80NSSC17K0044

Recent observations of the duskside thermosphere have revealed additional complexity to the coupling between the ionosphere/thermosphere regions. There are two dominant interactions in the low-latitude dusks-side ionosphere/thermosphere: Equatorial Ionization Anomaly (EIA) and Equatorial Temperature and Wind Anomaly (ETWA).

While the EIA has been extensively studied utilizing both observations and models, the study of ETWA has been limited because of infrequent observations due to a lack of suitably-instrumented spacecraft at appropriate altitudes. The Low-Latitude Ionosphere/Thermosphere Enhancements in Density (LLITED) mission proposes to fill this need by providing both ionosphere and thermosphere measurements for use in the study of the ETWA, its associated coupling physics, and the relationship between the ETWA and EIA.

Science Goals and Objectives:
LLITED will, for the first time, provide coincident measurements of the duskside thermosphere/ionosphere at lower altitudes, providing a detailed examination of the ETWA. The mission's overall goal is to characterize the variability and the coupling drivers of the ETWA. Specifically, the mission will:
1) Determine the mesoscale variability of the ETWA as a function of season and lon/lat, as well as its relationship to EIA heating.
2) Explore the relationship between neutral winds (i.e. tides) and the EIA zonal structure.
3) Investigate the small-scale wave fluctuations in neutral atmosphere quantities, such as those observed by earlier missions, to determine if they are similarly exhibited in the ionospheric density.

Methodology:
We propose a CubeSat mission consisting of two 1.5U CubeSats in a low-inclination orbit. Each CubeSat will host three payloads: an Ionization Gauge (IG), Plasma Probe (PP), and GPS Radio Occultation Sensor (GPSRO). The IG will provide in-situ relative neutral pressure from which neutral density is inferred. The PP will provide in-situ electron density. The IG and PP sensors will characterize the thermosphere/ionosphere densities at the spacecraft. The GPSRO will provide position/navigation/time to the spacecraft attitude control system, as well as provide background ionosphere density conditions for added context.

We propose to launch the two CubeSats from the ISS and maintain a separation of ~30 deg latitude in order to sample the ionosphere/thermosphere at multiple times to characterize the ETWA evolution. The observations from LLITED will be combined with the remote sensing observations of ICON to provide a comprehensive dataset of the ETWA.

Relevance:
LLITED directly addresses two of the goals in the 2014 NASA Science Plan: explore the physical processes in the space environment from the Sun to the Earth and throughout the solar system, and advance our understanding of the connections that link the Sun, the Earth, planetary space environments, and the outer reaches of our solar system by providing new measurements of the thermosphere/ionosphere that will be used to improve our understanding of the processes behind the ETWA. This study will also improve our knowledge of Sun/Earth connection since the changes in solar illumination (day/night) result in varying pressure/density gradients, which in turn drive the ETWA through forcing in the thermosphere/ionosphere.

The Aerospace Corporation

RECENT OBSERVATIONS OF THE DUSKSIDE THERMOSPHERE HAVE REVEALED ADDITIONAL COMPLEXITY TO THE COUPLING BETWEEN THE IONOSPHERE/ THERMOSPHERE REGIONS. THERE ARE TWO DOMINANT INTERACTIONS IN THE LOW-LATITUDE DUSKS-SIDE IONOSPHERE/THERMOSPHERE: EQUATORIAL IONIZATION ANOMALY (EIA) AND EQUATORIAL TEMPERATURE AND WIND ANOMALY (ETWA). WHILE THE EIA HAS BEEN EXTENSIVELY STUDIED UTILIZING BOTH OBSERVATIONS AND MODELS THE STUDY OF ETWA HAS BEEN LIMITED BECAUSE OF INFREQUENT OBSERVATIONS DUE TO A LACK OF SUITABLY-INSTRUMENTED SPACECRAFT AT APPROPRIATE ALTITUDES. THE LOW-LATITUDE IONOSPHERE/THERMOSPHERE ENHANCEMENTS IN DENSITY (LLITED) MISSION PROPOSES TO FILL THISNEED BY PROVIDING BOTH IONOSPHERE AND THERMOSPHERE MEASUREMENTS FOR USE IN THE STUDY OF THE ETWA ITS ASSOCIATED COUPLING PHYSICS AND THE RELATIONSHIP BETWEEN THE ETWA AND EIA. SCIENCE GOALS AND OBJECTIVES: LLITED WILL FOR THE FIRST TIME PROVIDE COINCIDENT MEASUREMENTS OF THE DUSKSIDE THERMOSPHERE/IONOSPHERE AT LOWER ALTITUDES PROVIDING A DETAILED EXAMINATION OF THE ETWA. THE MISSION S OVERALL GOAL IS TO CHARACTERIZE THE VARIABILITY AND THE COUPLING DRIVERS OF THE ETWA. SPECIFICALLY THE MISSION WILL: 1) DETERMINE THE MESOSCALE VARIABILITY OF THE ETWA AS A FUNCTION SEASON AND LON/LAT AS WELL AS ITS RELATIONSHIP TO EIA HEATING. 2) EXPLORE THE RELATIONSHIP BETWEEN NEUTRAL WINDS (I.E. TIDES) AND THE EIA ZONAL STRUCTURE. 3) INVESTIGATE THE SMALL-SCALE WAVE FLUCTUATIONS IN NEUTRAL ATMOSPHERE QUANTITIES SUCH AS THOSE OBSERVED BY EARLIER MISSIONS TO DETERMINE IF THEY ARE SIMILARLY EXHIBITED IN THE IONOSPHERIC DENSITY. METHODOLOGY: WE PROPOSE A CUBESAT MISSION CONSISTING OF TWO 1.5U CUBESATS IN A LOW-INCLINATION ORBIT. EACH CUBESAT WILL HOST THREE PAYLOADS: AN IONIZATION GAUGE (IG) PLASMA PROBE (PP) AND GPS RADIO OCCULTATION SENSOR (GPSRO). THE IG WILL PROVIDE IN-SITU RELATIVE NEUTRAL PRESSURE FROM WHICH NEUTRAL DENSITY IS INFERRED. THE PP WILL PROVIDE IN-SITU ELECTRON DENSITY. THE IG AND PP SENSORS WILL CHARACTERIZE THE THERMOSPHERE/IONOSPHERE DENSITIES AT THE S/C. THE GPSRO WILL PROVIDE POSITION/NAVIGATION/TIME TO THE S/CATTITUDE CONTROL SYSTEM AS WELL AS PROVIDE BACKGROUND IONOSPHERE DENSITY CONDITIONS FOR ADDED CONTEXT. WE PROPOSE TO LAUNCH THE TWOCUBESATS FROM THE ISS AND MAINTAIN A SEPARATION OF ~30 DEG LATITUDE IN ORDER TO SAMPLE THE IONOSPHERE/THERMOSPHERE AT MULTIPLE TIMES IN ORDER TO CHARACTERIZE THE ETWA EVOLUTION. THE OBSERVATIONS FROM LLITED WILL BE COMBINED WITH THE REMOTE SENSING OBSERVATIONS OFICON TO PROVIDE A COMPREHENSIVE DATASET OF THE ETWA. RELEVANCE: LLITED DIRECTLY ADDRESSES TWO OF THE GOALS IN THE 2014 NASA SCIENCEPLAN: EXPLORE THE PHYSICAL PROCESSES IN THE SPACE ENVIRONMENT FROM THE SUN TO THE EARTH AND THROUGHOUT THE SOLAR SYSTEM AND ADVANCE OUR UNDERSTANDING OF THE CONNECTIONS THAT LINK THE SUN THE EARTH PLANETARY SPACE ENVIRONMENTS AND THE OUTER REACHES OF OUR SOLAR SYSTEM BY PROVIDING NEW MEASUREMENTS OF THE THERMOSPHERE/IONOSPHERE THAT WILL BE USED TO IMPROVE OUR UNDERSTANDING OF THE PROCESSES BEHIND THE ETWA. THIS STUDY WILL ALSO IMPROVE OUR KNOWLEDGE OF SUN/EARTH CONNECTION SINCE THE CHANGES IN SOLAR ILLUMINATION (DAY/NIGHT) RESULTS IN VARYING PRESSURE/DENSITY GRADIENTS WHICH IN TURN DRIVE THE ETWA THROUGH FORCING IN THE THERMOSPHERE/IONOSPHERE

43.001 - Science

Shared Services Center (NSSC) [NASA]

El Segundo, California 90245-4609 United States

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NOT APPLICABLE

Amendment Since initial award the End Date has been extended from 05/21/20 to 05/23/25 and the total obligations have increased 300% from $951,896 to $3,807,377.