Artemis II: countdown to SLS launch

# Countdown Underway: Artemis II Gears Up for First Crewed SLS Flight

On March 30, the official countdown kicked off at Kennedy Space Center for the Artemis II test flight. The timer was activated at 16:44 Eastern Time (00:44 Moscow time on March 31). Target launch window: 18:24 ET on April 1. This marks the debut crewed launch of the Space Launch System (SLS) rocket and Orion spacecraft, laying the groundwork for future lunar missions.

Engineers are activating onboard systems, testing communications, and preparing cryogenic tanks. The rocket will be loaded with hundreds of thousands of gallons of supercooled liquid hydrogen (LH2) and liquid oxygen (LOX). At Launch Pad 39B, the sound suppression water tank is being filled—it will protect the structure from acoustic loads during RS-25 engine operation.

Crew and Preparation

Four-member crew:

• Reid Wiseman (commander, NASA);
• Victor Glover (pilot, NASA);
• Christina Koch (mission specialist, NASA);
• Jeremy Hansen (mission specialist, CSA).

Astronauts are wrapping up technical checks and medical exams in quarantine. NASA officers and U.S. Space Force meteorologists are monitoring weather for the Delta-45 rocket. Forecast: 80% "go" on April 1, risks—cloud cover and upper-level winds.

Live streams on NASA's YouTube channel: tanking from 7:45 ET, main launch from 12:50 ET.

Background on Delays

The mission was postponed from February due to issues during SLS tests. An LH2 leak was discovered in the launch system and a valve malfunction in the Orion capsule. Teams fixed the defects, ensuring safety for the crewed flight.

SLS is a heavy-lift rocket with a core stage powered by four RS-25 engines (total thrust ~8.8 million pounds) and two solid rocket boosters. Orion is equipped with AVCOAT heat shield, life support systems, and AJ10 engines for trajectory corrections.

Mission Technical Details

Artemis II is an orbital test without a lunar landing. Trajectory: TLI (translunar injection), lunar flyby, return. Duration: ~10 days. Main objectives:

• Verification of SLS in crewed mode;
• Testing Orion in deep space (radiation, microgravity);
• Checking life support and abort systems;
• Data collection for Artemis III (lunar landing).

Key metrics:

| Parameter | Value |

|----------|----------|

| Orbital altitude | ~100 km (post-escape) |

| Distance | 400,000+ km |

| Crew | 4 |

| Payload | ~27 t (Block 1) |

Key Points

• First crewed SLS/Orion: transition from uncrewed tests (Artemis I, 2022).
• Crew includes an international participant (CSA), highlighting Artemis Accords partnerships.
• Weather forecast 80% favorable, but winds and clouds are key risks.
• LH2 leak and Orion valve fixed after February tests.
• Tanking and launch streams available from 7:45 ET on April 1.

— Editorial Team