{"id":2748,"date":"2015-02-19T06:11:17","date_gmt":"2015-02-19T06:11:17","guid":{"rendered":"http:\/\/revoscience.com\/en\/?p=2748"},"modified":"2015-02-19T06:11:17","modified_gmt":"2015-02-19T06:11:17","slug":"for-the-first-time-spacecraft-catch-a-solar-shockwave-in-the-act","status":"publish","type":"post","link":"https:\/\/www.revoscience.com\/en\/for-the-first-time-spacecraft-catch-a-solar-shockwave-in-the-act\/","title":{"rendered":"For the first time, spacecraft catch a solar shockwave in the act"},"content":{"rendered":"

Solar storm found to produce \u201cultrarelativistic, killer electrons\u201d in 60 seconds.<\/strong><\/em><\/span><\/p>\n

\"The<\/a>
The Sun by the Atmospheric Imaging Assembly of NASA’s Solar Dynamics Observatory. Credit: NASA<\/figcaption><\/figure>\n

CAMBRIDGE, Mass. —\u00a0On Oct. 8, 2013, an explosion on the sun\u2019s surface sent a supersonic blast wave of solar wind out into space. This shockwave tore past Mercury and Venus, blitzing by the moon before streaming toward Earth. The shockwave struck a massive blow to the Earth\u2019s magnetic field, setting off a magnetized sound pulse around the planet.<\/span><\/p>\n

NASA\u2019s Van Allen Probes, twin spacecraft orbiting within the radiation belts deep inside the Earth\u2019s magnetic field, captured the effects of the solar shockwave just before and after it struck.<\/span><\/p>\n

Now scientists at MIT\u2019s Haystack Observatory, the University of Colorado, and elsewhere have analyzed the probes\u2019 data, and observed a sudden and dramatic effect in the shockwave\u2019s aftermath: The resulting magnetosonic pulse, lasting just 60 seconds, reverberated through the Earth\u2019s radiation belts, accelerating certain particles to ultrahigh energies.<\/span><\/p>\n

\u201cThese are very lightweight particles, but they are ultrarelativistic, killer electrons \u2014 electrons that can go right through a satellite,\u201d says John Foster, associate director of MIT\u2019s Haystack Observatory. \u201cThese particles are accelerated, and their number goes up by a factor of 10, in just one minute. We were able to see this entire process taking place, and it\u2019s exciting: We see something that, in terms of the radiation belt, is really quick.\u201d<\/span><\/p>\n

The findings represent the first time the effects of a solar shockwave on Earth\u2019s radiation belts have been observed in detail from beginning to end. Foster and his colleagues have published their results in the\u00a0Journal of Geophysical Research<\/em>.<\/span><\/p>\n

Catching a shockwave in the act<\/strong><\/span><\/p>\n

Since August 2012, the Van Allen Probes have been orbiting within the Van Allen radiation belts. The probes\u2019 mission is to help characterize the extreme environment within the radiation belts, so as to design more resilient spacecraft and satellites.<\/span><\/p>\n

One question the mission seeks to answer is how the radiation belts give rise to ultrarelativistic electrons \u2014 particles that streak around the Earth at 1,000 kilometers per second, circling the planet in just five minutes. These high-speed particles can bombard satellites and spacecraft, causing irreparable damage to onboard electronics.<\/span><\/p>\n

The two Van Allen probes maintain the same orbit around the Earth, with one probe following an hour behind the other. On Oct. 8, 2013, the first probe was in just the right position, facing the sun, to observe the radiation belts just before the shockwave struck the Earth\u2019s magnetic field. The second probe, catching up to the same position an hour later, recorded the shockwave\u2019s aftermath.<\/span><\/p>\n

Dealing a \u201csledgehammer blow\u201d<\/strong><\/span><\/p>\n

Foster and his colleagues analyzed the probes\u2019 data, and laid out the following sequence of events: As the solar shockwave made impact, according to Foster, it struck \u201ca sledgehammer blow\u201d to the protective barrier of the Earth\u2019s magnetic field. But instead of breaking through this barrier, the shockwave effectively bounced away, generating a wave in the opposite direction, in the form of a magnetosonic pulse \u2014 a powerful, magnetized sound wave that propagated to the far side of the Earth within a matter of minutes.<\/span><\/p>\n

In that time, the researchers observed that the magnetosonic pulse swept up certain lower-energy particles. The electric field within the pulse accelerated these particles to energies of 3 to 4 million electronvolts, creating 10 times the number of ultrarelativistic electrons that previously existed.<\/span><\/p>\n

Taking a closer look at the data, the researchers were able to identify the mechanism by which certain particles in the radiation belts were accelerated. As it turns out, if particles\u2019 velocities as they circle the Earth match that of the magnetosonic pulse, they are deemed \u201cdrift resonant,\u201d and are more likely to gain energy from the pulse as it speeds through the radiation belts. The longer a particle interacts with the pulse, the more it is accelerated, giving rise to an extremely high-energy particle.<\/span><\/p>\n

Foster says solar shockwaves can impact Earth\u2019s radiation belts a couple of times each month. The event in 2013 was a relatively minor one.<\/span><\/p>\n

\u201cThis was a relatively small shock. We know they can be much, much bigger,\u201d Foster says. \u201cInteractions between solar activity and Earth\u2019s magnetosphere can create the radiation belt in a number of ways, some of which can take months, others days. The shock process takes seconds to minutes. This could be the tip of the iceberg in how we understand radiation-belt physics.\u201d<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

Solar storm found to produce \u201cultrarelativistic, killer electrons\u201d in 60 seconds. CAMBRIDGE, Mass. —\u00a0On Oct. 8, 2013, an explosion on the sun\u2019s surface sent a supersonic blast wave of solar wind out into space. This shockwave tore past Mercury and Venus, blitzing by the moon before streaming toward Earth. The shockwave struck a massive blow […]<\/p>\n","protected":false},"author":6,"featured_media":2749,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[17],"tags":[],"class_list":["post-2748","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-research"],"featured_image_urls":{"full":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/02\/sun.jpg",500,476,false],"thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/02\/sun-150x150.jpg",150,150,true],"medium":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/02\/sun-300x285.jpg",300,285,true],"medium_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/02\/sun.jpg",500,476,false],"large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/02\/sun.jpg",500,476,false],"1536x1536":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/02\/sun.jpg",500,476,false],"2048x2048":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/02\/sun.jpg",500,476,false],"ultp_layout_landscape_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/02\/sun.jpg",500,476,false],"ultp_layout_landscape":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/02\/sun.jpg",500,476,false],"ultp_layout_portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/02\/sun.jpg",500,476,false],"ultp_layout_square":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/02\/sun.jpg",500,476,false],"newspaper-x-single-post":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/02\/sun.jpg",500,476,false],"newspaper-x-recent-post-big":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/02\/sun.jpg",378,360,false],"newspaper-x-recent-post-list-image":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/02\/sun.jpg",68,65,false],"web-stories-poster-portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/02\/sun.jpg",500,476,false],"web-stories-publisher-logo":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/02\/sun.jpg",96,91,false],"web-stories-thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/02\/sun.jpg",150,143,false]},"author_info":{"info":["Amrita Tuladhar"]},"category_info":"Research<\/a>","tag_info":"Research","comment_count":"0","_links":{"self":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/2748","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/comments?post=2748"}],"version-history":[{"count":0,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/2748\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media\/2749"}],"wp:attachment":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media?parent=2748"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/categories?post=2748"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/tags?post=2748"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}