Asteroids skimmed past Earth, and no one saw it coming

An asteroid skidded past Earth last week just 3,000 kilometers away from the planet’s surface, but no one noticed it until after that, as NASA data shows.

Named 2021 UA1, the asteroid that foamed off Antarctica last Sunday was very small – only about 2 meters in diameter, which is roughly the size of a golf cart. As such, it is unlikely that it would actually have done any harm if it affected the planet, as it would probably have burned up in the atmosphere.

But even though the damage it could have caused if it had hit was minimal, the true danger is that an asteroid came so close to the planet and no one noticed it until after the fact.

2021 UA1 flew very close to the planet and is estimated to have been the third closest bypass of asteroid ever recorded without impact, after 2020 QG in August 2020 and 2020 VT4 in November 2020.

At a distance of only 3,000 kilometers, 2021 UA1 was far closer to Earth than the Moon, which orbits at a distance of 384,400 kilometers from the planet. A simulation shows how close it was.

2021 UA1 is not as close to Earth as the International Space Station, which has an average altitude of 408 kilometers. However, it is far closer to the planet than many of Earth’s communications satellites, most of which are in orbit at a distance of about 35,785 kilometers.

Asteroid impacts are one of the biggest possible disasters that can affect the planet, and that’s why space agencies around the world monitor many of these asteroids and calculate their sizes, distance, orbits, and whether they could potentially hit the planet.

So why did scientists not discover 2021 UA1 before it passed the planet?

This is because it came from a blind spot.

Most asteroids detected by agencies like NASA come to Earth from the “front”, meaning that they come from the direction facing into the interior of the solar system, and come towards the Earth and the Sun.

But there are asteroids coming from the “back”, on their way to Earth from the direction of the Sun and on their way out.

It is therefore very difficult to see these objects as they approach the Earth, especially as they often tend to approach during the day when visibility is low due to the glare of the Sun.

In general, the best time to spot these objects is in the twilight. This is the case for all objects in space between the Earth and the Sun, such as the planets Mercury and Venus.

An asteroid is seen on its way to Earth in an illustrative image.  (Credit: PIXABAY)An asteroid is seen on its way to Earth in an illustrative image. (Credit: PIXABAY)

This is not the first time such an asteroid has passed the planet without anyone noticing: on September 16, 2021, SG, an asteroid with a diameter of between 42 and 94 meters, flew past the planet at about half the distance between Earth and The moon, and no one noticed it until a day later.

With its large size and time of 85,748 km / h (about 23.8 km / h), the asteroid could certainly have made an impression if it hit.

The last known significant asteroid impact was on February 15, 2013, when an asteroid exploded in the air over Chelyabinsk, Russia. This asteroid was 17 meters wide, and although it did not result in any injuries, the shock wave from the explosion shattered windows in six different Russian cities and caused 1,500 people to require medical attention.

This asteroid also came from the “back”.

The destructive nature of asteroids, even small ones, is something that is well known by experts, with space agencies around the world monitoring for potential catastrophic impacts, as well as investigating potential ways to stop them.

One method of possibly stopping an asteroid’s impact is through the use of deflection, which would mean sending up something too little to change an asteroid’s path. The most prominent of these efforts is the Double Asteroid Redirection Test (DART) Mission, to be launched in November, the result of efforts by NASA and the Applied Physics Laboratory.

In layman’s terms, hitting an asteroid with a rocket at enough speed to change its direction by a fraction of a percent.

However, this method has its shortcomings, especially timing. The spacecraft used in the DART mission has taken a significant amount of time and resources to develop and launch. In the event of an asteroid impact that seems so sudden, that kind of time can be a luxury that the planet cannot afford.

This is especially true with asteroids coming from the “back”, as they are much harder to track.

In fact, NASA currently has no means of accurately detecting asteroids closer to the Sun.

However, this may soon change. NASA is in the process of constructing a new space telescope that can help with this effort. Called the Near-Earth Object (NEO) Surveyor Space Telescope, it is set to be launched in 2026 and will be in orbit between Earth and the Sun, making it possible to better detect these objects. It is hoped that the NEO Surveyor will be able to help find about 90% of the Earth’s near asteroids with a width of 140 meters or more – a size that could destroy a city if they hit.

Back in March, NASA had announced that the planet had little or no risk of an asteroid impact in the next century, according to calculations by astronomers that 9942 Apophis – a massive 340 meter long asteroid – will safely pass the planet at a distance of less than 32,000 km. on April 13, 2029.

But as events like the dense bypass in 2021 UA1 show, the risk of unexpected asteroids closer to the Sun remains a potential threat.

Leave a Comment