NASA crashes into an asteroid spacecraft to test a plan that could one day save Earth from disaster

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(Conversation) On September 26, 2022, NASA plans to change the orbit of an asteroid.

The large binary asteroid Didymus and the moon Demorphos currently pose no threat to Earth. But by crashing a 1,340-pound (610 kg) probe into Didymos at roughly 14,000 mph (22,500 km/h), NASA will complete the world’s first full-scale planetary defense mission as a proof of concept. This task is called the Double Asteroid Redirection Test, or DART.

I am a researcher who studies space and international security, and it is my job to ask what is the probability of an object colliding with the planet – and whether governments are spending enough money to prevent such an event.

To find answers to these questions, one has to know what NEOs are out there. So far, NASA has tracked only an estimated 40% of the largest. Surprising asteroids have visited Earth in the past and will undoubtedly do so in the future. Experiments such as the DART task may help prepare humanity for such an event.

Threat from asteroids and comets

Millions of cosmic bodies, such as asteroids and comets, orbit the Sun and often collide with the Earth. Most are too small to pose a threat, but some can be cause for concern. Near-Earth objects include asteroids and comets whose orbits will bring them within 120 million miles (193 million km) from the Sun.

Astronomers consider a near-Earth object to be a threat if it were to lie within 4.6 million miles (7.4 million kilometers) of the planet, and if it was at least 460 feet (140 meters) in diameter. If an orb of this size collided with the Earth, it could destroy an entire city and cause severe regional devastation. Larger objects—0.6 miles (1 kilometer) or more—could have global impacts and even cause mass extinctions.

The most famous and devastating celestial collision occurred 65 million years ago when an asteroid 6 miles (10 km) in diameter smashed into what is now the Yucatan Peninsula. He wiped out most species of plants and animals on Earth, including dinosaurs.

But smaller objects can also cause significant damage. In 1908, a 164-foot (50-meter) orb exploded over the Podkamenaya Tunguska River in Siberia. It has cleared more than 80 million trees over an area of ​​830 square miles (2,100 square kilometers). In 2013, an asteroid 65 feet (20 meters) in the atmosphere exploded 20 miles (32 kilometers) above Chelyabinsk, Russia. It released the energy equivalent of 30 Hiroshima bombs, injuring more than 1,100 people and causing US$33 million in damage.

The next potentially large asteroid likely to hit Earth is asteroid 2005 ED224. When the 164-foot (50-meter) asteroid passes on March 11, 2023, there is a 1 in 500,000 chance of collision.

watch the sky

While the chances of a larger cosmic body hitting Earth are slim, the devastation would be massive.

Congress recognized this threat and, in the 1998 Spaceguard Survey, tasked NASA with finding and tracking 90% of the estimated total of NEOs 0.6 miles (1 kilometer) or larger in width within 10 years. NASA exceeded the 90% goal in 2011.

In 2005, Congress passed another bill requiring NASA to expand its research and track at least 90% of all NEOs 460 feet (140 meters) or greater by the end of 2020. This year has come and gone, mostly Because due to lack of financial resources, only 40% of these objects were appointed.

As of September 18, 2022, astronomers have identified 29,724 near-Earth asteroids, of which 10,189 are 460 feet (140 meters) in diameter or larger and 855 are at least 0.6 miles (1 kilometer) wide. About 30 new items are added every week.

A new 2018 Congress-funded mission is set for 2026 to launch an infrared space telescope – the NEO Surveyor – intended to search for potentially dangerous asteroids.

Cosmic surprises

We can only prevent a catastrophe if we know it’s coming, and that asteroids have infiltrated Earth before.

The so-called “city killer” asteroid the size of a football field passed less than 45,000 miles (72,420 kilometers) from Earth in 2019. An asteroid the size of a 747 plane approached in 2021, as did a 0.6-mile (1 kilometer) asteroid in 2012. Discover each one about a day before it passes Earth.

Research suggests that the Earth’s rotation creates a blind spot, causing some asteroids to hide from detection or make them appear stationary. This could be a problem, because some surprising asteroids don’t miss us. In 2008, astronomers discovered a small asteroid just 19 hours before it smashed into rural Sudan.

The recent discovery of an asteroid 1.2 miles (2 kilometers) in diameter indicates that large objects remain lurking.

What can he do?

To protect the planet from cosmic dangers, early detection is key. At the 2021 Planetary Defense Conference, scientists recommended a standby time of at least five to 10 years for a successful defense against dangerous asteroids.

If astronomers find a dangerous object, there are four ways to mitigate the disaster. The first relates to regional first aid and evacuation procedures. The second method involves sending a spacecraft to fly near a small or medium-sized asteroid. The vehicle’s gravity will slowly change the orbit of the object. To alter the course of a larger asteroid, we can either hit something at high speed or detonate a nuclear warhead nearby.

The DART mission will be the first ever attempt to deflect a large asteroid. But this wouldn’t be the first time humanity had sent something to an asteroid. NASA’s Deep Space Impact mission hit Comet 9P/Tempel in 2005 to make scientific measurements of the comet, and in 2018 Japan’s Hayabusa2 mission collected samples from the asteroid Ryugu and returned them to Earth, but none of these samples were designed as a planetary defense test.

The DART task should generate a lot of useful information. This data will come from a camera on board the DART spacecraft that will send images back to Earth until the time of impact. Additionally, a small satellite called LICIACube deployed from DART on September 11, 2022, will capture images of the impact. A follow-up mission from the European Space Agency, called HERA, will launch in 2024 and meet with Didymos in 2026 to begin collecting data.

Spending on Planetary Defense

In 2021, NASA’s planetary defense budget was $158 million, just 0.7% of NASA’s total budget and 0.02% of the $700 billion US defense budget.

Is this the right amount to invest in observing the sky, given the fact that about 60% of all potentially dangerous asteroids remain undiscovered? This is an important question to ask when considering the possible consequences.

Investing in planetary defense is like buying homeowners insurance. The probability of facing an event that destroyed your home is slim, yet people buy insurance.

Even if a single object larger than 460 feet (140 meters) hit the planet, the destruction and loss of life would be severe. The greatest impact could lead to the elimination of most species on Earth. Even if such an object is not expected to collide with Earth in the next 100 years, the chance is not zero. In a low probability vs high consequences scenario, investing in protecting the planet from dangerous cosmic objects might give humanity some peace of mind and could prevent a catastrophe.

This is an updated version of a story originally published on March 1, 2022.

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