Paul Estrada
Paul Estrada

Astronomy and Astrophysics Research Thrust Chair

Degree/Major: Ph.D., Planetary Science, 2002, Cornell University

Curriculum vitae: Estrada_CV.pdf

Paul.R.Estrada@nasa.gov
Biography

If planets are a dime a dozen, moons are less than a penny each. There are at least 139 moons in our solar system, and most of these are the property of the gas giant planets beyond Mars. More than just a nice accompaniment to planets, moons may frequently have habitats in which liquid water could ebb and flow – and possibly be home to life. Planetary scientist Paul Estrada investigates how moons around gas giants are formed, an important question since its answer would give us insight into the nature of moons around the myriad gas giant planets we know orbit other stars.

The birth of moons around gas giant planets is superficially similar to planetary formation; however, as Estrada points out, there are some very important differences. To begin with, the “environment” (pressure, density, temperature) of satellite birth is different from that of the planets. Perhaps most important, satellite systems are more compact, which means things tend to happen much faster than on the planetary scale. Consider that the giant planet Jupiter takes a dozen years to orbit the Sun, a lumbering pace compared to the days required for its moons to orbit once. As a result, once a moon forms, it has much less time to find a way to “survive.” This is because, just like the planets, there is the problem that the leftover gas which eventually dissipates over time (a time much longer than required to form the moons or planets) will slow down a newly forming satellite, causing it to spiral into its host planet. Clearly, this doesn’t always happen, and Estrada’s research elucidates exactly how such a catastrophic fate can be avoided. The incentive to understand satellite formation is strong, as these small worlds might be the most plentiful locations for life in the universe.

Links
Publications

Estrada, P. R., & Cuzzi, J. N., 2015. Global Evolution of Solids in the Nebula: the Role of Porosity in Particle Growth and Radial Migration. Presented at the 47th DPS Meeting, 2015, November 8-13, National Harbor, MD.

Estrada, P. R., Cuzzi, J. N., & Morgan, D. A., 2015. Global Modeling of Nebulae with Particle Growth, Drift and Evaporation Fronts. I: Methodology and Typical Results. Submitted to ApJ.  eprint arXiv:1506.01420.

Estrada, P. R., Durisen, R. H., Cuzzi, J. N., & Morgan, D. A., 2015. Combined structural and compositional evolution of planetary rings due to micrometeoroid impacts and ballistic transport. Icarus 252, 415-439.

Estrada, P. R., & Durisen, R. H., 2014. Evolution of structure and composition in Saturn’s rings due to ballistic transport of micrometeoroid impact ejecta. Presented (invited) at the EPSC Meeting, 2014, September 7-12, Estoril, Cascais, Portugal.

Estrada, P. R., & Cuzzi, J. N., 2014. The influence of evaporation fronts on the global evolution of solids and gas in the protoplanetary nebula. 45th LPSC Meeting, March 17-21 at The Woodlands, TX. No. 1777.

Cuzzi, J. N., Estrada, P. R., & Davis, S. S., 2014. Utilitarian opacity model for aggregate particles in protoplanetary nebulae and exoplanet atmospheres. Astrophys. J. Supp. 210, article id. 21, 18 pp.

Estrada, P. R., Durisen, R. H., & Cuzzi, J. N., 2013. The effects of micrometeoroid bombardment and ballistic transport on the C ring’s structure. 45th DPS Meeting, October 6-11, Denver, CO. #210.15.

Estrada, P. R., 2011. On the origins of satellites around gas giant planets. Presented (invited) at the 46th ESLAB Meeting, “Formation and Evolution of Moons”, June 25-28, Noordwijk, The Netherlands.

Mosqueira, I., & Estrada, P. R., 2011. On the origins of the Saturnian moon-ring system. 42nd LPSC Meeting, March 7-11, at The Woodlands, TX. No. 1609.

Estrada, P. R., & Mosqueira, I., 2011. Titan’s accretion and long term thermal history. 42nd LPSC Meeting, March 7-11, at The Woodlands, TX. No. 1608.

Mosqueira, I., & Estrada, P. R., 2010. Is Titan like Ganymede or like Callisto? 42nd DPS Meeting, October 3-8, Pasadena, CA. #61.07.

Estrada, P. R., & Mosqueira, I., 2010. Titan’s cold accretion and its internal structure. 42nd DPS Meeting, October 3-8, Pasadena, CA. #61.06.

Mosqueira, I., Estrada, P. R., & Turrini, D., 2010. Planetesimals and satellitesimals: Formation of the satellite systems. Spa. Sci. Rev. 153, 431-446.

Mosqueira, I. Estrada, P. R., & Charnoz, S., 2010. Deciphering the origin of the regular satellites of gaseous giants – Iapetus: The Rosetta ice-moon. Icarus 207, 448-460.

Estrada, P. R., & Durisen, R. H., 2010. An improved model for the modeling the coupled structural and compositional evolution of Saturn’s rings due to meteoroid bombardment. 41st LPSC Meeting, March 1-5, at The Woodlands, TX. No. 1533.

Estrada, P. R., Mosqueira, I., & Charnoz, S., 2009. The Ganymede, Titan, Callisto, Iapetus trend: interpretation of Iapetus’ composition. Presented at the Fall AGU Meeting 2009, San Francisco, CA. #P51C-1148.

Mosqueira, I., & Estrada, P. R., 2009. The Ganymede, Titan, Callisto, Iapetus trend: interpretation of Titan’s moment of inertia. Presented at the Fall AGU Meeting, 2009, San Francisco, CA. #P43F-08.

Estrada, P. R., & Cuzzi, J. N., 2009. A faster model for coagulative growth in nebular and subnebular environments. 40th LPSC Meeting, March 23-27, at The Woodlands, TX. No. 1241.

Charnoz, S., Dones, L., Esposito, L. W., Estrada, P. R., & Hedman, M. M., 2009. Origin and evolution of Saturn’s ring system. In Saturn from Cassini/Huygens (Dougherty, M. K., Esposito, L. W., Krimigis, S. M., eds.), Springer Science + Business Media B. V., pp. 537-575.

Johnson, T. V. & Estrada, P. R., 2009. Origin of the Saturn system. In. Saturn from Cassini/Huygens (Dougherty, M. K., Esposito, L. W., Krimigis, S. M., eds.), Springer Science + Business Media B. V., pp. 55-74.

Estrada, P. R., Mosqueira, I., Lissauer, J. J., D’Angelo, G., & Cruikshank, D. P., 2009. Formation of Jupiter and conditions for accretion of the Galilean satellites. In Europa (Pappalardo, R. T., McKinnon, W. B., Khurana, K. K., eds.) University of Arizona Press, Tucson, pp. 27-58.

Mosqueira, I., & Estrada, P. R., 2008. Origin of the regular satellites of Jupiter and Saturn. Mass and composition constraints. Presented at the Fall AGU Meeting 2008, San Francisco, CA. #P21B-03.

Estrada, P. R., & Cuzzi, J. N., 2008. Solving the coagulation equation by the moments method. Astrophys. J. 682, 515-526.

Estrada, P. R., & Mosqueira, I., 2006. A gas-poor planetesimal capture model for the formation of giant planet satellite systems. Icarus 181, 486-509.

Mosqueira, I., & Estrada, P. R., 2006. Jupiter’s obliquity and a long-lived circumplanetary disk. Icarus 180, 93-97.

Estrada, P. R., & Mosqueira, I., 2005. A gas-poor planetesimal feeding model for the formation of giant planet satellite systems: consequences for the atmosphere of Titan. 36th LPSC Meeting, March 14-18, in League City, TX. No. 2053.

Mosqueira, I., & Estrada, P. R., 2005. On the origin of the saturnian satellite system: did Iapetus form in-situ? 36th LPSC Meeting, March 14-18, in League City, TX. No. 1951.

Mosqueira, I., & Estrada, P. R., 2004. Phoebe and the icy Saturnian satellites: implications for satellite origins. Presented at the Fall AGU Meeting 2004, San Francisco, CA. #P43B-06.

Estrada, P. R., & Mosqueira, I., 2004. A gas-poor planetesimal feeding model for the formation of giant planet satellite systems: prediction for the composition of Iapetus. Presented at the Fall AGU Meeting 2004, San Francisco, CA. #P43B-04.

Estrada, P. R., & Mosqueira, I., 2004. A gas-poor planetesimal feeding model for the formation of giant planet satellite systems: constraints on the planetesimal size distribution. 36th DPS Meeting, November 8-12, Louisville, KY. #44.01.

Mosqueira, I., & Estrada, P. R., 2004. Phoebe and icy Saturnian satellites: implications for satellite origins. 36th DPS Meeting, November 8-12, Louisville, KY. #40.13.

Estrada, P. R., & Mosqueira, I., 2004. On the final mass of giant planets. 35th LPSC Meeting, March 15-19, in League City, TX. No. 1854.

Mosqueira, I., & Estrada, P. R., 2004. When push comes to shove: gap-opening, disk clearing and the in-situ formation of giant planets. 35th LPSC Meeting, March 15-19, in League City, TX. No. 1432.

Estrada, P. R., Cuzzi, J. N., and Showalter, M. R., 2003. Voyager color photometry of Saturn’s main rings: a correction. Icarus 166, 212-222.

Mosqueira, I., & Estrada, P. R., 2003. Are giant planet satellites mini-solar systems? Presented at the Fall AGU Meeting 2003, San Francisco, CA. #P51F-05.

Estrada, P. R., & Mosqueira, I., 2003. Time and length scales for planetary and satellite gas disk clearing. Presented at the Fall AGU Meeting 2003, San Francisco, CA. #P51F-01.

Mosqueira, I., & Estrada, P. R., 2003b. Formation of the regular satellites of giant planets in an extended gaseous nebula II: satellite migration and survival. Icarus 163, 232-255.

Mosqueira, I., & Estrada, P. R., 2003a. Formation of the regular satellites of giant planets in an extended gaseous nebula I:  subnebula model and accretion of satellites. Icarus 163, 198-231.

Estrada, P. R., & Mosqueira, I., 2003. Planetary growth: from the gap-opening mass to the final mass of the planet. 34th DDA Meeting, Ithaca, NY. #12.02.

Mosqueira, I., & Estrada, P. R., 2003. Constraints on the size of the circumplanetary gas disk. 34th DDA Meeting, Ithaca, NY. #11.02.

Estrada, P. R., & Mosqueira, I., 2003. A gas-poor planetesimal feeding model for the formation of giant planet satellite systems: disk size and formation timescale. 35thDPS Meeting, September 1-6, Monterey, CA. #25.09.

Mosqueira, I., & Estrada, P. R., 2003. Planetesimal break-up and the feeding of solids to the satellite disk: consequences for the formation timescale and composition of the satellites of Jupiter and Saturn. 34th LPSC Meeting, March 17-21, in League City, TX. No. 1832.

Estrada, P. R., & Mosqueira, I., 2003. Gap-opening, disk clearing, and the survival of the regular satellites of Jupiter and Saturn. 34th LPSC Meeting, March 17-21, in League City, TX. No. 1820.

Mosquiera, I., & Estrada, P. R., 2002. Apse alignment of the Uranian rings. Icarus 158, 545-556.

Mosqueira, I., & Estrada, P. R., 2002. Formation of the regular satellites in a two-component, extended gaseous subnebula: predictions for the Cassini mission. Presented at the Fall AGU Meeting 2002, San Francisco, CA. #P72B-0495.

Estrada, P. R., & Mosqueira, I., 2002. Gap-opening and the survival and composition of the Galilean satellites. Presented at the Fall AGU Meeting 2002, San Francisco, CA. #P12C-05.

Estrada, P. R., & Mosqueira, I., 2002. Gap opening as a probe of circumsolar and circumplanetary gas disk properties. 34th DPS Meeting, October, Birmingham, AL. #28.11.

Mosqueira, I., & Estrada, P. R., 2001. Satellite migration and the evolution of the gas disk. 33rd DPS Meeting, November, New Orleans, LA. #25.03.

Estrada, P. R., & Mosqueira, I., 2001. Satellite torques in a two-component giant planet subnebula. 33rd DPS Meeting, November, New Orleans, LA. #25.02.

Mosqueira, I., Estrada, P. R., Cuzzi, J. N., & Squyres, S. W., 2001. Circumjovian disk clearing after gap-opening and the formation of a partially differentiated Callisto. 32nd LPSC Meeting, March 12-16, Houston, TX. No. 1989.

Mosqueira, I., Estrada, P. R., & Chambers, J. E., 2000. Satellitesimal feeding and the formation of regular satellites. 32nd DPS Meeting, October, Pasadena, CA. #53.13.

Cuzzi, J. N., French, R. G., Dones, L., Estrada, P. R., & Showalter, M. R., 2000. Multicolor photometry os Saturn’s main rings from HST and Voyager: color variations with phase and opening angle, location and optical depth. 32nd DPS Meeting, October, Pasadena, CA. #48.05.

Mosqueira, I., & Estrada, P. R., 2000. New dynamical mass estimate of the Uranian alpha ring. 31st DDA Meeting, April 9-12, Yosemite Valley, CA. #08.06.

Estrada, P. R., & Squyres, S. W., 1999. Freezing of a liquid H20 layer on Europa. News Letter of the Astronomical Society of New York, 5, p. 28.

Mosqueira, I., Estrada, P. R., & Brookshaw, L., 1999. Hydrodynamical simulations of narrow planetary rings. I. Scaling. Icarus 139, 260-285.

Cuzzi, J. N., & Estrada, P. R., 1998. Compositional evolution of Saturn’s rings due to meteoroid bombardment. Icarus 132, 1-35.

Estrada, P. R., & Cuzzi, J. N., 1996. Voyager observations of the color of Saturn’s rings. Icarus 122, 251-272. Erratum, Icarus 125, 474.

Mosqueira, I., Estrada, P. R., & Brookshaw, L., 1996. Hydrodynamical simulations of the Uranian rings. 28th DPS Meeting, October, Tucson, AZ. #18.14.

Cuzzi, J. N., & Estrada, P. R., 1996. Compositional evolution of Saturn’s rings: ice, tholin and “Chiron” –dust. 28th DPS Meeting, October, Tucson, AZ. #18.06.

Cuzzi, J. N., Estrada, P. R., and Bode, P., 1992. Color, composition, and age at the B-C boundary. 24th DPS Meeting,  October, Munich, Germany. #44.07.

Cuzzi, J. N., Estrada, P. R., & Bode, P., 1991. Color variation and material transport in Saturn’s rings. 23rd DPS Meeting, November, Palo Alto, CA. BAAS 23, p. 1180.