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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 NTRS1994

High Performance Programming Using Explicit Shared Memory Model on the Cray T3D

The Cray T3D is the first-phase system in Cray Research Inc.'s (CRI) three-phase massively parallel processing program. In this report we describe the architecture of the T3D, as well as the CRAFT (Cray Research Adaptive Fortran) programming model, and contrast it with PVM, which is also supported on the T3D We present some performance data based on the NAS Parallel Benchmarks to illustrate both architectural and software features of the T3D.

Saini, Subhash↗

NASA NTRS2001

Determining Biosignatures by Complexity Analysis in Antarctic Cryptoendolithic Communities

One of the most difficult problems of life detection is that of identifying biosignatures across a wide range of scales using multiple co-registered probes. The technique should be of equal utility across a wide range of search spaces from remote sensors probing volumes of space or planetary surfaces, visual eye or camera searches across the surface of a rock in Antarctica, low resolution microscopic scanning of a rock or a space craft in situ, or high resolution electron microscope and computerized tomography scanning of geobiological samples. We describe here an approach to this problem which derives in large part from past work done in the area of astrophysics - namely the analysis of complexity in galactic signals by data compression methods. This approach is a radically new one for geobiology and astrobiology, and allows us to assess the complexity (and thus potential biogenicity) of an object being examined. This is done by considering the information within pixels of an image (regardless the sensor used to gather the information) as an energetic system capable of description in terms of classical thermodynamics. The image data space is searched by an algorithm that judges complexity via data compression (e.g., the more compressible it is, the less complex, and vice versa) and maximum entropy as originally outlined by Shannon. At present we are implementing methods to utilize images from multiple sensors gathering different kinds of information (e.g., visible gray-scale data, color analyses, UV fluorescence, chemical information, etc). We present here preliminary data from deep UV fluorescence and ESEM (Environmental Scanning Electron Microscope) images from a layered cryptoendolithic community of an Antarctic rock.

Storrie-Lombardi, M. C.↗

NASA NTRS2001

Research to Significantly Enhance Composite Survivability at 550 F in Oxidative Environments

Prairie View A&M University using the NASA FAR grant has embarked on several paths to accomplish the initial goals of: (1) synthesizing three ring aromatic diamines to be used as monomers in the synthesis of polyamide resins; and (2) study hydrothermal aging behaviors and glass transition changes of composites synthesized at NASA Glenn Research Center. In establishing the synthesis of the three ring aromatic diamine, it has become necessary to conduct preliminary synthesis to include the nitration of diphenylmethane. The concentration and temperature were altered to assess the effect of purity of isomeric product distribution in such electrophilic aromatic substitution reaction. Products were analyzed using H and C-NMR, Thin Layer Chromatography, High Pressure Liquid Chromatography and GC-Mass Spectrometry (in progress). Results indicate that by varying the concentration of the reaction, a mixture of products can be obtained. Other electrophilic aromatic substitution reactions are also in progress such as Friedel-Craft acylation reaction using diphenylmethane with 4-nitrobenzoyl chloride to afford other diamine products. Furthermore, PVAMU has nearly completed the hydrothermal studies to assess the oxidative stability of DSP443B and DSP442A panels formulated at NASA Glenn Research Center.

Byrd, Jim↗

NASA NTRS1997

TPS Materials for Planetary Exploration

This paper will review the current material options, and near term developments, for thermal protection systems (TPS) of future space craft involving atmospheric entry. TPS is a very important element in the design of these vehicles, and can have large impact on the project risk and cost. The new family of light weight ceramic ablators illustrated by SIRCA and PIC will be discussed, along with state-of-the-art ablators including SLA-561V, Avcoat-5026, carbon-phenolic, and carbon-carbon.

Rasky, Daniel J.↗

NASA NTRS1998

Gravity of Living Systems: May the Force Be With You

Gravity, the force which shapes the architecture of organisms from single cells to dinosaurs, has been the most constant environmental factor during the evolution of species on Earth. With long-duration space flight, an understanding of how gravity affects living systems gains greater urgency in order to maintain the health and performance of crews who will explore the solar system. For example, the cardiovascular and musculoskeletal systems are normally exposed to gravitational gradients of blood pressure and weight on Earth. Such gradients increase blood pressure and tissue weight in dependent tissues of the body. Thus, from a physiologic standpoint, these systems are greatly affected by altered gravity. Exposure to actual and simulated microgravity causes blood and tissue fluid to shift from the legs to the head. Studies of humans in space have documented facial edema, space adaptation syndrome, decreased plasma volume, muscle atrophy, and loss of bone strength. Return of astronauts to Earth is accompanied by orthostatic intolerance, decreased neuromuscular coordination, and reduced exercise capacity. These factors decrease performance during descent from orbit and increase risk during emergency egress from the space craft. Models of simulated microgravity include 60 head-down tilt, immersion, and prolonged horizontal bedrest. Head-down tilt and dry immersion are the most accepted models and studies using these models of up to one year have been performed in Russia. Sensitive animal models which offer clear insights into the role of gravity on structure and function include the developing giraffe and snakes from various habitats. Finally, possible countermeasures to speed readaptation of astronauts to gravity after prolonged space flight include exercise, lower body negative pressure, and centrifugation.

Hargens, Alan R.↗

NASA NTRS1999

Laser Lightcraft Vehicle Design

Current space deployment vehicle research is investigating ways to lower the cost to place payloads into orbit. Beamed energy propulsion is one of the areas that are being studied. The Laser lightcraft concept, which uses a ground based laser as part of its propulsion system, falls into this category. This concept has been developed by previous Strategic Defense Initiative Office (SDIO) research. In this concept, the laser energy is reflected off of a mirror on the craft and is focused inside the cowl to created optical breakdown of the propellant. There are several concerns about the design that must be further studied. These include: 1) Thermodynamic analysis of the cryogenic fuel storage and feed systems, 2) Analysis of the regenerative cooling system for the primary optic, and 3) Analysis of focal blurring of the laser due to off-axis flight.

Buch, Kevin↗

NASA NTRS2001

Science Autonomy in Robotic Exploration

Historical mission operations have involved: (1) return of scientific data; (2) evaluation of these data by scientists; (3) recommendations for future mission activity by scientists; (4) commands for these transmitted to the craft; and (5) the activity being undertaken. This cycle is repeated throughout the mission with command opportunities once or twice per day. For a rover, this historical cycle is not amenable to rapid long range traverses or rapid response to any novel or unexpected situations. In addition to real-time response issues, imaging and/or spectroscopic devices can produce tremendous data volumes during a traverse. However, such data volumes can rapidly exceed on-board memory capabilities prior to the ability to transmit it to Earth. Additionally, the necessary communication band-widths are restrictive enough so that only a small portion of these data can actually be returned to Earth. Such scenarios suggest enabling some science decisions to be made on-board the robots. These decisions involve automating various aspects of scientific discovery instead of the electromechanical control, health, and navigation issues associated with robotic operations. The robot retains access to the full data fidelity obtained by its scientific sensors, and is in the best position to implement actions based upon these data. Such an approach would eventually enable the robot to alter observations and assure only the highest quality data is obtained for analysis. Additionally, the robot can begin to understand what is scientifically interesting and implement alternative observing sequences, because the observed data deviate from expectations based upon current theories/models of planetary processes. Such interesting data and/or conclusions can then be prioritized and selectively transmitted to Earth; reducing memory and communications demands. Results of Ames' current work in this area will be presented.

Roush, Ted L.↗

NASA NTRS2001

Robotic Exploration: The Role of Science Autonomy

Historical mission operations have involved: (1) return of scientific data; (2) evaluation of these data by scientists; (3) recommendations for future mission activity by scientists; (4) commands for these transmitted to the craft; and (5) the activity being, undertaken. This cycle is repeated throughout the mission with command opportunities once or twice per day. For a rover, this historical cycle is not amenable to rapid long range traverses or rapid response to any novel or unexpected situations. In addition to real-time response issues, imaging and/or spectroscopic devices can produce tremendous data volumes during a traverse. However, such data volumes can rapidly exceed on-board memory capabilities prior to the ability to transmit it to Earth. Additionally, the necessary communication band-widths are restrictive enough so that only a small portion of these data can actually be returned to Earth. Such scenarios suggest enabling some science decisions to be made on-board the robots. These decisions involve automating various aspects of scientific discovery instead of the electromechanical control, health, and navigation issues associated with robotic operations. The robot retains access to the full data fidelity obtained by its scientific sensors, and is in the best position to implement actions based upon these data. Such an approach would eventually enable the robot to alter observations and assure only the highest quality data is obtained for analysis. Additionally, the robot can begin to understand what is scientifically interesting and implement alternative observing sequences, because the observed data deviate from expectations based upon current theories/models of planetary processes. Such interesting data and/or conclusions can then be prioritized and selectively transmitted to Earth; reducing memory and communications demands. Results of Ames' current work in this area will be presented.

Roush, Ted L.↗

NASA NTRS1999

Portable Inspection

The portable SpectroReflectometer, an instrument developed by AZ Technology, Inc. in partnership with NASA's Kennedy Space Center is now being manufactured and sold as a cost-effective solution to the development of scientific space flight hardware. This technology originated with the efforts to determine the degradation mechanisms of the space environment on space craft materials. AZ Technology's mission is to provide high quality products and services in electro-mechanical-optical design and hardware integration, advanced thermal and optical coatings and materials, and in the development of custom hardware systems for scientific measurements.

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NASA NTRS2002

Robotic Exploration: The Role of Science Autonomy

Historical mission operations have involved: (1) commands transmitted to the craft; (2) execution of commands; (3) return of scientific data; (4) evaluation of these data by scientists; and (5) recommendations for future mission activity by scientists. This cycle is repeated throughout the mission with command opportunities once or twice per day. For a rover, this historical cycle is not amenable to rapid long range traverses or rapid response to any novel or unexpected situations.

Roush, Ted L.↗

NASA NTRS1997

Improving Communications Systems

The Space Shuttle has many communications systems which are used throughout a typical mission. Given that the radio spectrum has become increasingly congested, the ability to hear extremely weak signals requires greater receiver sensitivity. Dryden Flight Research Center approached Angle Linear, a manufacturer of linear radio frequency products and peripherals for communications, to solve the problem. The solution was a receiving preamplifier specially crafted for NASA. Communications with the Space Shuttle are now more reliable,with Dryden being able to also support local missions without purchasing additional equipment. The work has carried over into the Mir Space Station communication support effort and is under evaluation by other NASA centers. The company's preamplifier line was greatly expanded to cover a broader range of frequencies, providing the same sensational improvement to other areas of communication including business, government, trucking, land mobile, cellular and broadcast.

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NASA NTRS2002

Continuously Connected With Mobile IP

Cisco Systems developed Cisco Mobile Networks, making IP devices mobile. With this innovation, a Cisco router and its connected IP devices can roam across network boundaries and connection types. Because a mobile user is able to keep the same IP address while roaming, a live IP connection can be maintained without interruption. Glenn Research Center jointly tested the technology with Cisco, and is working to use it on low-earth-orbiting research craft. With Cisco's Mobile Networks functionality now available in Cisco IOS Software release 12.2(4)T, the commercial advantages and benefits are numerous. The technology can be applied to public safety, military/homeland security, emergency management services, railroad and shipping systems, and the automotive industry. It will allow ambulances, police, firemen, and the U.S. Coast Guard to stay connected to their networks while on the move. In the wireless battlefield, the technology will provide rapid infrastructure deployment for U.S. national defense. Airline, train, and cruise passengers utilizing Cisco Mobile Networks can fly all around the world with a continuous Internet connection. Cisco IOS(R) Software is a registered trademark of Cisco Systems.

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NASA NTRS2002

STS-112 Flight Day 10 Highlights

On Flight Day 10 of the STS-112 mission, its crew (Jeffrey Ashby, Commander; Pamela Melroy, Pilot; David Wolf, Mission Specialist; Piers Sellers, Mission Specialist; Sandra Magnus, Mission Specialist; Fyodor Yurchikhin, Mission Specialist) on the Atlantis and the Expedition 5 crew on the International Space Station (ISS) (Valery Korzun, Commander; Peggy Whitson, Flight Engineer; Sergei Treschev, Flight Engineer) are shown exchanging farewells in the ISS's Destiny Laboratory Module following the completion of a week-long period of docked operations. The Expedition 5 crew is nearing the end of five and a half continuous months aboard the space station. Following the closing of the hatches, the Atlantis Orbiter undocks from the station, and Melroy pilots the shuttle slowly away from the ISS, and engages in a radial fly-around of the station. During the fly-around cameras aboard Atlantis shows ISS from a number of angles. ISS cameras also show Atlantis. There are several shots of each craft with a variety of background settings including the Earth, its limb, and open space. The video concludes with a live interview of Ashby, Melroy and Yurchikhin, still aboard Atlantis, conducted by a reporter on the ground. Questions range from feelings on the conclusion of the mission to the experience of being in space. The primary goal of the mission was the installation of the Integrated Truss Structure S1 on the ISS.

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NASA NTRS2002

STS-111 Flight Day 3 Highlights

On Flight Day 3 of STS-111, the crew of Endeavour (Kenneth Cockrell, Commander; Paul Lockhart, Pilot; Franklin Chang-Diaz, Mission Specialist; Philippe Perrin, Mission Specialist) and the Expedition 5 crew (Valery Korzun, Commander; Peggy Whitson, Flight Engineer; Sergei Treschev, Flight Engineer), begin their final approach towards the International Space Station (ISS). From cameras aboard the ISS, live video of Endeavour is shown as it approaches the station. The Orbiter is maneuvered slowly to a position for docking, and cameras from multiple angles show this process. As it is maneuvered, there are clear views of its payload bay, which includes the Leonardo MultiPurpose Logistics Module (MPLM) and the Mobile Base System (MBS), both of which will be installed on the ISS during this mission. In the final stages of the docking procedure there is close-up footage of Endeavour meeting the ISS's Pressurized Mating Adapter 2 on the Destiny Laboratory Module. Inside the ISS, the Expedition 4 crew (Yury Onufrienko, Commander; Daniel Bursch, Flight Engineer; Carl Walz, Flight Engineer), which will be replaced by the Expedition 5 crew, prepares for final docking. Crew members are shown transferring equipment from the Endeavour to the ISS, prior to a replay of the mating of the two crafts. In the replay, the hatch is shown being opened and the two newly arrived crews are greeted with excitement by Expedition 4 crewmembers. The video closes with footage of the Quest airlock used for EVA (extravehicular activity) egress, and the Canadarm 2 robotic arm.

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NASA NTRS2002

STS-111 Post Flight Presentation

The crews of STS-111 (Endeavour's crew: Ken Cockrell, Commander; Paul Lockhart, Pilot; Franklin Chang-Diaz, Mission Specialist (MS); Philippe Perrin, MS; International Space Station's (ISS) Expedition 4 crew: Yury Onufrienko, Commander; Daniel Bursch, Flight Engineer; Carl Walz, Flight Engineer; ISS Expedition 5 crew: Valery Korzun, Commander; Peggy Whitson, Flight Engineer; Sergei Treschev, Flight Engineer) narrate this video of highlights from the mission. It includes footage from each major portion of the mission: launch preparation, launch, entering orbit, opening payload bay doors, rendezvous of Endeavour with ISS, docking of the crafts and the meeting between Endeavour and Expedition 5 crews and the Expedition 4 crew, which Expedition 5 relieved. Docked operations include: crew transfer procedures, transfer of goods, EVA (extravehicular activity) prep, EVA performed by Chang-Diaz and Perrin which included installing a grapple fixture, mounting the Mobile Base System (MBS) to the Mobile Transporter (MT), and changing a joint on the station's Canadarm 2 robotic arm. The video ends with re-entry and landing of the shuttle.

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NASA NTRS2002

STS-112 Flight Day 3 Highlights

During the third flight day of STS-112 (Commander Jeff Ashby, Pilot Pam Melroy and Mission Specialists Sandy Magnus, Piers Sellers, David Wolf and Fyodor Yurchikhin), the Space Shuttle Atlantis begins its final approach to the International Space Station (ISS) with which it will dock. The Chinese mainland is seen, at night, at a height of 242 statute miles. In one section of video from a camera onboard the ISS, Atlantis can be seen to be almost directly below the station, at a distance of several hundred feet. The orbiter's docking system is shown, as it is slowly guided by Ashby towards the forward docking port on the ISS's Destiny Laboratory Module and its forward docking port. Above the docking port, the S0 truss structure can be seen, to which the S1 truss structure in Atlantis' payload bay will be attached during this mission. Also seen are the Unity airlock and other modules. Following the completion of docking, in which an excellent shot of the docking system in hard dock is visible, the hatches between the two crafts are opened and the members of Atlantis are greeted by the very excited members of Expedition 5, who have been aboard the ISS for several months.

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NASA NTRS2001

Work and Fatigue Characteristics of Unsuited and Suited Humans During Isolated, Isokinetic Joint Motions

The effects of a pressurized suit on human performance were investigated. The suit is known as an Extra-vehicular Mobility Unit (EMU) and is worn by astronauts while working outside of their space craft in low earth orbit. Isolated isokinetic joint torques of three female and three male subjects (all experienced users of the suit) were measured while working at 100% and 80% of their maximum voluntary torque (MVT). It was found that the average decrease in the total amount of work done when the subjects were wearing the EMU was 48% and 41% while working at 100% and 80% MVT, respectively. There is a clear relationship between the MVT and the time and amount of work done until fatigue. In general the stronger joints took longer to fatigue and did more work than the weaker joints. However, it is not clear which joints are most affected by the EMU suit in terms of the amount of work done. The average amount of total work done increased by 5.2% and 20.4% for the unsuited and suited cases, respectively, when the subject went from working at 100% to 80% MVT. Also, the average time to fatigue increased by 9.2% and 25.6% for the unsuited and suited cases, respectively, when the subjects went from working at 100% to 80% MVT. The EMU also decreased the joint range of motion. It was also found that the experimentally measured torque decay could be predicted by a logarithmic equation. The absolute average error in the predictions was found to be 18.3% and 18.9% for the unsuited and suited subject, respectively, working at 100% MVT, and 22.5% and 18.8% for the unsuited and suited subject, respectively, working at 80% MVT. These results could be very useful in the design of future EMU suits, and planning of Extra-Vehicular Activit). (EVA) for the upcoming International Space Station assembly operations.

Gonzalez, L. Javier↗