Moving an asteroid with electric solar wind sail S. Merikallio and P. Janhunen Finnish Meteorological Institute, Po. Box. 503, FIN-00101, Helsinki, Finland
Received: 12 Mar 2010 – Revised: 01 Nov 2010 – Accepted: 02 Nov 2010 – Published: 07 Dec 2010
Abstract. The electric solar wind sail (E-Sail) is a new propulsion method for interplanetary travel which was invented
in 2006 and is currently under development. The E-Sail uses charged tethers to extract momentum from the solar
wind particles to obtain propulsive thrust. According to current estimates, the E-Sail is 2-3 orders of
magnitude better than traditional propulsion methods (chemical rockets and ion engines) in terms of produced
lifetime-integrated impulse per propulsion system mass. Here we analyze the problem of using the E-Sail for
directly deflecting an Earth-threatening asteroid. The problem then culminates into how to attach the E-Sail
device to the asteroid. We assess alternative attachment strategies, namely straightforward direct towing with
a cable and the gravity tractor method which works for a wider variety of situations. We also consider possible
techniques to scale up the E-Sail force beyond the baseline one Newton level to deal with more imminent or
larger asteroid or cometary threats. As a baseline case we consider an asteroid of effective diameter of
140 m and mass of 3 million tons, which can be deflected with a baseline 1 N E-Sail within 10 years.
With a 5 N E-Sail the deflection could be achieved in 5 years. Once developed, the E-Sail would appear to
provide a safe and reasonably low-cost way of deflecting dangerous asteroids and other heavenly bodies in
cases where the collision threat becomes known several years in advance.
Citation: Merikallio, S. and Janhunen, P.: Moving an asteroid with electric solar wind sail, Astrophys. Space Sci. Trans., 6, 41-48, doi:10.5194/astra-6-41-2010, 2010.