PRE-LAUNCH | ARTEMIS II

LAUNCH DAY

PRE-LAUNCH COUNTDOWN + ASCENT EVENTS

Pre-Launch Timeline

Countdown milestones to liftoff

Pre-Launch Timeline

Countdown milestones to liftoff

T-38h Launch Readiness Review
04:24 EDT / 10:24 CEST

Final review of all systems, weather, and range safety. GO/NO-GO decision for propellant loading.

T-11h Launch Countdown Begins
07:24 EDT / 13:24 CEST

Official countdown clock starts. Ground systems power-up sequence initiated.

T-8h Clear Pad for Tanking
10:24 EDT / 16:24 CEST

All non-essential personnel evacuate the pad area. Hazardous operations zone established.

T-6h Propellant Loading Begins
12:24 EDT / 18:24 CEST

Liquid oxygen and liquid hydrogen loading into SLS core stage. Over 2.6 million liters of cryogenic propellant.

T-3h15m Crew Wake-up
15:09 EDT / 21:09 CEST

Flight crew awakened at Kennedy Space Center crew quarters. Final medical checks and meal.

T-3h Crew Suit-up
15:24 EDT / 21:24 CEST

Astronauts don Advanced Crew Escape Suits (ACES) — the iconic orange launch-entry suits.

T-2h30m Crew Walkout & Astrovan Ride
15:54 EDT / 21:54 CEST

Crew walks out of Neil Armstrong Operations & Checkout Building. Astrovan II drives to Launch Pad 39B.

T-2h Crew Ingress Orion
16:24 EDT / 22:24 CEST

All four astronauts board the Orion spacecraft. Seats configured, comm checks, survival kit verification.

T-1h Hatch Close & Leak Check
17:24 EDT / 23:24 CEST

Orion side hatch closed and sealed. Cabin pressure leak check to verify spacecraft integrity.

T-30m Terminal Countdown
17:54 EDT / 23:54 CEST

Terminal countdown sequence begins. Final system checks, range clear for launch.

T-10m Final GO/NO-GO Polls
18:14 EDT / 00:14 CEST

Launch director polls all stations for final GO/NO-GO. Artemis Launch Director confirms GO for launch.

T-2m Orion to Internal Power
18:22 EDT / 00:22 CEST

Orion spacecraft switches to internal battery power. Ground umbilicals prepared for disconnect.

T-31s Automated Launch Sequence
18:23 EDT / 00:23 CEST

Ground Launch Sequencer takes over. Automated final checks: hydraulics, engine gimbal, flight termination system.

T-0 LIFTOFF
18:24 EDT / 00:24 CEST

RS-25 engines at full thrust, SRB ignition, hold-down bolt separation. SLS clears the tower. GO ARTEMIS!

Launch & Ascent

Liftoff through Translunar Injection

1
T+0s LIFTOFF

SLS clears the tower at Launch Pad 39B. 8.8 million pounds of thrust.

ALT: 0 km
VEL: 0 km/s
2
T+2m SRB Separation

Twin solid rocket boosters jettisoned after burning 1.6 million kg of propellant each.

ALT: ~48 km
VEL: ~1.5 km/s
3
T+3m Fairing Panels Jettison

Launch Abort System and protective panels jettisoned. Orion spacecraft exposed.

ALT: ~67 km
VEL: ~1.8 km/s
4
T+8m Core Stage MECO

Main Engine Cutoff — four RS-25 engines shut down after consuming 2.7 million liters of propellant.

ALT: ~160 km
VEL: ~7.8 km/s
5
T+8m10s Core Stage Separation

SLS core stage separates. Now relying on the Interim Cryogenic Propulsion Stage (ICPS).

ALT: ~161 km
VEL: ~7.8 km/s
6
T+8m20s ICPS Ignition

Single RL-10B-2 engine of the ICPS fires for orbital insertion burn.

ALT: ~162 km
VEL: ~7.8 km/s
7
T+18m ICPS Cutoff — Orbit Achieved

Parking orbit achieved at ~185 km x 1,800 km. Systems checkout begins.

ALT: ~185 km
VEL: ~7.9 km/s
8
T+1h50m TLI Burn — Heading to the Moon

Translunar Injection burn. ICPS fires again to accelerate Orion to Earth escape velocity.

ALT: ~1,800 km
VEL: ~10.9 km/s
9
T+2h10m Orion Separation & Solar Deploy

Orion separates from spent ICPS. Solar arrays unfurl. Crew begins 10-day journey.

ALT: ~3,000 km
VEL: ~10.8 km/s