{"id":168803,"date":"2011-10-26T15:52:00","date_gmt":"2011-10-26T19:52:00","guid":{"rendered":"https:\/\/www.nasa.gov\/?migration=converted-node-345232"},"modified":"2023-07-25T11:23:44","modified_gmt":"2023-07-25T15:23:44","slug":"stories-of-missions-past-early-explorers","status":"publish","type":"post","link":"https:\/\/www.nasa.gov\/history\/stories-of-missions-past-early-explorers\/","title":{"rendered":"Stories of Missions Past: Early Explorers"},"content":{"rendered":"<div id=\"\" class=\"hds-media hds-module wp-block-image\"><div class=\"margin-left-auto margin-right-auto nasa-block-align-inline\"><div class=\"hds-media-wrapper margin-left-auto margin-right-auto\"><figure class=\"hds-media-inner hds-cover-wrapper hds-media-ratio-none \"><a href=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2018\/01\/599053main_0200146_full.jpg\"><img fetchpriority=\"high\" decoding=\"async\" width=\"2048\" height=\"1536\" src=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2018\/01\/599053main_0200146_full.jpg?w=2048\" class=\"attachment-2048x2048 size-2048x2048\" alt=\"This image is a cutaway illustration of the Explorer I satellite with callouts.\" style=\"transform: scale(1); transform-origin: 50% 50%; object-position: 50% 50%; object-fit: cover;\" block_context=\"nasa-block\" srcset=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2018\/01\/599053main_0200146_full.jpg 3000w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2018\/01\/599053main_0200146_full.jpg?resize=300,225 300w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2018\/01\/599053main_0200146_full.jpg?resize=768,576 768w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2018\/01\/599053main_0200146_full.jpg?resize=1024,768 1024w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2018\/01\/599053main_0200146_full.jpg?resize=1536,1152 1536w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2018\/01\/599053main_0200146_full.jpg?resize=2048,1536 2048w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2018\/01\/599053main_0200146_full.jpg?resize=400,300 400w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2018\/01\/599053main_0200146_full.jpg?resize=600,450 600w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2018\/01\/599053main_0200146_full.jpg?resize=900,675 900w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2018\/01\/599053main_0200146_full.jpg?resize=1200,900 1200w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2018\/01\/599053main_0200146_full.jpg?resize=2000,1500 2000w\" sizes=\"(max-width: 2048px) 100vw, 2048px\" loading=\"eager\" \/><\/a><\/figure><figcaption class=\"hds-caption padding-y-2\"><div class=\"hds-caption-text p-sm margin-0\">An exploded view of the first successful U.S. satellite launched in 1958, Explorer I.<\/div><div class=\"hds-credits\"><strong><em>NASA\/Marshall Space Flight Center Collection<\/em><\/strong><\/div><\/figcaption><\/div><\/div><\/div>\n\n\n<p>On September 29, 2011, NASA announced the short list for five potential new \u201cExplorer class\u201d spacecraft. These missions are by definition small and relatively inexpensive, designed to be led by a small team.<br>\nThe Explorer class missions are numbered at 92 so far, with more constantly planned. Explorer class spacecraft recorded the signature left over from the big bang. They mapped out the complex geometry of Earth\u2019s magnetic environment. They found gamma rays coming from everywhere in the sky. They help warn scientists of incoming radiation from solar flares.<br>\n\u201cThe neat thing about the Explorers is that they\u2019re tailored to a specific problem,\u201d says Wilt Sanders the program scientist for the Explorer\u2019s Program. \u201cThat\u2019s their strength. They\u2019re relatively inexpensive but they\u2019ve come up with game changing results.\u201d<br>\nAnd it all began over five decades ago.<br>\n<b>The First Explorer<\/b><br>\nIt was January 31, 1958 and a Juno 1 rocket was almost ready to launch. It carried precious cargo \u2013 a satellite called Explorer 1, that everyone hoped would be the first U.S. satellite in space. The mood among those at Cape Canaveral Air Force Station, Fla. was tense. Not only had the Soviets already successfully launched Sputnik into space, but three months earlier, a rocket attempting to launch a U.S. satellite had flown a mere four feet before tumbling back to the ground.<br>\nThe familiar countdown began: \u201c10 . . . 9 . . . 8 . . . \u201d and at 10:48 p.m. EDT, the Juno shot up, climbed over 200 miles into the sky, and released Explorer 1 into space. It wasn\u2019t until some two hours later, when the satellite had made its first complete orbit of Earth and was in close enough range to send a signal that it was operational, that the observers rejoiced. The very first U.S. satellite was officially a success.<br>\nFor many, the tale of Explorer 1 stops here, a triumph of human ingenuity in reaching space. But, truly, that\u2019s only the beginning of the story. \u201cExplorer 1 was also a science mission,\u201d says Willis Jenkins, the program executive for NASA\u2019s Explorer program. \u201cThis wasn\u2019t just launched to get a satellite up in space, it was meant to bring science data back.\u201d<br>\nAnd it certainly did. Explorer 1 contained experiments that turned our understanding of space upside down. To this day, scientists try to understand the dynamic, seething environment encircling Earth \u2013 known as the Van Allen radiation belts \u2013 that Explorer 1 helped discover.<br>\n <\/p>\n\n\n<div id=\"\" class=\"hds-media hds-module wp-block-image\"><div class=\"margin-left-auto margin-right-auto nasa-block-align-inline\"><div class=\"hds-media-wrapper margin-left-auto margin-right-auto\"><figure class=\"hds-media-inner hds-cover-wrapper hds-media-ratio-none \"><a href=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2015\/03\/1958_january_explorer_01_team_0.jpg\"><img loading=\"lazy\" decoding=\"async\" width=\"1615\" height=\"2048\" src=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2015\/03\/1958_january_explorer_01_team_0.jpg?w=1615\" class=\"attachment-2048x2048 size-2048x2048\" alt=\"\" style=\"transform: scale(1); transform-origin: 50% 50%; object-position: 50% 50%; object-fit: cover;\" block_context=\"nasa-block\" srcset=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2015\/03\/1958_january_explorer_01_team_0.jpg 2231w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2015\/03\/1958_january_explorer_01_team_0.jpg?resize=237,300 237w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2015\/03\/1958_january_explorer_01_team_0.jpg?resize=768,974 768w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2015\/03\/1958_january_explorer_01_team_0.jpg?resize=807,1024 807w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2015\/03\/1958_january_explorer_01_team_0.jpg?resize=1211,1536 1211w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2015\/03\/1958_january_explorer_01_team_0.jpg?resize=1615,2048 1615w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2015\/03\/1958_january_explorer_01_team_0.jpg?resize=315,400 315w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2015\/03\/1958_january_explorer_01_team_0.jpg?resize=473,600 473w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2015\/03\/1958_january_explorer_01_team_0.jpg?resize=710,900 710w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2015\/03\/1958_january_explorer_01_team_0.jpg?resize=946,1200 946w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2015\/03\/1958_january_explorer_01_team_0.jpg?resize=1577,2000 1577w\" sizes=\"(max-width: 1615px) 100vw, 1615px\" \/><\/a><\/figure><figcaption class=\"hds-caption padding-y-2\"><div class=\"hds-caption-text p-sm margin-0\">Holding a model of the Explorer I satellite in celebration after its successful orbiting: (left to right) William H. Pickering, former director of JPL, which built and operated the satellite; James A. van Allen, center, of the State University of Iowa, designed and built the instrument on Explorer that detected the radiation that circles Earth; and at right, Wernher von Braun, leader of the Army’s Redstone Arsenal team.<\/div><div class=\"hds-credits\">NASA\/JPL<\/div><\/figcaption><\/div><\/div><\/div>\n\n\n<p><b>Space Science Begins . . .<\/b><br>\nExplorer 1 was also, of course, the first in a long line of scientific workhorses.<br>\nSome of the latest explorers have names that are well known in the scientific community: the Swift Gamma Ray Burst Explorer (Swift) and the Cosmic Background Explorer (COBE). (The last one brought home data that earned a Nobel Prize.) But the early Explorers were simply named with numbers, and it is these that are some of the unsung heroes of space exploration \u2013 making new discoveries that scientist today take for granted.<br>\nExplorer 1 and Explorer 3, for example, launched in January and March of 1958, respectively. They carried an instrument built by the University of Iowa scientist James Van Allen that could detect energetic particles in space. This instrument was quite simply a single Geiger counter attached to a miniature tape recorder. As the satellites climbed upwards, the rates of the particles usually increased but, periodically, they zeroed out completely. Van Allen and his team realized this was neither because the particles disappeared nor because the instruments failed, but because the radiation counts were so high that the sensors overloaded. From this, Van Allen deduced that a swath of intensely energetic particles was trapped in a circle around Earth. Ultimately two such belts were found, and they\u2019re now known as the Van Allen Radiation Belts.<br>\nNot all was easy on those early missions. Neither Explorer 2 nor Explorer 5 even made it into orbit, due to launch rocket failure. While such losses were devastating, the amount of time going into building these early, simpler satellites was nothing like the years it takes today. All five of the first Explorers were launched within the first six months of 1958.<br>\nBy the time of Explorer 10 in 1961, the Explorer Program was now run by the newly founded NASA. They\u2019d also earned the right to have names as well as numbers, albeit modest ones: Explorer 10 was also known as P 14. It gathered data for only 52 hours since its goal was merely to fly up out of Earth\u2019s magnetic environment and bring back information from interplanetary space on the other side. But the satellite saw a far more complicated magnetic system than expected.<br>\n\u201cAt that point the magnetosphere was thought to be a sphere conforming to the shape of Earth,\u201d says Frank McDonald who became a project scientist for the Explorer Program at NASA\u2019s Goddard Space Flight Center in Greenbelt, Md. in 1961 and is now a professor emeritus at the University of Maryland. \u201cWe didn\u2019t know how complex a shape it was, or that there was a magnetotail flurrying out behind.\u201d<br>\nExplorer 10 discovered this \u201cmagnetotail\u201d as it moved through the night side of Earth, facing away from the sun. The instruments detected an area devoid of the electrically charged solar wind steadily streaming off the sun, since it was deflected by Earth\u2019s own magnetic field. This \u201cshadow\u201d, the magnetotail, extends some 800,000 miles long, well past the orbit of the moon.<br>\nAs the Explorer program grew, the satellites were eventually divided into those that study the sun-Earth system, or heliophysics, and those that study astrophysics. But in the early days this was originally considered all part of general space science. However, that was beginning to change.<br>\nThe next, Explorer 11 or S15, was used to search for cosmic gamma radiation, and indeed found that it came from all directions, giving birth to the field of gamma ray astronomy. The field has matured significantly over the decades and now studies such things as gamma ray bursts that originate from the distant universe, thought to be the signatures of black holes and certain supernovae.<br>\nExplorer 12 launched in August of 1961, just over 50 years ago, but it remains a historical highlight for many a contemporary studier of space. This satellite cemented into cannon much information we know about space today. It was the first to identify Earth\u2019s \u201cmagnetopause\u201d \u2013 the boundary between Earth\u2019s magnetic environment and interplanetary space. It also improved our understanding of the Van Allen radiation belts and Earth\u2019s magnetosphere. Notably, it helped establish that the radiation belts were not so strong that they would prevent manned spaceflight.<br>\n\u201cWe published science papers on solar activity almost every few weeks based on Explorer 12,\u201d says emeritus astrophysicist Thomas Cline at Goddard, whose first job at NASA focused on Explorer 12. \u201cWe had constant mini-discoveries. As soon as you put an instrument in space that has never been used before, you invariably observe things you\u2019ve never seen before.\u201d<br>\n<b>. . . And Continues<\/b><\/p>\n\n\n<div id=\"\" class=\"hds-media hds-module wp-block-image\"><div class=\"margin-left-auto margin-right-auto nasa-block-align-inline\"><div class=\"hds-media-wrapper margin-left-auto margin-right-auto\"><figure class=\"hds-media-inner hds-cover-wrapper hds-media-ratio-none \"><a href=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2015\/03\/599090main_1964_71365L.jpg\"><img loading=\"lazy\" decoding=\"async\" width=\"450\" height=\"357\" src=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2015\/03\/599090main_1964_71365L.jpg?w=450\" class=\"attachment-2048x2048 size-2048x2048\" alt=\"\" style=\"transform: scale(1); transform-origin: 50% 50%; object-position: 50% 50%; object-fit: cover;\" block_context=\"nasa-block\" srcset=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2015\/03\/599090main_1964_71365L.jpg 450w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2015\/03\/599090main_1964_71365L.jpg?resize=300,238 300w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2015\/03\/599090main_1964_71365L.jpg?resize=400,317 400w\" sizes=\"(max-width: 450px) 100vw, 450px\" \/><\/a><\/figure><figcaption class=\"hds-caption padding-y-2\"><div class=\"hds-caption-text p-sm margin-0\">Explorer 12, launched into orbit on August 16 of 1961, helped develop the understanding of Earth’s magnetic environment \u2013 or magnetosphere \u2013 scientists still hold today.<\/div><div class=\"hds-credits\"><em>NASA\/Glenn Research Center Collection<\/em><\/div><\/figcaption><\/div><\/div><\/div>\n\n\n<p>From Explorer 12 onward, many of the early Explorers had highly elliptical orbits that shot the spacecraft well outside of Earth\u2019s magnetosphere, into interplanetary space. Scientists like Cline would use these spacecraft to expand their understanding of interplanetary space. Explorers looked at the universe in many wavelengths, brought back information about the particles in space, and mapped out the structure of the early universe.<br>\nOn the heliophysics side, while those early missions simply identified the shape of Earth\u2019s magnetic environment, today\u2019s spacecraft try to spot currents in that magnetotail, to determine the shape of Earth\u2019s magnetic fields, and to see how large inputs of energy from the sun cause space weather storms that can affect Earth.<br>\nWhen funding is available ,NASA selects new Explorers \u2013 and while the time it takes to build an Explorer is several years compared to the several months it often took in the 1950s and 1960s \u2013 the price tag still remains low and the scientific output prodigious.<br>\nThe legacy of Explorer 1 goes on.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>On September 29, 2011, NASA announced the short list for five potential new \u201cExplorer class\u201d spacecraft. These missions are by definition small and relatively inexpensive, designed to be led by a small team. The Explorer class missions are numbered at 92 so far, with more constantly planned. Explorer class spacecraft recorded the signature left over [...]<\/p>\n","protected":false},"author":9,"featured_media":175309,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"nasa_hds_core_meta_l10n":"en-US","nasa_hds_core_meta_article_editor":"","nasa_hds_core_meta_article_contacts":[],"nasa_hds_core_meta_article_topic":"","nasa_hds_core_meta_linked_locations":[],"nasa_hds_core_meta_article_related_articles":[],"hds_migrate_meta_pr_release_id":"","hds_migrate_meta_pr_release_type":"","nasa_hds_core_meta_location_x":"","nasa_hds_core_meta_location_y":"","nasa_hds_core_meta_gallery_images":[],"footnotes":""},"categories":[2715,2671],"news-tags":[],"internal-terms":[],"coauthors":[],"parsely":{"version":"1.1.0","meta":{"@context":"https:\/\/schema.org","@type":"NewsArticle","headline":"Stories of Missions Past: Early Explorers","url":"https:\/\/www.nasa.gov\/history\/stories-of-missions-past-early-explorers\/","mainEntityOfPage":{"@type":"WebPage","@id":"https:\/\/www.nasa.gov\/history\/stories-of-missions-past-early-explorers\/"},"thumbnailUrl":"https:\/\/www.nasa.gov\/wp-content\/uploads\/2015\/03\/599090main_1964_71365L.jpg?w=150&h=150&crop=1","image":{"@type":"ImageObject","url":"https:\/\/www.nasa.gov\/wp-content\/uploads\/2015\/03\/599090main_1964_71365L.jpg"},"articleSection":"Missions","author":[{"@type":"Person","name":"NASA"}],"creator":["NASA"],"publisher":{"@type":"Organization","name":"NASA","logo":"https:\/\/www.nasa.gov\/wp-content\/themes\/nasa\/assets\/images\/nasa-logo.svg"},"keywords":["NASA History","Explorer"],"dateCreated":"2011-10-26T19:52:00Z","datePublished":"2011-10-26T19:52:00Z","dateModified":"2023-07-25T15:23:44Z"},"rendered":"<meta name=\"parsely-title\" content=\"Stories of Missions Past: Early Explorers\" \/>\n<meta name=\"parsely-link\" content=\"https:\/\/www.nasa.gov\/history\/stories-of-missions-past-early-explorers\/\" \/>\n<meta name=\"parsely-type\" content=\"post\" \/>\n<meta name=\"parsely-image-url\" content=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2015\/03\/599090main_1964_71365L.jpg?w=150&h=150&crop=1\" \/>\n<meta name=\"parsely-pub-date\" content=\"2011-10-26T19:52:00Z\" \/>\n<meta name=\"parsely-section\" content=\"Missions\" \/>\n<meta name=\"parsely-tags\" content=\"NASA History,Explorer\" \/>\n<meta name=\"parsely-author\" content=\"NASA\" \/>","tracker_url":"https:\/\/cdn.parsely.com\/keys\/nasa.gov\/p.js"},"read_time":7,"time_ago":"13 years","featured_image":{"id":175309,"file":"https:\/\/www.nasa.gov\/wp-content\/uploads\/2015\/03\/599090main_1964_71365L.jpg","title":"599090main_1964_71365L","alt":"","caption":""},"_links":{"self":[{"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/posts\/168803"}],"collection":[{"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/users\/9"}],"replies":[{"embeddable":true,"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/comments?post=168803"}],"version-history":[{"count":2,"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/posts\/168803\/revisions"}],"predecessor-version":[{"id":276827,"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/posts\/168803\/revisions\/276827"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/media\/175309"}],"wp:attachment":[{"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/media?parent=168803"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/categories?post=168803"},{"taxonomy":"news-tags","embeddable":true,"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/news-tags?post=168803"},{"taxonomy":"internal-terms","embeddable":true,"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/internal-terms?post=168803"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/coauthors?post=168803"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}