Delta B

{{Infobox Rocket

|image = Thor Delta B with TIROS 8 (Dec. 21 1963).gif

|caption = Delta B prior to the launch of TIROS-8

|function = Expendable launch system

|country-origin = United States

|sites = Cape Canaveral LC-17

|capacities =

{{Infobox rocket/Payload

|location = LEO

|altitude = {{convert|350|nmi}}

|mass = {{convert|800|lbs}}

}}

{{Infobox rocket/Payload

|location = Earth escape trajectory

|mass = {{convert|130|lbs}}

}}

|launches = 9

|success = 8

|fail = 1

|status = Retired

|first = 13 December 1962

|last = 19 March 1964

}}

The Delta B, or Thor-Delta B was an American expendable launch system used for nine orbital launches between 1962 and 1964.{{cite web |last1=Krebs |first1=Gunter D. |title=Delta B |url=https://space.skyrocket.de/doc_lau_det/delta-b.htm |website=Gunter's Space Page |access-date=May 31, 2023 |archive-url=https://web.archive.org/web/20230130091546/https://space.skyrocket.de/doc_lau_det/delta-b.htm |archive-date=January 30, 2023 |url-status=live}} A derivative of the Thor-Delta, it was a member of the Delta family of rockets.{{cite news |last1=Graham |first1=William |title=The evolution of Thor – Delta II prepares for swansong |url=https://www.nasaspaceflight.com/2018/09/evolution-thor-delta-swansong/2/ |access-date=May 31, 2023 |work=NASASpaceflight.com |date=September 13, 2018 |archive-url=https://web.archive.org/web/20230329025914/https://www.nasaspaceflight.com/2018/09/evolution-thor-delta-swansong/2/ |archive-date=March 29, 2023 |page=2 |url-status=live }}

The first stage was a Thor missile in the DM-21 configuration, and the second stage was the AJ10-118,{{cite tech report |title=Launch Vehicles of the National Launch Vehicle Program |url=https://ntrs.nasa.gov/api/citations/19630000838/downloads/19630000838.pdf |access-date=May 31, 2023 |archive-url=https://web.archive.org/web/20221206002333/https://ntrs.nasa.gov/api/citations/19630000838/downloads/19630000838.pdf |archive-date=December 6, 2022 |date=November 1962 |url-status=live |publisher=NASA |location=Washington, D.C. |id=N63-10712 |page=7 }} which was derived from the earlier Delta-A. An Altair solid rocket motor was used as a third stage.

All nine launches occurred from Cape Canaveral Air Force Station Launch Complex 17. Most of the launches carried communications satellites, including Syncom-1{{cite web |last1=Wade |first1=Mark |title=Thor Delta B |url=http://www.astronautix.com/t/thordeltab.html |website=Astronautix |access-date=May 31, 2023 |archive-url=https://web.archive.org/web/20230515080459/http://astronautix.com/t/thordeltab.html |archive-date=May 15, 2023 |url-status=live}} and Syncom-2. Syncom-1 was intended to be the first satellite to be placed into a geosynchronous orbit, however the spacecraft malfunctioned prior to reaching this orbit.{{cite tech report |title=NASA, The First 25 Years: 1958 - 1983 |url=https://ntrs.nasa.gov/api/citations/19840018495/downloads/19840018495.pdf |publisher=NASA |access-date=May 31, 2023 |archive-date=May 31, 2023 |location=Washington, D.C. |page=38 |date=1983 |url-status=live |archive-url=https://web.archive.org/web/20230531092026/https://ntrs.nasa.gov/api/citations/19840018495/downloads/19840018495.pdf }} Syncom-2 subsequently became the first geosynchronous satellite, and was placed at 55° west of the Greenwich Meridian. The final launch failed due to third stage underperformance,{{cite news |title=Satellite Rocket Failure Ends Winning Streak |url=https://www.newspapers.com/article/corpus-christi-times-satellite-rocket-fa/125615928/ |access-date=May 31, 2023 |work=Corpus Christi Times |agency=Associated Press |date=March 19, 1964 |archive-url=https://web.archive.org/web/20230531093106/https://www.newspapers.com/article/corpus-christi-times-satellite-rocket-fa/125615928/ |archive-date=May 31, 2023 |location=Cape Kennedy |page=1 |url-status=live |via=Newspapers.com }} all other launches were successful.