A large asteroid approximately 330 meters long is heading for Earth in early December, according to NASA’s asteroid tracker.
Dubbed 4660 Nereus, or 1982 DB, this vaguely egg-shaped asteroid has a size making it taller than the Eiffel Tower and nearly twice as tall as the Washington Monument. It is set to pass by the planet on December 11 at a distance of approximately 3.9 million kilometers and at a speed of 6.578 km/s. For comparison, the distance between the Earth and the Moon is around 385,000 kilometers. As such, despite being classified as a Potentially Hazardous Asteroid (PHA) due to its size and close proximity to Earth, it seems unlikely to pose a threat to the planet.
This is fortunate, as an impact from an asteroid of such a size could be devastating.
But what makes Nereus stand out among other asteroids is not its size or the possibility of it causing a planetary impact, but rather its potential for exploration.
As an Apollo-class asteroid, Nereus’s orbit frequently puts it close to Earth. In fact, its orbital resonance is approximately 2:1. This means that a mission to explore the asteroid is very feasible.
Asteroid illustrative (credit: Wikimedia Commons)
Scientists have given a hypothetical exploration mission on Nereus a delta-v (a measure of various values and factors determining how difficult it would be to properly maneuver a spacecraft during takeoff and/or landing) of approximately 5 km/s. This is significant, as the delta-v for the Moon is around 6 km/s. In fact, in 2000, NASA ranked Nereus as one of the lowest delta-v values out of near-Earth objects.
As delta-v can be used as a budget of sorts when determining how much force and propellant is needed for a mission, a lower delta-v value cold indicate a cheaper and more easy mission, as it could mean less is needed.
No missions are currently known to be ready to explore Nereus, however it has been considered before. Both NASA’s Near Earth Asteroid Rendezvous-Shoemaker (NEAR) robotic mission and the Japanese Hayabusa mission considered Nereus as targets, but both eventually chose other options.
Nonetheless, it is still an attractive target for many.
The asteroid is set to return 12 more times in the coming decades, but its closest approach is slated for February 14, 2060, when it will be just under 1.2 million kilometers away.
According to NASA, if a mission were to be launched this year, it would take anywhere between 426-146 days, though the delta-v this time around would be around 10.37 km/s, slightly higher than launching a rocket into low-orbit.
Asteroid exploration is a major field in astronomy, and many space agencies have expressed interest in exploring the many large objects in the solar system.
In October, the United Arab Emirates announced plans for a new mission to explore asteroids, and be the first Arab nation to successfully land a spacecraft on an asteroid.
Tentatively set to launch in 2028 with a seven-year development time for the spacecraft, the mission will see the UAE explore the planet Venus, as well as seven asteroids, culminating in a planned landing on an asteroid itself in 2033 after a five-year journey.
Three nations have landed on asteroids in the past, and many see them as possible sources for future mining operations, as these asteroids can be rich in raw materials.
Indeed, Nereus is no exception, with its spectral type indicating that it likely contains cobalt, nickel and iron.
Regardless of the potential though, many are also rightly worried about the dangers of near-Earth asteroids, as impacts can be devastating and humanity currently lacks an adequate means of defending against them.
One method for possibly stopping the impact of an asteroid is through the use of deflection, which would mean launching something to slightly alter an asteroid’s path.
In layman’s terms, it means punching an asteroid with a rocket with enough speed to change its direction by a fraction of a percent.
However, other measures have also been considered, such as disruption, meaning destroying the asteroid, but at this time, these remain hypothetical.