Massive, ‘potentially hazardous’ asteroid to pass by Earth Saturday

(NEXSTAR) – An asteroid about as wide as the Eiffel Tower is tall is expected to buzz past Earth on Saturday.

Asteroid 4660 Nereus will reach its closest proximity to our planet that day, according to NASA, but it will still be about 2.5 million miles away from Earth.

While that may sound like a lot, NASA deems any object that comes within 30 million miles of Earth’s orbit a “near-Earth object.” NASA classifies any object greater than 500 feet in size that passes within 4.7 million miles of Earth’s orbit “potentially hazardous” based on “the asteroid’s potential to make threatening close approaches to Earth.”

So just how close are we to an “Armageddon”-esque scenario with the approach of 4660 Nereus? Not remotely close, according to NASA. In fact, there is no known asteroid that poses a significant risk of impact with Earth over the next century.

Nereus, which is roughly 360 yards in size and shaped like an egg, was discovered in 1982 by astronomer Eleanor Helin. Over the years it has been a proposed candidate for space missions and is considered to be in the top 3% of the most accessible near-Earth asteroids.

Mining potential

The proximity and size of 4660 Nereus also make it a hypothetical mining target. According to Asterank, which maintains a database of asteroids and their estimated mining value, Nereus’ cobalt, iron and nickel is worth upwards of $4.7 billion.

4660 Nereus is traveling at roughly 14,719 mph, according to EarthSky, which is actually slow for asteroids. This further boosts its value as a potential mining candidate since it is easier for a robotic spacecraft to approach it.

The idea of mining asteroids has grown in popularity in recent years but has yet to become a reality on any scale greater than sample retrieval.

While asteroid 4660 Nereus doesn’t appear to be a threat to Earth, NASA continues to monitor future threats. The asteroid with the highest risk of hitting Earth, 2009 FD, won’t arrive until 2185. If projections hold, the object has a 1 in 714 chance of impact.

Preventing an asteroid strike

NASA calls an asteroid hitting Earth “the only natural disaster we might be able to prevent.”

In the case of a giant space rock hurtling toward us, NASA says there are a few ways to fend it off. One is to send a satellite to act as a “gravity tractor” that would use the pull between the two objects to slowly divert the asteroid.

A more direct approach is to fire a spacecraft directly into the asteroid. The collision would have to either speed up or slow down the asteroid by at least seven minutes, which is the amount of time it takes for Earth to travel the distance of its diameter. If successful, the asteroid would pass by the point of impact early or late, missing Earth in the process.

In November, NASA launched its Double Asteroid Redirection Test (DART) to see if it was possible to knock a potentially deadly asteroid off course. The target is Dimorphos, which orbits a larger asteroid called Didymos. If everything goes well, DART will reach its target in 10 months and slam into the 525-wide asteroid, changing its path but not destroying it.

If the gravity tractor and DART tactics both fail, there is the last resort — a nuclear explosive device.

“When warning time is short or the asteroid is large, deploying a nuclear device is the most effective option,” according to NASA.

In such a scenario, a nuclear device would be detonated above the asteroid, super-heating and vaporizing enough of the upper layers of the object to knock it onto a new trajectory.