Jack A. Jones

Searching For Ice And Ocean Biogenic Activity On Europa And Earth

One of the more likely places in the solar system for the existence of extraterrestrial life forms is the Jovian moon Europa. It has been postulated that a volcanically-heated ocean is likely to exist underneath Europas icy surface. If a detailed remote-sensing reconnaissance of Europa determines that an ocean does exist under the ice, then in- situ measurements will be needed to directly explore the Europan ocean and the ice that lies above it. In order to make quantitative measurements of the Europan environment, a lander spacecraft capable of penetrating the surface ice layer by melting through it is proposed. This vehicle, dubbed a `Cryobot, will be designed to carry a small deployable submersible (a `Hydrobot) equipped with a complement of instruments. The design of an instrument package to search for life across the wide range of thermal and pressure environments expected on Europa, the issues in sample handling, and long-term reliability for a potential multi-year transit through the ice all present difficult design issues. Opportunities for performing investigations of deep, submerged Antarctic lakes on Earth are described which would test the Cryobot/Hydrobot system while collecting intrinsically valuable terrestrial science data.

Simulation and Cryogenic Experiments of NaturalConvection for the Titan Montgolfiere

Natural convection in a spherical geometry is considered for prediction of the buoyancy of single- and double-walled nballoons in a cryogenic environment such as Titan’s atmosphere. The steady-state flow characteristics nobtained by solving the Reynolds-averaged Navier–Stokes equations with a standard turbulence model are used to ndetermine the net buoyancy as a function of heat input. Thermal radiation effects are shown to have a minor impact non the buoyancy, as would be expected at cryogenic conditions. The predicted buoyancy and temperature fields ncompare favorably with experiments preformed on a 1-m-diameter Montgolfiere prototype in a cryogenic facility. In naddition, both numerical and experimental results were compared with correlations for the heat transfer coefficients nfor free convection internal and external to the balloon as well as in the concentric gap of the double-walled balloons. nFinally, scaling issues related to inferring the performance of the full-scale Montgolfiere from the model-scale results nare examined.

Sorption Cryogenic Refrigeration — Status and Future

This paper describes sorption refrigeration development, which represents a relatively new breakthrough in cryogenic cooling. Sorption refrigerators have virtually no wear-related moving parts, have negligible vibration, and offer extremely long life (at least ten years). In sorption compressors, low pressure gas is physically adsorbed or chemically absorbed to cooled solids. When heated an additional 100°C to 200°C the gas becomes greatly pressurized and is desorbed, i.e., vented, from the solids. Precooling and expansion of the gas causes partial liquefaction, thus providing net cooling. Recent testing at JPL includes a 1000-hour life test of a hydrogen chemisorption refrigerator (14K–30K), a feasibility test of a nitrogen physisorption refrigerator (100K–200K) and a demonstration test of an oxygen chemisorption compressor (for 55K–90K). Although first stage sorption refrigeration systems require more power than mechanical systems, multiple-stage sorption systems are at least three times more efficient and at least ten times lighter than mechanical refrigerators for 7K–10K cooling (SH2 vacuum sublimation onto hydrides). Due to the high reliability, long-life, light-weight, low vibration characteristics of sorption refrigeration, it is presently being considered for many spacecraft applications and may eventually have many ground applications as well.

Inflatable rovers for planetary applications

A new task has recently been initiated at the Jet Propulsion Laboratory (JPL) to design, fabricate and test an inflatable rover that can be used for various planetary applications, including operation on the Earth’s moon, on Mars, on Saturn’s moon Titan and on Jupiter’s moon, Europa. The primary application is for operation on Mars and, as such, the prototype model in development has large inflatable wheels (1.5-m diameter) that can traverse over 99 percent of the Martian surface, which is believed to be populated by rocks smaller than 0.5 meters in diameter. The 20-kg prototype requires 18 W to travel 2 km/hr on Earth, and could be capable of traveling 30 km/hr on Mars with about 100 W of power. The bench-model unit has been tested with a simple ‘joy stick’ type of radio control system as well as with a commercially available color-tracking camera system.

Tumbleweed: A New Paradigm for Surveying the Surface of Mars for In-Situ Resources

Mars missions to date have interrogated the planet at very large scales using orbital platforms or at very small scales intensively studying relatively small patches of terrain. In order to facilitate discovery and eventual utilization of Martian resources for future missions, a strategy that will bridge these scales and allow assessment of large areas of Mars in pursuit of a resource base will be essential. Long-range surveys of in-situ resources on the surface of Mars could be readily accomplished with a fleet of Tumbleweeds - vehicles capable of using the readily available Martian wind to traverse the surface of Mars with minimal power, while optimizing their capabilities to perform a variety of measurements over relatively large swaths of terrain. These low-cost vehicles fill the niche between orbital reconnaissance and landed rovers, which are capable of much more localized study. Fleets of Tumbleweed vehicles could be used to conduct long-range, randomized surveys with simple, low-cost instrumentation functionally equivalent to conventional coordinate grid sampling. Gradients of many potential volatile resources (e.g. H2O, CH4, etc.) will also tend to follow wind-borne trajectories thus making the mobility mode of the vehicles well matched to the possible target resources. These vehicles can be suitably instrumented for surface and near-surface interrogation and released to roam for the duration of a season or longer, possibly on the residual ice cap or anywhere orbital surveillance indicates that usable resources may exist. Specific instrument selections can service the exact exploration goals of particular survey missions. Many of the desired instruments for resource discovery are currently under development for in-situ applications, but have not yet been miniaturized to the point where they can be integrated into Tumbleweeds. It is anticipated that within a few years, instruments such as gas chromatograph mass spectrometers (GC-MS) and ground-penetrating radar (GPR) will be deployable on Tumbleweed vehicles. The wind-driven strategy conforms to potential natural gradients of moisture and potentially relevant resource gases that also respond to wind vectors. This approach is also useful for characterizing other resources and performing a variety of basic science missions. Inflatable and deployable structure Tumbleweeds are wind-propelled long-range vehicles based on well-developed and field tested technology (Antol et al., 2005; Behar et al., 2004; Carsey et al., 2004; Jones and Yavrouian, 1997; Wilson et al., 2008). Different Tumbleweed configurations can provide the capability to operate in varying terrains and accommodate a wide range of instrument packages making them suitable for autonomous surveys for in-situ natural resources. Tumbleweeds are lightweight and relatively inexpensive, making them very attractive for multiple deployments or piggybacking on larger missions.

Expanding venue and persistence of planetary mobile robotic exploration: new technology concepts for Mars and beyond

The domain and technology of mobile robotic space exploration are fast moving from brief visits to benign Mars surface regions to more challenging terrain and sustained exploration. Further, the overall venue and concept of space robotic exploration are expanding-“from flatland to 3D”-from the surface, to sub-surface and aerial theatres on disparate large and small planetary bodies, including Mars, Venus, Titan, Europa, and small asteroids. These new space robotic system developments are being facilitated by concurrent, synergistic advances in software and hardware technologies for robotic mobility, particularly as regard on-board system autonomy and novel thermo-mechanical design. We outline these directions of emerging mobile science mission interest and technology enablement, including illustrative work at JPL on terrain-adaptive and multi-robot cooperative rover systems, aerobotic mobility, and subsurface ice explorers.

Self-contained harpoon and sample handling device for a remote platform

A key objective of the NASA exploration missions is to explore the Solar System and beyond in an implementation that is safe, sustainable and affordable. One of the major enabling technologies for meeting this objective is the development of effective autonomous sampling systems for robotic in-situ analysis and scientific experiments for life and water detection as well as the potential to conduct materials characterization and mineralogy. Rapid sampling techniques with minimum deterioration of the sample and the potential to capture volatiles have long been an objective of the planetary science community. Tethered penetrator sampling whether the penetrator is driven by gravity [Jones et al. 2006], chemical means [Jones et al. 2006], mechanical springs [Backes et al. 2008] or air guns [Lorenz and Shandera 2000] has the potential to meet this objective. In this paper we present the development of a tethered harpoon sampling and sample handling system operated from an aerial platform for in-situ astrobiological investigations. The harpoon system can be driven into the sample using gravity, pyro, spring or compressed gas mechanisms and is retrieved using a spooling mechanism. The system description and preliminary test results are presented.