The interplanetary station Hayabusa2 has sent new data to Earth. The spacecraft managed to determine the mass of the asteroid Ryugu and map the distribution of gravity on its surface.
Distribution of the gravitational acceleration. © JAXA
The celestial body has a mass of up of 450 million tons and it was calculated in the following manner: the spacecraft conducted a gravity experiment, during which it descended from the home position at an altitude of 20km to an altitude of 6km, and then in free fall it descended to the minimum altitude of 851 meters from the surface of Ryugu, then fired its thrusters and returned to the same altitude.
Since the space station knows other parameters of the asteroid, for example, its shape and volume, it managed to calculate the average density of the asteroid and create a map of the distribution of the gravitational acceleration on Ryugu’s surface. The gravitational acceleration on the surface of the object is about 0.11~0.15 mm/s2, which is about 1/800,000 the strength of the Earth’s gravity, and the gravity near Ryugu’s poles is greater than near its equator.
Hayabusa2 is an automatic interplanetary station of the Japan Aerospace Exploration Agency (JAXA). It was launched in 2014 and is supposed to deliver soil samples from the C-type asteroid. Hayabusa2 arrived at Ryugu in the summer of 2018 and has been studying the object from the orbit and from the surface. The mission is expected to return to Earth in 2020.