Artemis: Sequence of events during a mission

Artemis, NASA

Artemis: Sequence of events during a mission

Rollout to launch pad

  • Artemis I dates:
  • 15-08-2022 All platforms in the VAB in retract position.
  • 16-08-2022 Call for Rollout.
  • 17-08-2022 No Rollout when:
      • Lightning forecast is greater than 10% within 20 nautical miles of the launch area during rollout.
      • There is greater than a 5% chance of hail forecast in the launch area during rollout.
      • The peak winds exceed 40 knots in the launch area during rollout.
      • Temperature is less than 40 degrees Fahrenheit or exceeds 95 degrees Fahrenheit at the launch area during rollout.
  • 17-08-2022 Poll Go/No Poll for Rollout. About 12 days before launch window. SLS on Mobile Launcher (ML2) leaving the VAB for Launch Pad 39B with Crawler Transporter. It takes 10 hours from VAB to Lauch Pad. 
  • 00-00-0000 When on the pad:
    • Validate the services.
    • Check communication.
    • Check telemetry.
    • Commodity connects.
    • Extend the crew access arm.
    • Open the hatch.
    • Engineering tests.
    • Servicing the boosters.
    • Launch countdown preps.
    • Launch countdown.
  • 00-00-0000 Crawler downhill.


Hours before launch

  • 48:00:00 Launch Team (LT, LCT) arrives on their stations at Launch Control Center (LCC at KSC, Florida). About 48 hours before the opening of the launch window. 
  • 48:00:00 Countdown begins.
  • 45:00:00 Fill the water tank for the Sound Suppression Water System (SSWS).
  • 40:00:00 Orion Spacecraft is powered up.
  • 34:45:00 Core Stage (CS) powered up.
  • 30:50:00 Final preparations of the four RS-25D engines.
  • 30:05:00 Orion Crew Module (CM) hatch closed.
  • 28:50:00 Leak checks are completed and the hatch on the Launch Abort System (LAS) is closed.
  • 26:05:00 Crew access arm retract.
  • 21:00:00 Side flame deflectors are moved into place.
  • 12:45:00 Interim Cryogenic Propulsion Stage (ICPS) is powered up. ICPS consists of Forward Skirt (houses computers and avionics), LOX Tank, Intertank, LH2 Tank, Engine section. Cryogenic means very low temperatures.
  • 12:00:00 All non-essential personnel leave Launch Complex 39B (LC-39).
  • 08:40:00 Built in countdown Hold. LCT conducts a weather and tanking briefing. Hold lasts approximately 2 hours. T- time stopped while L- time continues to advance. 
  • 08:40:00 LT Go/No Go Poll to Enter Terminal Countdown. Start of the tanking process.
  • 07:20:00 Core Stage LOX Chilldown start.
  • 06:25:00 Core Stage LOX Slow fill start.
  • 06:10:00 Core Stage LOX Fast fill start.
  • 06:05:00 Core Stage LH2 Chilldown start. 
  • 05:55:00 Core Stage LH2 Slow fill start.
  • 05:40:00 Core Stage LH2 Fast fill start.
  • 04:25:00 ICPS LH2 Chilldown start.
  • 04:20:20 Orion Launch Communications Segment (LCS) activated. Radio Frequency (RF) to Mission Control Center (MCC, Houston). Near Space Network.
  • 04:30:00 Core Stage LH2 Topping start.
  • 04:25:00 Core Stage LH2 Replenish start.
  • 04:00:00 ICPS LH2 Fast fill start.
  • 03:25:00 Core Stage LOX Topping start.
  • 03:20:00 ICPS LOX Chilldown start.
  • 03:15:00 ICPS LH2 Validation and leak test start.
  • 03:18:00 Core Stage LOX Replenish start.
  • 03:10:00 ICPS LOX Fast fill start.
  • 03:00:00 ICPS LH2 Topping start.
  • 02:50:00 ICPS and SLS Telemetry data verified with MCC (Houston) and the Space Launch System’s Engineering Support Center (Huntsville).
  • 02:35:00 ICPS LH2 Replenish start.
  • 02:30:00 ICPS LOX Validation and leak test.
  • 02:20:00 ICPS LOX Topping start.
  • 02:10:00 ICPS LOX Replenish start.

Minutes before launch

  • 00:40:00 Built in countdown Hold. Final NASA Test Director (TD) briefing. Hold lasts 30 minutes. T- time stopped while L- time continues to advance. Weather Launch Criteria.
  • 00:15:00 LD Polls the team Go/No Go for Launch.
  • 00:06:00 Ground Launch Sequencer (GLS ) gives a Go for Core Stage tank Pressurisation (brings tanks to flight levels). GLS does the countdown.
  • 00:06:00 Orion Ascent pyros armed.
  • 00:06:00 Orion To internal power.
  • 00:05:57 Core Stage LH2 Replenish termination.
  • 00:05:00 GLS gives a Go for Flight Termination System (FTS) to Arm (align the firing chain for a destruction of the vehicle in flight when needed).
  • 00:04:00 Core Stage LOX Replenish termination.
  • 00:04:00 Go for Core Stage Auxiliary Power Unit (APU) (needed for hydrolic systems).
  • 00:03:30 ICPS LOX Replenish termination.
  • 00:03:10 Go for Perch sequence 4 (final healing in perch of the RS-25 engines).
  • 00:02:02 Go for Upper Stage to Internal Power. ICPS to battery power.
  • 00:01:56 ICPS switches to internal battery power.
  • 00:01:30 Core stage switches to Internal power.
  • 00:01:20 ICPS Enters terminal countdown mode.
  • 00:00:50 ICPS LH2 Replenish termination.
  • 00:00:33 GLS sends Go for Automated Launch Sequencer (ALS).
  • 00:00:30 Core Stage flight computer to ALS.
  • 00:00:15 Sound Suppression System (SSS) activated (water flow under the launch pad).
  • 00:00:12 Hydrogen burn off igniters initiated.
  • 00:00:10 GLS sends the command for Core Stage Engine Start.
  • 00:00:06 RS-25D engines startup (T-6.36 seconds).
          • ENGINES: 4 x RS-25D Engines, Aerojet RocketDyne. Together, the set of four-engines generates more than 2 million pounds of thrust for the climb to overcome the pull of Earth’s gravity. The engines will burn more than 90,000 gallons of liquid hydrogen and liquid oxygen every minute before the Core Stage separates from the ICPS and Orion. Burn: 8 minutes (3 minutes boosters plus core stage + 8 minutes core stage only)
  • 00:00:00 Umbilical separation.
  • 00:00:00 Boosters ignition.
          • ENGINES: 2 x Solid Booster Ignition engines. Northrop Grumman. These motors ignite the solid propellant in each solid booster at Liftoff. Burn: Less than a second.
          • ENGINES: 2 x Solid Boosters. Northrop Grumman. Together the twin boosters provide more than 75% of the total thrust at liftoff. Each booster generates a maximum thrust of 3.6 million pounds and will burn 6 tons of solid propellant every second before separating from the Core Stage. Burn: 3 minutes.

Reconfiguration (first two hours)

Seconds and minutes in flight

  • 00:00:00 Liftoff and handover to the Flight Control Team. 
  • 00:00:07 Tower Clear and Initiate Roll/Pitch Maneuver.
          • ENGINE: 1 x Launch Abort System (LAS) Abort Engine. Northrop Grumman. In the event of an emergency on the launch pad or during ascent, the abort motor fires, producing about 400,000 pounds of thrust, to quickly pull the crew capsule away from danger. Burn: 3 seconds.
          • ENGINE: 1 x Launch Abort System (LAS) Attitude Control Engine. Northrop Grumman. As the abort motor pulls Orion away from the rocket during an emergency on the pad or during launch, the LAS attitude control motor fires and provides variable thrust as needed to stabilize the crew capsule and steer it in any direction to re-orient it before the LAS is jettisoned in preparation for parachute deployment and splashdown. The motor can exert up to 7,000 pounds of steering force in any direction. Burn: 30 seconds.
  • 00:01:10 Maximum Dynamic Pressure (Max Q). Throttle down for that period.
  • 00:02:12 Solid Rocket Separation (Rocket Boosters jettison).
  • 00:03:00 Fairings jettison (3 panels). Space adaptor: Attaches Orion to the rocket when the vehicle is on its way to space, the two fairings are jettisoned.
  • 00:03:30 Launch Abort System (LAS) jettison.
          • ENGINE: 1 x Launch Abort System (LAS) Jettison engine. Aerojet RocketDyne. built by Aerojet Rocketdyne. The motor fires during a normal launch sequence to separate the launch abort system from Orion when it is no longer needed or following an abort to allow Orion to deploy parachutes for a safe splashdown in the ocean. In the unlikely event of an emergency during launch or ascent, the jettison motor will provide approximately 40,000 pounds of thrust to separate the LAS from the crew module during an abort. Burn: 1,5 seconds.
  • 00:05:24 Solid Rocket Booster (SRB) Atlantic Separation.
  • 00:08:20 Core Stage Main Engine Cut Off) MECO.
  • 00:08:30 Core Stage /ICPS Separation.
  • 00:18:00 Orion deploys Solar Arrays (ESA Netherlands). Takes 12 minutes to deploy (00:30:00 finished)
  • 00:51:00 ICPS Perigee Raise Burn. (Orbital Raise Maneuver): ICPS RL10 engine fires to boost the spacecraft in a higher orbit around the Earth:
          • ENGINE: RL10-B2 Engine (First burn). United Launch Alliance (ULA). Raises the Orion spacecraft after Core Stage separation to put the ship in a stable orbit around the Earth. First burn: Less than 1 minute to about 20 minutes.

Hours and minutes in flight

  • 01:37:00 Trans Lunar Injection (TLI): ICPS RL10 engine To increase spacecraft velocity to send Orion on a trajectory towards the Moon.
          • ENGINE: RL10-B2 Engine (Second burn). (ICPS TLI Burn). United Launch Alliance (ULA). Will generate 24,750 pounds of thrust to propel the Orion spacecraft out of Earth’s orbit to set it on its precise trajectory to the Moon. The RL10 will boost Orion for 7,700 miles before separating from the spacecraft. Second burn: 18 minutes.
  • 01:46:00 Core Stage Pacific splashdown.
  • 02:05:00 Orion separation: Orion separate from the ICPS an heads towards the Moon to continue the Artemis Mission (ICPS/Orion Separation).
  • 02:10:00 Handover to Lead Flight Director.

Three Orion components

  1. Orion Crew Module: Four astronauts, cargo, from launch to landing, the only part that lands back on Earth. 10,387 kg.
  2. Orion Crew Module Adaptor: Connects electrical, data and fluid systems between the main modules, contains electronic equipment for communications, power and control.
  3. Orion Service Module (SM): Provides electricity, propulsion, air and water. 15,461 kg. SM components:
        • Propulsion: 33 engines, 3 types. 4 tanks with 8000 litres of fuel.
        • Thermal control system: Heater and coolant (6 radiators outside the SM).
        • Consumables: Air and water (for 6 astronauts on a 20-day mission).
        • Solar Arrays: Turn on 2 axes to remain aligned with the Sun. 4 arrays.
        • Chassis structure: Holds everything together, absorbs vibrations, covered with Kevlar.
        • Avionics: Computers control all aspects of the SM: Propulsion, water, electronics and temperature.
        • Three abort scenario using the SM:
            1. Untargeted abort splashdown,
            2. Targeted abort splashdown,
            3. Ascent abort to orbit.

Orion and SM heading for the Moon

  • Outbound Trajectory Correction (OTC) burns: As necessary adjust trajectory for lunar flyby to Distant Retrograde Orbit (DRO).
        • ENGINE: 1 x Orbital Maneuvering System Engine (OMS-E). Aerojet RocketDyne. This is the main engine on the Service Module (SM) that will provide the primary propulsion for Orion’s major in-space maneuvers as it travels around the Moon. The engine provides 6,000 pounds of thrust and is equipped to steer the spacecraft. It can also be used in some abort cases to safely return Orion to Earth. Burn: Less than 1 minute to more than 16 minutes.
        • ENGINES: 8 x Fixed 490N auxiliary thrusters, model R-4D-11. Aerojet RocketDyne .These are fixed at the bottom of the SM to provide trajectory corrections and as a backup to the main engine. Each provide about 100 pounds of thrust. The auxiliary engines can provide steering during burns by pulsing on and off. Burn: Less than 1 minute up to 45 minutes.
        • ENGINES: 24 x Reaction Control System 220N Engines (6 pods x4). ArianeGroup. These engines are in fixed positions and can be fired individually as needed to move the spacecraft in different directions or rotate it into any position. Each engine provides about 50 pounds of thrust. Burn: From milliseconds up to one hour.
  • Release CubeSats from Orion Stage Adapter.
  • Testing guidance and navigation control systems.
  • Trajectory correction burns.
  • Testing oribital maneuvering system. This is the large engine that will be used for the OPF.

Around the Moon

  • Oribital manouvering.
  • MM polls the team to commit to the Outbound Powered Flyby (OPF) burn. 60 nmi from the Moon. Targets DRO insertion. The big burn. 60 miles of the surface of the moon. Orion is at the back of the moon at that time.
  • OPF performed. 
  • Lunar Orbit Insertion (LOI): Enter Distant Retrograde Orbit (DRO). Half or one and a half revolutions in the orbit period 38,000 nmi from the surface of the Moon. Artemis I will stay two weeks here. Correction burns.
  • MM polls the team to commit to a departure burn to exit the Distant Retrograde Orbit (DRO) and return to Earth. Large burn.  DRO: Perform half or one and a half revolutions in the orbit period 34,000 nmi from the surface of the moon.
  • Return Trajectory Correction (RTC) Burns.


  • MM polls the team to commit to the positioning of recovery assets for entry, descent, and landing.
  • Return Powered Flyby (RPF) burn. Most critical burn of the mission. A week before entering the Earth’s atmosphere.
  • Return Transit: Return Trajectory Correction (RTC) burns as necessary to aim for Earth’s atmosphere. RTC6.

Entry, Descent and Landing

Minutes before splashdown / altitude

  • 00:42:00 Command Module, Service Module Separation
        • ENGINES: Command Module Raise Burn: 24 x Reaction Control System 220N Engines (6 pods x4). ArianeGroup. The reaction control system will guide the Orion crew module after it separates from the SM in preparation for re-entering Earth’s atmosphere and splashdown into the ocean. Capable of 160 pounds of thrust for each engine, the system will ensure the spacecraft is properly oriented for re-entry, with its heat shield pointed forward, and stable during descent under parachutes. Burn: From less than 1 second up to 50 seconds.
  • 00:22:00 / 400,000 Feet Entry Interface (EI): Orion will enter the upper Earth atmosphere, then “skip” back out with the help of the atmosphere’s friction and the capsule’s lift, and finally re-enter the atmosphere for its final descent. Thermal Protection System Heat Shield. The heat shield is to slow down the vehicle. Aerobraking. Not specifically to withstand air resistance. The further out you go, the faster you come back. The Lunar-return velocities anticipated for Orion are expected to reach Mach 32 (39.000 km/hour) with temperatures between 2200 and 3300 degrees Celcius. The heat shield is 4,8 meters in diameter. Slowing down by the heat shield to 480 km/hour.
  • Plasma started building up around the vehicle, causing a two and a half minute blackout in communications.
  • 30.0000 Feet Forward Bay Cover Jettison. Parachute deployment begins with three forward bay cover parachutes used in conjunction with pyrotechnic linear thrusters to ensure separation of the forward baycover, which protects Orion and its parachutes during the heat of reentry. The forward bay cover parachutes are packed using a hydraulic press, with forces as high as 3,000 pounds.

  • 22,000 Feet Two drogue parachutes are deployed to slow and stabilize the crew module during descent and establish proper conditions for main parachute deployment to follow. The drogues are deployed by cannon-like mortars from the crew module forward bay 122 km/hour. The drogues are packed using a hydraulic press, with forces as high as 10,000 pounds.

  • 6,800-5,600 Feet Three pilot parachutes will lift and deploy the main parachutes from the crew module forward bay. They are mortar-deployed from the crew module forward bay at 122 km/hour. The pilots are packed using a hydraulic press for convenience but are much lower density and can be “hand packed” if required.

  • 5,000 Feet Three main parachutes will then slow the crew module to a speed that ensures astronaut safety during landing. Each of Orion’s main parachutes weighs 270 pounds and is packed to the density of oak wood to fit in the top part of the spacecraft, but once fully inflated, the three mains would cover almost an entire football field. The mains are packed using a hydraulic press, with forces as high as 50,000 pounds. They are autoclaved with a vacuum applied to the parachute at 190 degrees Fahrenheit (88 degrees Celsius) for 48 hours to help “set” the packing and remove atmospheric moisture.


  • Landing Platform Dock (LPD) class Navy ship.
  • Communication and data via MCC at JSC.
  • Deploy helicopters.
  • Deploy divers on Rigid Inflatable Boats (RIBs).
  • Data collecting upon entry (parachutes, temperatures).
  • Recovery of the jettisoned Forward Bay Cover and three parachutes by divers.
  • Splashdown Pacific Ocean near San Diego (50 to 60 nm of the coast). 20 miles/hour.
  • Main parachute cut and Crew Module (CM) Upright System Deploy.
  • As soon as Orion splashes down in the Pacific after its lunar mission, a team of divers, engineers, and technicians will depart the ship on small boats and arrive at the capsule.
  • Cooling down test of the CM in powered up mode (Artemis I).
  • Ready to recover the CM.
  • Divers approach the CM.
  • Divers attach a ponycolar (black-yellow-red-orange colors), an oversized fishing reel that can be adjusted pneumatically to secure the capsule while inside the well deck of the ship.
  • CM towed into the well deck of ship above the Orion Recover Cradle Assembly (ORCA).
  • Water is pumped out of the well deck and the CM lands in the ORCA.
  • For the uncrewd Artemis I mission the complete recovery will take 4-5 hours for data collection.