1-Km Asteroid 1997 NC1 Passes Earth June 27 for Rare Study at 7 Lunar Distances

Q: NASA's DART mission moved a small asteroid. Could we deflect a 'city-killer' like the one approaching Earth this week?

Yes—but only if we find it early enough. NASA’s DART mission proved that a spacecraft can change an asteroid’s motion by slamming into it, but scaling that up to a “city-killer” depends far more on warning time than on the basic physics. DART struck Dimorphos, a moonlet about 160 meters wide, and shortened its orbit by 32 minutes. That was a real-world demonstration that a kinetic impactor works. For an asteroid in the size range of 1997 NC1—roughly 710 to 1,650 meters across—or even a smaller “city-killer” of around 50 to 140 meters, the same principle could work if scientists had years, and ideally a decade or more, to act. A tiny change in speed made far from Earth can add up to a miss. What DART did not prove is that we could stop a dangerous asteroid discovered only days or weeks before impact. In that case, current options are poor. Launching, intercepting and delivering enough momentum in such a short window would be extremely difficult. Larger objects also carry much more mass, and some are “rubble piles,” which complicates any attempt to push or break them apart safely. That is why planetary defense experts stress detection as much as deflection. NASA and international partners are still trying to find most hazardous near-Earth objects larger than 140 meters. For the asteroid passing on June 27, there is no threat: it will remain about 1.59 million miles away, more than six times the Earth-moon distance.

3 articles · Updated · WRAL News · Jun 24

NASA classifies 152637 (1997 NC1) as one of just 872 known near-Earth asteroids at least 1 kilometer wide, making Saturday’s flyby an unusually valuable observation chance.
Current orbit calculations show no threat to Earth for at least the next century, despite the asteroid’s “potentially hazardous” label, which applies to objects over 50 meters that come within about 20 lunar distances.
About 1.5 million miles away, the pass is roughly seven times the Earth-moon distance; radar can refine its orbit and reveal shape, rotation and surface features.
Close approaches themselves are not rare — 211 near-Earth objects passed within one lunar distance in the past year — but most were much smaller and discovered only shortly before flyby.
The last known object this large to pass within 10 lunar distances came in February 1976, underscoring why researchers see 1997 NC1 as a useful planetary-defense test case.