1 00:00:00,167 --> 00:00:04,004 [Music] 2 00:00:04,004 --> 00:00:07,107 Hi, I'm Jim Green, the director of Planetary Science 3 00:00:07,107 --> 00:00:08,108 here at NASA. 4 00:00:14,615 --> 00:00:20,354 OSIRIS-REx is an opportunity to go back in time and visit an 5 00:00:20,354 --> 00:00:21,555 asteroid called Bennu. 6 00:00:21,555 --> 00:00:26,026 Bennu is a very primitive object, created at the birth of 7 00:00:26,026 --> 00:00:27,494 our solar system. 8 00:00:27,494 --> 00:00:31,231 OSIRIS-REx is going to go there, orbit Bennu for more than a 9 00:00:31,231 --> 00:00:33,200 year, and bring back a sample. 10 00:00:37,537 --> 00:00:41,408 Since September, when we launched OSIRIS-REx, it has made 11 00:00:41,408 --> 00:00:44,778 wonderful progress in the solar system, but is getting close to 12 00:00:44,778 --> 00:00:46,546 a very important place. 13 00:00:46,546 --> 00:00:50,884 This is the Earth's Lagrangian point L4. 14 00:00:50,884 --> 00:00:54,955 Now a Lagrangian point are special regions in and around 15 00:00:54,955 --> 00:00:57,991 our orbit, for which the gravitational interaction 16 00:00:57,991 --> 00:01:02,663 between the Earth and the sun nearly cancels out. 17 00:01:02,663 --> 00:01:05,499 This allows an object to be trapped 18 00:01:05,499 --> 00:01:07,601 and remain in that location. 19 00:01:11,505 --> 00:01:13,974 So what's trapped at L4? 20 00:01:13,974 --> 00:01:15,509 Well we don't really know. 21 00:01:15,509 --> 00:01:18,745 We only know what's trapped at L4 around other planets. 22 00:01:18,745 --> 00:01:22,816 At Jupiter these are hundreds and hundreds of objects 23 00:01:22,816 --> 00:01:24,685 that we call Trojans. 24 00:01:24,685 --> 00:01:28,255 And so, at Earth's L4, if we find anything 25 00:01:28,255 --> 00:01:30,624 we'll be calling them Earth Trojans. 26 00:01:33,160 --> 00:01:34,294 Now what are Trojans? 27 00:01:34,294 --> 00:01:38,432 Well, these are small bodies caught in this orbit for 28 00:01:38,432 --> 00:01:39,733 billions of years. 29 00:01:39,733 --> 00:01:43,770 The Earth has swept up all kinds of material to be created as we 30 00:01:43,770 --> 00:01:46,907 know it today, and what's left are those things 31 00:01:46,907 --> 00:01:49,376 that are sitting at L4. 32 00:01:49,376 --> 00:01:52,779 That's what makes it really exciting to be able to go there, 33 00:01:52,779 --> 00:01:55,482 and OSIRIS-REx is nearly there. 34 00:01:55,482 --> 00:01:59,152 Beginning February 9th, OSIRIS-REx is going to turn on 35 00:01:59,152 --> 00:02:01,688 its scanning camera. It's going to scan the areas, 36 00:02:01,688 --> 00:02:04,157 it's going to look for these objects. 37 00:02:08,362 --> 00:02:11,298 To follow along with OSIRIS-REx, please go to 38 00:02:11,298 --> 00:02:18,605 nasa.gov/osiris-rex, or go to asteroidmission.org 39 00:02:19,606 --> 00:02:28,015 [satellite beeping]