The Station Explorer for X-ray Timing and Navigation Technology (SEXTANT) is a NASA funded technologydemonstration. SEXTANT will, for the first time, demonstrate real-time, on-board X-ray Pulsar-based Navigation (XNAV), a significant milestone in the quest to establish a GPS-like navigation capability available throughout our Solar System and beyond.This paper describes the basic design of the SEXTANT system with a focus on core models and algorithms, and the design and continued development of the GSFC X-ray Navigation Laboratory Testbed (GXLT) with its dynamic pulsar emulation capability. We also present early results from GXLT modeling of the combined NICER X-ray timing instrument hardware and SEXTANT flight software algorithms.
The Station Explorer for X-ray Timing and Navigation Technology (SEXTANT) is a technology demonstration enhancement to the Neutron-star Interior Composition Explorer (NICER) mission, which is scheduled to launch in late 2016 and will be hosted as an externally attached payload on the International Space Station (ISS) via the ExPRESS Logistics Carrier (ELC). During NICER's 18-month baseline science mission to understand ultra-dense matter though observations of neutron stars in the soft X-ray band, SEXTANT will, for the first-time, demonstrate real-time, on-board X-ray pulsar navigation, which is a significant milestone in the quest to establish a GPS-like navigation capability that will be available throughout our Solar System and beyond. Along with NICER, SEXTANT has proceeded through Phase B, Mission Definition, and received numerous refinements in concept of operation, algorithms, flight software, ground system, and ground test capability. NICER/SEXTANT's Phase B work culminated in NASA's confirmation of NICER to Phase C, Design and Development, in March 2014. Recently, NICER/SEXTANT successfully passed its Critical Design Review and SEXTANT received continuation approval in September 2014. In this paper, we describe the X-ray pulsar navigation concept and provide a brief history of previous work, and then summarize the SEXTANT technology demonstration objective, hardware and software components, and development to date.
Hispanics have become the largest ethnic minority in the US Better serving Hispanics to succeed in tertiary education and scientific fields like computing is critical to build equitable life opportunities and strengthen the US workforce. Typically, the most selective postsecondary institutions are emphasized as exemplary models for developing human capital in the US. Yet, due to the nation's tertiary education institutional stratification, relatively low numbers of Hispanics are enrolled in these institutions. We examine how Hispanic-Serving Institutions (HSIs), federally designated institutions in the US that enroll at least 25% Hispanics, develop strategies to raise Hispanic attainment in computing fields. Specifically, we explore the activities of HSIs in the Computing Alliance for Hispanic-Serving Institutions (CAHSI), a network of over 60 HSIs and other stakeholders that are committed to raising Hispanic attainment in postsecondary computing. We address the question: How do HSIs in CAHSI employ strategies to develop talent in computing among Hispanics? Specifically, we examine how CAHSI institutions apply values that are grounded in Hispanic communities, including emphases on confianza, respeto, and familia, to support Hispanic students in computer science. Our findings indicate the importance of centering Hispanic cultural assets to improve Hispanic success in computing.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.