ispace's unmanned Resilience lander was launched in January on the SpaceX Falcon 9 rocket together with Firefly Aerospace's Blue Ghost -- which aced its lunar landing on Sunday.

Blue Ghost is only the second private mission to achieve the milestone, and the first to do so upright after a separate US company's lander toppled over on arrival.

Now ispace hopes to have its own moment of glory, after the unsalvageable "hard landing" of its initial attempt in 2023.

"Compared to Mission 1, Mission 2 is progressing as smoothly as can be expected from the moment of launch," ispace CEO Takeshi Hakamada said in a statement.

"I feel that the experience and knowledge from the previous mission have been put to good use," he added.

The window for landing is from June 6 to June 8 depending on conditions, according to ispace.

Although Resilience and Blue Ghost shared a rocket, Resilience is taking longer to reach the Moon and will "complete a lunar flyby" and "enter a low energy transfer orbit", ispace says.

Landing on the Moon is highly challenging due to its lack of atmosphere, making parachutes useless. Instead, spacecraft must rely on precisely controlled thruster burning to slow their descent while maneuvering over hazardous terrain.

Only five nations have soft-landed spacecraft on the Moon: the Soviet Union, the United States, China, India and Japan.

Private companies are also vying to offer cheaper and more frequent space exploration opportunities than governments.

Last year, Houston-based Intuitive Machines became the first private company to touch down on the Moon.

Although its uncrewed craft landed at the wrong angle, it was still able to complete tests and send photos.

The US company is now aiming for another Moon landing of its Athena probe on March 6, planning to touch down farther south on the Moon than any previous mission.

Athena's payloads include three rovers, a drill to search for ice, and the star of the show: a first-of-its-kind hopping drone.