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At least 649 records · Page 36

One Year Old and Growing: A Status Report on the International Space Station and Its Partners

The first elements of the International Space Station have been launched and docked together, and are performing well on-orbit. The Station is currently being operated jointly by NASA and Russian space organizations. In May 1999, the Space Shuttle was the first vehicle to dock to the International, Space Station. A crew of seven U.S. and Russian astronauts delivered 4000 pounds of supplies, made repairs to communications and battery systems, and installed external hardware during an EVA. The next module, the Russian Service Module, is due to join the orbital complex this year. This will initiate a period of rapid growth, with new modules and equipment continually added for the next five to six years, through assembly complete. The first crew is scheduled to begin permanent occupation of the International Space Station early next year. Hardware is being developed by Space Station partners and participants around the world and is largely on schedule for launch. Mission control centers are fully functioning in Houston and Moscow, with operations centers in St. Hubert, Darmstadt, Tsukuba, Turino, and Huntsville going on line as they are required. International crews are selected and in training. Coordination efforts continue with each of the five partners and two participants, involving 16 nations. All of them continue to face their own challenges and have achieved their own successes. This paper will discuss the status of the ISS partners and participants, their contributions and accomplished milestones, and upcoming events. It will also give a status report on the developments of the remainder of the ISS modules and components by each partner and participant. The ISS, the largest and most complicated peacetime project in history, is flying, and, with the help of all the ISS members, will continue to grow.

Bartoe, John-David F.↗

Integrated launch and emergency vehicle system

A heavy launch vehicle is discussed. The launch vehicle is comprised of an expendable, multi-container, propellant tank that has a plurality of winged booster propulsion modules at one end and a payload supported by adapter structure at the other end. The preferred payload is an entry module that can be adapted for docking to the space station and used as a return vehicle for the space station crew. Additionally, the payload may include communication satellites, supplies, equipment, and/or structural elements for the space station. The winged propulsion modules are released from the expendable propellant tank, in pairs, and they return to Earth in a controlled glide. After a safe landing, at or near the launch site, the modules are prepared for reuse. The rocket engines for each propulsion module are dual-fuel, dual-mode engines and use methane-oxygen and hydrogen-oxygen from the multi-containers of the propellant tank. When the propulsion modules are released from the expendable propellant tank, the rocket engines are moved into the module cargo bay for the return glide flight.

Martin, James A.↗

Case Study of Risk Mitigation Based on Hardware/Software Integration (HSI) Testing for the International Space Station (ISS) Node 2 Module

Within the pressurized elements of the International Space Station (ISS), requirements exist to ensure a safe, habitable environment for the crew. In order to provide this environment, thermal control components work in conjunction with software controls to provide heat rejection for subsystem avionics equipment, for the environmental control system and for experiment payloads. It is essential to ISS operations, mission success and crew safety that necessary testing incorporates the extreme conditions to ensure proper performance. This paper provides a general description and methodology applied to thermal related Hardware/Software Integration (HSI) tests for the ISS Node 2 module. A detailed test plan was developed and implemented with two objectives: the first was for risk mitigation of the thermal control algorithms and software qualification, and the second was for data collection which will substantiate thermalhydraulic models of the Internal Active Thermal Control System (IATCS). Analytical models are utilized to determine on-orbit performance for conditions and scenarios where the simulation of actual on-orbit system performance is limited by test configuration constraints. Node 2 IATCS HSI activities were performed at the Alenia Spazio facility in Torino, Italy with participation from the National Aeronautics and Space Administration (NASA), Alenia Spazio, Jacobs Engineering Sverdrup (JE Sverdrup) and Boeing.

Holt, James Mike↗

ISS Technology Demonstrations for Future Spaceflight Medical Systems

Throughout the history of human spaceflight, crewmembers have experienced various in-flight medical conditions including illness and injury. Planned missions to the Moon and Mars will require capabilities to maintain the health of future space travelers. Mass, power, and volume available in the vehicles and habitats for these missions will be severely constrained; resupply of resources will be limited or non-existent, as will opportunities for evacuation to Earth. Furthermore, ground-based support will be hampered by communication latencies and blackouts. These vehicle and mission constraints will necessitate a medical system that has been efficiently planned, providing on-board procedural guidance in addition to a variety of medical devices and consumable resources. Medical capabilities required for the diagnosis and treatment of potential medical conditions during future spaceflight missions may include real-time health monitoring, medical imaging, and biomarker analyses ( e.g., blood or urine). Terrestrial medicine shares these needs, thus many of these medical capabilities could likely be satisfied by Commercial-Off-The-Shelf (COTS) devices and methodologies; however, in some cases the unique space environment and increased mission duration will drive the need to modify technologies and the way care is provided. NASA’s Human Research Program (HRP) Exploration Medical Capability (ExMC) Element and Mars Campaign Office’s Exploration Medical Integrated Product Team (XMIPT) are working together to decrease medical risk during exploration missions. Flight-tested medical diagnostic and treatment technologies are necessary to effectively manage medical conditions relevant to exploration missions while meeting vehicle constraints, integrating with medical decision-support tools, and enabling increasingly Earth-independent operations. Several projects have leveraged the ISS as a testbed for exploration, including 1) i n- situ blood analysis, 2) medical inventory, 3) intravenous fluid generation, and 4) autonomous medical procedure guidance. Management of several in-flight medical conditions, such as bacterial and viral infections and acute radiation syndrome, is dramatically improved with ability to assess blood cell populations, electrolytes, and metabolites. I n December 2020 and January 2021 ExMC performed an ISS technology demonstration (Tech Demo) of the HemoCue® WBC DIFF analyzer (HemoCue, Brea, CA), a COTS device that was modified to enable functionality in a spaceflight environment. This Tech Demo marked the first time that hematology measurements were successfully performed real-time in microgravity. Also modified and demonstrated was the reusable Handheld Electrolytes and Lab Technology for Humans (rHEALTH) ONE analyzer (rHEALTH, Bedford, MA), which uses flow cytometry and sheath-based hydrodynamic focusing methodologies. The rHEALTH ONE ISS Tech Demo in May 2022 demonstrated test results obtained in-flight matched those on the ground. NASA currently relies on crew self-reporting to manage and maintain medical inventory on ISS.The ability to maintain an accurate inventory becomes more critical during long duration missions since the crew will need to be increasingly autonomous in finding and utilizing medical items, including those scenarios when alternative treatments need to be considered due to limited or no resupply. HRP’s Medical Consumables Tracking (MCT) project was developed by ZIN Technologies, Inc. (Cleveland, OH), and demonstrated real-time tracking of medical supplies aboard the ISS between December 2016 and July 2018. The MCT system design utilized Radio Frequency Identification Device (RFID) technology to perform automated inventory and was installed in the Crew Health Care System (CHeCS) Resupply Stowage Rack (RSR). The challenge of limited shelf life, exacerbated by the lack of resupply opportunities, affects a plethora of medical system components including consumables, pharmaceuticals, and intravenous (IV) fluid. In 2010, ExMC funded ZIN Technologies, Inc. (Cleveland, OH), to develop the Intravenous Fluid Generation (IVGEN) system. IV fluids were successfully generated with IVGEN using the potable water supply on ISS during ISS Expedition 23. The XMIPT is in the process of developing a miniaturized version of the original IVGEN hardware for a future Tech Demo aboard the ISS. Current ISS medical operations rely heavily on preflight training and real-time remote guidance, both of which become impractical or impossible for exploration missions. The primary goal of the Autonomous Medical Officer Support (AMOS) Software Tech Demos on ISS was to confirm telemedical proof-of-concept for autonomous medical imaging in an operational setting. This novel software tool shifts emphasis from preflight training and real-time remote guidance to in-flight just-in-time instruction, a new and necessary paradigm for crew medical autonomy. AMOS introduces a novel, streamlined skill management concept for exploration missions featuring comprehensive training and guidance modules for ultrasound examinations using the ISS Ultrasound 2 (a modified GE Vivid-q™; General Electric HealthCare, Chicago, IL). With no prior crew training or remote guidance, two Tech Demos on the ISS (April 2020 and June 2022) resulted in high quality, clinically useful image sets. We will provide a review of historical, current, and planned medical devices and technologies considered for inclusion within future spaceflight medical systems and summarize hardware development activities and medical device tech demos conducted on the ISS.

Astronaut health and performance↗

Concept of Operations for a Prospective "Proving Ground" in the Lunar Vicinity

NASA is studying conceptual architectures for a "Proving Ground" near the Moon or in high lunar orbit to conduct human space exploration missions that bridge the gap between today's operations with the International Space Station (ISS) and future human exploration of Mars beginning in the 2030s. This paper describes the framework of a concept of operations ("Conops") for candidate activities in the Proving Ground. The Conops discusses broad goals that the Proving Ground might address, such as participation from commercial entities, support for human landings on the Moon, use of mature technologies, and growth of capability through a steady cadence of increasingly ambitious piloted missions. Additional Proving Ground objectives are outlined in a companion paper. Key elements in the Conops include the Orion spacecraft (with mission kits for docking and other specialized operations) and the Space Launch System (SLS) heavy-lift rocket. Potential additions include a new space suit, commercial launch vehicles and logistics carriers, Solar Electric Propulsion (SEP) stages to move elements between different orbits and eventually take them on excursions to deep space, a core module with multiple docking ports, a habitation block, and robotic and piloted lunar landers. The landers might include reusable ascent modules which could remain docked to in-space elements between lunar sorties. A module providing advanced regenerative life support functions could launch to the ISS, and later move to the Proving Ground. The architecture will include infrastructure for launch preparation, communication, mission control, and range safety. The Conops describes notional missions chosen to guide the design of the architecture and its elements. One such mission might be the delivery of a approximately 10-t Transit Habitat element, comanifested with Orion on a Block 1B SLS launcher, to the Proving Ground. In another mission, the architecture might participate in direct human exploration of an asteroidal boulder brought to high lunar orbit by the Asteroid Redirect Mission. The Proving Ground stack could serve as a staging point and tele-operation center for robotic and piloted Moon landings. With the addition of a SEP stage, the architecture could support months-long excursions within and beyond the Earth's sphere of influence, possibly culminating in a year-long mission to land humans on a near-Earth asteroid. In the last case, after returning to near-lunar space, two of the asteroid explorers could join two crewmembers freshly arrived from Earth for a Moon landing, helping to quantify the risk of landing deconditioned crews on Mars. In a conceptual mission particularly stressing to system design, Proving Ground elements could transit to Mars orbit. Other possible design-driving operations include relocation of the stack with no crew on board, the unpiloted journey of the advanced life support module from ISS to the lunar vicinity, excursions to other destinations in near-Earth space, and additional support for Mars exploration in conjunction with the Evolvable Mars Campaign. The Proving Ground Conops concludes with a discussion of aborts and contingency operations

Love, Stanley G.↗

Roles of the ground and flight crew in Apollo operations.

The functions performed by ground personnel and flight crews of Apollo missions are reviewed, covering vehicle systems operation and management, Saturn launch vehicle, command-service and lunar modules, lunar rover, communication relay unit and ground-commanded TV assembly. Details of the flight path, scientific experiments, photographic equipment and crew health monitoring are also discussed in terms of these functions. The coordinated combination of large numbers of experts and data processing equipment on the ground with the crew's capabilities to operate the spacecraft and exercise on-the-spot judgements is viewed as the backbone of the successful fulfillment of Apollo missions.

Wolfer, B. M.↗

Meteoroid and Orbital Debris Threats to NASA's Docking Seals: Initial Assessment and Methodology

The Crew Exploration Vehicle (CEV) will be exposed to the Micrometeoroid Orbital Debris (MMOD) environment in Low Earth Orbit (LEO) during missions to the International Space Station (ISS) and to the micrometeoroid environment during lunar missions. The CEV will be equipped with a docking system which enables it to connect to ISS and the lunar module known as Altair; this docking system includes a hatch that opens so crew and supplies can pass between the spacecrafts. This docking system is known as the Low Impact Docking System (LIDS) and uses a silicone rubber seal to seal in cabin air. The rubber seal on LIDS presses against a metal flange on ISS (or Altair). All of these mating surfaces are exposed to the space environment prior to docking. The effects of atomic oxygen, ultraviolet and ionizing radiation, and MMOD have been estimated using ground based facilities. This work presents an initial methodology to predict meteoroid and orbital debris threats to candidate docking seals being considered for LIDS. The methodology integrates the results of ground based hypervelocity impacts on silicone rubber seals and aluminum sheets, risk assessments of the MMOD environment for a variety of mission scenarios, and candidate failure criteria. The experimental effort that addressed the effects of projectile incidence angle, speed, mass, and density, relations between projectile size and resulting crater size, and relations between crater size and the leak rate of candidate seals has culminated in a definition of the seal/flange failure criteria. The risk assessment performed with the BUMPER code used the failure criteria to determine the probability of failure of the seal/flange system and compared the risk to the allotted risk dictated by NASA's program requirements.

deGroh, Henry C., III↗

Meteoroid and Orbital Debris Threats to NASA's Docking Seals: Initial Assessment and Methodology

The Crew Exploration Vehicle (CEV) will be exposed to the Micrometeoroid Orbital Debris (MMOD) environment in Low Earth Orbit (LEO) during missions to the International Space Station (ISS) and to the micrometeoroid environment during lunar missions. The CEV will be equipped with a docking system which enables it to connect to ISS and the lunar module known as Altair; this docking system includes a hatch that opens so crew and supplies can pass between the spacecrafts. This docking system is known as the Low Impact Docking System (LIDS) and uses a silicone rubber seal to seal in cabin air. The rubber seal on LIDS presses against a metal flange on ISS (or Altair). All of these mating surfaces are exposed to the space environment prior to docking. The effects of atomic oxygen, ultraviolet and ionizing radiation, and MMOD have been estimated using ground based facilities. This work presents an initial methodology to predict meteoroid and orbital debris threats to candidate docking seals being considered for LIDS. The methodology integrates the results of ground based hypervelocity impacts on silicone rubber seals and aluminum sheets, risk assessments of the MMOD environment for a variety of mission scenarios, and candidate failure criteria. The experimental effort that addressed the effects of projectile incidence angle, speed, mass, and density, relations between projectile size and resulting crater size, and relations between crater size and the leak rate of candidate seals has culminated in a definition of the seal/flange failure criteria. The risk assessment performed with the BUMPER code used the failure criteria to determine the probability of failure of the seal/flange system and compared the risk to the allotted risk dictated by NASA s program requirements.

deGroh, Henry C., III↗

STS-108 Mission Highlights Resource Tape

A continuation of 'STS-108 Mission Highlights Resource Tape, Part 1 of 3' (internal ID 2002049331) and 'STS-108 Mission Highlights Resource Tape, Part 2 of 3' (internal ID 2002049330), this video shows footage from flight days 9-12. The control of the International Space Station (ISS) is handed from the Expedition 3 crew (Commander Frank Culbertson, Jr. and Flight Engineers Mikhail Turin and Vladimir Dezhurov) to the Expedition 4 crew (Commander Yuri Onufrienko and Flight Engineers Carl Walz and Daniel Bursch) in an on-orbit ceremony. Both Expedition crews and the STS-108 crew (Commander Dominic Gorie, Pilot Mark Kelly, and Mission Specialists Linda Godwin and Daniel Tani) are seen reloading the Rafaello Multipurpose Logistics Module (MPLM). External shots show the MPLM demating from the ISS and returning to the payload bay of Endeavour. The three crews bid farewell to each other before closing the hatches between ISS and Endeavour. The orbiter undocks from ISS and performs its flyarounds. ISS is seen against a backdrop of stars as Endeavour flies away. On the return flight to Earth, the Starshine 2 satellite is deployed. The video ends with the orbiter's landing as seen from several viewpoints.

Source record↗

The Headache of Carbon Dioxide Exposures

Carbon dioxide (CO2), a natural product of human metabolism, accumulates quickly in sealed environments when humans are present, and can induce headaches, among other symptoms. Major resources are expended to control CO2 levels to concentrations that are tolerable to the crews of spacecraft and submersible craft. It is not practical to control CO2 levels to those found in the ambient environment on earth. As NASA looks ahead to long-duration missions conducted far from earth, difficult issues arise related to the management and effects of human exposure to CO2. One is the problem of pockets of CO2 in the habitat caused by excess generation of the gas in one location without a mechanism to purge the area with fresh air. This results in the crew rebreathing CO2 from their exhaled breath, exposing them to a much higher concentration of CO2 than whole-module measurements would suggest. Another issue is the potential increased sensitivity to CO2 in microgravity. For example, based on anecdotal information, it appears that space crews may be more susceptible than submarine crews to some of the subtle, yet adverse effects of CO2 exposure. Another issue, not unique to spaceflight, is the possibility of inter-individual differences in the susceptibility of crewmembers to CO2 exposure. Again, anecdotal reports from the International Space Station (ISS) crews suggest that certain individuals may experience a greater susceptibility. The implications associated with these issues are extremely important as NASA sets CO2 exposure limits that protect the crew from this compound s subtle adverse effects, without causing an unwarranted expenditure of resources to scrub CO2 from the habitat atmosphere.

James, John T.↗

Affordable Space Tourism: SpaceStationSim

For over 5 years, people have been living and working in space on the International Space Station (ISS), a state-of-the-art laboratory complex orbiting high above the Earth. Offering a large, sustained microgravity environment that cannot be duplicated on Earth, the ISS furthers humankind s knowledge of science and how the body functions for extended periods of time in space all of which will prove vital on long-duration missions to Mars. On-orbit construction of the station began in November 1998, with the launch of the Russian Zarya Control Module, which provided battery power and fuel storage. This module was followed by additional components and supplies over the course of several months. In November 2000, the first ISS Expedition crew moved in. Since then, the ISS has continued to change and evolve. The space station is currently 240 feet wide, measured across the solar arrays, and 171 feet long, from the NASA Destiny Laboratory to the Russian Zvezda Habitation Module. It is 90 feet tall, and it weighs approximately 404,000 pounds. Crews inhabit a living space of about 15,000 cubic feet. To date, 90 scientific investigations have been conducted on the space station. New results from space station research, from basic science to exploration research, are being published each month, and more breakthroughs are likely to come. It is not all work on the space station, though. The orbiting home affords many of the comforts one finds on Earth. There is a weightless "weight room" and even a musical keyboard alongside research facilities. Holidays are observed, and with them, traditional foods such as turkey and cobbler are eaten, with lemonade to wash them down

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A preliminary investigation of the environmental Control and Life Support Subsystems (EC/LSS) for animal and plant experiment payloads

A preliminary study of the environmental control and life support subsystems (EC/LSS) necessary for an earth orbital spacecraft to conduct biological experiments is presented. The primary spacecraft models available for conducting these biological experiments are the space shuttle and modular space station. The experiments would be housed in a separate module that would be contained in either the shuttle payload bay or attached to the modular space station. This module would be manned only for experiment-related tasks, and would contain a separate EC/LSS for the crew and animals. Metabolic data were tabulated on various animals that are considered useful for a typical experiment program. The minimum payload for the 30-day space shuttle module was found to require about the equivalent of a one-man EC/LSS; however, the selected two-man shuttle assemblies will give a growth and contingency factor of about 50 percent. The maximum payloads for the space station mission will require at least a seven-man EC/LSS for the laboratory colony and a nine-man EC/LSS for the centrifuge colony. There is practically no room for growth or contingencies in these areas.

Wells, H. B.↗

The Lunar Lab Initiative

Analogous to terrestrial Antarctic basecamps at our south pole, space exploration outposts will be a combination of habitation and science-focused assets. The Artemis Exploration Roadmap endeavors to establish a sustained human presence on the lunar south pole starting in 2028. Within the planned Artemis Base Camp, most efforts to date have focused on the habitation assets or a mixture of science and habitation assets . With the recent advent of commercial lunar landing capabilities, the trade space can be further expanded to include dedicated science focused assets that ensure adequate science capability. To that end, the Forge, an innovation team initiative created at the Johnson Space Center (JSC), explored alternative ways to increase the science capabilities within the basecamp. The Forge uses structured brainstorming and facilitation to increase innovation within the assigned team, while executing its process in a rapid turnaround fashion for ideation and design study. As a pilot study for the Forge, a multi-disciplinary team investigated a lunar lab module to augment the lunar surface plans for Artemis. This formulation study evaluated the scientific and operational considerations for this dedicated crew space that would increase the capabilities of lunar surface science operations. The trade space evaluated single lunar lander delivery versus multiple lunar lander delivery for module assembly, alternative structural designs, the science instrument outfitting with mapping to scientific goals to maximize lunar science objectives, and how the lab would be operated. The lab operations options explored a stand-alone facility, as well as a facility integrated into a larger lunar surface complex, while evaluating crew usage and habitability considerations. The resulting alternatives were evaluated by the Forge team with a set of metrics to determine their originality, feasibility, and science performance, and thereby provide a recommendation to the lunar architecture planning team. Lessons learned from the lunar lab study were compiled to improve the process and tools for future Forge studies. Forward work, open issues, and challenges to further refine the design of the various science-focused asset options were also documented. By providing a robust science capability at humanity’s furthest outpost, we can plan for a sustained human lunar presence once the initial lunar surface access capability is well established.

Lunar outpost↗

Electrical power systems for Mars

Electrical power system options for Mars Manned Modules and Mars Surface Bases were evaluated for both near-term and advanced performance potential. The power system options investigated for the Mission Modules include photovoltaics, solar thermal, nuclear reactor, and isotope power systems. Options discussed for Mars Bases include the above options with the addition of a brief discussion of open loop energy conversion of Mars resources, including utilization of wind, subsurface thermal gradients, and super oxides. Electrical power requirements for Mission Modules were estimated for three basic approaches: as a function of crew size; as a function of electric propulsion; and as a function of transmission of power from an orbiter to the surface of Mars via laser or radio frequency. Mars Base power requirements were assumed to be determined by production facilities that make resources available for follow-on missions leading to the establishment of a permanently manned Base. Requirements include the production of buffer gas and propellant production plants.

Giudici, Robert J.↗

Summary Report of Mission Acceleration Measurements for STS-79. Launched 16 Sep. 1996

The Space Acceleration Measurement System (SAMS) collected acceleration data in support of the Mechanics of Granular Materials experiment during the STS-79 Mir docking mission, September 1996. STS-79 was the first opportunity to record SAMS data on an Orbiter while it was docked to Mir. Crew exercise activities in the Atlantis middeck and the Mir base module are apparent in the data. The acceleration signals related to the Enhanced Orbiter Refrigerator Freezer had different characteristics when comparing the data recorded on Atlantis on STS-79 with the data recorded on Mir during STS-74. This is probably due, at least in part, to different transmission paths and SAMS sensor head mounting mechanisms. Data collected on Atlantis during the STS-79 docking indicate that accelerations due to vehicle and solar array structural modes from Mir transfer to Atlantis and that the structural modes of the Atlantis-Mir complex are different from those of either vehicle independently. A 0.18 Hz component of the SAMS data, present while the two vehicles were docked, was probably caused by the Mir solar arrays. Compared to Atlantis structural modes of about 3.9 and 4.9 Hz, the Atlantis-Mir complex has structural components of about 4.5 and 5.1 Hz. After docking, apparent structural modes appeared in the data at about 0.8 and 1.8 Hz. The appearance, disappearance, and change in the structural modes during the docking and undocking phases of the joint Atlantis-Mir operations indicates that the structural modes of the two spacecraft have an effect on the microgravity environment of each other. The transfer of structural and equipment related accelerations between vehicles is something that should be considered in the International Space Station era.

Rogers, Melissa J. B.↗

STS-104 Flight Day 11 Highlights

On this 11th day of the STS-104 mission, Expedition 2 crewmembers, Commander Yuriy Usachev and Flight Engineers James Voss and Susan Helms, are seen in the Destiny Laboratory Module as they prepare for the departure of the STS-104 crew. Both the Expedition 2 crew and the STS-104 crew (Commander Steven Lindsey, Pilot Charles Hobaugh, and Mission Specialists Mike Gernhardt, Jim Reilly, and Janet Kavandi) are seen as they say their farewells and the STS-104 crew returns to the Space Shuttle. The undocking of Atlantis is shown and the International Space Station is seen against Earth and space as the orbiter flys around the station. The STS-104 crew answers questions about the mission in an on-orbit interview.

Source record↗

Solar Electric Propulsion Technologies Being Designed for Orbit Transfer Vehicle Applications

There is increasing interest in employing Solar Electric Propulsion (SEP) for new missions requiring transfer from low Earth orbit to the Earth-Moon Lagrange point, L1. Mission architecture plans place the Gateway Habitat at L1 in the 2011 to 2016 timeframe. The Gateway Habitat is envisioned to be used for Lunar exploration, space telescopes, and planetary mission staging. In these scenarios, an SEP stage, or "tug," is used to transport payloads to L1--such as the habitat module, lunar excursion and return vehicles, and chemical propellant for return crew trips. SEP tugs are attractive because they are able to efficiently transport large (less than 10,000 kg) payloads while minimizing propellant requirements. To meet the needs of these missions, a preliminary conceptual design for a general-purpose SEP tug was developed that incorporates several of the advanced space power and in-space propulsion technologies (such as high-power gridded ion and Hall thrusters, high-performance thin-film photovoltaics, lithium-ion batteries, and advanced high-voltage power processing) being developed at the NASA Glenn Research Center. A spreadsheet-based vehicle system model was developed for component sizing and is currently being used for mission planning. This model incorporates a low-thrust orbit transfer algorithm to make preliminary determinations of transfer times and propellant requirements. Results from this combined tug mass estimation and orbit transfer model will be used in a higher fidelity trajectory model to refine the analysis.

Sarver-Verhey, Timothy R.↗

THE MATERIALS ON INTERNATIONAL SPACE STATION EXPERIMENT (MISSE): FIRST RESULTS FROM MSFC INVESTIGATIONS

Marshall Space Flight Center worked with the Air Force Research Laboratory, Naval Research Laboratory, Langley Research Center, Glenn Research Center, the Jet Propulsion Laboratory, Johnson Space Center, Boeing, Lockheed Martin, TRW, the Aerospace Corporation, Triton Systems, AZ Technology, Alion (formerly IITRI), ENTECH, and L'Garde to bring together the first external materials exposure experiment on International Space Station (ISS). MISSE re-uses hardware from the MEEP flown on the Russian space station Mir. MISSE has returned a treasure trove of materials data that will be useful not only for ISS but also for programs as diverse as the new Crew Exploration Vehicle, the James Webb Telescope, the Lunar Surface Access Module, the Robotic Lunar Exploration Program, High Altitude Airships, and solar sails. MISSE-1 and -2 (Figure 1) were attached to the Quest airlock on ISS for 4 years and were retrieved during STS-114. MISSE-3 and -4 were bumped fr-om STS-114 and are currently slated for deployment during STS-121. MISSE-5 (Figure 2) was deployed during STS-114.

Finckenor, Miria↗