Space Exploration II: Always Looking up

WisconsinWildcard said:

Yes. Great book by an excellent web comic writer if you are into that sort of thing.

Also recommend the abridged beyond usefulness series

https://www.smbc-comics.com/covid/files/minibibleWebV2.pdf

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• L-49H50M – Launch team arrives to stations
• L-49H40M – Countdown clock begins
• L-49H40M – L-42H30M: Liquid oxygen (LOX)/Liquid hydrogen (LH2) system
  preparations for vehicle loading
• L-45H30M – L-44H: Orion spacecraft powered up
• L-42H20M – L-41H: Core stage powered up
• L-42H10M – L-40H30M: Interim cryogenic propulsion stage (ICPS) powered up
• L-39H45M – L-35H30M: Final preparations of the four RS-25 engines

• L-34H45M – L-34H10M: ICPS is powered down
• L-33H30M – L-29H30M: Charge Orion flight batteries to 100%
• L-31H30M – L-24H30M: Charge core stage flight batteries
• L-20H15M – L-18H45M: ICPS is powered up for launch

• L-15H30M – L-14H: All non-essential personnel leave Launch Complex 39B (complete)
• L-14H15M – L-12H05M: Air-to-gaseous nitrogen (GN2) changeover and rocket
  cavity inerting (complete)
• L-13H15M – L-11H45M: Ground launch sequencer (GLS) activation

• L-12H35M – L-9H50M: 2-hour 45-minute built in countdown hold begins
• L-10H50M – Launch team decides “go” or “no-go” to begin tanking
• L-10H50M – L-9H35M: Orion cold soak
• L-10H40M – L-10H35M: Core stage LOX transfer line chilldown
• L-10H40M – L-9H55M: Core stage LH2 chilldown
• L-10H25M – L-9H40M: Core stage LOX main propulsion system chilldown

• L-9H55M – L-9H25M: Core stage LH2 slow fill start
• L-9H50M – Resume T-Clock from T-8H10M
• L-9H40M – L-9H30M: Core stage LOX slow fill
• L-9H30M – L-6H40M: Core stage LOX fast fill
• L-9H25M – L-8H: Core stage LH2 fast fill
• L-9H05M – L-8H30M: ICPS LH2 chilldown
• L-8H30M – L-7H45M: ICPS LH2 fast fill start
• L-8H – L-7H55M: Core stage LH2 topping
• L-7H55M – terminal count: Core stage LH2 replenish
• L-7H45M – L-7H20M: ICPS LH2 vent and relief test
• L-7H20M – L-7H10M: ICPS LH2 tank topping start
• L-7H05M – terminal count: ICPS LH2 replenish
• L-6H40M – L-6H10M: Orion communications system activated (radio frequency to mission control)
• L-6H40M – L-6H05M: Core stage LOX topping
• L-6H40M – L-6H30M: ICPS LOX main propulsion system chilldown
• L-6H30M – L-5H45M: ICPS LOX fast fill
• L-6H10M – Stage pad rescue
• L-6H10M: – Closeout crew assemble
• L-6H05M – terminal count: Core stage LOX replenish

• L-6H – Flight crew weather brief
• L-5H45M – L-5H30M: ICPS LOX vent and relief test
• L-5H30M – L-5H10M: ICPS LOX topping
• L-5H10M – terminal count: ICPS LOX replenish
• L-5H10M – All stages replenish
• L-5H10M – Start 1-hour 10-minute built in hold
• L-5H10M – L-4H55M: Closeout crew to white room
• L-4H40M – L-4H10M: Flight crew deployment to pad
• L-4H: Flight crew board Orion
• L-3H40M – L-3H10M: Crew module hatch preps and closure
• L-3H10M – L-2H45M: Counterbalance mechanism hatch sealpress decay
  checks
• L-2H20M – L-1H40M: Crew module hatch service panel install/closeouts
• L-1H40M – L1H30M: Launch abort system (LAS) hatch closure for flight
• L-1H10M – Launch director brief – rocket & thermal protection system scan results with the imagery console
• L-50M – L-40M: Closeout crew departs Launch Complex 39B
• L-50M – Final NASA test director briefing is held

• L-40M – Built in 30-minute countdown hold begins

• L-25M – Transition team to Orion to Earth communication loop following final NTD briefing
• L-17M – Launch director polls team to ensure they are “go” for launch
• L-15M – Flight crew visors down
• L-14M – Flight crew short purge verification

• T-10M – GLS initiates terminal count
• T-8M – Crew Access Arm retract
• T-6M – GLS go for core stage tank pressurization
• T-6M – Orion ascent pyros are armed
• T-6M – Orion set to internal power
• T-5M57S – Core stage LH2 terminate replenish
• T-5M20S – LAS capability is available
• T-5M20S – NTD lets commander knows LAS capability is available
• T-4M40S – GLS go for LH2 high flow bleed check
• T-4M30S – Flight termination system armed
• T-4M – GLS is go for core stage auxiliary power unit (APU) start
• T-4M – Core Stage APU starts
• T-4M – Core stage LOX terminate replenish
• T-3M30S – ICPS LOX terminate replenish
• T-3M10S – GLS go for purge sequence 4
• T-2M02S – ICPS switches to internal battery power
• T-2M – Booster switches to internal batter power
• T-1M30S – Core stage switches to internal power
• T-1M20S – ICPS enters terminal countdown mode
• T-50S – ICPS LH2 terminate replenish
• T-33S – GLS sends “go for automated launch sequencer” command
• T-30S – Core stage flight computer to automated launching sequencer
• T-12S – Hydrogen burn off igniters initiated
• T-10S – GLS sends the command for core stage engine start
• T-6.36S– RS-25 engines startup

• Booster ignition, umbilical separation, and liftoff

• The launch team can hold at 6 minutes for the duration of the launch window, less the 6 minutes needed to launch, without having to recycle back to 10 minutes.
• If teams need to stop the clock between T-6 minutes and T-1 minute, 30 seconds, they can hold for up to 3 minutes and resume the clock to launch. If they require more than 3 minutes of hold time, the countdown would recycle back to T-10.
• If the clock stops after T-1 minute and 30 seconds, but before the automated launch sequencer takes over, then teams can recycle back to T-10 to try again, provided there is adequate launch window remaining.
• After handover to the automated launch sequencer, any issue that would stop the countdown would lead to concluding the launch attempt for that day.

• Vostok: Yuri Gagarin (April 12, 1961)
• Mercury: Alan Shepard (May 5, 1961)
• Voskhod: Vladimir Komarov, Konstantin Feoktistov, Boris Yegorov (October 12, 1964)
• Gemini: Gus Grissom and John Young (March 23, 1965)
• Soyuz: Vladimir Komarov (April 23, 1967)
• Apollo: Wally Schirra, Donn Eisele, Walter Cunningham (October 11, 1968)
• Space Shuttle STS-1: John Young and Robert Crippen (April 12, 1981)
• Shenzhou: Yang Liwei (October 15, 2003)
• SpaceShipOne SS1: Mike Melvill (June 21, 2004)
• SpaceX Commercial Crew Program Demo-2: Bob Behnken and Doug Hurley (May 30, 2020)
• Artemis: Reid Wiseman, Victor Glover, Christina Koch, Jeremy Hansen (April 1, 2026)