NASA is crashing a spacecraft into an asteroid

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

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

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I am a scholar who studies space and international security, and it is my job to ask myself what the real likelihood is of an object crashing into the planet and whether governments are spending enough money to prevent such an event.

To find the answers to these questions, you need to know what near-Earth objects are out there. To date, NASA has only tracked about 40% of the largest ones. Surprise asteroids have visited Earth in the past and will no doubt do so in the future. Experiments such as the DART mission can help prepare humanity for such an event.

The threat of asteroids and comets

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

Astronomers view a near-Earth object as a threat if it arrives within 4.6 million miles (7.4 million kilometers) of the planet and is at least 460 feet (140 meters) in diameter. If a celestial body this size crashed into Earth, it could destroy an entire city and cause extreme regional devastation. Larger objects – 0.6 miles (1 kilometer) or more – could have global effects and even cause mass extinctions.

The most famous and most destructive celestial impact took place 65 million years ago when an asteroid with a diameter of 6 miles (10 kilometers) crashed into what is now the Yucat√°n Peninsula. It wiped out most of the plant and animal species on Earth, including dinosaurs.

But even smaller objects can cause significant damage. In 1908, a 50-meter celestial body exploded on the Podkamennaya Tunguska River in Siberia. It leveled more than 80 million trees across 830 square miles (2,100 square kilometers). In 2013, an asteroid only 65 feet (20 meters) in diameter exploded in the atmosphere 20 miles (32 kilometers) above Chelyabinsk, Russia. It released the energy equivalent of 30 Hiroshima bombs, injured over 1,100 people and caused $ 33 million in damage.

The next major asteroid to potentially hit Earth is the 2005 ED224 asteroid. When the 50-meter asteroid passes on March 11, 2023, there is about 1 in 500,000 chance of impact.

Looking at the skies

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

acknowledged this threat to Congress and, in the 1998 Spaceguard Survey, instructed NASA to find and track 90% of the estimated total near-Earth objects 0.6 miles (1 kilometer) in diameter or larger within 10 years . NASA surpassed the 90% target in 2011.

In 2005, Congress passed another bill that required NASA to expand its research and track at least 90% of all near-Earth objects of 460 feet (140 meters) or more by the end of 2020. year has passed and, mainly due to lack of financial resources, only 40% of those objects have been mapped.

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

A new Congress-funded mission in 2018 is expected in 2026 to launch an infrared space telescope, NEO Surveyor, dedicated to searching for potentially dangerous asteroids.

Cosmic surprises

We can only prevent a disaster if we know it is coming and asteroids have already sneaked up on Earth.

A so-called “city-killer” asteroid the size of a football field passed within 45,000 miles (72,420 kilometers) of Earth in 2019. A 747 jet-sized asteroid approached in 2021, as did an asteroid to 0.6 miles (1 kilometer) wide in 2012. Each of these were only discovered about a day before they passed Earth.

Research suggests that Earth’s rotation creates a blind spot, hiding some asteroids from detection or making them appear stationary. This could be a problem, as there are some surprise asteroids out there. In 2008, astronomers spotted a small asteroid just 19 hours before it crashed in rural Sudan.

The recent discovery of a 2-kilometer-diameter asteroid suggests that there are still large objects lurking.

What can be done?

To protect the planet from cosmic dangers, early diagnosis is key. At the 2021 Planetary Defense Conference, scientists recommended a minimum preparation time of five to ten years to organize a successful defense against dangerous asteroids.

If astronomers find a dangerous object, there are four ways to mitigate a disaster. The first concerns the regional first aid and evacuation measures. A second approach would involve sending a spacecraft to fly close to a small or medium-sized asteroid; the aircraft’s gravity would slowly change the object’s orbit. To change the path of a larger asteroid, we can crash into something at high speed or detonate a nearby nuclear warhead.

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

The DART mission should generate a lot of useful information. This data will come from a camera aboard the DART spacecraft that will send the images back to Earth until the moment of impact. Additionally, a tiny satellite called LICIACube that was deployed by DART on Sept. 11, 2022, will take photos of the impact. A follow-up mission from the European Space Agency, called Hera, will be launched in 2024 and will meet with Didymos in 2026 to begin collecting data.

Expenditure on planetary defense

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

Is this the right amount to invest in monitoring the skies, given that around 60% of all potentially dangerous asteroids go undetected? This is an important question to ask when considering the potential consequences.

Investing in planetary defense is like buying homeowner’s insurance. The likelihood of an event that destroys your home will occur is small, however people still buy insurance.

If even a single object larger than 460 feet (140 meters) hit the planet, the devastation and loss of life would be extreme. A greater impact could literally wipe out most species on Earth. While no such body is expected to hit Earth in the next 100 years, the chance is not zero. In this low-probability versus high-consequence scenario, investing in protecting the planet from dangerous cosmic objects can give humanity some peace of mind and could prevent a catastrophe.

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

This article was republished by The Conversation under a Creative Commons license. Read the original article here: https://theconversation.com/nasa-is-crashing-a-spacecraft-into-an-asteroid-to-test-a-plan-that-could-one-day-save-earth – from-catastrophe-190888.

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