Humankind has had its closest look yet at a binary asteroid. As 1999 KW4 skimmed past our planet at 70 000 km/h, the most advanced visible-light telescope on Earth resolved the 1.3-km diameter asteroid and its 360-m sized moon. An even closer encounter will come next decade, when NASA will send a spacecraft to deflect the moon of the distant Didymos binary. Then ESA’s Hera mission will perform a follow-up survey right down to the body’s surface.
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Source: ESA Space Engineering & Technology