Kinetic Integrated Thermal Protection System (KnITPS)

Principal Investigator: Sylvia Johnson

Many thermal protection materials are composites that rely on a fibrous substrate, often infiltrated with a resin or combination of materials. Fibrous substrates can have a variety of architectures involving both short and continuous fibers. In this project we are investigating an alternative fiber architecture that may allow for easier fabrication of TPS.

Back to Top

Mars Sample Return Utilizing Next Generation Mars Landers

Principal Investigator: Carol Stoker

We are studying mission architecture for Mars sample return. The goal is to explore architecture solutions that return samples to Earth with a single Mars launch. We will examine a next generation lander under development by Space X corp. that is capable of delivering a 1 MT payload to the Mars surface as the landing system. The landed mission elements include a spacecraft stack consisting of a Mars Ascent Vehicle (MAV) and Earth Return Vehicle (ERV) that collectively will carry a sample canister from Mars back to Earth orbit. The MAV will use a one or two stage chemical propellant rocket to achieve trans-earth injection, where it will place the ERV en route to Earth. The study will consider the trade between chemical and electric propulsion for the ERV, and between sending the ERV on direct return to Earth vs Mars Orbit Rendezvous. The lander payload will include sample collection hardware such as an arm, drill, or small rover. Packaging of the MAV/ ERV and sample collection hardware will be a key study product. The study will examine the following elements:

• Design of the MAV /ERV stack with mass and performance uncertainty < 10%, including a sensitivity analysis of the design to technology performance.
• Recommended technology investment strategy to reduce cost risk to MSR architecture of MAV performance.
• Accommodation analysis of the MAV/ERV vehicle in a capsule form factor lander.
• Accommodation analysis of the sample collection hardware in the remaining volume of the capsule. The type of sample collection system possible depends on what landed payload mass is available after accommodating MAV/ERV. Options include (in order of increasing mass) a sampling arm, a drill, and a rover. Each of these has unique accommodation requirements.
• Analysis of how to accomplish planetary protection within this mission architecture.

The final product will be a report detailing the results of the analysis.

Back to Top

Materials Manufactured from 3D Printed Synthetic Biology Arrays

Principal Investigators: Diana Gentry, NASA Ames Research Center, SGE, Samson Phan, Stanford University, Lynn J. Rothschild (POC), NASA Ames Research Center, SGE

The Problem
Complex, biologically derived materials (such as wood and silk) often have extremely useful properties. However, their use in space-related applications is hampered by two primary drawbacks:

Expensive, specific production. Many of these materials can only be produced as part of significant support ecosystem. For example, spider silk can only be produced by providing a contained, sustainable habitat and appropriate food for selected species of spiders, and can then only be harvested in relatively small quantities by a laborious human-intensive process. These overhead requirements simply add too much upmass for a potential Mars habitat mission.

Limited manufacturing compatibility. Collecting and processing many such materials (for example, cotton) requires specialized equipment that adds impractical upmass or resource requirements to a potential self-contained habitat. Many cannot be worked with modern micro-scale manufacturing techniques at all (e.g., wood), limiting their use in creating potentially useful composite structures.

The Vision

• Using structured arrays of biologically engineered cells to deposit or excrete biological materials in a specified composite pattern creating novel biomaterials and biocomposites.
• Complex, biologically derived materials (such as wood and silk) often have extremely useful properties but their use in space-related applications is hampered by expensive production, and the limited manufacturing compatibility with space (e.g., upmass and resource requirements.) Many cannot be worked with micro-scale manufacturing techniques (e.g., wood).
• The innovation of this project is the application of synthetic biology to 3D printing technology. Their combination presents significant challenges.

Potential impact
If successful, this application would dramatically expand manufacturing capabilities on Earth and in space:

In situ resource utilization. The ability to make a far greater range of materials and products out of the limited basic resource palette offered by existing in situ resource extraction techniques.

Reduced equipment and material upmass for off-Earth habitats. Production of a wide variety of ready-to-use highly specialized construction materials (radiation hardened, compressive/tensile, light or dense) from an extremely low starting mass, allowing for flexible production of working and living spaces tailored to off planet environments.

Structured biomaterial production. New ready-to-use macro, micro, and molecular manufacturing techniques for traditional materials such as wood, including finely calibrated microstructures.

New and novel biocomposite creation. The ability to create completely novel material composites from any base material that cells can be engineered to produce opens up a new frontier in materials design and manufacturing.

Back to Top

Photon-Counting Integrated Circuit (PCIC) Photodetector Arrays

Principal Investigator: Ted Roush

Technological improvements in sensors available to NASA have a significant cross-cutting impact for an array of NASA instruments measuring over a broad range of the electromagnetic spectrum. Improvements of detector performance would cause a significant shift in capability.
The commonly used avalanche photodiode (APD) boosts the signal level of input optical power. However, high avalanche excess noise and extreme sensitivity to bias voltage makes it very difficult to achieve high gain or gain uniformity across an APD 2-D focal plane array, let alone the Geiger recovery time. The PCIC is an enabling technology potentially providing for greater detector sensitivity in a wide range of thermal and radiation environments.

Back to Top

Surface Spectroscopy Center of Excellence

Principal Investigator: Diane Wooden

Project Summary
We propose to develop a national center of excellence in modeling spectral reflectivity and emissivity of grainy or structured surfaces. The focus is the regime where the structural elements of grainy surfaces have grain sizes and separations of tens of microns, comparable to the wavelengths carrying diagnostic compositional information. This regime is of fundamental interest to remote sensing of planetary and terrestrial surfaces, and has potential applications to nanoscale materials and biological surfaces. This regime is of critical and widespread interest, yet all current models of regolith radiative transfer make simplifying assumptions that are invalid in this regime. Current models cannot explain mysterious Spitzer mid-IR spectra of Trojan Asteroids, targets of a future New Frontiers Mission. We will leverage our unique, state-of-the-art numerical model, Ames’ computational facilities, and laboratory studies of colleagues in developing this resource.

The core capability on which we will build is an innovative numerical model of a surface composed of grains of arbitrary size, shape, composition, and porosity (Vahidinia et al 2010, 2011, 2012). Our code is an extension of the well-known “Discrete Dipole Approximation” (DDA; Draine and Flatau 1994), expanded to determine the near-field emergent intensity from a “surface” using periodic horizontal boundary conditions. Over the past four years, we have parallelized the code with MPI and OpenMP for efficient operation on the NAS HEC machines. Currently we have shown how increasing particle filling factor alone can affect the scattering properties of ensembles of otherwise identical particles. This effect sets in at surprisingly low filling factors (a few percent or less). The code can handle embedded nanoparticles by using suitable models of how their size changes their refractive indices (for instance, the Drude model for metals). It also can handle compositionally heterogeneous surfaces. In fact, it can handle any surface structure in complete generality. The code is currently limited primarily by memory per processor on the NAS machines, which will grow with time, but we have successfully modeled many cases each containing millions of dipoles to date.

Specific near-term milestones we need to achieve include: (1) The basic code needs to be exercised over a wider range of porosity, composition, and wavelengths; (2) A doubling-adding code must be implemented to represent a surface, to build upon our basic “unit cell” that represents only a slab 5-10 particles thick; we have made some progress in that direction, obtaining and implementing the facility code “DISORT”, which now runs separately, but needs to be linked with our DDA results; (3) DISORT has a thermal emission capability which can handle non-isothermal temperature structure within the medium; this needs to be implemented to study emission spectroscopy of, for instance, comets, Centaurs, and Trojan Asteroids with mystifying spectra. (4) We aim to establish a collaboration with at least one laboratory group to produce more experimental reflectance and emissivity spectra for well-characterized samples, for comparison with model results.

Developing an innovative computational methodology to compute the emergent scattering and emissivity spectra of surfaces of airless bodies is the aim of this proposal. Trojan asteroid spectra reveal the same silicate features as comets, but asteroids are surfaces and not comae of lofted particles so the hypothesis is that their surfaces have loosely packed particles (Emery et al. 2006; Fig. above shows Spitzer spectra of scaled emissivity of Trojan Asteroid 624 Hektor, comet Hale-Bopp, and Centaur Schwassman-Wachmann 1 or SW1, where 624 Hektor is unexplainable by current modeling methods. If asteroid surface spectroscopy cannot be explained, the aim of surface spectroscopy may be ‘out of sight’ of mission goals, and yet, suitable models of these spectra might provide breakthroughs in understanding the surface composition of these objects.

References
Draine, B. T.; Flatau, P. J. (1994), J. Opt. Soc. Am. A, 11, 1491

Emery, J. P.; Cruikshank, D. P.; van Cleve, J. (2006), “Thermal emission spectroscopy (5.2-38 µm) of three Trojan asteroids with Spitzer Space Telescope: Detection of fine-grained silicates”, Icarus, 182, 496

Vahidinia, S.; Cuzzi, J. N.; Hedman, M.; Draine, B.; Clark, R. N.; Roush, T.; Filacchione, G.; Nicholson, P. D.; Brown, R. H.; Buratti, B.; Sotin, C. (2010), “Saturn’s F ring grains: Aggregates made of crystalline water ice”, Icarus, 215, 682

Vahidinia, S. V.; Cuzzi, J. N.; Draine, B. D.; Marouf, E. M. (2011) A.A.P.P. 89, SUPP.1: Proc. Proceedings of the Electromagnetic and Light Scattering Conference, XIII, Taormina, Italy, 26-30 Sept 2011

Vahidinia, S. V.; Cuzzi, J. N.; Draine, B. D.; Marouf, E. M. (2012), “Radiative Transfer of Closely Packed Realistic Regoliths”, 43rd LPSC, No. 1659, id.2880

Back to Top