Almost fifty years after the Apollo mission, NASA is gearing up to return humanity to the Moon with its Artemis program. Artemis I, an uncrewed mission that is the first in a series of increasingly complex missions, is scheduled for launch on August 29 and will test the agency’s Space Launch System (SLS) rocket and Orion crew capsule.

Artemis I launch

The SLS rocket and Orion spacecraft completed their approximately six-and-a-half kilometre journey from their assembly building to Launch Complex 39B at the Kennedy Space Centre in Florida on August 17. The mission is scheduled to launch no earlier than August 29.

At launch, the rocket will produce a maximum of more than 3.9 million kilograms of thrust from its four RS-25 engines and five-segment boosters. Shortly after launch, the boosters, service module and launch abort systems will be jettisoned. Then, the core stage engines will be shut down and the core stage will separate from the spacecraft.

Artemis I: Trajectory to the moon

After launch, the spacecraft will orbit the Earth and deploy its solar arrays. Next, the Interim Cryogenic Propulsion Stage (ICPS) will give Orion a “push” to help it leave Earth’s orbit and travel toward the planet’s only natural satellite. Then, within about two hours from launch time, when the spacecraft is on a trajectory to the Moon, it will separate from ICPS.

When it separates from the spacecraft, ICPS will deploy small satellites, known as CubeSats to send them on their journey to deep space. This includes BioSentinel, which will carry yeast into deep space to study the effects of deep space radiation on living matter. The other CubeSats will also perform many science and technology demonstrations.

Artemis I: Moon orbit

On its path to the Moon, Orion will be propelled by a service module built by the European Space Agency. Apart from supplying the spacecraft’s propulsion system and power, the service module is also designed to house air and water for future crewed missions. The trip to the Moon will take several days.

Once it enters the Moon’s orbit, the spacecraft will stay there for approximately six days as it collects data, also giving the mission team enough time to assess its performance. After the six days, Orion will get very close to the moon, about 95 kilometres above its surface, and it will use a precisely timed engine firing of the service module in combination with the Moon’s gravity to accelerate back towards our planet.

Artemis I: Reentry into Earth’s atmosphere

After a total mission time of around 6 weeks and having travelled more than 3 million kilometres, Orion will enter Earth’s atmosphere at around 40,000 kilometres per hour, or 11 kilometres per second. During reentry, it will produce temperatures close to 3,000 degrees Celsius. And if all goes as planned, it will land in the sea, within eyesight of a recovery ship which will be waiting, stationed off the coast of Baja in California.

After landing, the spacecraft will remain powered for some time till a team of US Navy divers and NASA Exploration Ground System members approach it in small boats from the ship. The team will first inspect the aircraft before the divers tow the capsule towards the recovery ship.