1 00:00:00,000 --> 00:00:03,530 [ MUSIC ] 2 00:00:03,550 --> 00:00:15,080 The Mystery of High-Energy Cosmic Rays – presented by Science@NASA 3 00:00:15,100 --> 00:00:21,870 Hold out your hand for 10 seconds. A dozen electrons and muons just zipped unfelt through your palm. 4 00:00:21,890 --> 00:00:25,850 The ghostly particles are what scientists call "secondary cosmic rays" 5 00:00:25,870 --> 00:00:33,940 subatomic debris from collisions between molecules high in Earth's atmosphere and high-energy cosmic rays from outer space. 6 00:00:33,960 --> 00:00:39,850 This daily shower, which never stops, is a sign of violent events in deep space. 7 00:00:39,870 --> 00:00:44,480 It’s believed that the majority of cosmic rays come from supernova explosions. 8 00:00:44,500 --> 00:00:48,900 When massive stars explode they blast most of their material into space. 9 00:00:48,920 --> 00:00:57,290 The expanding shock waves can break apart interstellar atoms and accelerate the debris to unimaginably high energies. 10 00:00:57,310 --> 00:01:03,920 Other, unknown cataclysmic phenomena may be at work, too, especially for the most energetic cosmic rays. 11 00:01:03,940 --> 00:01:08,000 Eun-Suk Seo, a professor of physics at the University of Maryland says, 12 00:01:08,020 --> 00:01:15,210 “Cosmic ray particles with energies as high as 1020 electron volts have been measured on the ground. 13 00:01:15,230 --> 00:01:20,190 This is more energy than we have achieved in the most powerful manmade particle accelerators.” 14 00:01:20,210 --> 00:01:26,110 “But how do natural cosmic ray accelerators pump so much energy into these particles? 15 00:01:26,130 --> 00:01:29,350 This is one of the biggest mysteries in astrophysics.” 16 00:01:29,370 --> 00:01:33,600 While indications of the energies of cosmic ray particles can be measured from the ground, 17 00:01:33,620 --> 00:01:37,970 Seo and colleagues have taken their studies to higher elevations, 18 00:01:37,990 --> 00:01:42,560 directly measuring particles from space before they break up in Earth’s atmosphere. 19 00:01:42,580 --> 00:01:48,050 The cosmic ray detector known as CREAM (The Cosmic-Ray Energetics and Mass investigation) 20 00:01:48,070 --> 00:01:53,920 has been launched to the stratosphere above Antarctica onboard long-duration helium-filled balloons. 21 00:01:53,940 --> 00:01:57,960 By lofting the detector above 99% of Earth’s atmosphere, 22 00:01:57,980 --> 00:02:05,100 researchers get a better idea of what cosmic rays are like before they collide with nuclei in the air above the detector. 23 00:02:05,120 --> 00:02:09,430 CREAM is able to measure the energy and direction of each incoming cosmic ray particle 24 00:02:09,450 --> 00:02:12,950 and identify the particle type by measuring its charge, 25 00:02:12,970 --> 00:02:18,420 thereby providing clues to the particles’ origin and acceleration mechanisms. 26 00:02:18,440 --> 00:02:22,750 Since 2004, the team has flown CREAM seven times over Antarctica 27 00:02:22,770 --> 00:02:29,520 accumulating more than 191 days of data from altitudes as high as 120,000 feet. 28 00:02:29,540 --> 00:02:33,810 They’re about to go even higher. CREAM is heading for space. 29 00:02:33,830 --> 00:02:39,640 A reconfigured CREAM detector is scheduled to travel to the International Space Station in 2017 30 00:02:39,660 --> 00:02:43,700 aboard SpaceX’s Dragon spacecraft on a Falcon 9 rocket. 31 00:02:43,720 --> 00:02:48,680 Named “ISS-CREAM,” it will remain installed on the Japanese Experiment Module, 32 00:02:48,700 --> 00:02:52,270 also known as Kibo, for at least three years. 33 00:02:52,290 --> 00:02:58,620 Seo says, “The ISS provides an excellent monitoring platform for high-energy cosmic rays. 34 00:02:58,640 --> 00:03:04,070 The station allows for longterm monitoring in lieu of multiple limited-duration balloon flights, 35 00:03:04,090 --> 00:03:10,610 providing direct, unimpeded access to incoming cosmic rays without atmospheric interference. 36 00:03:10,630 --> 00:03:15,860 The longer exposure times on the space station allow for the measurement of higher energies. 37 00:03:15,880 --> 00:03:23,210 ISS-CREAM has a goal of measuring the highest energy possible for direct measurement of high-energy cosmic rays.” 38 00:03:23,230 --> 00:03:30,950 She adds, “The mysterious nature of cosmic rays serves as a reminder of just how little we know about our universe.” 39 00:03:30,970 --> 00:03:38,988 For more high-energy science from beyond Earth’s atmosphere, stay tuned to science.nasa.gov.