Power and Propulsion Element (PPE) Spacecraft Reference Trajectory Document

This document captures example reference trajectories for the PPE including a reference delivery orbit and orbit maintenance, an example cislunar orbit transfer and end-of-mission (EOM) disposal trajectory. The flexibility of electric propulsion offers, by its low thrust nature, multiple different trajectory options to transfer from one orbit to another. The trajectories captured in this document are representative examples of a low thrust transfer from the NRHO and to multiple cislunar orbits. This document provides a consistent set of data from mission design to be used in the design of the vehicle capable of flying the trajectory described. The data in this document will be used to create conference papers. In order to do so, we are ending this document through for external release

Implementing the information prescription protocol in a family medicine practice: a case study.

QUESTION: Can an information prescription protocol be successfully integrated into a family medicine practice seeking to enhance patient education and self-management? SETTING: Milton Family Practice, an outpatient clinic and resident teaching site of the University of Vermont and Fletcher Allen Health Care, is located in a semirural area fifteen miles from main campus. OBJECTIVES: The objectives were to increase physicians\u27 knowledge and use of information prescriptions, sustain integration of information prescription use, and increase physicians\u27 ability to provide patient education information. METHODS: Methods used were promotion of the National Library of Medicine\u27s Information Rx, physician instruction, installation of patient and provider workstations, and a collaborative approach to practice integration. MAIN RESULTS: A post-intervention survey showed increased physician knowledge and use of the Information Rx protocol. Support procedures were integrated at the practice. CONCLUSIONS: Sustainable integration of Information Rx in a primary care clinic requires not only promotion and education, but also attention to clinic organization and procedures

Why Did the Terrapin Cross the Runway?

Diamondback terrapins (Malaclemys terrapin) have been nesting at John F. Kennedy International Airport (JFK) for decades. In 2009, the airport experienced a surge in terrapin activity that led to closing a portion of a runway. Runway closures may delay aircraft traffic at JFK which in turn can cause a ripple effect with delays at airports across the country. During the months of June and July, the terrapin nesting season coincides with peak travel for aircraft passengers with about 1,200-1,300 aircraft movements per day. The airport began collecting data on terrapins in 2010 to help understand the dynamics. From 2000-2012, aircraft struck an average of 3.8 terrapins per year. However, no aircraft were damaged as a result of striking terrapins and there were no other negative effects on flights. The airport did experience operational effects such as brief runway closures in order to move terrapins off runways or taxiways. Data collected from 2010-2012 showed increases from 200 to 1,300 terrapins relocated during the annual nesting season. At peak times, more than 200 terrapins have been relocated in a two-hour period. The dates of the peak nesting activity varied by year; however, there was a peak during the second week of June and no nesting activity observed after 17 July. The number of terrapins nesting and relocated per day was similar in 2011-2012, ranging from about 50-200 terrapins. In contrast, researchers observed 30-50 terrapins nesting each day in 2011-2012 at the nearby Jamaica Bay Wildlife Refuge. Terrapins that were collected in 2010-2012 were also measured to determine plastron and carapace length, marked with shell notches and passive integrated transponder (PIT) tags, and then released. In 2012, over 84% of the terrapins collected were ≤ 160 mm, suggesting that this is a young terrapin population. Terrapins at JFK also captured the attention of media around the world and resulted in positive images of the airport’s wildlife program. Management of terrapins at the airport must take into account the socio-political aspects of the issue, but also address potential safety hazards and operational problems posed by the large numbers of terrapins in the aircraft movement area. The airport was directed by FAA to address the terrapins in 2012 and set up a trial of two different barriers. Trail cameras were used to test the effectiveness of the barriers and provided results that helped to refine our survey techniques

Analysis of Cislunar Transfers from a Near Rectilinear Halo Orbit with High Power Solar Electric Propulsion

As government and commercial interest in the exploration of the Moon and cislu- nar space has grown, Near Rectilinear Halo Orbits (NRHOs) have shown to be of particular interest as staging orbits for human exploration of the Moon. Once in such staging orbits, low thrust solar electric propulsion (SEP) can enable efficient transfer to other orbits in cislunar space. This paper captures ongoing analysis to design efficient transfers of a massive spacecraft from a L2 Southern NRHO to a Distant Retrograde Orbit, L1 Northern NRHO, and Flat L2 Halo Orbit using low thrust SEP. For each transfer type, reference transfer is designed for an assumed 39 t spacecraft with 26.6 kW SEP system. For each reference transfer, analysis is completed to understand the sensitivity of the transfer to changes in initial mass and SEP power and identify the optimal number of thrusters to use for a given combination of mass and power

Technology-Enhanced Practice for Patients with Chronic Cardiac Disease: Home Implementation and Evaluation

Objective: This 3-year field experiment engaged 60 nurses and 282 patients in the design and evaluation of an innovative home-care nursing model, referred to as technology-enhanced practice (TEP). Methods: Nurses using TEP augmented the usual care with a web-based resource (HeartCareII) that provided patients with self-management information, self-monitoring tools, and messaging services. Results: Patients exposed to TEP demonstrated better quality of life and self-management of chronic heart disease during the first 4 weeks, and were no more likely than patients in usual care to make unplanned visits to a clinician or hospital. Both groups demonstrated the same long-term symptom management and achievements in health status. Conclusion: This project provides new evidence that the purposeful creation of patient-tailored web resources within a hospital portal is possible; that nurses have difficulty with modifying their practice routines, even with a highly-tailored web resource; and that the benefits of this intervention are more discernable in the early postdischarge stages of care

Analysis of Near Rectilinear Halo Orbit Insertion with a 40-kW Solar Electric Propulsion System

This paper examines low thrust trajectories for delivery of a 40-kW solar electric propulsion spacecraft and potential additional payload to a desired NRHO. One option considered is a trans-lunar injection launch as a co-manifested payload on the Space Launch System. For this option, a reference trajectory is designed and a scan of launch dates is completed to understand the propellant mass sensitivity. A 15-day period cyclical variation in required propellant is observed that is attributed to solar gravity effects. A second option considered is to launch on a smaller commercial launch vehicle to a less energetic elliptical orbit and use SEP to spiral out to NRHO. For this option, analysis is completed to understand the trades between delivered mass to NRHO, total propellant required, time of flight, and solar array degradation. Results show that, while launching to lower altitudes can deliver greater payload mass to NRHO, significant solar array degradation can be observed

NASA GRC Compass Team Conceptual Point Design and Trades of a Hybrid Solar Electric Propulsion (SEP)/Chemical Propulsion Human Mars Deep Space Transport (DST) Vehicle

NASA has long been conducting studies which apply different in-space propulsion technology assumptions to the mission of sending humans to Mars. Two of the technologies under study that are considered to be the most near-term with respect to technology readiness level (TRL) are traditional chemical propulsion systems and high-power Solar Electric Propulsion (SEP) systems. The benefit of relatively low trip times inherent in using impulsive chemical propulsion systems to perform the full round-trip delta V is hampered by the large propellant mass required to perform these burns for human Mars missions. SEP systems offer the benefit of much lower propellant requirements to perform the same round-trip missions, at the cost of longer trip times. Traditionally, impulsive chemical systems are better suited than SEP when used in a gravity well, and SEP systems are more efficient than traditional impulsive systems when used in interplanetary space. A mission to Mars includes both of these scenarios, and thus several NASA architecture studies performed over the last few years have looked to combine the use of both SEP and chemical propulsion systems where they are the most beneficial to human Mars missions. This combined propulsion system concept has been referred to as a SEP/Chem hybrid Mars Transfer Vehicle and is currently shown as the concept Deep Space Transport (DST) in the March 2017 NASA presentation to the National Aerospace Council (NAC)

Comparison of Solar Electric and Chemical Propulsion Missions

Solar Electric Propulsion (SEP) offers fuel efficiency and mission robustness for spacecraft. The combination of solar power and electric propulsion engines is currently used for missions ranging from geostationary stationkeeping to deep space science because of these benefits. Both solar power and electric propulsion technologies have progressed to the point where higher electric power systems can be considered, making substantial cargo missions and potentially human missions viable. This paper evaluates and compares representative lunar, Mars, and Sun-Earth Langrangian point missions using SEP and chemical propulsion subsystems. The potential benefits and limitations are discussed along with technology gaps that need to be resolved for such missions to become possible. The connection to NASA's human architecture and technology development efforts will be discussed