Spectrophotometer, an instrument that is now deployed on the ground worldwide. To quantify the effect of ozone depletion on shielding and simultaneously apprise the population of the level of danger, I co-developed the UV Index. My students and I continue to develop new methods and techniques for measuring and modeling the chemical composition of our atmosphere.

Space-based remote sensing of Earth's atmosphere, especially low-altitude pollution; Evolution of ozone layer; Information retrieval from atmospheric spectra.

I use remote sensing observations by satellites to better quantify and understand the distribution, evolution, sources and sinks of air pollutants. Primarily, I develop models for the retrieval of atmospheric composition from UV-visible spectra acquired by satellites, and then use the results to quantify, map, and evaluate trends in emissions of surface pollutants over urban and industrial locations. I am also interested in understanding and quantifying the evolution of stratospheric ozone and ozone-related trace gases, especially those composed of species of nitrogen and bromine. Additionally, I am engaged in monitoring how the extraction of oil from oil sands is affecting atmospheric composition.

Planetary volatiles, from ices to atmospheres; Laboratory simulation of planetary bodies; Space mission operations, design, and data analysis; Planetary instrument design and development.

My research interests lie in the planetary sciences, particularly planetary atmospheres and interactions with planetary surfaces. Questions that I address span the solar system, from Earth to Mars to Comets to Ceres to Giant Planets and their icy satellites. For example, how is it that Mars went from being a warm and wet world in the ancient past to the dry and frozen desert world of today? How is it that an icy body like Enceladus can geyser water droplets out into space, and what can that material tell us about the ocean that lies within? In order to find answers to such questions, it is necessary to send spacecraft out to explore and to establish ground-based facilities to interpret returned data.

I am currently supporting Surface Operations on the Mars Science Laboratory Rover (Curiosity) and developing planetary simulation facilities at York University as part of the Planetary Volatile Laboratory. Previously, I have led experimental studies into interactions of volatiles with the Martian surface and polar caps. After my training with the Mars Exploration Rovers, I worked on the Huygens probe to Titan and I also participated in the development of the Surface Stereo Imager for the Phoenix Mars Lander. Also, I have been involved in several conceptual space mission design studies and analogue planetary missions. I have experience modeling scattering in the atmospheres of Earth and of Mars from the ultraviolet into the near infra-red and dynamical modeling of the Martian atmosphere. Recently, my work has led to the first direct detection of fog on Mars, to estimates of the methane content of the martian atmosphere from exogenous sources, and to an understanding of the origin of ridges of ice on the surface of Pluto.

Space instrumentation; Space test processes; Planetary atmospheres; Radio astronomy.

My research focuses on the development of space-based instrumentation, data analysis techniques and tools, and space test processes to advance planetary research and to improve the performance and reliability of space systems. For example, I am a member of the York University Argus team that is currently operating a pollution monitoring spectrometer in low Earth orbit on the CanX-2 spacecraft. This technology was awarded the Canadian Astronautics and Space Institute Alouette award in 2010. Also, I am the inventor of a novel construction technology for a space elevator which has attracted world-wide interest. In collaboration with Thoth Technology, Inc., I am currently developing a mission to Mars called Northern Light which will explore new regions of the planet. In the process, I have revived Algonquin Park Radio Observatory, and am presently using it for endeavours ranging from spacecraft tracking to very-long-baseline interferometry of pulsars.

Spacecraft dynamics, control and navigation; Formation flying; Active vibration control; Membrane structures; Smart materials and structures; Multi-agent systems; Motion synchronization; Trajectory design and optimization.

I conduct research in spacecraft dynamics, control and navigation. I am particularly interested in cooperative and coordinated control of multiple vehicles, i.e., formation flying. Consequently, I must delve into such areas as active vibration control, smart materials and structures, membrane structures, and motion synchronization. For this purpose, I founded and direct the Spacecraft Dynamics Control and Navigation Laboratory at York University.

Airglow; Aurorae; Atmospheric dynamics and composition; Space instrumentation.

I am interested in the properties of the upper atmosphere, and develop ground- and space-based instruments for conducting measurements. The upper atmosphere, in the region from 80 to 300 km, is where solar energy input first begins to interact with the atmosphere, producing optical emission known as airglow, and aurora. With specialized instrumentation, this emitted light can be used as a diagnostic tool to determine the properties of the atmosphere in this region. With support from NSERC, and the Canadian Space Agency, the Doppler Michelson Interferometer technique was developed for spectral imaging of the atmosphere, yielding images of optical emission rate, temperature and wind. As Principal Investigator for WINDII, the Wind Imaging Interferometer, a joint Canada-France instrument was placed in orbit from 1991 to 2003 on NASA’s Upper Atmosphere Research Satellite and acquired 23 million images of the atmosphere. The data are still providing exciting new information on the dynamics of the upper atmosphere, and how these dynamics influence the distribution of atmospheric species, such as atomic oxygen. Ground-based instruments have been deployed also. For example, an optical observatory was operated at Resolute Bay in Northern Canada to study the polar upper atmosphere. More recently a derivative of WINDII, the Spectral Heterodyne Spectrometer (SHS), has been developed and flown on a high altitude balloon for the measurement of water vapour in the lower atmosphere. Currently, a collaboration with Germany is in place, intended to lead to the launch of a Cubesat satellite carrying an SHS instrument to measure waves in the upper atmosphere.

Atmospheres of Earth and Mars; Applications of lasers to remote sensing (LIDAR); Laboratory simulations of the Martian environment.

I specialize in the study of the atmospheres of Earth and Mars, primarily compositions, climate, and dynamics. To further atmospheric measurements, my group develops and applies laser remote sensing (or LIDAR) instruments for use from the ground, from aircraft, and on Mars. I led the design, testing, and implementation of a LIDAR system on the Phoenix Mars Lander to measure the distribution of dust and clouds. It resulted in the discovery of snow falling from Martian clouds. The next generation of Mars LIDAR will be directed at the surface of Mars to detect the deposition of water. It is being tested in a chamber that simulates the environment on Mars. Scientific progress is already being made with the finding that water can condense out of the atmosphere onto salts on the surface of Mars. To measure ozone, clouds, and aerosols in the Earth’s atmosphere, we have built a LIDAR system for installation on various aircraft. Recently, it was installed on the Polar-5 aircraft (DC-3) and on the Amundsen icebreaker for measurements of the impact of sea ice on air chemistry and ozone. Another recent field campaign has involved installing a LIDAR instrument on a Twin Otter aircraft for measurements of air pollution form the oil sands industry in northern Alberta.

Tethered spacecraft systems; Multifunctional materials; Additive manufacturing in space; Computational solid mechanics.

My research interests include computational solid mechanics, dynamics of mechanical systems, and numerical methods and their applications in the aerospace and defence industries. I am particularly interested in space tethers, such as the dynamics and control of tethered spacecraft systems and the application of electrodynamic tether control to the removal of space debris. Other applications include aerial refuelling systems, aerial cable-towed instruments, and underwater cable-towed systems. Additionally I am engaged in developing autonomous space robotics for on-orbit servicing. In support of many of these endeavours, I also study multi-functional composite materials and additive manufacturing in space.