Editing Delta II (section)

== Launch profile ==
; [[Launch vehicle]] build-up: A Delta II launch vehicle was assembled vertically on the launch pad. Assembly started by hoisting the first stage into position. The solid rocket boosters were then hoisted into position and mated with the first stage. Launch vehicle build-up then continued with the second stage being hoisted atop the first stage.<ref>{{cite web |url=http://www.nasa.gov/centers/kennedy/launchingrockets/status/2007/elvstatus-20070606.html |title=Expendable Launch Vehicle Status Report |date=June 6, 2007 |publisher=NASA |access-date=June 8, 2007 |archive-url=https://web.archive.org/web/20070608140719/http://www.nasa.gov/centers/kennedy/launchingrockets/status/2007/elvstatus-20070606.html |archive-date=June 8, 2007 |url-status=live}} {{PD-notice}}</ref>

; Fueling: It took approximately 20 minutes to load the first stage with {{cvt|10000|USgal|L|-2|order=flip|sp=us}} of fuel.<ref>{{cite web |url=http://www.nasa.gov/mission_pages/swift/launch/pad.html |title=Swift Launch Pad Activities |date=2004-11-18 |access-date=2007-12-20 |archive-url=https://web.archive.org/web/20070808154914/http://www.nasa.gov/mission_pages/swift/launch/pad.html |archive-date=2007-08-08 |url-status=live}} {{PD-notice}}</ref>

: At T-45 minutes, fueling completion was confirmed. At T-20 minutes, the [[Flight termination|FTS]] pyros were armed. At T-20 minutes and T-4 minutes, two built-in holds occurred. During these holds, final launch checkouts were performed. At T-11 seconds SRB igniters were armed. Ignition of the main engine was at T-0.4 seconds. The ascent profile varies between missions.

; SRB staging: If 9 solid rocket boosters were used, only six were ignited at launch. After about a minute, once the first six were depleted, three air-start motors would ignite for another minute and the ground-start motors would separate.<ref>{{Cite book |last=Squyres |first=Steve |title=Roving Mars: Spirit, Opportunity, and the Exploration of the Red Planet |publisher=Hachette Books |year=2005 |isbn=9781401308513}}</ref> The air-start motors had nozzles optimized for high-altitude as they operated mostly in a near-vacuum during the flight.

: If only 3 or 4 boosters were used, all were ignited on the ground and jettisoned at the same time.