Artemis III sequence of events
1. The Pre-Rollout Phase (3 Days Before Rollout to Rollout Day)
- 3 Days Before Rollout: Senior engineering teams at the Kennedy Space Center conduct the Rollout Readiness Review, confirming ground support systems and Crawler-Transporter 2 are green for operations.
- 2 Days Before Rollout: Technicians inside the Vehicle Assembly Building (VAB) retract the final structural work platforms surrounding the integrated SLS rocket and Orion capsule.
- 1 Day Before Rollout: Engineers mate the Mobile Launcher to the massive Crawler-Transporter 2 and perform initial power-up diagnostics on the umbilical lines.
- Rollout Day: The Rollout Begins: The 322-foot-tall Artemis II stack exits the VAB and begins its slow, 4.2-mile trek to Launch Pad 39B, moving at a top speed of 0.8 mph.
2. Intermediate Pad Preparations (Post-Rollout to L-11 Days)
- L-20 days: Engineering teams at Pad 39B perform an extensive structural walkdown and alignment check of the SLS mobile launcher.
- L-18 days: Ground crews load the final flight kits, fresh food, and scientific experiment payloads into the storage lockers of the Orion capsule.
- L-16 days: Pad technicians initiate the dry nitrogen purge of the Orion cabin and service module to eliminate moisture before sealing the vehicle.
- L-14 days: Mission Control in Houston and the launch team in Florida run an all-encompassing, simulated 24-hour launch-abort scenario.
- L-12 days: The U.S. Navy recovery fleet, including the USS San Diego, departs port to take up rescue positions in the Pacific Ocean splashdown zone.
- L-11 days: Hydraulic and flight-control actuation systems on the SLS core stage and solid rocket boosters undergo final pressurization tests
3. Final Pre-Launch Phase (L-10 Days to L-24 Hours)
- L-10 days: Completion of final end-to-end flight software validation and testing of the S-band/X-band radio communication loops between Orion and Mission Control.
- L-9 days: Final physical inspections of the Space Launch System (SLS) solid rocket booster joints and structural seals at the pad.
- L-8 days: Flight readiness testing of the Orion Environmental Control and Life Support Systems (ECLSS) using ground power simulators.
- L-7 days: The integrated SLS rocket and Orion capsule undergo final closeout inspections and all umbilical connections are locked.
- L-6 days: NASA officially publishes the formalized countdown timeline, establishing precise times for ground crews and tracking networks.
- L-5 days: Battery charging protocols are completed for Orion’s internal flight batteries and the emergency launch abort system.
- L-4 days: Crew Arrival: The four crew members fly from Houston to Kennedy Space Center to begin final medical isolation and flight suit fit checks.
- L-3 days: Flight controllers conduct the final L-3 weather briefing, analyzing wind shear and lightning constraints for the launch window.
- T-43 hours: The official countdown clock begins ticking; ground control boots up Orion’s avionics and initializes the core stage flight computers.
- L-2 days: Senior managers conduct the definitive Flight Readiness Review (FRR), signing off on rocket safety telemetry and ground recovery fleet positions.
- L-24 hours: Crew Weather Briefing: The flight crew attends their final comprehensive pre-launch weather briefing and undergoes an evening medical checkup to clear them for the physical strains of liftoff.
4. The Launch Countdown (L-11 Hours to T-0)
- L-11 hours: The Launch Director issues the official “Go” for cryogenic tanking procedures.
- L-10 hours: Slow-fill operations begin, pumping supercooled liquid oxygen (LOX) into the SLS core stage tanks.
- L-8 hours: Fast-fill operations begin for both liquid oxygen (LOX) and liquid hydrogen (LH2) across the core and upper stages.
- L-5 hours: Cryogenic tanks enter “replenish” mode, continuously topping off boiled-off propellant until minutes before launch.
- L-3 hours & 15 minutes: Suit-Up and Transport: The crew suits up in their custom Orion Crew Survival System pressure suits and is transported to Pad 39B via the crew vehicle.
- L-3 hours: Crew Ingress: The crew members are systematically strapped into their custom-molded seats inside the Orion capsule by the pad closeout team.
- L-2 hours: Hatch Closure & Comms Check: The hatch of the Orion capsule is officially sealed, and the crew performs an extensive audio check with the Capcom in Houston.
- L-1 hour & 30 minutes: Ground crews evacuate the danger zone of Launch Complex 39B, leaving the pad completely clear.
- L-45 minutes: The Orion spacecraft transitions from ground power lines to its internal flight batteries.
- L-15 minutes: Launch Abort System Arming: The spacecraft’s Launch Abort System (LAS) pyrotechnics are armed, giving Commander Wiseman the ability to trigger a crew escape if an emergency arises on the pad.
- T-10 minutes: The Flight Director polls all stations (Propulsion, Avionics, Weather, Safety) for the final “Go/No-Go” for launch.
- T-6 minutes: The SLS core stage auxiliary power units (APUs) are started to power the rocket’s hydraulic steering systems.
- T-90 seconds: The ground launch sequencer hands over control to the automated onboard flight computers of the SLS.
- T-33 seconds: The SLS rocket transitions entirely to internal battery power.
- T-6 seconds: The four main RS-25 core engines ignite sequentially in milliseconds, building up to full operational thrust.
- T-0: The twin Solid Rocket Boosters (SRBs) ignite, producing 8.8 million pounds of thrust as the hold-down bolts release to lift Artemis II off the pad.
5. Ascent & Early Orbit Phase (T-0 to T+4 Hours)
- T+1 minute & 10 seconds: G-Force Management: The rocket reaches Max Q (maximum aerodynamic pressure), where the crew experiences their first intense acceleration vibration peaking at nearly 3 Gs.
- T+2 minutes: Exhausting their fuel, the two massive SRB boosters split cleanly away from the SLS core stage and plummet into the Atlantic Ocean.
- T+3 minutes & 15 seconds: The Launch Abort System (LAS) tower separates from the nose of the capsule, as aerodynamic abort limits are cleared.
- T+8 minutes: Core Stage Cutoff (MECO). The main RS-25 engines shut down after burning all core stage fuel.
- T+8 minutes & 15 seconds: Zero-G Entry: The core stage separates from the Interim Cryogenic Propulsion Stage (ICPS) and Orion, entering the crew into microgravity for the first time.
- T+18 minutes: Orion’s four European-built solar array wings deploy seamlessly in a cross formation to begin generating electrical power.
- T+40 minutes: Perigee Raise Maneuver: The ICPS upper stage fires its RL10 engine for the first time, raising the lowest point of the orbit to prevent premature re-entry.
- T+1 hour & 15 minutes: Flight controllers verify data connections through the Tracking and Data Relay Satellite (TDRS) network to ensure continuous video and telemetry loops.
- T+2 hours: Unsuiting Phase: The crew receives clearance from Mission Control to safely open their pressure-suit helmet visors, unbuckle, and unpack their zero-g flight gear.
- T+2 hours & 30 minutes: Life Support Evaluation: Mission Specialists Christina Koch and Jeremy Hansen complete the first extensive structural and atmospheric checks on Orion’s life support systems (ECLSS) to monitor carbon dioxide scrubbing.
- T+3 hours: First Space Meal: The crew gathers to prepare and consume their first meal in space using the newly activated Orion food rehydration and water dispensing systems.
- T+3 hours & 40 minutes: Manual Proximity Operations Initiation: The Orion capsule detaches from the ICPS upper stage using small thrusters.
- T+3 hours & 50 minutes: Automated backflip, manually orienting the capsule toward the spent ICPS rocket stage.
- T+4 hours: Prox Ops Testing (Artemis II): The crew completes the first manual piloting approach within 30 feet of the target stage, testing handling characteristics for future moon-docking missions.
Footnote
- Sources: Aerospace dashboard, funkystuff.org
- Outgoing: NASA
- Keywords: Table, Artemis3, Artemis 2