Discovery of an Earth Trojan Asteroid

Near-Earth asteroid 2010 TK7 was discovered by the Widefield Infrared Survey Explorer (WISE) satellite on October 1, 2010. With followup observations from the Canada-France-Hawaii telescope, it has been shown to be the first known Trojan companion of Earth, in an orbit with large librational and epicyclic range about the leading L4 Lagrange point. The orbit is very chaotic, with transitions between triangular Lagrange points ("jumping") and temporary residence at the L3 (opposite) Lagrange point being possible. Nevertheless, this appears to be "stable" chaos with a restricted range of behaviors. Chaos limits the ability to determine the behavior of the real body over long periods of time, but clone studies can indicate the probable lifetime and origins. We speculate that a larger population of Earth Trojans may exist. Trojans of low inclination, and similar related co-orbital objects, could present low energy (delta-V) opportunities for space missions, including potentially as part of the future manned program aim of sending astronauts to asteroids. 2010 TK7 is not a suitable target due to its inclination of nearly 21 degrees, but its discovery may provide an impetus for further searches for co-orbital objects, with Trojan searches likely to also detect horseshoe or co-orbital asteroids. Horseshoe objects can come closer to Earth than Trojans, which could be a mission consideration. The possibility of obtaining primordial material from such objects would be of scientific and possibly economic interest.