Session
Session IX: Science and Exploration
Abstract
This paper describes the FalconSAT-2 mission objectives to take advantage of targets of opportunity to make multipoint in situ measurements of ionospheric plasma depletions simultaneously with other spacecraft. Because these plasma depletions are known to interfere with radio transmissions over a broad range of frequencies, including 100-1000 MHz, the international space weather community is investigating the instigation, temporal evolution, and spatial propagation of these structures in the hopes that a prediction tool may be developed to warn operators of outages in communications or navigation. FalconSAT-2 will be launched into a low altitude (360 km), medium inclination (52 degrees) orbit with sensors designed to measure in situ suprathermal plasma spectra at a rate of 10 samples per second. The primary mission objectives are to 1) investigate F region ionospheric plasma depletion morphology relative to geomagnetic activity, and 2) demonstrate the utility of the Miniature Electrostatic Analyzer (MESA) in measuring energy-resolved spectra of ionospheric electrons over a dynamic range such that plasma density depletions down to 0.1% of the background may be resolved at a rate of 10 Hz. Simultaneous in situ multipoint observations of ionospheric plasma depletions are designated as a secondary objective since FalconSAT-2 consists of a single spacecraft, and opportunities to make these simultaneous measurements with other spacecraft in compatible orbits are not in our control. Both deep and shallow bubbles, frequently observed in the pre- and post-midnight sectors, respectively [Singh at al., 1997], are known to exhibit magnetic field-aligned behavior [Fagundes et al., 1997]; thus, there is the expectation (to first order) that multiple spacecraft entering a magnetic flux tube simultaneously have the opportunity to observe a depletion structure at different points within the structure. This observation would provide insight into the plasma depletion extent along the field line. Other conjunction types, such as non-simultaneous intersection of a flux tube or crossing of orbital paths simultaneously in different magnetic flux tubes, provide insight into other aspects of depletion structure, such as constraining the plasma depletion extent and propagation speed along the magnetic field line, or plasma depletion vertical extent. With this paper, a statistical analysis of the probability that FalconSAT-2 will intersect a magnetic flux tube during eclipse simultaneously with other spacecraft capable of measuring thermal electrons is presented.
Target of Opportunity Multipoint in Situ Measurements with Falconsat-2
This paper describes the FalconSAT-2 mission objectives to take advantage of targets of opportunity to make multipoint in situ measurements of ionospheric plasma depletions simultaneously with other spacecraft. Because these plasma depletions are known to interfere with radio transmissions over a broad range of frequencies, including 100-1000 MHz, the international space weather community is investigating the instigation, temporal evolution, and spatial propagation of these structures in the hopes that a prediction tool may be developed to warn operators of outages in communications or navigation. FalconSAT-2 will be launched into a low altitude (360 km), medium inclination (52 degrees) orbit with sensors designed to measure in situ suprathermal plasma spectra at a rate of 10 samples per second. The primary mission objectives are to 1) investigate F region ionospheric plasma depletion morphology relative to geomagnetic activity, and 2) demonstrate the utility of the Miniature Electrostatic Analyzer (MESA) in measuring energy-resolved spectra of ionospheric electrons over a dynamic range such that plasma density depletions down to 0.1% of the background may be resolved at a rate of 10 Hz. Simultaneous in situ multipoint observations of ionospheric plasma depletions are designated as a secondary objective since FalconSAT-2 consists of a single spacecraft, and opportunities to make these simultaneous measurements with other spacecraft in compatible orbits are not in our control. Both deep and shallow bubbles, frequently observed in the pre- and post-midnight sectors, respectively [Singh at al., 1997], are known to exhibit magnetic field-aligned behavior [Fagundes et al., 1997]; thus, there is the expectation (to first order) that multiple spacecraft entering a magnetic flux tube simultaneously have the opportunity to observe a depletion structure at different points within the structure. This observation would provide insight into the plasma depletion extent along the field line. Other conjunction types, such as non-simultaneous intersection of a flux tube or crossing of orbital paths simultaneously in different magnetic flux tubes, provide insight into other aspects of depletion structure, such as constraining the plasma depletion extent and propagation speed along the magnetic field line, or plasma depletion vertical extent. With this paper, a statistical analysis of the probability that FalconSAT-2 will intersect a magnetic flux tube during eclipse simultaneously with other spacecraft capable of measuring thermal electrons is presented.
