In the past, there have been some asteroids that have almost hit Earth.
Much as is it easy to dismiss the idea of a giant asteroid colliding into Earth, it
has been widely reported that 66 million years ago, such an event happened and changed the
course of history.
This occurrence, known as the Chicxulub impactor, involved a plummeting asteroid that left behind
a gaping crater on the coast of Mexico.
The crater spanned 93 miles and went 12 miles deep.
It is on this that seven billion years later, many studies have gone into the possibility
of a repeat occurrence.
And if so, how can it be prevented?
Enter NASA's Double Asteroid Redirection Test.
But before we cover this, let's get into a bit of the history of the number of times
asteroids have almost hit Earth.
From 1972 to 2017, some very notable instances have been documented.
To begin with, in 1972, the Great Daylight Fireball was one of the first scientifically
observed objects that entered and exited the Earth's atmosphere.
The object was estimated to be about 5 meters in diameter and could have weighed between
10,000 and 100,000 kilograms in mass.
It was 36 miles in altitude.
It is important to understand that when this occurred, the instruments used for the study
were not as advanced and therefore, whatever the scientists came up with were only approximations.
In 2004, there was the FU162 which was about 8000 miles away from Earth.
This asteroid was approximately 4 to 12 meters in diameter.
It was burning up in the atmosphere, and even if it had survived and got to Earth, many
pundits have argued that it would have caused minimal destruction.
This occurrence was followed closely in 2006 by the Fireball above Japan.
Like one in 1972, this asteroid was an Earth-grazer, meaning that it entered and exited the atmosphere.
More importantly, it weighed 100 kilograms and was 44.3 miles in altitude.
Had it managed to pierce through Earth's lower atmosphere, it could have destroyed property
or hurt some people.
2011 and 2013 had the CQ1 and the Duende.
CQ1 was only one meter in diameter and 7300 miles from Earth, while Duende was 30 meters
in diameter and 21000 miles away from Earth.
Against the backdrop of these and many other occurrences, NASA launched the DART asteroid
mission intending to save planet Earth if there is a threat from a wayward asteroid.
On November 23rd 2021, Tuesday night, NASA's Double Asteroid Redirection Test (DART) mission
was launched at 10.20 p.m. from Space Launch Complex 4 at Vandenberg Space Force Base in
California.
DART soared to the skies atop a SpaceX Falcon 9 rocket, on its way to slam with an asteroid
in a planetary defense test millions of kilometers away.
The idea behind this first planetary defence test liftoff was to have an intentional crash
into an asteroid.
The mission employed the kinetic impact technique to change the asteroid's orbit.
To put it another way, the spacecraft was to smash a rock that was in space.
The collision between DART and Dimorphos, a moonlet that revolves around the much bigger
asteroid Didymos, helped reduce Dimorphos' orbit by several minutes.
Interestingly, after about nine minutes, the SpaceX Falcon 9 booster returned to Earth.
How this happened is that it had managed to secure a perfect landing atop "Of Course I
Still Love You", the company's drone ship.
Astronomy Live This ship had been installed in the Pacific
Ocean.
And since SpaceX is known for the reusability of their rockets, this landing marked the
95th they had recovered an orbital class rocket booster.
However, according to lead astronomers, there is very little chance of the asteroid system
impacting Earth, but that does not rule out the possibility that an asteroid could pose
a serious danger to Earth on a given day in the future and its inhabitants.
This demonstration will show NASA how a kinetic impact approach might work against a real-world
asteroid.
If a massive asteroid were to be discovered in the future that posed a threat to Earth,
NASA might hypothetically send out a spacecraft like DART to smash into it and shift it in
a different path.
Ultimately, the determining factor in how to defend our planet against rogue space rocks
is time.