Japan's space agency said Thursday it has been unable to establish stable communication with the country's mini moon lander launched on a U.S. rocket the previous day along with a mini satellite.

The Japan Aerospace Exploration Agency said it is now trying to control the position of the Omotenashi lander, adding its system of automatically turning to the Sun to gain solar power appears to be not functioning.

Supplied rendered image shows the Omotenashi CubeSat landing on the surface of the Moon. (Courtesy of Japan Aerospace Exploration Agency)(Kyodo)

The other device, Equuleus, is operating normally, it said.

The two devices are traveling to the moon after successfully separating themselves from a megarocket called Space Launch System launched by the National Aeronautics and Space Administration on Wednesday together with the uncrewed U.S. spacecraft Orion.

JAXA hopes the Omotenashi lander, measuring 11 centimeters in length, 24 cm in width, and 37 cm in height, will become the country's first probe to land on the lunar surface.

The lander will travel to the surface at a velocity of 180 kilometers per hour after being released over the Moon. JAXA said before the launch it estimated the mission's probability of success at 60 percent.

It has said the mission will be deemed a success if it receives transmissions from the moon on early Tuesday in Japan.

The Equuleus mini satellite, fueled by water, is heading to the Moon's far side.

The United States and Japan are deepening cooperation in space and affirmed earlier this year their "shared ambition" to realize a future Moon landing by a Japanese astronaut.

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