Forty years ago today — August 9, 1969 — an LTTAT-Delta rocket launched from Cape Canaveral carrying the sixth Orbiting Solar Observatory (OSO-6). According to the National Space Science Data Center, “OSO 6 was the sixth in a series of satellites designed to conduct solar physics experiments above the earth’s atmosphere during a complete solar cycle.” The spacecraft operated successfully until the end of 1972.
One curious thing: the first source on which I found the OSO-6 anniversary said it launched from Vandenberg Air Force Base. Just goes to show, you can’t believe everything you read on the Internet.
Oh, and LTTAT-Delta refers to a “long-tank thrust augmented Thor-Delta,” which started launching in 1968 and made many successful launches according to NASA.* In case you were wondering.
*Yes, some other Internet sources contradict this. So pick the source in which you have the most trust.