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Expaliner: Can NASA’s DART save us from asteroids that killed Dinosaurs ?

Sep 27, 2022

The Double Asteroid Redirection Test (DART) spacecraft of the National Aeronautics and Space Administration (NASA) on Tuesday successfully crashed into an asteroid. The first-of-its-kind mission was aimed to ensure whether asteroids that may threaten the Earth in the future could be destroyed safely.

“NASA’s DART mission is a step towards preparing the world for a potential future asteroid strike like the one which killed dinosaurs some 66 million years ago, the chances of which are very slim in our lifetime,” Indian scientists said.

In the world’s first planetary defense technology demonstration, DART targeted a small asteroid moonlet Dimorphos, which was 160 meters in diameter.

“We are surrounded by several asteroids and comets that orbit our Sun. Very few of them are potentially hazardous to Earth. Hence, It is better to prepare our defenses to avoid such asteroids on a collision course with Earth in the future,” said Chrisphin Karthick, a scientist at the Indian Institute of Astrophysics (IIA), Bengaluru.

Karthick, who is involved in the DART project, noted that the mission “certainly is a step towards” preparing the world for a potential future event like the one which is believed to have led to the extinction of dinosaurs some 66 million years ago.

“This successful DART mission is an example of that. We now know to precisely aim the spacecraft for such a small body. We can also prepare ourselves for the larger body from the post-impact observations of this DART mission,” Karthick told PTI.

DART mission was a one-way trip by NASA to destroy asteroid Dimorphos which actually revolve around a bigger asteroid Didymos, which is 780 meters in diameter. Practically, both the asteroids don’t posses any threat to earth. The asteroid that led to the extinction of dinosaurs was 10 kilometers in diameter.

NASA used a technique called kinetic impact and successfully navigated the spacecraft to intentionally collide with the asteroid to deflect it.

Senior scientist at NASA’s Jet Propulsion Laboratory (JPL), Goutam Chattopadhyay noted that the mission will help to prepare for future-threatening asteroids.

“DART is an experimental mission to try out the concept of deflecting an asteroid. The idea is, if we can encounter these asteroids whose trajectory is towards us and we do that at a sufficient distance from the Earth, then a minor deflection will be enough to change the path of the asteroid,” he added.

Large asteroids have less chance of hitting Earth

However, scientist also asserts that most asteroids with huge size and a potential to damage or impact the Earth, have a very less chance of hitting the planet.

“However, the probability of that is non-zero and we must always be vigilant. There is always a possibility that a big one might be headed towards us and the question becomes, what would be our approach and how we could mitigate that? That’s why these programs are important,” Chattopadhyay told PTI.

“At least for the next century, there is no such threat from the known asteroids that can cause mass casualties,” said Karthick, adding that this risk assessment is, however, based on the asteroids known to science so far.

Earth is usually hit by small asteroids all the time which are burned in the air due to atmospheric pressure. When it comes to sufficiently large asteroids, atmospheric pressure can burn their outer core but a significant part of these asteroids will still hit the Earth and cause damage.

The team will now use ground-based telescopes to confirm that DART’s impact altered Dimorphos’ orbit around Didymos.

The impact is expected to shorten Dimorphos’ orbit by about 1%, or about 10 minutes; one of the primary goals of the full-scale test is to precisely measure how much the asteroid was deflected.

“Post impact, the team will observe Dimorphos using ground-based telescopes to confirm that DART’s impact altered the asteroid’s orbit around Didymos,” Karthick said.

“The expected output of the impact is to shorten Dimorphos’ orbit by about 1 percent, or roughly 10 minutes. One of the primary goals is to measure the deflection of the asteroid’s orbit,” he added.

Chattopadhyay also mentioned that whether the mission was successfully able to deflect the orbit of the asteroid will be ascertained only after all the data is collected.

“I would emphasize that our calculations and small-scale lab experiments show that it might work well,” he added.

To monitor Near Earth Asteroids (NEA), NASA has a multi-prong approach with observation programs initiated in 1998. The majority of the discoveries were supported by ground-based telescopic surveys.

“We primarily use radars and lidars for this. Mostly they are ground-based systems. However, our existing satellites in space are also used to image and track these objects,” the scientist added.

Lidar is a distance measurement technique that involves using a laser to target an object or a surface and measuring the time it takes for the reflected light to return.

“The DART mission is humanity’s first attempt to alter the trajectory of an asteroid by crashing a human-made object into it. Today’s successful impact is a big step forward in that direction.

“However, to know the eventual success of this concept, we have to wait a few more years by when any significant change in the trajectory would be clearly apparent,” said Dibyendu Nandi, a space scientist at the Indian Institutes of Science Education and Research, Kolkata.

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