Session
Session 6: Science Mission Payloads 1
Abstract
The Asteroid Probe Experiment (APEX) is a mission to determine the interior structure of the Near-Earth Asteroid Apophis and the response of that body to the tidal forces it experiences during a close encounter with the Earth. Apophis will make a close encounter of the Earth in 2029 (approaching within 0.000245 ± 0.000060 AU, 36700 ± 9000 km or 5.7 ± 1.4 Earth radii, 3σ uncertainties), which is just below geosynchronous orbit. While this distance is beyond the Roche limit and the asteroid is not expected to break up due to tidal forces, those tidal forces should be sufficient to deform the body, reorient its rotation and produce deformation that will create seismic energy. The baseline objectives of the mission include: (1) determine rotational dynamics, (2) establish physical dimensions, (3) determine topography, (4) determine interior structure, and (5) define surface morphology. Additional objectives could include the chemical and mineralogic composition and the surface physical properties. The mission will also provide data needed to calibrate interpretations of Earth- and space-based astronomical observations and Earthbased radar observations of NEOs. We will employ a small spacecraft (Discovery or Deep Space Smallsat) that will rendezvous with Apophis and conduct a suite of observations before and after Earth encounter and deploy a seismometer on the surface. We have already examined a mission employing a spacecraft having a dry mass of about 200 kg and are now examining if it is possible to conduct the mission using a Deep Space Smallsat concept. As part of that analysis, we examine different types of propulsion (solar electric and chemical) and different spacecraft concepts to determine the minimum spacecraft requirements necessary to achieve the scientific goals of the mission.
Presentation
The Asteroid Probe Experiment (APEX) Mission
The Asteroid Probe Experiment (APEX) is a mission to determine the interior structure of the Near-Earth Asteroid Apophis and the response of that body to the tidal forces it experiences during a close encounter with the Earth. Apophis will make a close encounter of the Earth in 2029 (approaching within 0.000245 ± 0.000060 AU, 36700 ± 9000 km or 5.7 ± 1.4 Earth radii, 3σ uncertainties), which is just below geosynchronous orbit. While this distance is beyond the Roche limit and the asteroid is not expected to break up due to tidal forces, those tidal forces should be sufficient to deform the body, reorient its rotation and produce deformation that will create seismic energy. The baseline objectives of the mission include: (1) determine rotational dynamics, (2) establish physical dimensions, (3) determine topography, (4) determine interior structure, and (5) define surface morphology. Additional objectives could include the chemical and mineralogic composition and the surface physical properties. The mission will also provide data needed to calibrate interpretations of Earth- and space-based astronomical observations and Earthbased radar observations of NEOs. We will employ a small spacecraft (Discovery or Deep Space Smallsat) that will rendezvous with Apophis and conduct a suite of observations before and after Earth encounter and deploy a seismometer on the surface. We have already examined a mission employing a spacecraft having a dry mass of about 200 kg and are now examining if it is possible to conduct the mission using a Deep Space Smallsat concept. As part of that analysis, we examine different types of propulsion (solar electric and chemical) and different spacecraft concepts to determine the minimum spacecraft requirements necessary to achieve the scientific goals of the mission.
