Speaker
Description
Introduction. The Milo Space Science Institute, a nonprofit entity co-founded by Arizona State University (ASU) and Lockheed Martin (LM), in partnership with the University of Colorado at Boulder (CU), aims to conduct a pioneering reconnaissance flyby of (99942) Apophis approximately 1 year before its close approach to Earth in April 2029. The mission, called Apophis Pathfinder, would employ two small satellites comparable to the NASA Janus spacecraft, or potentially repurpose NASA’s two existing Janus spacecraft themselves.
The goals of the Apophis Pathfinder mission are both programmatic and scientific:
A Low Cost, Planetary Defense Reconnaissance Mission to a PHA. The programmatic goals of the mission are to complete the first demonstration of a rapid-response reconnaissance flyby of a PHA to acquire data relevant to Planetary Defense, and to accomplish the mission using a low cost innovative international partnering arrangement. Both the United States National Preparedness Strategy for near-Earth Object Hazards and Planetary Defense and the NASA Planetary Defense Strategy and Action Plan focus on the unique opportunity of the Apophis Earth encounter to advance numerous Planetary Defense goals and objectives. The mission would be a simulation of a planetary defense reconnaissance scenario. Arriving at Apophis ~1 year prior to its close Earth flyby, the mission would determine characteristics that are critical to creating a defense strategy, e.g., a deflection mission like DART. The Apophis Pathfinder mission establishes a low-cost implementation baseline for planetary defense missions using small spacecraft technology piloted by Janus-class smallsat spacecraft.
Scientific Characterization of a Hazardous NEO. Many studies by the planetary science and small bodies communities have advocated for spacecraft missions to exploit the rare, extremely close 2029 Apophis Earth flyby. The 2023–2032 Planetary Science Decadal Survey noted that a “flyby mission to Apophis could be carried out with a SIMPLEx-class mission” and that a “rendezvous well in advance of the Earth flyby could map the asteroid in detail before and after its Earth passage”. Although significant physical changes in the body (except for its spin state) are not expected, this prediction could be tested by scrutinizing the surface for changes in regolith placement and distribution.” The Small Bodies Assessment Group (SBAG) Specific Action Team Report called for flight science investigations “to directly observe a geophysical process, resurfacing due to tidal effects, ... performed by a multi-band high resolution optical-near IR imager on one or more spacecraft near the asteroid before and after the close approach.”
The science objectives of the Apophis Pathfinder mission are focused on the assessment of the shape, geology, and physical, orbital, and rotational parameters of the asteroid prior to its Earth encounter using high-heritage optical and thermal-IR imaging instruments. Specifically, a close flyby of Apophis could provide visible-wavelength images for geologic and topographic assessment and mapping of the sunlit side of the asteroid at scales from ≈1-10 m/pixel, and thermal-IR images of an entire hemisphere for thermophysical properties assessment (e.g., thermal inertia) at scales from ≈10-100 m/pixel. Because the asteroid’s rotation period is ≈30.5 hours, phasing of the two spacecraft flybys by ≈15.25 hours could enable nearly the entire surface to be imaged at optical and IR wavelengths. Such a data set would enable improved derivation of the asteroid’s shape, mapping of the asteroid’s surface morphology, identification of regolith covered regions, and derivation of its pre-Earth-flyby spin state and moments of inertia. The shape and morphology assessments would be critical for enabling the detection of any reconfigurations that have changed its overall structure after the Earth flyby.
Summary. Apophis Pathfinder is an innovative, cost-effective, and non-NASA led flyby mission to Apophis. The mission’s primary objective is to understand the properties and rotation state of the asteroid well before its close approach to Earth. The scientific and Planetary Defense communities can compare the properties and rotation state with data derived from other missions during and after its close approach to measure or infer unique details about the surface and interior of Apophis. The mission’s secondary purpose is to provide data to others ~1 year before the April 2029 Earth encounter, so that missions like ESA’s Ramses and NASA’s OSIRIS-APEX that will encounter Apophis immediately before, during, and after the Earth encounter have ample time to use Apophis Pathfinder initial reconnaissance data to inform mission planning and augment their own scientific and Planetary Defense results.
Apophis Pathfinder also includes a pioneering workforce development and mission implementation approach to Planetary Defense and space science by bringing together emerging universities, research institutes, companies, and space agencies that are seeking relatively low-cost and rapid ways to increase their experience in deep space mission planning, calibration and testing, operations, and science data analysis.