The Capture of Asteroids

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H. Y. Chiu (2018), JBIS, 71, pp.20-26

Refcode: 2018.71.20
Keywords: Gravitation, Celestial Mechanics, Minor Planets, Asteroids: Individual, 8 Flora, Planets and Satellites: General

Recently there has been much discussion on the capture and mining of asteroids. While the technology might be years away, in this paper we will discuss an energy-efficient method of transporting a small asteroid, or materials gathered from asteroids, to Earth. In particular, the paper will concentrate on one of the nearest and largest asteroids – 8 Flora in the Flora family. Generally, asteroids are located 2-3 AU (astronomical units) from Earth, and in transporting materials from asteroids to Earth, an energy equivalent of the gravitational potential energy difference must be dissipated. This amount of potential energy is a sizeable fraction of the orbital kinetic energy of the Earth around the Sun, and with the Earth's orbital speed at around 29 km/s, the amount of energy to be dissipated is considerable. In this paper we propose to use the planet Mars as a medium to remove much of the gravitational energy difference through gravity-assisted deceleration (“gravity braking”). To achieve this aim, it is necessary to launch the payload in the reverse direction of the asteroid with a certain velocity; in the case of 8 Flora, this launch velocity is around 3 km/s. The deceleration could be achieved by non-rocket powered ejection platforms on 8 Flora. The landing velocity on Earth is about 3 km/s over the escape velocity of the Earth (11.2 km/s). It is also proposed to separate a pair of contact asteroid binaries by using impulse propulsion, and to propel one component of the separated asteroids to pass by Mars to receive gravity-assisted deceleration to reach the Earth, or to become captured by the Earth or the Moon. The feasibility of this ambitious project will be discussed.


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