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2. 9 Impact History of the Moon

Author

Cohen, Barbara A., primary, Bogert, Carolyn H. van der, additional, Bottke, William F., additional, Curran, Natalie M., additional, Fassett, Caleb I., additional, Hiesinger, Harald, additional, Joy, Katherine H., additional, Mazrouei, Sara, additional, Nemchin, Alexander, additional, Neumann, Gregory A., additional, Norman, Marc V., additional, and Zellner, Nicolle E. B., additional

Published
2024
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4. What's Happening in Lab? Multi-Dimensional Assessment Tools to Track Student Experience through a Unit Operations Laboratory Sequence

Author

Chenette, Heather C. S., Neumann, Gregory T., and Anastasio, Daniel D.

Abstract

Unit operations laboratory courses culminate many topics from the curriculum and are often the first time students apply their knowledge in hands-on settings. However, many instructors do not directly assess key learning objectives, creating a disparity between desired and actual learning. Using multiple assessment tools, we analyzed student survey and test data throughout a unit operations laboratory sequence to reveal student attitudes and perceptions of their learning experience alongside their actual knowledge and abilities gained.

Published
2021
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7. ICESat/GLAS Altimetry Measurements: Received Signal Dynamic Range and Saturation Correction.

Author

Sun, Xiaoli, Abshire, James B, Borsa, Adrian A, Fricker, Helen A, Yi, Donghui, DiMarzio, John P, Paolo, Fernando S, Brunt, Kelly M, Harding, David J, and Neumann, Gregory A

Subjects
ice sheets, laser ranging, lidar, remote sensing, satellite laser altimetry, Ice sheets, Geological & Geomatics Engineering, Geophysics, Electrical and Electronic Engineering, Geomatic Engineering
Abstract

NASA's Ice, Cloud, and land Elevation Satellite (ICESat), which operated between 2003 and 2009, made the first satellite-based global lidar measurement of Earth's ice sheet elevations, sea-ice thickness and vegetation canopy structure. The primary instrument on ICESat was the Geoscience Laser Altimeter System (GLAS), which measured the distance from the spacecraft to Earth's surface via the roundtrip travel time of individual laser pulses. GLAS utilized pulsed lasers and a direct detection receiver consisting of a silicon avalanche photodiode (Si APD) and a waveform digitizer. Early in the mission, the peak power of the received signal from snow and ice surfaces was found to span a wider dynamic range than planned, often exceeding the linear dynamic range of the GLAS 1064-nm detector assembly. The resulting saturation of the receiver distorted the recorded signal and resulted in range biases as large as ~50 cm for ice and snow-covered surfaces. We developed a correction for this "saturation range bias" based on laboratory tests using a spare flight detector, and refined the correction by comparing GLAS elevation estimates to those derived from Global Positioning System (GPS) surveys over the calibration site at the salar de Uyuni, Bolivia. Applying the saturation correction largely eliminated the range bias due to receiver saturation for affected ICESat measurements over Uyuni and significantly reduced the discrepancies at orbit crossovers located on flat regions of the Antarctic ice sheet.

Published
2017

8. Evidence for surface water ice in the lunar polar regions using reflectance measurements from the Lunar Orbiter Laser Altimeter and temperature measurements from the Diviner Lunar Radiometer Experiment

Author

Fisher, Elizabeth A, Lucey, Paul G, Lemelin, Myriam, Greenhagen, Benjamin T, Siegler, Matthew A, Mazarico, Erwan, Aharonson, Oded, Williams, Jean-Pierre, Hayne, Paul O, Neumann, Gregory A, Paige, David A, Smith, David E, and Zuber, Maria T

Subjects
Space Sciences, Physical Sciences, Astronomical and Space Sciences, Geochemistry, Geophysics, Astronomy & Astrophysics, Astronomical sciences, Space sciences
Abstract

We find that the reflectance of the lunar surface within 5 ° of latitude of the South Pole increases rapidly with decreasing temperature, near ~110K, behavior consistent with the presence of surface water iceThe North polar region does not show this behavior, nor do South polar surfaces at latitudes more than 5° from the pole. This South pole reflectance anomaly persists when analysis is limited to surfaces with slopes less than 10° to eliminate false detection due to the brightening effect of mass wasting, and also when the very bright south polar crater Shackleton is excluded from the analysis. We also find that south polar regions of permanent shadow that have been reported to be generally brighter at 1064 nm do not show anomalous reflectance when their annual maximum surface temperatures are too high to preserve water ice. This distinction is not observed at the North Pole. The reflectance excursion on surfaces with maximum temperatures below 110K is superimposed on a general trend of increasing reflectance with decreasing maximum temperature that is present throughout the polar regions in the north and south; we attribute this trend to a temperature or illumination-dependent space weathering effect (e.g. Hemingway et al. 2015). We also find a sudden increase in reflectance with decreasing temperature superimposed on the general trend at 200K and possibly at 300K. This may indicate the presence of other volatiles such as sulfur or organics. We identified and mapped surfaces with reflectances so high as to be unlikely to be part of an ice-free population. In this south we find a similar distribution found by Hayne et al. 2015 based on UV properties. In the north a cluster of pixels near that pole may represent a limited frost exposure.

Published
2017

13. Locating the LCROSS Impact Craters

Author

Marshall, William, Shirley, Mark, Moratto, Zachary, Colaprete, Anthony, Neumann, Gregory, Smith, David, Hensley, Scott, Wilson, Barbara, Slade, Martin, Kennedy, Brian, Gurrola, Eric, and Harcke, Leif

Subjects
Physics - Space Physics, Physics - Geophysics
Abstract

The Lunar CRater Observations and Sensing Satellite (LCROSS) mission impacted a spent Centaur rocket stage into a permanently shadowed region near the lunar south pole. The Sheperding Spacecraft (SSC) separated \sim9 hours before impact and performed a small braking maneuver in order to observe the Centaur impact plume, looking for evidence of water and other volatiles, before impacting itself. This paper describes the registration of imagery of the LCROSS impact region from the mid- and near-infrared cameras onboard the SSC, as well as from the Goldstone radar. We compare the Centaur impact features, positively identified in the first two, and with a consistent feature in the third, which are interpreted as a 20 m diameter crater surrounded by a 160 m diameter ejecta region. The images are registered to Lunar Reconnaisance Orbiter (LRO) topographical data which allows determination of the impact location. This location is compared with the impact location derived from ground-based tracking and propagation of the spacecraft's trajectory and with locations derived from two hybrid imagery/trajectory methods. The four methods give a weighted average Centaur impact location of -84.6796\circ, -48.7093\circ, with a 1{\sigma} un- certainty of 115 m along latitude, and 44 m along longitude, just 146 m from the target impact site. Meanwhile, the trajectory-derived SSC impact location is -84.719\circ, -49.61\circ, with a 1{\sigma} uncertainty of 3 m along the Earth vector and 75 m orthogonal to that, 766 m from the target location and 2.803 km south-west of the Centaur impact. We also detail the Centaur impact angle and SSC instrument pointing errors. Six high-level LCROSS mission requirements are shown to be met by wide margins. We hope that these results facilitate further analyses of the LCROSS experiment data and follow-up observations of the impact region., Comment: Accepted for publication in Space Science Review. 24 pages, 9 figures

Published
2011
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15. Laser Ranging for Gravitational, Lunar, and Planetary Science

Author

Merkowitz, Stephen M., Dabney, Philip W., Livas, Jeffrey C., McGarry, Jan F., Neumann, Gregory A., and Zagwodzki, Thomas W.

Subjects
General Relativity and Quantum Cosmology
Abstract

More precise lunar and Martian ranging will enable unprecedented tests of Einstein's theory of General Relativity and well as lunar and planetary science. NASA is currently planning several missions to return to the Moon, and it is natural to consider if precision laser ranging instruments should be included. New advanced retroreflector arrays at carefully chosen landing sites would have an immediate positive impact on lunar and gravitational studies. Laser transponders are currently being developed that may offer an advantage over passive ranging, and could be adapted for use on Mars and other distant objects. Precision ranging capability can also be combined with optical communications for an extremely versatile instrument. In this paper we discuss the science that can be gained by improved lunar and Martian ranging along with several technologies that can be used for this purpose., Comment: 14 pages, 3 figures, To appear in the International Journal of Modern Physics D

Published
2007
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20. New Perspectives on Ancient Mars

Author

Solomon, Sean C., Aharonson, Oded, Aurnou, Jonathan M., Banerdt, W. Bruce, Carr, Michael H., Dombard, Andrew J., Frey, Herbert V., Golombek, Matthew P., Hauck, Steven A., Head, James W., Jakosky, Bruce M., Johnson, Catherine L., McGovern, Patrick J., Neumann, Gregory A., Phillips, Roger J., Smith, David E., and Zuber, Maria T.

Published
2005

22. Evidence for surface water ice in the lunar polar regions using reflectance measurements from the Lunar Orbiter Laser Altimeter and temperature measurements from the Diviner Lunar Radiometer Experiment

Author

Fisher, Elizabeth A., Lucey, Paul G., Lemelin, Myriam, Greenhagen, Benjamin T., Siegler, Matthew A., Mazarico, Erwan, Aharonson, Oded, Williams, Jean-Pierre, Hayne, Paul O., Neumann, Gregory A., Paige, David A., Smith, David E, and Zuber, Maria T.

Published
2017
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24. Summary of the results from the lunar orbiter laser altimeter after seven years in lunar orbit

Author

Smith, David E., Zuber, Maria T., Neumann, Gregory A., Mazarico, Erwan, Lemoine, Frank G., Head III, James W., Lucey, Paul G., Aharonson, Oded, Robinson, Mark S., Sun, Xiaoli, Torrence, Mark H., Barker, Michael K., Oberst, Juergen, Duxbury, Thomas C., Mao, Dandan, Barnouin, Olivier S., Jha, Kopal, Rowlands, David D., Goossens, Sander, Baker, David, Bauer, Sven, Gläser, Philipp, Lemelin, Myriam, Rosenburg, Margaret, Sori, Michael M., Whitten, Jennifer, and Mcclanahan, Timothy

Published
2017
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27. First two-way laser ranging to a lunar orbiter: infrared observations from the Grasse station to LRO’s retro-reflector array

Author

Mazarico, Erwan, Sun, Xiaoli, Torre, Jean-Marie, Courde, Clément, Chabé, Julien, Aimar, Mourad, Mariey, Hervé, Maurice, Nicolas, Barker, Michael K., Mao, Dandan, Cremons, Daniel R., Bouquillon, Sébastien, Carlucci, Teddy, Viswanathan, Vishnu, Lemoine, Frank G., Bourgoin, Adrien, Exertier, Pierre, Neumann, Gregory A., Zuber, Maria T., and Smith, David E.

Published
2020
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28. The Geophysics of Mercury: Current Status and Anticipated Insights from the MESSENGER Mission

Author

Zuber, Maria T, Aharonson, Oded, Aurnou, Jonathan M, Cheng, Andrew F, Hauck, Steven A, Heimpel, Moritz H, Neumann, Gregory A, Peale, Stanton J, Phillips, Roger J, Smith, David E, Solomon, Sean C, and Stanley, Sabine

Subjects
Clinical Research, Mercury, MESSENGER, core, rotational state, magnetic dynamos, thermal history, Astronomical and Space Sciences, Astronomy & Astrophysics
Abstract

Current geophysical knowledge of the planet Mercury is based upon observations from ground-based astronomy and flybys of the Mariner 10 spacecraft, along with theoretical and computational studies. Mercury has the highest uncompressed density of the terrestrial planets and by implication has a metallic core with a radius approximately 75% of the planetary radius. Mercury's spin rate is stably locked at 1.5 times the orbital mean motion. Capture into this state is the natural result of tidal evolution if this is the only dissipative process affecting the spin, but the capture probability is enhanced if Mercury's core were molten at the time of capture. The discovery of Mercury's magnetic field by Mariner 10 suggests the possibility that the core is partially molten to the present, a result that is surprising given the planet's size and a surface crater density indicative of early cessation of significant volcanic activity. A present-day liquid outer core within Mercury would require either a core sulfur content of at least several weight percent or an unusual history of heat loss from the planet's core and silicate fraction. A crustal remanent contribution to Mercury's observed magnetic field cannot be ruled out on the basis of current knowledge. Measurements from the MESSENGER orbiter, in combination with continued ground-based observations, hold the promise of setting on a firmer basis our understanding of the structure and evolution of Mercury's interior and the relationship of that evolution to the planet's geological history. © 2007 Springer Science+Business Media B.V.

Published
2007

33. The Global Topography of Mars and Implications for Surface Evolution

Author

Smith, David E., Zuber, Maria T., Solomon, Sean C., Phillips, Roger J., Head, James W., Garvin, James B., Banerdt, W. Bruce, Muhleman, Duane O., Pettengill, Gordon H., Neumann, Gregory A., Lemoine, Frank G., Abshire, James B., Aharonson, Oded, Brown, C. David, Hauck, Steven A., Ivanov, Anton B., McGovern, Patrick J., Zwally, H. Jay, and Duxbury, Thomas C.

Published
1999

34. The Roughness Properties of Small Ice-Bearing Craters at the South Pole of the Moon: Implications for Accessing Fresh Water Ice in Future Surface Operations

Author

Deutsch, Ariel N, Head, James W, and Neumann, Gregory A

Subjects
Lunar And Planetary Science And Exploration
Abstract

The lunar poles provide a fascinating thermal environment capable of cold-trapping water ice on geologic timescales [1]. While there have been many observations indicating the presence of water ice at the lunar surface [e.g., 2–4], it is still not clear when this ice was delivered to the Moon. The timing of volatile dep-osition provides important constraints on the origin of lunar ice because different delivery mechanisms have been active at different times throughout lunar history. We previously found that some small (<10 km) cra-ters at the south pole of the Moon have morphologies suggestive of relatively young ages, on the basis of crisp crater rims [5]. These craters are too small to date with robust cratering statistics [5], but the possibility of ice in young craters is intriguing because it suggests that there is some recent and perhaps ongoing mechanism that is delivering or redistributing water to polar cold traps. Therefore, understanding if these small, ice-bear-ing craters are indeed young is essential in understand-ing the age and source of volatiles on the Moon. Here we take a new approach to understand the ages of these small polar cold traps: analyzing the roughness properties of small ice-bearing craters. It is well under-stood that impact crater properties (e.g., morphology, rock abundance, and roughness) evolve with time due to a variety of geologic and space-weathering processes [6–11]. Topographic roughness is a measurement of the local deviation from the mean topography, providing a measurement of surface texture, and is a powerful tool for evaluating surface evolution over geologic time [e.g., 11–14]. In this study we analyze the roughness of southern lunar craters (40°S–90°S) from all geologic eras, and determine how the roughness of small (<10 km) ice-bearing craters compare. We discuss the implications of the ages of ice-bearing south polar craters, and potential strategies for accessing fresh ice on the Moon.

Published
2020

35. Observations of the North Polar Region of Mars from the Mars Orbiter Laser Altimeter

Author

Zuber, Maria T., Smith, David E., Solomon, Sean C., Abshire, James B., Afzal, Robert S., Aharonson, Oded, Fishbaugh, Kathryn, Ford, Peter G., Frey, Herbert V., Garvin, James B., Head, James W., Ivanov, Anton B., Johnson, Catherine L., Muhleman, Duane O., Neumann, Gregory A., Pettengill, Gordon H., Phillips, Roger J., Sun, Xiaoli, Zwally, H. Jay, Banerdt, W. Bruce, and Duxbury, Thomas C.

Published
1998

38. Gravity field of the Orientale basin from the Gravity Recovery and Interior Laboratory Mission

Author

Zuber, Maria T., Smith, David E., Neumann, Gregory A., Goossens, Sander, Andrews-Hanna, Jeffrey C., Head, James W., Kiefer, Walter S., Asmar, Sami W., Konopliv, Alexander S., Lemoine, Frank G., Matsuyama, Isamu, Melosh, H. Jay, McGovern, Patrick J., Nimmo, Francis, Phillips, Roger J., Solomon, Sean C., Taylor, G. Jeffrey, Watkins, Michael M., Wieczorek, Mark A., Williams, James G., Jansen, Johanna C., Johnson, Brandon C., Keane, James T., Mazarico, Erwan, Miljković, Katarina, Park, Ryan S., Soderblom, Jason M., and Yuan, Dah-Ning

Published
2016

39. Mercury’s Polar Deposits

Author

Chabot, Nancy L., primary, Lawrence, David J., additional, Neumann, Gregory A., additional, Feldman, William C., additional, and Paige, David A., additional

Published
2018
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40. The Contribution of Small Impact Craters to Lunar Polar Wander

Author

Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences, Smith, David E, Viswanathan, Vishnu, Mazarico, Erwan, Goossens, Sander, Head, James W, Neumann, Gregory A, Zuber, Maria T, Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences, Smith, David E, Viswanathan, Vishnu, Mazarico, Erwan, Goossens, Sander, Head, James W, Neumann, Gregory A, and Zuber, Maria T

Abstract

Abstract Changes in mass distribution affect the gravitational figure and reorient a planetary body’s surface with respect to its rotational axis. The mass anomalies in the present-day lunar gravity field can reveal how the figure and pole position have evolved over the Moon’s history. By examining sequentially each individual crater and basin, working backward in time order through the catalog of nearly 5200 craters and basins between 1200 and 20 km in diameter, we investigate their contribution to the lunar gravitational figure and reconstruct the evolution of the pole position by extracting their gravitational signatures from the present-day Moon. We find that craters and basins in this diameter range, which excludes South Pole–Aitken, have contributed to nearly 25% of the present-day power from the Moon’s degree-2 gravitational figure and resulted in a total displacement of the Moon’s pole by ∼10° along the Earth–Moon tidal axis over the past ∼4.25 billion years. This also implies that the geographical location of the Moon’s rotational pole has not moved since ∼3.8 Ga by more than ∼2° in latitude owing to impacts, and this has implications for the long-term stability of volatiles in the polar regions.

Published
2023

43. Analysis of Mercury Laser Altimeter Crossovers with Improved Mercury and MESSENGER Ephemerides

Author

Bertone, Stefano, Mazarico, Erwan, Barker, Michael K, Goossens, Sander, Genova, Antonio, and Neumann, Gregory

Subjects
Lunar And Planetary Science And Exploration
Abstract

Based on previous applications of laser altimetry to planetary geodesy at GSFC [Mazarico et al. (2014),(2016)] and taking advantage of new accurate Mercury and MESSENGER orbits by [Genova et al. (2019)], we analyze altimetric crossovers from the MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging) Laser Altimeter (MLA) to solve for orbital and geodetic parameters (e.g., rotation and orientation). We present our results based on a new Python software package recently developed at GSFC that can simulate and process altimetry data in a closed-loop. Realistic simulations of MLA data, including an appropriate range noise from the instrument and realistic terrain roughness, are performed in order to fully characterize the robustness of the solution. The simulation results are then applied to our analysis of the full dataset acquired by the MLA instrument.

Published
2019

45. Investigating Diurnal Changes in the Normal Albedo of the Lunar Surface at 1064 nm: A New Analysis with the Lunar Orbiter Laser Altimeter

Author

Deutsch, Ariel N, Neumann, Gregory A, Head, James W, and Lucey, Paul G

Subjects
Lunar And Planetary Science And Exploration
Abstract

The thermal environment of the lunar surface is extreme. At the equator, temperatures drop ~300 K between local noon and night. Laboratory studies demonstrate that minerals common to the lunar surface (e.g.,pyroxene, olivine) show spectral changes with respect to temperature in near infrared wavelengths. Over temperature changes equivalent to the lunar thermal environment (ΔT ≈ 300K), the reflectance of pure pyroxene samples can vary by a factor of two.

Published
2019

47. Terrestrial Snow

Author

Nghiem, Son V., Hall, Dorothy K., Foster, James L., Neumann, Gregory, and Njoku, Eni G., editor

Published
2014
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