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All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Disorder-driven localization and electron interactions in Bi x ⁢ TeI thin films

Strong disorder has a crucial effect on the electronic structure in quantum materials by increasing localization, interactions, and modifying the density of states. Bi x TeI films grown at room temperature and 230 K exhibit dramatic magnetotransport effects due to disorder, localization, and electron correlation effects, including a metal-insulator transition at a composition that depends on growth temperature. The increased disorder caused by growth at 230 K causes the conductivity to decrease by several orders of magnitude for several compositions of Bi x TeI. The transition from metal to insulator with decreasing composition x is accompanied by a decrease in the dephasing length, which leads to the disappearance of the weak-antilocalization effect. Electron-electron interactions cause low temperature conductivity corrections on the metallic side and Efros-Shklovskii variable range hopping on the insulating side, effects which are absent in single crystalline Bi x TeI. Finally, the observation of a tunable metal-insulator transition and the associated strong localization and quantum effects in Bi x TeI shows the possibility of tuning spin transport in quantum materials via disorder.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TeI by Materials Project

TeI crystallizes in the triclinic P-1 space group. The structure is one-dimensional and consists of two TeI ribbons oriented in the (1, 0, 0) direction. there are four inequivalent Te sites. In the first Te site, Te is bonded in a distorted single-bond geometry to two Te and one I atom. There are one shorter (2.87 Å) and one longer (2.89 Å) Te–Te bond lengths. The Te–I bond length is 2.78 Å. In the second Te site, Te is bonded in a rectangular see-saw-like geometry to two Te and two I atoms. The Te–Te bond length is 2.87 Å. There are one shorter (3.23 Å) and one longer (3.26 Å) Te–I bond lengths. In the third Te site, Te is bonded in a distorted single-bond geometry to two Te and one I atom. The Te–Te bond length is 2.89 Å. The Te–I bond length is 2.78 Å. In the fourth Te site, Te is bonded in a rectangular see-saw-like geometry to two Te and two I atoms. There are one shorter (3.18 Å) and one longer (3.20 Å) Te–I bond lengths. There are four inequivalent I sites. In the first I site, I is bonded in a single-bond geometry to one Te atom. In the second I site, I is bonded in a single-bond geometry to one Te atom. In the third I site, I is bonded in an L-shaped geometry to two Te atoms. In the fourth I site, I is bonded in an L-shaped geometry to two Te atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Re3(TeI)7 by Materials Project

Re3(TeI)7 crystallizes in the triclinic P-1 space group. The structure is two-dimensional and consists of one Re3(TeI)7 sheet oriented in the (0, 0, 1) direction. there are three inequivalent Re7+ sites. In the first Re7+ site, Re7+ is bonded to five Te2- atoms to form edge-sharing ReTe5 square pyramids. There are a spread of Re–Te bond distances ranging from 2.71–2.73 Å. In the second Re7+ site, Re7+ is bonded to five Te2- atoms to form edge-sharing ReTe5 square pyramids. There are a spread of Re–Te bond distances ranging from 2.69–2.74 Å. In the third Re7+ site, Re7+ is bonded to five Te2- atoms to form edge-sharing ReTe5 square pyramids. There are a spread of Re–Te bond distances ranging from 2.71–2.73 Å. There are seven inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 4-coordinate geometry to one Re7+ and three I1- atoms. There are a spread of Te–I bond distances ranging from 2.80–3.36 Å. In the second Te2- site, Te2- is bonded in a 3-coordinate geometry to one Re7+ and three I1- atoms. There are a spread of Te–I bond distances ranging from 2.80–3.85 Å. In the third Te2- site, Te2- is bonded in a 3-coordinate geometry to one Re7+ and three I1- atoms. There are a spread of Te–I bond distances ranging from 2.79–3.72 Å. In the fourth Te2- site, Te2- is bonded in a 7-coordinate geometry to three Re7+ and two equivalent I1- atoms. There are one shorter (4.06 Å) and one longer (4.27 Å) Te–I bond lengths. In the fifth Te2- site, Te2- is bonded in a 6-coordinate geometry to three Re7+ and one I1- atom. The Te–I bond length is 4.12 Å. In the sixth Te2- site, Te2- is bonded in a 11-coordinate geometry to three Re7+ atoms. In the seventh Te2- site, Te2- is bonded in a 6-coordinate geometry to three Re7+ and two equivalent I1- atoms. There are one shorter (4.36 Å) and one longer (4.60 Å) Te–I bond lengths. There are seven inequivalent I1- sites. In the first I1- site, I1- is bonded in a distorted single-bond geometry to one Te2- atom. In the second I1- site, I1- is bonded in a single-bond geometry to one Te2- atom. In the third I1- site, I1- is bonded in a distorted single-bond geometry to one Te2- atom. In the fourth I1- site, I1- is bonded in a 1-coordinate geometry to eight Te2- atoms. In the fifth I1- site, I1- is bonded in a single-bond geometry to one Te2- atom. In the sixth I1- site, I1- is bonded in a distorted single-bond geometry to one Te2- atom. In the seventh I1- site, I1- is bonded in a distorted single-bond geometry to one Te2- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Th(TeI)2 by Materials Project

Th(TeI)2 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one Th(TeI)2 sheet oriented in the (0, 0, 1) direction. Th4+ is bonded in a 8-coordinate geometry to four Te1- and four equivalent I1- atoms. There are two shorter (3.21 Å) and two longer (3.24 Å) Th–Te bond lengths. There are two shorter (3.19 Å) and two longer (3.23 Å) Th–I bond lengths. There are two inequivalent Te1- sites. In the first Te1- site, Te1- is bonded in a 2-coordinate geometry to two equivalent Th4+ atoms. In the second Te1- site, Te1- is bonded in a 2-coordinate geometry to two equivalent Th4+ atoms. I1- is bonded in a distorted water-like geometry to two equivalent Th4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TeI by Materials Project

TeI crystallizes in the triclinic P-1 space group. The structure is one-dimensional and consists of one TeI ribbon oriented in the (1, 0, 0) direction. there are two inequivalent Te sites. In the first Te site, Te is bonded in a 2-coordinate geometry to three equivalent Te and two equivalent I atoms. There are a spread of Te–Te bond distances ranging from 2.96–3.38 Å. There are one shorter (3.12 Å) and one longer (3.13 Å) Te–I bond lengths. In the second Te site, Te is bonded in a distorted single-bond geometry to three equivalent Te and one I atom. The Te–I bond length is 2.80 Å. There are two inequivalent I sites. In the first I site, I is bonded in an L-shaped geometry to two equivalent Te atoms. In the second I site, I is bonded in a single-bond geometry to one Te atom.

36 MATERIALS SCIENCE↗
NASA NTRS2006

MOI to TEI : a Mars Sample Return strategy

This paper describes the issues and challenges related to the design of the rendezvous between the Earth Return Vehicle (ERV) and the Orbiting Sample (OS) for the Mars Sample Return (MSR) mission. In particular, attention will be focused on the strategy for 'optimizing' the intermediate segment of the rendezvous process, during which there are a great number of variables that must be considered and well understood.

rendezvous↗
DOE OSTI2024

Transportation Electrification Impact Study (TEIS)

Recent U.S. Environmental Protection Agency (EPA) notices of proposed rulemakings for GHG emissions standards for light-, medium-, and heavy-duty on-road vehicles would accelerate ongoing advancements already happening in the industry because of private investment, consumer demand, state-level policies, and federal incentives. As the EPA finalizes these regulations, questions persist regarding the cost of the requisite charging infrastructure and associated upgrades to the nation's electric grid. With support from the U.S. Department of Energy, U.S. Joint Office of Energy and Transportation, and the EPA, a multidisciplinary team conducted a Multi-State Transportation Electrification Impact Study that quantitatively assesses the incremental investment necessary to enable the levels of vehicle electrification expected to be induced by pending EPA regulations and to estimate the potential value of deferred investments in electric distribution infrastructure stemming from proactive vehicle-grid integration planning and deployment. This study finds the simulated incremental capital cost of charging infrastructure (including grid upgrades) to be at least 2.5 times smaller than the lifetime net benefits of vehicle electrification (including fuel savings but excluding the value of avoided emissions). Additionally, the incremental distribution grid upgrade cost of the EPA Action-Unmanaged scenario was found to be approximately 3% of existing utility distribution system investments (on an annual basis). Finally, the potential for managed charging to defer distribution grid upgrades was found to be significant with costs found to decrease from $2.3 billion to an incremental cost of $1 billion across five states in the Action-Managed scenario (relative to the No Action-Unmanaged scenario).

ADVANCED PROPULSION SYSTEMS,POWER TRANSMISSION AND↗
NASA NTRS1994

Formative and summative evaluation efforts for the Teacher Enhancement Institute conducted at the NASA Langley Research Center, summer 1994

The Teacher Enhancement Institute (TEI) at NASA Langley Research Center was developed in response to Executive Order 12821 which mandates national laboratories to 'assist in the mathematics and science education of our Nation's students, teachers, parents, and the public by establishing programs at their agency to provide for training elementary and secondary school teachers to improve their knowledge of mathematics and science. Such programs, to the maximum extent possible, shall involve partnerships with universities, state and local elementary and secondary school authorities, corporations and community based organizations'. The faculty worked closely with one another and the invited speakers to insure that the sessions supported the objectives. Speakers were informed of the objectives and given guidance concerning form and function for the session. Faculty members monitored sessions to assist speakers and to provide a quality control function. Faculty provided feedback to speakers concerning general objective accomplishment. Participant comments were also provided when applicable. Post TEI surveys asked for specific comments about each TEI session. During the second of the two, two week institutes, daily critiques were provided to the participants for their reflection. This seemed to provide much improved feedback to speakers and faculty because the sessions were fresh in each participant's mind. Between sessions one and two, some changes were made to the program as a result of the formative evaluation process. Those changes, though, were minor in nature and comprised what may be called 'fine tuning' a well conceived and implemented program. After the objectives were written, an assessment instrument was developed to test the accomplishment of the objectives. This instrument was actually two surveys, one given before the TEI and one given after the TEI. In using such a series, it was expected that changes in the participants induced by attendance at TEI may be discovered. Because the institute was limited in time and depth of exposure, attitudinal changes (self-assessment of ability and confidence) were chosen to be surveyed. On the pre-survey, seven general categories of questions were asked. The post-survey repeated three of these categories, providing a pre and post evaluation of the same questions and added a fourth category which asked the participant to self-assess objective accomplishment. The assessment process for TEI was valuable when one looks at the final accomplishments of the TEI. A number of aspects stand out: (1) formative evaluation during project development allowed the goals and objectives to guide the development of the institute; (2) formative evaluation provided positive guidance to presenters in developing and implementing their session; (3) formative evaluation helped presenters to improve or focus their sessions; (4) summative evaluation provided managers a way to gauge the success of the institute; (5) summative evaluation provided a benchmark for future programs to be measured against.

Carlson, Randal D.↗
NASA NTRS1998

Technology Development, Implementation, and Assessment: K-16 Pre-Service, In-Service, and Distance Learning Initiatives

This summer 22 kindergarten through 8th grade teachers attended a 3-week Teacher Enhancement Institute (TEI) at NASA Langley Research Center. TEI is funded by NASA Education Division and is a collaborative effort between NASA Langley's Office of Education and Christopher Newport University. Selected teacher teams were drawn from Langley's 5-state precollege service region, which includes Kentucky, North Carolina, South Carolina, Virginia, and West Virginia. The goal of TEI was for teachers to learn aeronautics and the broad application of science and technology through a problem-based learning (PBL) strategy. PBL is an instructional method using a real world problem, also known as an ill-structured problem, as the context for an in-depth investigation. Most real life problems are ill-structured, as are all the really important social, political and scientific problems. The teachers were immediately immersed in an ill-structured problem to design a communication strategy for the White House Commission on Aviation Safety and Security to educate and disseminate aviation information to the general public. Specifically, the communication strategy was to focus on aeronautics principles, technology and design associated with US general aviation revitalization and aviation safety programs. The presented problem addressed NASA's strategic outcome to widely communicate the content, relevancy and excitement of its missions and discoveries to the general population. Further, the PBL scenario addressed the technological challenges being taken up by NASA to revolutionize air travel and the way in which aircraft are designed, built, and operated. It also addressed getting people and freight safely and efficiently to any location in the world at a reasonable cost. With a "real" need-to-know problem facing them, the teachers set out to gather information and to better understand the problem using inquiry-based and scientific methods. The learning in this aeronautics scenario was driven by the direction taken by participants. With the support of the TEI faculty, the teachers quickly identified NASA Langley researchers that served as consultants to help solve the problem. To achieve their goal, the teacher teams developed lesson plans for elementary and middle school students, wrote a newspaper, published a brochure to educate the general public, constructed games for children of all ages, and produced a video. As a second problem, the TEI participants will design their own aeronautic lesson plan and immerse their 1997-98 school year students in the problem. The problem is for the students "to create a traveling hands-on, minds-on aeronautics museum exhibit created for children by children." As a culminating activity, the Virginia Air and Space Center in Hampton, VA, will set up a special display of the exhibits in the Summer 1998. The TEI faculty will visit each TEI teacher's classroom during the academic school year to observe the implementation of the unit. In addition to the classroom observations, electronic follow-up sessions will be conducted during the school year to support the teachers' efforts in developing their PBL units to integrate technology in math and science instruction. These sessions eill be conducted using the Internet. Teachers will be connected through a chat-line to share ideas, ask questions, and generate solutions.

Petersen, Richard↗
NASA NTRS1994

Design and implementation of two two-week Teacher Enhancement Institutes

During this summer, I have been part of a four team effort that planned and executed two two-week Teacher Enhancement Institutes (TEI) for 40 K-8 teachers from this area. The TEI was designed to enhance teachers' background in aeronautics and technology so that they would be better equipped to encourage and to train students in the mathematics, science, and technology fields. The teachers were given a stipend and three graduate credits from Christopher Newport University for their participation in this program. The four ASEE fellows worked together to develop objectives and a schedule of activities for each two-week session based on the program outline given in the grants that were funding this effort. We divided the responsibilities in coordinating and implementing each part of the TEI based on the specific strengths and background of each ASEE fellow. My specific responsibilities were: (1) to develop the course syllabus and generally handle all matters involved with the graduate course; (2) coordinate the follow-up sessions; and (3) design and manage half of the technology sessions that we had scheduled (approximately 30% of the TEI was devoted to technology). Because the first two responsibilities were primarily administrative in nature, I will address only the last. The technology sessions were divided into computer-only and other technologies (e.g., television and digital technology including scanning, digital photography and CD-ROM). I had responsibility for the computer-only technology sessions. The emphasis of these sessions was on use of the Internet specifically to locate and use educational resources. To maximize learning, these sessions were hands-on with two teachers at each computer. Each teacher received instruction in, and actually used, the most popular tools available on the Internet: email (they were given temporary accounts at NASA LaRC), anonymous ftp and archie, gopher and veronica, mosaic, and telnet. Teachers participated in hands-on workshops to learn about these programs, but were also given time during the two-week session to explore on their own and to find resources on the Net that specifically met their needs. In order to ensure that Internet access continues after their return to the classroom, aIl teachers who did not have them also applied for Learning Link accounts (from WHRO, the local public television station) and Virginia Pen accounts (from the Department of Education of Virginia), both of which allow textbased access to Internet. In addition to getting exposure to and practice with Internet tools, teachers were aIso given a hands-on seminar (and also given practice time) on ClarisWorks, an integrated word processing, spreadsheet, database, and paint package. The technology sessions (and TEI as a whole) were enthusiastically received by both new and more experienced teachers as extremely helpful in improving their ability to use technology in developing lesson pIans.

Lambert, Lynn↗
NASA NTRS1995

Three two-week enhancement institutes: Design and implementation of the technology and telecomputing component

The Teacher Enhancement Institute (TEI), under the direction of the Center Education Programs Officer offered three two-week workshops to 58 elementary and middle school teachers in science, math, and technology using the Problem Based Learning Model. The 1995 program was designed with input from evaluations and recommendations from previous TEI participants and faculty. The TEI focused on Aviation and Aeronautics as the unifying theme. Four specific objectives were developed. After completing the requirements for the TEI, the participants should be able to: (1) Increase their content knowledge, particularly in aeronautics, science, math, and technology; (2) Design and implement lessons that use scientific inquiry through Problem Based Learning; (3) Demonstrate knowledge of instructional technologies, their uses, and applications to curricula; and (4) Disseminate to their school communities the information acquired through the TEI. Thirty percent of the program was devoted to the effective use of computer technology. SpaceLink, the NASA telecomputing service for educators, was the primary tool used in the technology component of the institute. The training focused on the use of SpaceLink and its many educational services, and Internet tools because of its universal, nongraphical link to any computer plafform the participant may use at his or her school or home. All participants were given Educator Accounts to facilitate the use of E-mail, and access to the Internet and the World Wide Web using their SpaceLink accounts. Classroom demonstrations used videotaped guides and handouts to support concepts presented followed by intensive hands-on activities. Each participant was assigned to an individual Power Mac networked workstation and introduced to the state of the art, graphical, Word Wide Web with the Netscape browser. The methodology proved very effective in reaching the program's goals for technology integration by having the participants learn to use the computer as a tool for communication and research rather than teaching the use of any particular software application alone. However, because of the skill level of the majority of the participants, more hands-on computer time is recommended for future Teacher Enhancement Institutes.

Hale, L. Vincent↗
NASA NTRS2007

CEV Trajectory Design Considerations for Lunar Missions

The Crew Exploration Vehicle (CEV) translational maneuver Delta-V budget must support both the successful completion of a nominal lunar mission and an "anytime" emergency crew return with the potential for much more demanding orbital maneuvers. This translational Delta-V budget accounts for Earth-based LEO rendezvous with the lunar surface access module (LSAM)/Earth departure stage (EDS) stack, orbit maintenance during the lunar surface stay, an on-orbit plane change to align the CEV orbit for an in-plane LSAM ascent, and the Moon-to-Earth trans-Earth injection (TEI) maneuver sequence as well as post-TEI TCMs. Additionally, the CEV will have to execute TEI maneuver sequences while observing Earth atmospheric entry interface objectives for lunar high-latitude to equatorial sortie missions as well as near-polar sortie and long duration missions. The combination of these objectives places a premium on appropriately designed trajectories both to and from the Moon to accurately size the translational V and associated propellant mass in the CEV reference configuration and to demonstrate the feasibility of anytime Earth return for all lunar missions. This report examines the design of the primary CEV translational maneuvers (or maneuver sequences) including associated mission design philosophy, associated assumptions, and methodology for lunar sortie missions with up to a 7-day surface stay and with global lunar landing site access as well as for long duration (outpost) missions with up to a 210-day surface stay at or near the polar regions. The analyses presented in this report supports the Constellation Program and CEV project requirement for nominal and anytime abort (early return) by providing for minimum wedge angles, lunar orbit maintenance maneuvers, phasing orbit inclination changes, and lunar departure maneuvers for a CEV supporting an LSAM launch and subsequent CEV TEI to Earth return, anytime during the lunar surface stay.

Condon, Gerald L.↗
NASA NTRS2010

Implementation of an Autonomous Multi-Maneuver Targeting Sequence for Lunar Trans-Earth Injection

Using a fully analytic initial guess estimate as a first iterate, a targeting procedure that constructs a flyable burn maneuver sequence to transfer a spacecraft from any closed Moon orbit to a desired Earth entry state is developed and implemented. The algorithm is built to support the need for an anytime abort capability for Orion. Based on project requirements, the Orion spacecraft must be able to autonomously calculate the translational maneuver targets for an entire Lunar mission. Translational maneuver target sequences for the Orion spacecraft include Lunar Orbit Insertion (LOI), Trans-Earth Injection (TEI), and Trajectory Correction Maneuvers (TCMs). This onboard capability is generally assumed to be supplemental to redundant ground computation in nominal mission operations and considered as a viable alternative primarily in loss of communications contingencies. Of these maneuvers, the ability to accurately and consistently establish a flyable 3-burn TEI target sequence is especially critical. The TEI is the sole means by which the crew can successfully return from the Moon to a narrowly banded Earth Entry Interface (EI) state. This is made even more critical by the desire for global access on the lunar surface. Currently, the designed propellant load is based on fully optimized TEI solutions for the worst case geometries associated with the accepted range of epochs and landing sites. This presents two challenges for an autonomous algorithm: in addition to being feasible, the targets must include burn sequences that do not exceed the anticipated propellant load.

Whitley, Ryan J.↗
NASA NTRS1994

Teacher Enhancement Institute

During the 1980's, a period of intense concern over educational quality in the United States, few indicators of U.S. student achievement garnered the interest of policy makers and pundits as successfully as the results of international testing in mathematics and science. This concern was so great that as a part of the Goals 2000 initiative, President George Bush indicated that 'By the year 2000, U.S. students should be first in the world in mathematics and science.' The Clinton Administration is placing a major emphasis, not only on rigorous academic standards and creating a new system for assessing students' progress, but also including professional development as a major focus. The argument being that teachers need more sustained, intensive training to prepare them to teach to higher standards. Executive order 12821 mandates that national laboratories 'assist in the mathematics and science education of our Nation's students, teachers, parents and the public by establishing programs at their agency to provide for training elementary and secondary school teachers to improve their knowledge of mathematics and science'. These and other issues led to the development of ideas for a project that addresses the need for excellence in mathematics, science and technology instruction. In response to these initiatives the NASA/LaRC Teacher Enhancement Institute was proposed. The TEI incorporated systemic reform perspectives, enhanced content knowledge for teachers, and teacher preparation. Emphasis was also placed on recruiting those educators who teach in impoverished urban school districts with at-risk student populations who have been traditionally under represented in science, mathematics, technology and engineering. Participants in the Teacher Enhancement Institute were 37 teachers from grades K-8, teaching in Region 2 in the state of Virginia, as well as 2 preservice teachers from Norfolk State University and one teacher from Dublin, Virginia, where a Science/Mathematics model school has been established. Teachers selected for this project represented school systems where income levels are extremely low, and students served tend not to receive innovative instruction in mathematics and science and their use of technology is limited. The Teacher Enhancement Institute contained several features, that when combined, allowed for a unique experience. Some of these features included local teachers, administrators and school board members as presenters, instruction and use of technology every day, tours of select features of the research facility, briefings by NASA/LaRC scientists, engineers and researchers as well as individuals from the Continuous Electron Beam Accelerator Facility (CEBAF). Another unique feature of this program is to have participants convene on three separate occasions throughout the academic year to discuss strategies for information dissemination and implementation results. Teachers' attitudes towards the use of technology, their ability to develop lessons using technology and their ability to develop lessons using information obtained through TEI were assessed using instruments developed by TEI summer faculty members. Data from these instruments were analyzed and reported in a final report submitted to the director of the Office of Education.

Marshall-Bradley, Tina↗
NASA NTRS2009

Right Ventricular Tissue Doppler Assessment in Space During Circulating Volume Modification using the Braslet-M Device

This joint U.S. - Russian work aims to establish a methodology for assessing cardiac function in microgravity in association with manipulation of central circulating volume. Russian Braslet-M occlusion cuffs were used to temporarily increase the volume of blood in the lower extremities, which effectively reduces the volume returning to the heart in the central circulation. A novel methodology was tested on the International Space Station (ISS) to assess the volume status of crewmembers by evaluating the responses to application and release of the Braslet-on-occlusion cuffs, as well as to modified Valsalva and Mueller maneuvers. Baseline echocardiographic tissue Doppler imaging (TDI) of the right ventricular free wall with no Braslet applied shows early diastolic E' (16 cm/sec), late diastolic A' (14 cm/sec), and systolic (12 cm/sec) velocities compatible with normal subjects on Earth. TDI of the RV free wall with Braslet applied shows that early diastolic E' decreased by 50% (8 cm/sec), late diastolic A' increased by 45%, and systolic S' remains unchanged. TDI of the RV free wall approximately 8 beats after the Braslet was released shows early diastolic E' (8 cm/sec), late diastolic A' (12 cm/sec), and systolic S' (13 cm/sec) velocities. During this portion of the release, early diastolic E' did not recover to baseline values but late diastolic A' and systolic S' recovered to pre-Braslet values. The pre-systolic cross-sectional area of the internal jugular vein with Braslet off was 1.07 cm(sup 2) and 1.13 cm(sup 2) 10 min after the Braslet was applied. The presystolic cross-sectional area of the common femoral vein with Braslet off was 0.50 cm(sup 2), and was 0.54 cm(sup 2) 10 min after the Braslet was applied. The right ventricular myocardial performance Tei index also was calculated for comparison with typical values found in healthy subjects on Earth. Baseline and Braslet-on values for Tei index were 0.25 and 0.22 respectively. Braslet Tei indices are within normal ranges found in healthy subjects and temporarily become greater than 0.4 during the dynamic Braslet release portion of this study. Tissue Doppler imaging of the right ventricle revealed that the Braslet influenced cardiac preload and that fluid was sequestered in the lower-extremity interstitial and vascular space after only 10 minutes of application. This report demonstrates that Braslet application affects right ventricular physiology in long-duration space flight based on TDI and that this effect is in part due to venous hemodynamics.

Hamilton, D. R.↗
NASA NTRS2009

Global Performance Characterization of the Three Burn Trans-Earth Injection Maneuver Sequence over the Lunar Nodal Cycle

The Orion spacecraft will be required to perform a three-burn trans-Earth injection (TEI) maneuver sequence to return to Earth from low lunar orbit. The origin of this approach lies in the Constellation Program requirements for access to any lunar landing site location combined with anytime lunar departure. This paper documents the development of optimized databases used to rapidly model the performance requirements of the TEI three-burn sequence for an extremely large number of mission cases. It also discusses performance results for lunar departures covering a complete 18.6 year lunar nodal cycle as well as general characteristics of the optimized three-burn TEI sequence.

Williams, Jacob↗
NASA NTRS2009

Right Ventricular Tissue Doppler in Space Flight

Tissue Doppler (TD) registers movement of a given sample of cardiac tissue throughout the cardiac cycle. TD spectra of the right ventricle (RV) were obtained from a long-duration ISS crewmember as a portion of an ongoing experiment ("Braslet" test objective). To our knowledge, this is the first report of RV TD conducted in space flight, and the data represent reproducibility and fidelity of this application in space and serve as the first "space normal" data set. Methods RV TD was performed by astronaut scientists remotely guided by an ultrasound expert from Mission Control Center, Houston, TX. In four of the subjects, RV TD was acquired from the free wall near the tricuspid annulus in two separate sessions 4 to 7 days apart. A fifth subject had only one session. All digital DICOM frames were exported for off-line analysis. Systolic (S ), early diastolic (E ) and late diastolic (A ) velocities were measured. RV Tei-index was calculated using diastolic and systolic time intervals as a combined measure of myocardial performance. Results and Discussion The mean values from the first 4 subjects (8 sessions) were used as the on-orbit reference data, and subject 5 was considered as a hypothetical patient for comparison (see Table). The greatest difference was in the early diastolic A (31 %) yet the standard deviation (a) for A amongst the reference subjects was 2.25 (mean = 16.02). Of interest is the Tei index, a simple and feasible indicator of overall ventricular function; it was similar amongst all the subjects. The late diastolic A seems to compensate for the variance in E . Normal Tei index for the RV is < 0.3, yet our data show all but one subject consistently above this level, notwithstanding their nominal responses to daily exercise in microgravity. These data remind us that the physiology of RV preload in altered gravity environments is still not completely understood.

Hamilton, Douglas R.↗