Astronauts beyond the Moon: Mission operations at a near-earth object

Abstract

The 2009 Augustine Committee review of U.S. human spaceflight plans cited Near-Earth Objects (NEOs) as promising, practical astronaut destinations. NEOs provide the National Aeronautics and Space Administration (NASA) an attractive focus for future deep-space exploration, and will reinforce the scientific, operations, economic, programmatic, international, planetary defense, and public outreach elements of NASA's human exploration program. Astronauts exploring a NEO would provide synergistic scientific return from a new "planetary" surface, substantially different in origin, age, and composition from those of the Moon or Mars. Explorers would assay NEO resources vital to future U.S. explorations and economic activities in space, and demonstrate extraction and utilization techniques for water, volatiles, and valuable metals. Piloted missions will also provide structural and civil engineering data needed for future deflection of hazardous NEOs. Preventing a damaging collision with Earth is a fundamental mission for our exploration efforts, one widely understood and supported by the public. NASA continues to investigate NEO operations concepts and possible mission profiles to nearby asteroids. The most suitable NEO targets for a crewed mission are those in heliocentric orbits similar to Earth's. For a growing number of such targets, total mission Δv's from low Earth orbit (LEO) are < 9 km/s, less than that of a lunar round trip. Next-generation NEO search systems will discover tens of thousands of new NEOs (and hundreds of accessible NEO targets), and should be funded as soon as possible. Human expeditions beyond the Moon present unique challenges for the crew, spacecraft systems, and the mission control team. Because NEOs have very low surface gravity, the spacecraft will not require a lander; the crew will station-keep alongside or "dock" to the NEO's surface. Initial remote sensing and telerobotic reconnaissance would be followed by surface extravehicular activity (EVA). Docking and proximity operations experience gained during the Apollo and Space Shuttle programs shows that crews should be able to operate safely in the NEO environment. Challenges for the mission include communications time delays, consumables management, crew health during a multi-month cruise in free-fall, and radiation exposure beyond Earth's magnetosphere. Thus, NEO targets offering minimum round trip times are highly desirable. Promising avenues for reducing risk and increasing the spacecraft capability at the NEO include augmented life support systems, ISS-derived or inflatable modules for increased habitable volume, a dedicated EVA airlock, and upgraded service module propulsion capability (compared with Constellation baselines). Some of these improvements, along with robotic precursors, offer opportunities for substantial international cooperation and cost-sharing. NEO missions offer programmatic and budgetary advantages to NASA as it considers future deep-space exploration. These include a large and scientifically significant sample suite of pristine asteroidal materials, physical properties measurements useful for future deflection of a hazardous NEO, crucial long-duration, deep-space operational experience, and much-reduced infrastructure compared to lunar exploration. These astronaut expeditions beyond the Moon offer dramatic next steps toward economic opportunity in Earth-Moon space, and the eventual exploration of Mars and beyond. © 2010 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.