Diamond shaped asteroid one of 29k+ NEO’s detected

Japan’s space agency is preparing to attempt two landings on a diamond shaped asteroid called Ryugu. It is one of over 18,000 Near Earth objects that have now been detected.

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900 metre wide Ryugu asteroid

Ryugu has been described as ‘unusually shaped’ but I think it has become obvious that asteroids are a wide variety of seemingly random shapes, so no particular shape should be seen as unusual. It would be very unusual if they all looked similar,

Ryugu is a C-type asteroid. Asteroids (NASA):

C-type (carbonaceous): Includes more than 75 percent of known asteroids. Very dark with an albedo of 0.03-0.09.
Composition is thought to be similar to the Sun, depleted in hydrogen, helium, and other volatiles. C-type asteroids inhabit the main belt’s outer regions.

S-type (silicaceous): Accounts for about 17 percent of known asteroids. Relatively bright with an albedo of 0.10-0.22. Composition is metallic iron mixed with iron- and magnesium-silicates. S-type asteroids dominate the inner asteroid belt.

M-type (metallic): Includes many of the rest of the known asteroids. Relatively bright with an albedo of 0.10-0.18. Composition is apparently dominated by metallic iron. M-type asteroids inhabit the main belt’s middle region.


Japan’s space agency will attempt to land a robotic unmanned landing craft on the surface of an asteroid 300 million-kilometers (186.4 million-miles) away from Earth next month.

The Hayabusa-2 spacecraft is currently orbiting around the diamond-shaped asteroid Ryugu, which it reached in June after a three-and-a-half year journey.

On September 21, the spacecraft will deploy the first of two landers onto the asteroid itself, where they will gather samples and conduct experiments. A second lander will be launched on October 3.

Later in the mission, the spacecraft itself will land on the asteroid after blowing a small crater in it using explosives, so samples can be gathered from below the object’s surface which have not been exposed to space.

JASA’s Asteroid Explorer “Hayabusa2” descended from its orbiting position (at a 20km altitude from Ryugu) to a minimum altitude of 851 m, on 6 -7 August 2018.

NASA has detected more than 29,000 Near Earth Objects, most over the last ten years, so the number is likely to keep increasing.


Near-Earth Objects (NEOs) are comets and asteroids that have been nudged by the gravitational attraction of nearby planets into orbits that allow them to enter the Earth’s neighborhood. Composed mostly of water ice with embedded dust particles, comets originally formed in the cold outer planetary system while most of the rocky asteroids formed in the warmer inner solar system between the orbits of Mars and Jupiter.

On a daily basis, about one hundred tons of interplanetary material drifts down to the Earth’s surface. Most of the smallest interplanetary particles that reach the Earth’s surface are the tiny dust particles that are released by comets as their ices vaporize in the solar neighborhood.

With an average interval of about 10,000 years, rocky or iron asteroids larger than about 100 meters would be expected to reach the Earth’s surface and cause local disasters or produce the tidal waves that can inundate low lying coastal areas. On an average of every several hundred thousand years or so, asteroids larger than a kilometer could cause global disasters.

No one should be overly concerned about an Earth impact of an asteroid or comet. The threat to any one person from auto accidents, disease, other natural disasters and a variety of other problems is much higher than the threat from NEOs. Over long periods of time, however, the chances of the Earth being impacted are not negligible so that some form of NEO insurance is warranted.