capture-and-orbital-transfer-of-asteroid-2

Three challenges when capturing an asteroid in Earth's gravity are attaching a vehicle to the asteroid, halting tumbling, and changing its orbit to intersect Earth's.

To attach to the asteroid, we will use a tethered inflatable sail with a flexible capture membrane to contain the asteroid. Tether control allows us to finely control the asteroid's movement during the capture process.

To stop an asteroid from tumbling once we have a vehicle attached, we will use several spacecraft thrusters in strategic positions. These thrusters stabilize the asteroid by applying a torque counter to the current rotation. Stopping the asteroid's rotation nearly completely is essential for our means of changing the asteroid's orbit to intersect Earth's.

To change the orbit to intersect Earth's, we have calculated the requirements for both ion engines and VASIMR engines to make the orbit change. If we capture a water ice asteroid, we can use the asteroid's material as fuel for these engines. At a minimum, we need to use 15-20% of the asteroid's mass as fuel for the trip. Once attached to the engines, changing the orbit for a 1000 ton asteroid in the asteroid belt takes at least 3 years for four VASIMR engines and 15 years for ion engines.

Video narration script: "The COTA project provides solutions to some problems encountered in a mission to move a near-earth sun-orbiting asteroid into high-Earth orbit, including: (first) capturing the asteroid on approach using a sail-like device attached to the spacecraft with a bearing, allowing the asteroid to spin freely on one axis while the spacecraft orbits the others; (second) an application which calculates thrust vectors required to de-spin the asteroid while attached via tethering; and (third) using materials mined from the asteroid itself as propellant in an existing VASIMR plasma engine to provide the required delta-v."

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