What to know about the USA's Artemis II Moon mission

NASA's Artemis II Moon mission lifted off on Wednesday from the U.S. state of Florida, carrying four astronauts on the first crewed flight around the Moon in more than 50 years.

The Space Launch System rocket, with the Orion spacecraft on top, launched from NASA's Kennedy Space Centre at 6:35pm Eastern Time.

It is NASA's first crewed mission under the Artemis program. The four-member crew consists of NASA astronauts Reid Wiseman, Victor Glover and Christina Koch, along with Canadian Space Agency astronaut Jeremy Hansen.

What's the purpose?

A sweeping collection of astronaut health studies planned for the mission will soon provide agency researchers with a glimpse into how deep space travel influences the human body, mind and behaviour, NASA said on its website.

During an approximately 10-day mission, the astronauts are set to collect and store saliva, wear wrist monitors that track movement and sleep, and provide other essential data for NASA's Human Research Program and other agency science teams.

The mission will explore how the immune system reacts to spaceflight and evaluate how crew members perform individually and as a team throughout the mission, including how easily they can move around within the confined space of their Orion spacecraft.

Astronauts will also collect a standardised set of measurements spanning multiple physiological systems to provide a comprehensive snapshot of how spaceflight affects the human body.

What's more, radiation sensors placed inside the Orion capsule cells will collect additional information about radiation shielding functionality and organ-on-a-chip devices containing astronaut cells will study how deep space travel affects humans at a cellular level.

The crew will also conduct science investigations that will inform future deep space missions, including a lunar science investigation as Orion flies about 4,000 to 6,000 miles (approximately 6,400 to 9,600 kilometres) from the Moon's surface.

As Orion passes on the far side of the Moon, the side that always faces away from Earth, the crew will analyse and photograph geologic features on the surface, such as impact craters and ancient lava flows.

 Why is the mission crucial?

The studies focusing on the health of Artemis II astronauts will provide researchers with an unprecedented glimpse into how deep space travel influences the human body, mind and behaviour, said NASA.

Results will help the agency develop future interventions, protocols, and preventive measures to best protect astronauts on future missions to the lunar surface and Mars, it said.

"Artemis II is a chance for astronauts to implement the lunar science skills they've developed in training," said Kelsey Young, Artemis II lunar science lead at NASA's Goddard Space Flight Centre in Greenbelt, Maryland.

"It's also an opportunity for scientists and the engineers in mission control to collaborate during real-time operations, building on the years of testing and simulations that our teams have done together," she said.

The crew's observations will also help pave the way for lunar science activities on future Artemis missions to the Moon's surface, said NASA.

The astronauts could be the first humans to see some parts of the Moon's far side with the naked eye, it said. During the nine Apollo missions that left Earth's orbit, astronauts saw parts of the Moon's far side, but not all of it, limited by which sections were lit during their orbits.

The astronauts may also get to observe flashes of light from space rocks striking the surface, clues that help reveal how often the Moon gets hit, or dust floating above the Moon's edge, a mysterious phenomenon scientists want to understand, it added.

"Whether they're looking out the spacecraft's windows or walking the surface, Artemis astronauts will be working on behalf of all scientists to collect clues to the ancient geologic processes that shaped the Moon and our solar system," said Cindy Evans, NASA's Artemis geology training and strategic integration lead.

Why the moon?

The Artemis II mission is part of the Artemis program that aims to return astronauts to the Moon and develop space defence technologies. According to NASA, there will be two more missions under the program in the next two years.

Scheduled for 2027, the Artemis III mission will launch a crew in the Orion spacecraft atop the Space Launch System rocket to test rendezvous and docking capabilities between Orion and commercial spacecraft needed to land astronauts on the Moon.

NASA targets early 2028 for the launch of Artemis IV to lunar orbit, where two crew members will land on the Moon and spend approximately a week near its South Pole, investigating the landforms, rocks and other features around their landing site.

The program envisions humans living beyond Earth's orbit, said Clayton Swope, deputy director of the Aerospace Security Project at the Washington-based Centre for Strategic and International Studies, a think tank.

All roads to the cosmos naturally lead through the Moon, making it ideal for NASA to test new technologies and figure out how to sustain human life far from Earth, thereby preparing for future missions to Mars and beyond, Swope wrote in a commentary on the think tank's website.

It will serve as a jumping-off point for scientific expeditions, he said, adding that lunar infrastructure will serve as a key waystation and transit hub, possibly within decades, like a service plaza on an interstellar toll road for journeys between Earth and beyond.

The Moon is also important because of its natural resources, he said. "Today, transporting the materials needed to support space activities into orbit, let alone to deep space, is expensive. Water ice on the Moon can be broken down and used for a variety of purposes, such as manufacturing propellant."

The Moon contains certain resources that may be valuable enough to extract and bring back to Earth, including rare earth elements used in modern electronics, while helium-3 -- scarce on Earth but abundant on the Moon -- could support future advances in quantum technologies, he added.

Some experts also argue that during a time when Americans are polarised once more, and the United States is at war, the program could offer a rare moment of collective national pride. "Space is one of the few areas that Americans with different political views can enjoy and watch together," Esther Brimmer, a senior fellow at the Council on Foreign Relations who specialises in space policy, told the BBC. "The space programme is something that most Americans have grown up with and see as a point of pride," Brimmer added. "It's by and large unifying, in terms of the social impact."