Debra Hurwitz Needham

• PhD
• Research Associate at Marshall Space Flight Center

Understanding the origin and evolution of the lunar volatile system is not only compelling lunar science, but also fundamental Solar System science. This white paper (submitted to the US National Academies' Decadal Survey in Planetary Science and Astrobiology 2023-2032) summarizes recent advances in our understanding of lunar volatiles, identifies...

Studies of the lunar atmosphere have shown it to be a stable, low-density surface boundary exosphere for the last 3 billion years. However, substantial volcanic activity on the Moon prior to 3 Ga may have released sufficient volatiles to form a transient, more prominent atmosphere. Here, we calculate the volume of mare basalt emplaced as a function...

The International Space Exploration Coordination Group (ISECG) developed an integrated Global Exploration Roadmap (GER) that outlines plans for human-assisted sample return from the lunar surface in ∼2024 and for human presence on the lunar surface in ∼2028. Previous studies have identified the Schrödinger basin, situated on the far side of the Moo...

The origin of the boulders sampled during the Apollo 17 mission to the Taurus–Littrow Valley has been debated since the completion of the mission four decades ago. No consensus has yet been reached whether the sampled boulders originated in material emplaced as a result of the Serenitatis impact (i.e., massifs), the Imbrium impact (i.e., Sculptured...

Understanding how shallow reservoirs store and redirect magma is critical for deciphering the relationship between surface and subsurface volcanic activity on the terrestrial planets. Complementing field, laboratory and remote sensing analyses, elastic models provide key insights into the mechanics of magma reservoir inflation and rupture, and henc...

Determining the age of the South Pole-Aitken (SPA) basin ranks among the highest priorities in lunar science. This datum would constrain the timing of the oldest and largest basin-forming event on the Moon, information that is essential to any evaluation of the collisional evolution of the early Solar System. To locate material that preserves the a...

We modeled the differentiation of SPA impact melt to determine whether noritic lithologies observed within SPA formed as a result of the impact. Results indicate differentiation of SPA impact melt can produce noritic layers that may accommodate observed surface compositions but only in specific scenarios. One of nine modeled impact melt composition...

This paper identifies destinations where SPA impact melt samples can be collected. Analyses of these samples can identify the age of this oldest lunar basin.

Our field mapping demonstrates a need for caution when inferring planetary eruption conditions from morphology due to effects of local lava storage and release.

Impact melt sheets at lunar basins make a moderate positive contribution to the free-air gravity. At Orientale, the melt sheet is 5-10% of the observed anomaly.

We consider the science operations implications comparing “Apollo-style” site investigations with the same site investigated with conventional geologic mapping.

This abstract offers basic insights into how geologic maps created from different tactics can be reconciled in support of exploratory missions.

In a recent survey of Sudbury shatter cones, we identified an outcrop of stacked, curvilinear foliations with well-developed, nested shatter cones that trend toward the apex of the foliations. We interpret this structure as a composite cone.

contrast to other terrestrial planets, Mercury does not possess a great variety of volcanic features, its history of volcanism instead largely manifest by expansive smooth plains. However, a set of landforms at high northern latitudes on Mercury resembles surface flow features documented on Earth, the Moon, Mars, and Venus. The most striking of suc...

Lunar sinuous rilles (SRs) are enigmatic features interpreted to have formed as the result of lava erosion into the lunar surface. While specific SRs have been studied in detail over the past few decades, the most recent general survey of these features was conducted in 1969 using Lunar Orbiter IV and V photographs. The current global study updates...

Volcanic plains identified on Mercury are morphologically similar to lunar mare plains but lack constructional and erosional features that are prevalent on other terrestrial planetary bodies. We analyzed images acquired by the MESSENGER spacecraft to identify features on Mercury that may have formed by lava erosion. We used analytical models to est...

The differentiation of the lunar SPA basin impact melt sheet is modeled to determine if it is consistent with noritic and gabbroic lithologies observed within SPA.

Lunar sinuous rilles have long been interpreted as features that formed as the result of surficial lava flow, though the precise mechanism responsible for channel formation (constructed versus eroded origins) is still debated. In assessing the origin of Rima Prinz, a channel interpreted to have formed by erosion, two erosion regimes, mechanical and...

Features consistent with channelized lava flow and erosion have been identified in images collected by MESSENGER. Analytical models are used to estimate potential erosion rates and eruption durations required to form these observed channels.

Analytical models estimate the fluid volumes, effusion rates, and erosion rates required to erode Athabasca Valles by water and by lava. Results are put in context with geomorphologic observations to assess the potential for each origin hypothesis.

MESSENGER data are interpreted to mean that the small vertical extent of Mercury’s mantle may inhibit convection and favor sublithospheric magma buildup and extensional lithospheric stresses on regional scales in the planet’s early history.

The formation of large impact basins played a critical role in the early evolution of the surfaces of Mercury and the Moon. New data from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) and Lunar Reconnaissance Orbiter (LRO) missions have enabled a re-evaluation of the sequence and chronology of large impact basin form...

Since the confirmation of widespread volcanism on Mercury by MESSENGER spacecraft observations, a key objective has been to understand how volcanic deposits were emplaced, what volume of lava was erupted, and over what timescale volcanism occurred in a given area. Many of Mercury's smooth plains, including a broad expanse of such plains at high nor...

Volcanism has been conclusively identified on the surface of Mercury from images and color data collected by the Mercury Dual Imaging System (MDIS) instrument aboard the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. Most of the volcanic deposits on Mercury are similar in morphology to lunar mare flood basalt...

The MESSENGER spacecraft began orbital observations of Mercury in March 2011. The Mercury Dual Imaging System is acquiring global monochrome and multispectral image maps. Complementing the global maps are special targeted observations with resolutions as good as 10 m/pixel for monochrome and 80 m/pixel for multispectral images. These high-resolutio...

Following the Mariner 10 flybys in 1974-75, the presence and importance of volcanism on Mercury was extensively debated. Uncertainty persisted until the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) flybys in 2008-2009 confirmed that volcanism had been widespread. Questions that remain after those flybys include the glob...

MESSENGER observations from Mercury orbit reveal that a large contiguous expanse of smooth plains covers much of Mercury’s high northern latitudes and occupies more than 6% of the planet’s surface area. These plains are smooth, embay other landforms, are distinct in color, show several flow features, and partially or completely bury impact craters,...

High-resolution images of Mercury's surface from orbit reveal that many bright deposits within impact craters exhibit fresh-appearing, irregular, shallow, rimless depressions. The depressions, or hollows, range from tens of meters to a few kilometers across, and many have high-reflectance interiors and halos. The host rocks, which are associated wi...

The Ganiki Planitia (V–14) quadrangle on Venus, which extends from 25° N. to 50° N. and from 180° E. to 210° E., derives its name from the extensive suite of plains that dominates the geology of the northern part of the region. With a surface area of nearly 6.5 x 106 km2 (roughly two-thirds that of the United States), the quadrangle is located nort...

Analytical models are used to determine relative roles of mechanical and thermal erosion in the formation of lunar sinuous rilles. Variations in surface slope, temperature, and material properties are explored to simulate the formation of Rima Prinz.

The Ganiki Planitia quadrangle (25-50degN, 180-210degE) is located north of Atla Regio, south of Vinmara Planitia, and southeast of Atalanta Planitia. The region contains a diverse array of volcanic-, tectonic-and impact-derived features, and the objectives for the ongoing mapping effort are fivefold: 1) explore the formation and evolution of radia...

Sinuous rilles have been observed on Mars and the Moon as well as other terrestrial planets, and the erosion regime present during the formation of many of these features has been debated, with proposed origins including mechanical erosion and thermal erosion. This study investigates the dominant erosion regime present during the formation of a cla...

a b s t r a c t A lava channel identified on the wall of an Elysium Planitia impact crater is investigated to identify the dominant erosion mechanism, mechanical vs. thermal, acting during channel formation. Observations of channel morphology are used to supplement analytical models of lava channel formation in order to cal-culate the duration of c...

One of the most enigmatic features observed within the lunar maria are sinuous rilles, meandering channel-like features ranging from tens of meters to several kilometers in width and from a few to several hundreds of kilometers in length. Sinuous rilles generally form within maria, but they also originate in adjacent highlands and continue in the h...

We describe a channel observed in an Elysium Planitia impact crater and constrain the viscosity and velocity of the lava that formed the channel. We can thus explore whether thermal or mechanical erosion was responsible for channel formation.

Eruptions fed from subsurface reservoirs commonly construct volcanic edifices at the surface, and the growth of an edifice will in turn modify the subsurface stress state that dictates the conditions under which subsequent rupture of the inflating reservoir can occur. We re-examine this problem using axisymmetric finite element models of ellipsoida...

Images from MESSENGER's first flyby of Mercury have shown convincing evidence for surface volcanism. Here we report on evidence in the new data for several features that are characterized by fractures and graben — rare features on a planet dominated by contractional deformation — that may be linked to intrusive activity. These features include: (1)...

We present our progress in mapping the spatial and stratigraphic relationships of material units of Snegurochka Planitia (V1) and our initial interpretations of the tectonic and volcanic history of the region surrounding the north pole of Venus.

Introduction Geologic mapping of Snegurochka Planitia (V-1) reveals a complex stratigraphy of tectonic and volcanic features that can provide insight into the geologic history of Venus and Archean Earth [1,2] including 1) crustal thickening environments and processes, 2) the nature of diapirism, 3) the nature and origin of deformation belts, and 4)...

Axisymmetric finite element models of ellipsoidal magma reservoir failure beneath a volcanic edifice are employed to investigate whether elastic models are able to reproduce the observed stratigraphy of two volcanoes on Venus.

Axisymmetric finite element models of ellipsoidal magma reservoir failure within crust loaded by an edifice are used to challenge previously published characterizations of this fundamental volcanic situation.

The Ganiki Planitia quadrangle (25-50degN, 180-210degE) is located north of Atla Regio, south of Vinmara Planitia, and southeast of Atalanta Planitia. The region contains a diverse array of volcanic-, tectonic- and impact-derived features, and the objectives for the ongoing mapping effort are fivefold: 1) explore the formation and evolution of radi...

The Ganiki Planitia quadrangle, located between the Atla Regio highland to the south and the Atalanta Planitia lowland to the north, is deformed by many tectonic lineaments which have been mapped previously but have not yet been assessed in detail. As a result, neither the characteristics of these lineaments nor their relationship to material unit...

We present a geologic map and descriptions of features in the north polar region of Venus and discuss implications for a comparison between the geologic histories of Venus and Archean Earth.