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

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

The Large binary asteroid Didymos Its moon Demorphos does not currently pose a 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 Double Asteroid Redirect Testor DART.

I am a scientist Space Studies and International SecurityIt is my job to ask what is the probability of an object hitting 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% bigger. 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.

The orbits of thousands of asteroids (in blue) intersect with the orbits of the planets (in white), including the orbits of the Earth.

Threat from asteroids and comets

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

Astronomers consider a near-Earth object to be a threat if it were to occur Comes within 4.6 million miles (7.4 million kilometers) from the planet and if it is 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 celestial collision and its destruction occurred 65 million years ago when an asteroid was 6 miles (10 km) in diameter. It crashed in what is now the Yucatan Peninsula. He. She It wiped out most of the plant and animal species On Earth, including dinosaurs.

But smaller objects can also cause significant damage. In 1908, an orb 164 feet (50 meters) above exploded Podkamenaya Tunguska River in Siberia. He. She level More than 80 million trees cover 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. fired the equivalent of 30 Hiroshima bombs of energy, More than 1,100 people were injured It caused $33 million in damages.

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 will be approximately 1 in 500,000 chance of impact.

watch the sky

while the The chances of a larger cosmic body colliding with the Earth are smalldestruction It will be huge.

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

in 2005, Congress passed another bill Claiming NASA to expand its search and track at least 90% of all near-Earth objects 460 feet (140 meters) or larger by the end of 2020. This year has come and gone, mostly due to Lack of financial resourcesJust 40% of these objects are mapped.

As of September 18, 2022, Astronomers have identified 29,724 locations 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) in diameter. Around 30 new objects added every week.

A new task Funded by Congress in 2018 The year 2026 is scheduled to release infrared space telescope – NEO Surveyor – Dedicated to Search for potentially dangerous asteroids.

Smaller asteroids, such as the one that exploded over Russia in 2013, can hit Earth without warning, but larger, more dangerous objects also surprised astronomers.

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 passed the size of a football field Less than 45,000 miles (72,420 kilometers) from Earth in 2019. An asteroid the size of a 747 get closer In 2021, as he did asteroid 0.6 miles (1 kilometer) wide in 2012. Only each of these has been discovered about a day before passing to the ground.

Research indicates that the rotation of the Earth Creates a blind spotOr hide some asteroids from detection or make them appear stationary. This could be a problem, because some surprising asteroids don’t miss us. In 2008, astronomers observed small asteroid Just 19 hours before it crashed in rural Sudan.

The latest discovery The asteroid is 1.2 miles (2 kilometers) in diameter, indicating that there are still large objects lurking.

Huge hole in the desert.

This crater was created near Flagstaff, Arizona, when an asteroid estimated to be 160 feet (50 meters) in diameter collided with Earth about 50,000 years ago.
USGS / d. Rudy via Wikimedia Commons

What can he do?

To protect the planet from cosmic dangers, early detection is key. At the 2021 Planetary Defense Conference, scientists recommended a minimum Preparation time from five to 10 years To launch a successful defense against dangerous asteroids.

If astronomers find something dangerous, there is 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 me Changing the course of a larger asteroidwe 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 Probe crashed into Comet 9P/Temple In 2005 for scientific measurements of the comet, and in 2018, the Japanese Hayabusa 2 mission collected samples from the asteroid Ryugu and brought them back to earthHowever, neither of these tests was designed as a planetary defense test.

The DART task should generate a lot of useful information. This data will come from a The camera on board the DART . spacecraft That will Send pictures to Earth up to the time of effect. In addition, a A small satellite called LICIACube Published from DART on September 11, 2022, will capture images of the effect. A follow-up mission from the European Space Agency, called HERA, will do Set off in 2024 and meet Didymus In 2026 to start collecting data.

Spending on Planetary Defense

In 2021, NASA’s planetary defense budget was 158 million dollarsJust 0.7% from NASA total budget and approximately 0.02% The US defense budget is $700 billion.

Is this the right amount to invest in observing the skies, given the fact that some 60% of all potentially dangerous asteroids remain undetected? 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 was not expected to hit the ground in the next hundred 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.