Planetary Exploration

The robotic and human exploration of our Solar System has been facilitated by the detailed characterization of planetary surfaces. For example, ground-based radar observations have significantly helped in potential landing site selection, as well as the search for subsurface ice reservoirs. Understanding and interpreting the data we obtain from ground-, space-based, and in situ observations necessitates statistical techniques. In my research, I work to enhance the output from ground-based observatories and NASA missions by using modern data science methods. I have particularly investigated volatile transport, stability, and characterization to improve the identification of in situ resources, as well as new techniques to inform selection of mission instrumentation, and strategies to improve mission science operations.

Here I list active and past funded projects related to the applied planetary science of planetary exploration.

Arecibo Observatory Planetary Radar Program

Project Summary

Period of Performance: 07/2019 – 03/2023
Funder: NASA Solar System Observations Program
Role: Institutional PI
Summary: The 305-meter William E. Gordon telescope at the Arecibo Observatory has studied the Solar System for over 50 years, and its S-band (2380 MHz, 12.6 cm) planetary radar system is arguably the world’s most powerful instrument for post-discovery orbital refinement and physical characterization of near-Earth objects. In addition to monitoring asteroids and comets, Arecibo has mapped the geologic surface of Venus, discovered the anomalous reflection properties of icy surfaces at radio wavelengths (e.g., the Galilean satellites), suggested ice deposits at the poles of Mercury and hydrocarbon lakes on Titan, and provided multi-polarization imagery of the Moon and terrestrial planets.
One of my projects involves using machine learning algorithms to improve the identification of buried ice through ground-based radar observations. By studying the prominent icy polar deposits on Mercury we can refine the diagnostic tools we use to find ice elsewhere, such as on the Moon, where it can be used by astronauts as an in-situ resource.

Peer-Reviewed Manuscripts

  1. Rivera-Valentín, E. G., Meyer, H. M, Taylor, P. A., Mazarico, E., Bhiravarasu, S. S., Virkki, A. K., Nolan, M. C., Chabot, N. L., Giorgini, J. D., 2022. Arecibo S-band radar characterization of local-scale heterogeneities within Mercury’s North Polar deposits. Planetary Science Journal, accepted.
  2. Nypaver, C. A., Thomson, B. J., Fassett, C. I., Rivera-Valentín, E. G., Patterson, G. W., 2021. Prolonged rock exhumation at the rims of kilometer-scale lunar craters. JGR Planets, doi:10.1029/2021JE006897.

Selected Conference Abstracts

  1. Meyer, H., Rivera-Valentín, E. G., Chabot, N., 2021. A multiwavelength study of Mercury’s polar anomalies: New data from Arecibo informed by MESSENGER. LPSC LII, Abstract #1508.
  2. Nypaver, C. A., Thomson, B. J., Rivera-Valentín, E. G., Fassett, C. I., Neish, C. D., Patterson, G. W., Virkki, A. K., Taylor, P. A., 2021. Prolonged boulder exhumation at the rims of kilometer-scale craters on the lunar maria. LPSC LII, Abstract #2324.
  3. Rivera-Valentín, E. G., Meyer, H. M., Taylor, P. A., Bhiravarasu, S. S., Nolan, M. C., Chabot, N. L., Virkki, A. K., 2021. Arecibo S-band radar characterization of the Mercurian north polar deposits. LPSC LII, Abstract #2104.
  4. Rivera-Valentín, E. G., Bhiravarasu, S. S., Meyer, H. M., Rodriguez Sanchez- Vahamonde, C., Taylor, P., Nolan, M., Chabot, N., Virkki, A., 2020. High-resolution radar images of Mercury from the 2019 and 2020 inferior conjunctions. 52nd DPS, Abstract #302.06.
  5. Rivera-Valentín, E. G., Bhiravarasu, S. S., Meyer, H. M., Taylor, P. A., Nolan, M. C., Chabot, N. L., Virkki, A. K., 2020. High-resolution radar images of Mercury from the 2019 inferior conjunction. LPSC LI, Abstract #1593.
  6. Rodriguez Sanchez-Vahamonde, C., Neish, C., Rivera-Valentín, E. G., Taylor, P. Nolan, M., 2020. Constraints on the surface roughness properties of Martian lava flows from planetary radar observations and HiRISE imagery. 52nd DPS, Abstract #311.08.
  7. Bhiravarasu, S. S., Rivera-Valentín, E. G., Taylor, P. A., Patterson, G. W., Neish, C. D., Thomson, B. J., 2019. Radar circular polarization ratio characteristics of lunar terrain as a function of viewing geometry. LPSC L, Abstract #2742.
  8. Bhiravarasu, S. S., Taylor, P. A., Rivera-Valentín, E. G., Virkki, A. K., Patter- son, G. W., Cahill, J. T. S., Nolan, M. C., 2018. Bistatic radar observations of a sample of lunar pyroclastic deposits. LPSC XLIX, Abstract #2496.

Saturn’s recent crater flux as constrained by Cassini VIMS

Project Summary

Period of Performance: 02/2017 – 08/2022
Funder: NASA Cassini Data Analysis Program
Summary: The proposed goal of this grant was to place new constraints on the recent crater flux incident on the mid-sized moons of Saturn by providing crater formation age estimates. The proposed objectives were to: (1) determine the formation age of young craters, (2) resolve the recent crater flux, and (3) constrain the recent geologic activity of the mid-sized moons of Saturn, in particular Dione.

Our work showed that water ice crystallinity is associated with the morphology of several craters on Dione and Rhea. Given the Cassini measured ion bombardment rate, the amount of amorphous water ice associated with such craters can be used to estimate their formation / exposure age. We found that the crystallinity-based age of such craters correlates well with their superposed crater density. As such, water ice crystallinity can be used as a chronometer for craters on icy moons.

Our analysis of the wispy terrain and craters on Dione showed three major results. First, Dione hosts craters with exposure ages as young as 274 Ma ± 83 Ma and as old as 1.4 Ga ± 0.45 Ga. These measurements meet our proposed objective 1. We note that the oldest crater exposure age suggests Dione is at least 1 Ga; therefore, we find evidence to suggest that models requiring a younger formation for the Saturnian moons are inconsistent with inferred crater crystallinity ages. Second, we were able to develop a crater flux model using the crystallinity ages and superposed crater densities. We found
that the crater flux of small projectiles is consistent with a population primarily derived from planetocentric objects. This helps to answer our Objective 2. Finally, we found that Dione was likely recently geologically active. Dione hosts faults with exposed nearly pure crystalline water ice. This suggests that Dione has had active faults within the past ~100 Ma, which helps to answer our objective 3.

Our work resulted in 2 peer-reviewed publications, 1 in-prep manuscript, 9 conference abstracts, support for 4 summer student projects, and support for 1 postbaccalaureate research assistant.

Meet the Team!

Principal Investigator: Edgard G. Rivera-Valentín, Lunar and Planetary Institute

Co-Investigator: Cristina Dalle Ore, SETI Institute

Co-Investigator: Michelle Kirchoff, Southwest Research Institute

Manuscripts

  1. Aponte Hernández, B., Rivera-Valentín, E. G., Kirchoff, M. R., Schenk, P. M., 2021. Morphometric study of craters on Saturn’s moon Rhea. Planetary Science Journal, doi: 10.3847/PSJ/ac32d4.
  2. Dalle Ore, C. M., Long, C. J., Nichols-Fleming, F., Scipioni, F., Rivera-Valentín, E. G., López Oquendo, A. J., Cruikshank, D. P., 2021. Dione’s Wispy Terrain: A cryovolcanic story?, Planetary Science Journal 2:83, doi: 10.3847/PSJ/abe7ec.

Conference Presentations

  1. Rivera-Valentín, E. G., López Oquendo, A. J., Kirchoff, M. R., Dalle Ore, C. M., Scipioni, F., 2020. Constraints on the recent cratering rate in the Saturn System from water ice crystallinity derived crater formation ages. LPSC 51, Abstract #2839.
  2. Aponte Hernandez, B., Rivera-Valentín, E. G., Schenk, P. M., Kirchoff, M. R., 2019. Crater formation and modification on Rhea from topography. LPSC L, Abstract #3052.
  3. Kirchoff, M. R., Aponte Hernandez, B., Rivera-Valentín, E. G., Schenk, P. M., 2019. Post-impact Processes on Rhea: Analysis of Crater Modification from Topographic Data. Joint Meeting of the DPS and EPSC, Abstract #313-5.
  4. López Oquendo, A., Rivera-Valentín, E. G., Dalle Ore, C. M., Kirchoff, M. R., Nichols- Fleming, F., Long, C. J., Scipioni, F., 2019. Constraints on crater formation ages on Dione from Cassini VIMS and ISS. LPSC L, Abstract #2435.
  5. Kirchoff, M. R., Dalle ore, C. M., Rivera-Valentín, E. G., 2018. Constraints on the recent saturnian crater flux from Cassini VIMS and ISS: Crater ages on Rhea. The Final Cassini Science Symposium.
  6. Rivera-Valentín, E. G., Kirchoff, M. R., Dalle Ore, C. M., 2018. Constraints on the impactor source for the Saturnian system from two independent tests. AAS/DPS 50th, Abstract #407.10.
  7. Rivera-Valentín, E. G., Kirchoff, M. R., Dalle Ore, C. M., Rodriguez Sanchez-Vahamonde, C., 2018. Constraints on crater ages on Rhea from Cassini VIMS and ISS: Insights to the recent crater flux. LPSC XLIX, Abstract #2812.
  8. Rivera-Valentín, E. G., Leight, C., Barr, A. C., Kirchoff, M. R., 2017. On the late formation of the mid-sized moons of Saturn: Insights from Iapetus, Rhea, and Dione. LPSC XLVIII, Abstract #1534.
  9. Rodriguez Sanchez-Vahamonde, C. M., Rivera-Valentín, E. G., Kirchoff, M., 2017. Crater densities within young, large craters on Rhea and Dione: Towards understanding the recent Saturnian bombardment. DPS #214.17.