Jet Propulsion Laboratory

About: Jet Propulsion Laboratory is a facility organization based out in La Cañada Flintridge, California, United States. It is known for research contribution in the topics: Mars Exploration Program & Telescope. The organization has 8801 authors who have published 14333 publications receiving 548163 citations. The organization is also known as: JPL & NASA JPL.

Mars Global Ionosphere‐Thermosphere Model: Solar cycle, seasonal, and diurnal variations of the Mars upper atmosphere

Abstract: A new Mars Global Ionosphere-Thermosphere Model (M-GITM) is presented that combines the terrestrial GITM framework with Mars fundamental physical parameters, ion-neutral chemistry, and key radiative processes in order to capture the basic observed features of the thermal, compositional, and dynamical structure of the Mars atmosphere from the ground to the exosphere (0–250 km). Lower, middle, and upper atmosphere processes are included, based in part upon formulations used in previous lower and upper atmosphere Mars GCMs. This enables the M-GITM code to be run for various seasonal, solar cycle, and dust conditions. M-GITM validation studies have focused upon simulations for a range of solar and seasonal conditions. Key upper atmosphere measurements are selected for comparison to corresponding M-GITM neutral temperatures and neutral-ion densities. In addition, simulated lower atmosphere temperatures are compared with observations in order to provide a first-order confirmation of a realistic lower atmosphere. M-GITM captures solar cycle and seasonal trends in the upper atmosphere that are consistent with observations, yielding significant periodic changes in the temperature structure, the species density distributions, and the large-scale global wind system. For instance, mid afternoon temperatures near ∼200 km are predicted to vary from ∼210 to 350 K (equinox) and ∼190 to 390 k (aphelion to perihelion) over the solar cycle. These simulations will serve as a benchmark against which to compare episodic variations (e.g., due to solar flares and dust storms) in future M-GITM studies. Additionally, M-GITM will be used to support MAVEN mission activities (2014–2016).

Application of Dynamical Systems Theory to Trajectory Design for a Libration Point Mission

Abstract: Recently, there has been accelerated interest in missions utilizing trajectories near libration points. The trajectory design issues involved in missions of such complexity go beyond the lack of preliminary baseline trajectories (since conic analysis fails in this region of the solution space). Successful and efficient design of mission options will require new persepectives; a more complete understanding of the solution space is imperative. In this investigation, dynamical systems theory is applied to better understand the geometry of the phase space in the three-body problem via stable and unstable manifolds. Then, the manifolds are used to generate various solution arcs and establish trajectory options that are then utilized in preliminary design for the proposed Suess-Urey mission.

Dawn Mission to Vesta and Ceres Symbiosis between Terrestrial Observations and Robotic Exploration

Abstract: The initial exploration of any planetary object requires a careful mission design guided by our knowledge of that object as gained by terrestrial observers. This process is very evident in the development of the Dawn mission to the minor planets 1 Ceres and 4 Vesta. This mission was designed to verify the basaltic nature of Vesta inferred both from its reflectance spectrum and from the composition of the howardite, eucrite and diogenite meteorites believed to have originated on Vesta. Hubble Space Telescope observations have determined Vesta’s size and shape, which, together with masses inferred from gravitational perturbations, have provided estimates of its density. These investigations have enabled the Dawn team to choose the appropriate instrumentation and to design its orbital operations at Vesta. Until recently Ceres has remained more of an enigma. Adaptive-optics and HST observations now have provided data from which we can begin to confidently plan the mission. These observations reveal a rotationally symmetric body with little surface relief, an ultraviolet bright point that can be used as a control point for determining the pole and anchoring a geographic coordinate system. They also reveal albedo and color variations that provide tantalizing hints of surface processes.

Comparative Metagenomics and Population Dynamics of the Gut Microbiota in Mother and Infant

Abstract: Colonization of the gastrointestinal tract (GIT) of human infants with a suitable microbial community is essential for numerous aspects of health, but the progression of events by which this microbiota becomes established is poorly understood Here, we investigate two previously unexplored areas of microbiota development in infants: the deployment of functional capabilities at the community level and the population genetics of its most abundant genera To assess the progression of the infant microbiota toward an adult-like state and to evaluate the contribution of maternal GIT bacteria to the infant gut, we compare the infant’s microbiota with that of the mother at 1 and 11 months after delivery These comparisons reveal that the infant’s microbiota rapidly acquires and maintains the range of gene functions present in the mother, without replicating the phylogenetic composition of her microbiota Microdiversity analyses for Bacteroides and Bifidobacterium, two of the main microbiota constituents, reveal that by 11 months, the phylotypes detected in the infant are distinct from those in the mother, although the maternal Bacteroides phylotypes were transiently present at 1 month of age The configuration of genetic variants within these genera reveals populations far from equilibrium and likely to be undergoing rapid growth, consistent with recent population turnovers Such compositional turnovers and the associated loss of maternal phylotypes should limit the potential for long-term coadaptation between specific bacterial and host genotypes