Engineering topics

Mantovani, J. G.

Publications and source records attributed to Mantovani, J. G..

12 records

NASA NTRS2016

TransFormers for Ensuring Long-Term Operations in Lunar Extreme Environments

"Surviving Extreme Space Environments" (EE) is one of NASA's Space Technology Grand Challenges. Power generation and thermal control are the key survival ingredients that allow a robotic explorer to cope with the EE using resources available to it, for example, by harvesting the local solar energy or by utilizing an onboard radioisotope thermoelectric generator (RTG). TransFormers (TFs) are a new technology concept designed to transform a localized area within a harsh extreme environment into a survivable micro-environment by projecting energy to the precise location where robots or humans operate. For example, TFs placed at a location on the rim of Shackleton Crater, which is illuminated by solar radiation for most of the year, would be able to reflect solar energy onto robots operating in the dark cold crater. TFs utilize a shape transformation mechanism to un-fold from a compact volume to a large reflective surface, and to control how much-and where-the energy is projected, and by adjusting for the changing position of the sun. TFs would enable in-situ resource utilization (ISRU) activities within locations of high interest that would normally be unreachable because of their extreme environment

ISRU↗

NASA NTRS2016

Launch Pad in a Box

NASA Kennedy Space Center (KSC) is developing a new deployable launch system capability to support a small class of launch vehicles for NASA and commercial space companies to test and launch their vehicles. The deployable launch pad concept was first demonstrated on a smaller scale at KSC in 2012 in support of NASA Johnson Space Center's Morpheus Lander Project. The main objective of the Morpheus Project was to test a prototype planetary lander as a vertical takeoff and landing test-bed for advanced spacecraft technologies using a hazard field that KSC had constructed at the Shuttle Landing Facility (SLF). A steel pad for launch or landing was constructed using a modular design that allowed it to be reconfigurable and expandable. A steel flame trench was designed as an optional module that could be easily inserted in place of any modular steel plate component. The concept of a transportable modular launch and landing pad may also be applicable to planetary surfaces where the effects of rocket exhaust plume on surface regolith is problematic for hardware on the surface that may either be damaged by direct impact of high speed dust particles, or impaired by the accumulation of dust (e.g., solar array panels and thermal radiators). During the Morpheus free flight campaign in 2013-14, KSC performed two studies related to rocket plume effects. One study compared four different thermal ablatives that were applied to the interior of a steel flame trench that KSC had designed and built. The second study monitored the erosion of a concrete landing pad following each landing of the Morpheus vehicle on the same pad located in the hazard field. All surfaces of a portable flame trench that could be directly exposed to hot gas during launch of the Morpheus vehicle were coated with four types of ablatives. All ablative products had been tested by NASA KSC and/or the manufacturer. The ablative thicknesses were measured periodically following the twelve Morpheus free flight tests. The thermal energy from the Morpheus rocket exhaust plume was only found to be sufficient to cause appreciable ablation of one of the four ablatives that were tested. The rocket exhaust plume did cause spalling of concrete during each descent and landing on a landing pad in the hazard field. The Extended Abstract ASE Earth and Space Conference April, 2016 - Orlando, FL concrete surface was laser scanned following each Morpheus landing, and the total volume of spalled concrete that eroded between the first and final landings of the Morpheus Project's test campaign was estimated. This paper will also describe a new deployable launch system (DLS) capability that is being developed at KSC and was publicly announced in May 2015 (KSC Partnerships, 2015). The DLS is a set of multi-user Ground Support Equipment that will be used to test and launch small class launch vehicles. The system is comprised of four main elements: the Launch Stand, the Flame Deflector, the Pad Apron and the KAMAG transporter. The system elements are designed to be deployed at launch or test sites within the KSC/CCAFS boundaries. The DLS is intended to be used together with the Fluid and Electrical System of the Universal Propellant Servicing Systems and Mobile Power Data and Communications Unit.

Ablatives Testing↗

NASA NTRS2016

Low Force Penetration of Icy Regolith

A percussive cone penetrometer measures the strength of granular material by using percussion to deliver mechanical energy into the material. A percussive cone penetrometer was used in this study to penetrate a regolith ice mixture by breaking up ice and decompacting the regolith. As compared to a static cone penetrometer, percussion allows low reaction forces to push a penetrometer probe tip more easily into dry regolith in a low gravity environment from a planetary surface rover or a landed spacecraft. A percussive cone penetrates icy regolith at ice concentrations that a static cone cannot penetrate. In this study, the percussive penetrator was able to penetrate material under 65 N of down-force which could not be penetrated using a static cone under full body weight. This paper discusses using a percussive cone penetrometer to discern changes in the concentration of water-ice in a mixture of lunar regolith simulant and ice to a depth of one meter. The rate of penetration was found to be a function of the ice content and was not significantly affected by the down-force. The test results demonstrate that this method may be ideal for a small platform in a reduced gravity environment. However, there are some cases where the system may not be able to penetrate the icy regolith, and there is some risk of the probe tip becoming stuck so that it cannot be retracted. It is also shown that a percussive cone penetrometer could be used to prospect for water ice in regolith at concentrations as high as 8 by weight.

surface stabilization↗

NASA NTRS2011

Low Force Icy Regolith Penetration Technology

Recent data from the Moon, including LCROSS data, indicate large quantities of water ice and other volatiles frozen into the soil in the permanently shadowed craters near the poles. If verified and exploited, these volatiles will revolutionize spaceflight as an inexpensive source of propellants and other consumables outside Earth's gravity well. This report discusses a preliminary investigation of a method to insert a sensor through such a soiVice mixture to verify the presence, nature, and concentration of the ice. It uses percussion to deliver mechanical energy into the frozen mixture, breaking up the ice and decompacting the soil so that only low reaction forces are required from a rover or spacecraft to push the sensor downward. The tests demonstrate that this method may be ideal for a small platform in lunar gravity. However, there are some cases where the system may not be able to penetrate the icy soil, and there is some risk ofthe sensor becoming stuck so that it cannot be retracted, so further work is needed. A companion project (ISDS for Water Detection on the Lunar Surface) has performed preliminary investigation of a dielectric/thermal sensor for use with this system.

Metzger, P. T.↗

NASA NTRS2010

Pneumatic Regolith Transfer Systems for In Situ Resource Utilization

This slide presentation reviews the testing of a pneumatic system for transfering regolith, to be used for In Situ Resource Utilization (ISRU). Using both the simulated microgravity of parabolic flight and ground testing, the tests demonstrated that lunar regolith can be conveyed pneumatically into a simulated ISRU oxygen production plant reactor. The ground testing also demonstrated that the regolith can be expelled from the ISRU reactor for disposal or for other resource processing.

Mueller, R. P.↗

NASA NTRS2006

Electrodynamic Dust Shield for Surface Exploration Activities on the Moon and Mars

The Apollo missions to the moon showed that lunar dust can hamper astronaut surface activities due to its ability to cling to most surfaces. NASA's Mars exploration landers and rovers have also shown that the problem is equally hard if not harder on Mars. In this paper, we report on our efforts to develop and electrodynamic dust shield to prevent the accumulation of dust on surfaces and to remove dust already adhering to those surfaces. The parent technology for the electrodynamic dust shield, developed in the 1970s, has been shown to lift and transport charged and uncharged particles using electrostatic and dielectrophoretic forces. This technology has never been applied for space applications on Mars or the moon due to electrostatic breakdown concerns. In this paper, we show that an appropriate design can prevent the electrostatic breakdown at the low Martian atmospheric pressures. We are also able to show that uncharged dust can be lifted and removed from surfaces under simulated Martian environmental conditions. This technology has many potential benefits for removing dust from visors, viewports and many other surfaces as well as from solar arrays. We have also been able to develop a version of the electrodynamic dust shield working under. hard vacuum conditions. This version should work well on the moon.

Calle, C. I.↗

NASA NTRS2004

Electrodynamic Dust Shield for Solar Panels on Mars

The Materials Adherence Experiment on the Mars Pathfinder mission measured an obscuration of the solar arrays due to dust deposition at a rate of about 0.2 8% per day. It was estimated that settling dust may cause degradation in performance of a solar panel of between 22% and 89% over the course of two years [1, 2]. These results were obtained without the presence of a global dust storm. Several types of adherence forces keep dust particles attached to surfaces. The most widely discussed adherence force is the electrostatic force. Laboratory experiments [3] as well as indirect evidence from the Wheel Abrasion Experiment on Pathfinder [4] indicate that it is very likely that the particles suspended in the Martian atmosphere are electrostatically charged.

Calle, C. I.↗

NASA NTRS2004

Preliminary Results of a New Type of Surface Property Measurement Ideal for a Future Mars Rover Mission

The success of the recent rover missions to Mars has stressed the importance of acquiring the maximum amount of geological information with the least amount of data possible. We have designed, tested and implemented special sensors mounted on a rover s wheel capable of detecting minute changes in surface topology thus eliminating the need for specially- made science platforms. These sensors, based on the previously designed, flight qualified Mars Environmental Compatibility Assessment (MECA) Electrometer, measure the static electricity (triboelectricity) generated between polymer materials and the Martian regolith during rover transverses. The sensors are capable of detecting physical changes in the soil that may not be detectable by other means, such as texture, size and moisture content. Although triboelectricity is a surface phenomenon, the weight of a rover will undoubtedly protrude the sensors below the dust covered layers, exposing underlying regolith whose properties may not be detectable through other means.

Buhler, C. R.↗

NASA NTRS2002

Development of a Charged Particle Detector for Windborne Martian Dust

A prototype of an aerodynamic electrometer to measure the electrostatic properties of Martian atmospheric dust has been constructed. The instrument will enable a more thorough understanding of the potential for electrostatic discharge of different materials on Mars. Additional information is contained in the original extended abstract.

Calle, C. I.↗

NASA NTRS2001

Electrostatic Charging of Polymers by Particle Impact at Low Pressures

Studies of the electrostatic interaction between micrometer-sized particles and polymer surfaces are of great interest to NASA's planetary exploration program. The unmanned landing missions to Mars planned for this decade as well as the possible manned missions that might take place during the second decade of this century require a better understanding of the electrostatic response of the materials used in landing crafts and equipment when exposed to wind-blown dust or to surface dust and sand particles. We report on preliminary experiments designed to measure the electrostatic charge developed on five polymer surfaces as they are impacted simultaneously by Mars simulant particles less than 5 micrometers in diameter moving at 20 m/s. Experiments were performed in a CO2 atmosphere at 10 mbars of pressure using a particle delivery method that propels the particles with contact. Experiments were also performed in dry air at atmospheric pressures using a pressurized particle delivery system. The five polymer surfaces, commonly used in space applications, were chosen so that they span the triboelectric series.

Calle, Carlos I.↗

NASA NTRS1998

Electrodeposited CulnSe2 Thin Film Junctions

We have investigated thin films and junctions based on copper indium diselenide (CIS) which have been grown by electrochemical deposition. CIS is a leading candidate for use in polycrystalline thin film photovoltaic solar cells. Electrodeposition is a cost-effective method for producing thin-film CIS. We have produced both p and n type CIS thin films from the same aqueous solution by simply varying the deposition potential. A CIS pn junction was deposited using a step-function potential. Stoichiometry of the single layer films was determined by energy dispersive spectroscopy. Carrier densities of these films increased with deviation from stoichiometry, as determined by the capacitance versus voltage dependence of Schottky contacts. Optical bandgaps for the single layer films as determined by transmission spectroscopy were also found to increase with deviation from stoichiometry. Rectifying current versus voltage characteristics were demonstrated for the Schottky barriers and for the pn junction.

Raffaelle, R. P.↗

NASA NTRS1997

Electrodeposited CuInSe2 Thin Film Junctions

Raffaelle, R. P.↗