Planetary Seminar

In our Solar System, there are numerous mean-motion resonances for the minor bodies and satellites, but there are no mean-motion resonances between the planets. The first mean-motion resonance in an extrasolar planetary system – the 2:1 resonance between two Jupiter-mass planets around the star GJ 876 – was discovered in 2001. Since then, an increasing number of pairs of planets in or near mean-motion resonances and resonant chains of three or more planets have been detected. I will discuss the dynamics of these systems and the constraints that they provide on the formation and dynamical evolution of planets. Topics will include high-order mean-motion resonances in the HD 202206 and nu Ophiuchi systems and the formation of resonant chains near the inner edge of protoplanetary disks.

 Venus, Earth’s twin, is not only the closest planet to us in the solar system, it the closest to Earth in mass, density and size and yet it evolved very differently than the Earth. Venus has an atmosphere that has 90 times the surface pressure as the Earth with a surface temperature of 460 C. Venus does not have a system of plate tectonics like the Earth which is one of the key reasons that Earth is a habitable planet. So how did two planets with roughly the same physical parameters evolve so differently? The NASA Magellan mission to Venus in the Early 1990’s used radar to image the planet’s surface through the optically opaque atmosphere at ~150 m resolution and showed that Venus has a young surface that had been volcanically resurfaced with the last 500 million years. As much a Magellan informed us about Venus it also left many key questions about Venus’s planetary evolution unanswered. Two missions to Venus, VERITAS by NASA, and EnVision by ESA in partnership with NASA, will return to Venus in the 2030’s with the goal of answering how these planet’s evolved so differently. The answer to this question will help inform how many Earth and Venus like planets are there in other solar systems. Radars play a key role on each mission and this talk will describe their role in these missions to Venus and how in combination with the other instruments hope to resolve one of the key mysteries in planetary science.  

Our knowledge of the satellite population in the solar system has grown rapidly in the past 100 years.
In the early 1900s almost every known moon was a regular satellite — the large, primordial bodies that formed with their parent planets.
The Voyager flybys fundamentally changed that picture by revealing numerous small inner satellites of the giant planets, bodies likely tied
to ring-system evolution and ongoing collisional processing near the planet. Beginning around 2000, wide-field CCD surveys (e.g. CFHT, Subaru) opened a third population regime: most new discoveries were irregular or outer satellites — dynamically distinct, highly inclined, often retrograde
objects whose origins are not native to the planet system but are best explained as captured heliocentric planetesimals from the early solar system. At JPL, we develop and maintain ephemerides for all known satellites. The orbital models range from simple precessing ellipses to full dynamical models that include tides, relativistic terms, satellite libration, and high order gravity field expansions. These models draw on data sets spanning more than a century of astrometric measurements, from early visual observations to modern spacecraft tracking. Ultimately, satellite ephemerides are not just navigation products needed to point a telescope or fly a spacecraft – they are scientific observables that encode the history and dynamics of entire planetary systems. Each orbit tells a story about its origin, its interactions, and its ongoing evolution.
We will review the current state of satellite ephemerides across the solar system and highlight some interesting dynamical puzzles.

High-resolution spectroscopy is essential for resolving fine spectral features that reveal important physical processes in planetary, astrophysical, and heliophysical environments. However, traditional high-R instruments are large, complex, and incompatible with compact or distributed space platforms. We present a new generation of Spatial Heterodyne Spectroscopy (SHS) systems that overcome these limitations through a fully integrated, all-reflective, and monolithic design. Optimized for the FUV/EUV regime (10–200 nm), our SHS architecture delivers resolving powers of R ~20,000–100,000 in a compact form factor (<2U volume, <10 kg), making it ideal for CubeSats, SmallSats, and deep-space missions. We highlight critical system-level innovations, including thermal, optomechanical, and detector interfacing, as well as a validated performance model that includes sensor and electronics noise, optomechancial alignment tolerance, calibration and operation stability. These developments establish SHS as a scalable, high-fidelity spectroscopic solution for the next generation of space science missions.

Astrophotonics is the application of versatile photonic technologies to channel, manipulate, and disperse guided light from one or more telescopes to achieve scientific objectives in astronomy in an efficient and cost-effective way. The photonic platform of guided light in fibers and waveguides has opened the doors to next-generation instrumentation for both ground- and space-based telescopes. Utilizing the photonic advantage is a promising approach to massively miniaturize the next generation of spectrographs for ground- and space-based telescopes. I will discuss some of our recent results from our efforts to design and fabricate high-throughput on-chip astrophotonic spectrographs. These devices are ideally suited for enabling exciting science cases, such as measuring exoplanet masses and characterizing exoplanet atmospheres. I will also discuss specific approaches to make this technology science-ready and qualified for the next generation of space missions and potentially, planetary missions.

Surface observations of Saturn’s moon Titan revealed features characterized as dissected, elevated plateaus with high valley density known as labyrinth terrains. Of this terrain class, a subtype referred to as radial labyrinth is described as dome-shaped uplifts with radial channel patterns. Uplift of these radial labyrinths has been explained as cryomagmatic intrusions at the brittle-ductile transition zone. Here we propose an alternative hypothesis, that crustal heterogeneities in Titan’s upper clathrate crust introduce density differentials due to ethane-methane substitution, as ethane-rich liquids percolate into methane clathrate, inducing solid state flow and generating domal topography. This mechanism is analogous to salt tectonics on Earth and has similarly been evoked for dome formation on the dwarf planet Ceres. We show that the elevation and width of the observed radial labyrinths is consistent with domal uplift driven by a hydraulic head within the uppermost portion of Titan’s crust, given a plausible set of elastic parameters for clathrate hydrates. Additionally, the insulating effect of clathrate, combined with partial mixing with water-ice, allows for sufficiently low viscosity for geologic flow: uplift of the domes could have occurred early in Titan’s history, a billion years ago, or could have uplifted within the last 100 Myr during a recent phase of orbital excitation.

In this talk I will share our recently published results on the detection of potential biosignatures within the Neretva Vallis ancient riverbed on Mars, and then extend outward to our efforts to characterize and explore worlds of the outer solar system that harbor contemporary liquid water oceans beneath lithospheres of ice. At least six ice-covered moons of the outer solar system present compelling evidence for subsurface oceans, and thus provide highly compelling targets in our search for life beyond Earth. I will focus on Jupiter’s moon Europa, and detail experiments conducted in my lab that help us better understand Europa’s ocean chemistry and surface morphology. If time permits, I will also provide an overview of missions that will explore these worlds in the coming decades, and describe how exploration of Earth’s ocean and cryosphere is helping to guide our understanding of the potential habitability of these alien oceans.

Martian meteorites provide key information about the geological history of Mars. However, our collection is biased by geologically young samples that are not representative of Mars’ exposed surface, which is dominated by ancient rocks. This generates gaps in our knowledge of Mars’ early evolution. Recently, we discovered that a Martian meteorite, Teghaza 001, is a gabbroic diorite with a crystallization age > 4.1 Ga. In this presentation, I will describe this unique sample, how it compares to other Martian meteorites and igneous rocks studied by rovers, what results imply to our understanding of early Mars differentiation.

In our Solar System, there are numerous mean-motion resonances for the minor bodies and satellites, but there are no mean-motion resonances between the planets. The first mean-motion resonance in an extrasolar planetary system – the 2:1 resonance between two Jupiter-mass planets around the star GJ 876 – was discovered in 2001. Since then, an increasing number of pairs of planets in or near mean-motion resonances and resonant chains of three or more planets have been detected. I will discuss the dynamics of these systems and the constraints that they provide on the formation and dynamical evolution of planets. Topics will include high-order mean-motion resonances in the HD 202206 and nu Ophiuchi systems and the formation of resonant chains near the inner edge of protoplanetary disks.