Firefly Aerospace became the second US company to land on the moon on Sunday with its debut Blue Ghost lander, kicking off a two-week research mission as one of a handful of private firms to reach the frontlines of a global moon race.

The size of a compact car, the four-legged Blue Ghost carried 10 scientific payloads as it touched down near an ancient volcanic vent on Mare Crisium, a large basin in the northeast corner of the moon's Earth-facing side.

Flight controllers at Firefly's Austin, Texas headquarters watched as Blue Ghost descended toward the moon's surface at a gentle two miles per hour, confirming on a live stream that the spacecraft had entered lunar gravity.

"We're on the moon," declared Will Coogan, Blue Ghost Chief Engineer at Firefly Aerospace, from mission control.

Firefly became the second private firm to score a soft moon landing.

Houston-based Intuitive Machines' Odysseus lander made a lopsided soft touchdown last year.

Five nations have made successful soft landings in the past - the then-Soviet Union, the US, China, India and, last year, Japan.

"Every single thing was clockwork, even when we landed, and then after, we saw everything was stable and upright," Firefly CEO Jason Kim said on stage at a company watch event in Austin.

In the audience were hundreds of Firefly employees, space industry officials and senior Nasa leaders, including the agency's acting administrator Janet Petro.

The moonshot by Firefly, an upstart primarily building rockets, is one of three lunar missions actively in progress.

Japan's ispace launched its second lander on the same rocket as Firefly's in January, before Intuitive Machines embarked on its second lunar mission on Wednesday.

Two navigation cameras onboard Blue Ghost were used to spot hazards on the lunar surface during its final descent, helping the spacecraft steer toward an ideal landing spot.

Impact sensors on the craft's four carbon-composite legs triggered Blue Ghost's engine to shutdown upon landing.

Two solar panels on the side and one of the top will power the lander and its research instruments for a 14-day mission on the moon, before the frigid lunar night brings temperatures as low as minus minus 173 degrees Celsius.

Backed by Nasa and its flagship Artemis moon programme, private companies are playing an outsized role in the modern moon race with the hopes of stimulating a lunar market.

Elon Musk's SpaceX and Jeff Bezos' Blue Origin are building landers to put US astronauts on the moon as soon as 2027 for the first time since 1972. (Reuters)