"If they formed in the same location they are in today [you would expect them to be much more homogenous.]"-Cathy Olkin

https://www.youtube.com/watch?v=NPEVJy3e5rQ

Skip ahead to 3:24. The formal lectures have long, tedious, speaker introductions.

This LPI is a preview of the Lucy mission to Jupiter's Trojans. It has already launched, and is flying to it's first target at the time this blog is published, which in turn is two years younger than the lecture. Trojans are objects that sit in Jupiter's Lagrange Points. There are five Lagrange Points for every planet, Jupiter has clusters of objects at L3, L4, and L5. Specifically Lucy will be going through L4 and later L5 too. L4 leads and L5 trails Jupiter. If you want to get picky, L3's objects are "Hilda Trojans," L4 are "Greek Trojans," and L5 are "Trojan Trojans." You now can call every group 'Trojans' but when they were first discovered they got different names per group. Some people remain OCD about it. 

The centers of L4, & 5 are always the same distance from the planet as the planet is from The Sun, L3 is always a little closer to The Sun. So Earths are 1 AU away. Jupiter's are 5.2 AU, but L4 and L5 are blurred quite a bit. L4 and L5 are about four AU long and two AU wide, The biggest by far Trojan is named Hektor and is 225 km in diameter, so Trojans are very small things occupying's a space too large to intuitively visualize.

• Slide at 7:55 she begins explaining why this mission got selected. 
• At 14:45 she mentions the first target, a inner main-belt C-type asteroid called DonaldJohanson, expected to be debris from a collision on a larger asteroid. Could be very interesting.
• At 15:50 she lists some of their planned targets, including a binary, only the second binary we will have had a close look at after the Pluto-Charon system.
• At 21:45 she goes over the instrument payload. Note that much of it is the exact same instruments New Horizons carried. They got their instruments off the shelf.
• At 28:20 Q&A begins. 

Trojans aren't just asteroids. Some resemble KBO's and many will be a mix. Tholins have been suspected and so that will be another interesting thing to test. Frankly we don't know much aside a loose mass and Earth-based spectroscopy, so the numbers we do have will certainly undergo refining. This mission has a lot of potential for discoveries to come out of the woodwork.