Neptune Trojan - Discovery and Exploration

Discovery and Exploration

In 2001, the first Neptune trojan was discovered, 2001 QR₃₂₂, near Neptune's L₄ region, and with it the fifth known populated stable reservoir of small bodies in the Solar System. In 2005, the discovery of the high-inclination trojan 2005 TN₅₃ has indicated that the Neptune trojans populate thick clouds, which has constrained their possible origins (see below).

On August 12, 2010, the first L₅ trojan, 2008 LC₁₈, was announced. It was discovered by a dedicated survey that scanned regions where the light from the stars near the galactic center is obscured by dust clouds. This suggests that large L₅ trojans are as common as large L₄ trojans, to within uncertainty, further constraining models about their origins (see below).

It may be possible for the New Horizons spacecraft to investigate L₅ Neptune trojans discovered by 2014, when it passes through this region of space en route to Pluto. Some of the patches where the light from the Galactic Center is obscured by dust clouds are along New Horizons's flight path, allowing detection of objects that the spacecraft could image. 2011 HM₁₀₂, the highest-inclination Neptune trojan known, may be just bright enough for New Horizons to observe in end-2013 at a distance of 1.2 AU.