Eureka! Mars Has Trojan Asteroids

The planet Jupiter has a large collection of trojan asteroids. But until 1990 it was not known whether or not Mars posessed them too.

A trojan asteroid is an asteroid that shares an orbit with a planet. These asteroids orbit the Sun with the same semi-major axis and orbital period as one of the planets. Usually a trojan asteroid traces "orbits" around a planet's Lagrange 4 or 5 point in what is known as a tadpole orbit. Sometimes they trace a path around the L3, L4, and L5 points in what is known as a horseshoe orbit.

In 1990, astronomer David Levy, who became a household name in 1993 for his role in the discovery of a comet that would slam into Jupiter, discovered the first known Martian trojan. Asteroid 5261 Eureka, also known as 1990 MB orbits the Sun while trapped in Mars' L5 region.

Since Levy's discovery of Eureka, several other asteroids that share Mars' orbit have been discovered. Two of them, 1999 UJ7 and 1998 VF31 are also trojans of Mars. Asteroids 2001 DH47, 2001 FG24, 1998 QH56, 2001 FR127, and 1998 SD4 orbit the Sun in a resonance close to 1:1 with Mars, but they are not trapped in the L4 or L5 points. The simulation eureka.gsim shows Mars and the asteroids 5261 Eurkea, 1998 VF31, 2001 DH47, 2001 FG24, 2001 FR127, 1998 QH56, and 1998 SD4 in a rotating frame . The initial starting positions and velocity vectors were obtained from JPL Horizons Ephemeris Computation Service.

Download eureka.gsim

(You need to have the program Gravity Simulator installed on your computer first. Click Here to download Gravity Simulator.)