| 英文摘要: | This project is to design, develop, construct, operate and analyze the results of a spacecraft CubeSat mission named "Ionospheric-Thermospheric Scanning Photometer for Ion-Neutral Studies" (IT-SPINS). The ionosphere affects modern technologies such as civilian and military communications and navigation and surveillance systems. Reliable communication and navigation, therefore, often requires correction of the signals for effects imposed by the ionosphere. To do that the properties of the ionosphere, such as its variability with respect to magnetospheric disturbance, time of day, season of the year, and solar cycle variability must be well understood and modeled. The fundamental measurements of IT-SPINS are high-sensitivity line-of-sight observations of Ultra Violet nightglow radiance produced by the recombination of Oxygen ions with electrons in the upper ionosphere. IT-SPINS will rotate at two rotations per minute about the orbit normal and will acquire 60 radiance measurements per revolution. Observations from several rotations will then be combined in a tomographic inversion algorithm to produce two-dimensional altitude/in-track images of the emissions. In this way, IT-SPINS will provide the first-ever set of unambiguous, geographically-extended measurements of the Oxygen ion distributions within the nightside ionosphere. Specifically, IT-SPINS will provide crucial information on the ion gradient structures in the, so-called, Topside Transition Region, from approximately 500km to 1000km altitude, where a transition takes place in the plasma conditions from being dominated by Oxygen ions to being dominated by Hydrogen ions. Prior studies of the TTR have primarily used large incoherent scatter radars at only a few locations around the World. Consequently, a thorough climatological study of the TTR's dependence on latitude, local time, and solar and geomagnetic activity does not exist at present. Lacking fundamental understanding of the variability of the TTR and the detailed morphology of Oxygen ion distributions throughout the TTR is a critical limitation currently in our ability to accurately model and predict ionospheric variability.
Beyond fundamental space weather objectives, the IT-SPINS project places a significant priority on experimental learning in Science, Technology, Engineering and Mathematics (STEM) education at the university undergraduate level. Undergraduate students will participate in responsible roles on all aspects of the project. This provides the students with rare and valuable opportunities to learn and practice project management; systems engineering; engineering design, development and testing; and flight operations and data analysis skills through first-hand, project-based learning while being mentored by faculty and professional staff. In addition, through affiliation with the statewide Montana Space Grant Consortium
(MSGC), the project will engage traditionally disadvantaged students at MSGC affiliated Tribal Colleges with IT-SPINS operational activities during the orbital phase.
IT-SPINS can achieve compelling science results over a wide range of available orbit inclinations (>40 degrees) and altitudes (500-700 km). This altitude range puts us at optimal viewing of the TTR above, and plasma structures below the satellite while ensuring a 25-year de-orbit criteria. The following primary and secondary science objectives and derived science questions are designed so that a subset of them can be addressed by IT-SPINS regardless of the satellite orbit it will be given. The primary science objective for the mission is to study the variability of the TTR and O+ altitude profiles. The following three questions will be addressed: 1) How does the altitude and thickness of the boundary between O+ dominated ionospheric physics and H+, He+ dominated plasmasphere physics vary as a function of magnetic L-shell, magnetic longitude, local time and geomagnetic activity? 2) How well do Geospace numerical models predict the observed variability of the TTR and O+ altitude profiles? 3) What is the importance of the charge exchange between O+ and neutral hydrogen to the TTR? Imaging the mesoscale structuring of equatorial plasma bubbles and polar cap patches constitutes a secondary science objective for the mission. The equatorial part of the secondary science objective can be addressed by both mid- and high inclination orbits, whereas the polar patch part can only be addressed for high inclination orbits
(~70 degrees or higher). |