Four astronauts set off aboard a NASA spacecraft this morning on a journey that will take them farther from Earth than any human has travelled since the Apollo program more than five decades ago.

The astronauts, Reid Wiseman, Victor Glover and Christina Koch of the United States, and Jeremy Hansen of Canada, will travel to the Moon, loop around it once, and return to Earth in about ten days. The Artemis II mission carrying the four astronauts launched from the Kennedy Space Centre in Florida, US, a little before 4 AM India time on Thursday.

Hundreds of astronauts have travelled into space since the end of the Apollo programme that landed 12 humans on the Moon on six different missions in the 1960s and 1970s, but none of them ventured beyond the low Earth orbits, where space stations operate at altitudes of about 400 kilometres.

Koch, 47, who has spent almost a year on the International Space Station, will be the first woman to reach Moon’s neighbourhood. The 24 astronauts on the six expeditions of the Apollo programme that reached the Moon — 12 who landed, and 12 who remained in orbit — were all men.

The Artemis programme of NASA is about getting humans back on the Moon, this time to prepare the ground for frequent and prolonged stays, creation of a permanent base, and explore possibilities of exploitation of local resources for sustainable long-term human presence. The first flight of the Artemis programme, an uncrewed mission, happened in 2022. Artemis II, which launched on Thursday morning, is what is known as a flyby, a space mission that goes very near to a planetary body but does not land on it. This is a sort of a rehearsal for a successor mission in 2028 which will land the first humans on the Moon since Apollo 17 in 1972.

In between, NASA has another mission planned for next year to carry out additional checks on the hardware and systems that will enable the human landing.

This is one of the crucial differences between the Apollo era and the missions that are now planned to mark the return of humans to Moon. The kind of technical and operational risks that were inherent in the Apollo missions simply not acceptable in today’s age.

Artemis II is more than just a rehearsal, though. It has a lot of science objectives as well. The astronauts on board the Orion spacecraft will work with the scientists on ground stations to carry out scientific investigations that will help human spaceflights in future. Their journey will take them towards the far side of the Moon, the side that is permanently looking away from the Earth.

This will be the first time human eyes would look towards this part of the moon.

“During this three-hour period, astronauts will analyze and photograph geologic features, such as impact craters and ancient lava flows. They will rely on the extensive geology training they received in the classroom and in Moon-like places on Earth to describe nuances in shapes, textures, and colors — the type of information that reveals the geologic history of an area. These skills will be critical to exploring the Moon’s South Pole region through future missions,” according to NASA description.

Their eventual trajectory might also take them further in space than any human being has ever ventured, more than the distance the Apollo missions travelled from Earth.