Artemis II: how eight explosions ensured safe return to Earth

NASA's Artemis II mission ended successfully thanks to eight controlled explosions that fine-tuned the Orion capsule's trajectory during atmospheric reentry. Astronauts Reid Wiseman, Christina Koch, Victor Glover, and Jeremy Hansen completed this milestone after a lunar flyby, proving vital systems for future crewed missions.

These explosions were not accidents but precise firings of thrusters on the crew module and the European Service Module (ESM). The system, developed with the European Space Agency (ESA), triggered a sequence of impulses to correct the capsule's atmospheric entry angle. A margin of just 0.7 degrees separated success from catastrophic failure.

The ideal reentry angle was 6.2 degrees. Too steep, and the capsule would face extreme heat capable of destroying it. Too shallow, and it would bounce off the atmosphere like a stone on water. The eight impulses ensured Orion entered precisely within this narrow window.

The thrusters use liquid fuel that, when burned, expels gas at high speed. This creates thrust in the opposite direction, according to Newton's third law. The main AJ10 engine handles large maneuvers, while smaller reaction control system (RCS) thrusters make fine adjustments like those in Artemis II.

Inside Orion, astronauts heard the impulses as sharp knocks on the hull. "That was incredible," said Christina Koch. "That was good. Everything is fine. Pressure is correct," added Victor Glover. The sound was the physical confirmation that systems were working as planned.

The sound was the physical confirmation that systems were working as planned.

The mission launched from Kennedy Space Center in Florida using the Space Launch System (SLS) rocket. Its path followed a free-return trajectory, using lunar and Earth gravity. But without those eight impulses, a safe return would not have been possible.