The tiny Minerva-II asteroid rovers will unusually “hop” around the giant space rock to study the surface.
But Japan’s mission control has been unable to confirm whether or not the lander successfully touched down on the asteroid.
JAXA said it lost contact with its instruments just before touchdown today.
The space agency tweeted: “Communication with MINERVA-II1 has currently stopped.
“This is probably due to the rotation to Ryugu, and MINERVA-II1 is now on the far side of the asteroid.
“We are currently working to confirm if there are images capturing the MINERVA-II1 landing.”
Prior to touchdown, the Hayabusa2 descended from an orbital height of 12.4 miles (20km) to just 196.85ft (60m) above Ryugu.
The Japanese spacecraft first arrived at the distant space rock earlier in June this year.
The Hayabusa2 completed a 170 million mile (280 million km) trip from Earth to reach Ryugu.
JAXA said today it will have to wait until Saturday to confirm the safe landing of its space rovers.
Project spokesman Takashi Kubota said the rover’s solar-powered voltage plunged as night fell over the asteroid – a potential sign of successful landing.
The small, cylindrical robots are no bigger than a tin of biscuits and measure about seven by 2.8 inches (18cm by 7cm).
They both weigh approximately one kilogram and were designed to snap pictures of the asteroid’s rugged surface.
The rovers, dubbed ROVER-1A and ROVER 1-B, do not have any wheels or threads but rather move around by hopping.
Approximately one year from now, they will be joined by a bigger rover known as ROVER-2.
JAXA specifically targeted Asteroid Ryugu for this mission because it is believed to be rich in frozen water, organic compounds and carbon.
Ryugu is a C-type, diamond shaped asteroid measuring 0.6 miles (1km) in diameter.
Much of the asteroid’s composition is believed not have changed since the earliest days of the solar system, making a valuable space rock to study.
If successful, JAXA’s spacecraft will return to Earth with a sample of the asteroid’s rock.
Japan last attempted to land on an asteroid in 2005 with the Hayabusa first-generation spacecraft but the probe failed to release its rovers on time.