Jovian Trojan Asteroids’ Secrets Uncovered by NASA’s WISE

    October 15, 2012

NASA’s Wide-field Infrared Survey Explorer (WISE) may have been decommissioned last year, but the data it has provided is continuing to reveal clues about our solar system.

NASA today announced that researchers using data from WISE have discovered a bit more about the mysterious asteroids called Jovian Trojans. The Trojans orbit the sun on the same path as Jupiter and travel in “packs,” with one group orbiting ahead of Jupiter, and one trailing behind.

The observations of the WISE data by the NEOWISE team (the asteroid-hunting portion of the WISE mission) show that the Trojans are made up of dark, reddish rocks and have a matte, non-reflective surface. Also shown is that the leading pack of Trojans outnumbers the pack that trails Jupiter. In addition, scientists have been able to determine that the packs are “strikingly” similar to each other and do not include any objects from elsewhere in the solar system. The Trojans do not resemble asteroids from the asteroid belt between Mars and Jupiter or objects from the Kuiper belt on the outskirts of the system.

“Jupiter and Saturn are in calm, stable orbits today, but in their past, they rumbled around and disrupted any asteroids that were in orbit with these planets,” said Tommy Grav, a WISE scientist from the Planetary Science Institute. “Later, Jupiter re-captured the Trojan asteroids, but we don’t know where they came from. Our results suggest they may have been captured locally. If so, that’s exciting because it means these asteroids could be made of primordial material from this particular part of the solar system, something we don’t know much about.”

The NEOWISE team has analyzed the colors and classified 400 Trojans so far. Grav stated that the Trojans are D-type asteroids, which are dark burgundy, though some are C- and P-type grey-bluish asteroids.

“More research is needed, but it’s possible we are looking at some of the oldest material known in the solar system,” said Grav.

These results were presented today at the 44th annual meeting of the Division for Planetary Sciences of the American Astronomical Society. Two studies outlining the results have been accepted for publication in The Astrophysical Journal.

(Image courtesy NASA/JPL-Caltech)