http://www.rssboard.org/rss-specification 720 http://ecuip-xtf.lib.uchicago.edu/xtf/search?f4-type%3DArtwork;f5-subject%3DObservatory%20(space-based);f7-subject%3DExplorer%2011;f6-associated-Lesson%3DX-Ray%20Science Results for your query: f4-type=Artwork;f5-subject=Observatory (space-based);f7-subject=Explorer 11;f6-associated-Lesson=X-Ray Science Thu, 01 Jan 1970 12:00:00 GMT http://ecuip-xtf.lib.uchicago.edu/xtf/view?docId=grxr/NASA-Explorer-11-Flight/NASA-Explorer-11-Flight.dc.xml Explorer 11, the first gamma-ray detection satellite flown, was launched on April 27, 1961. The satellite could not be actively pointed, so it was put into a tumble in order to get a "rough" scan of the entire celestial sphere.. http://ecuip-xtf.lib.uchicago.edu/xtf/view?docId=grxr/NASA-Explorer-11-Flight/NASA-Explorer-11-Flight.dc.xml Thu, 01 Jan 1970 12:00:00 GMT