Are we ready for the threat of asteroids? Planetary Defense Issues

February 15 marks the tenth anniversary of the so-called Chelyabinsk event. On that cold morning, over a Russian city in the foothills of the Urals, an asteroid 17 to 20 meters in diameter collided with the Earth’s atmosphere, causing an explosion equivalent to 500 kilotons of TNT (about 35 times the energy released by the explosion in Hiroshima). bomb).

For the first time, an event of this magnitude could be followed and studied in detail thanks to the many cameras that were in cars that that morning drove several hundred kilometers from the impact site.

The air explosion occurred at an altitude of about 30 kilometers. When the shock wave reached the ground a few minutes later, it knocked out many windows and roofs of some objects. About 1,500 people had to be treated in varying degrees of severity.

The Chelyabinsk event marked the before and after in the public’s perception of the danger posed by near-Earth bodies (NEOs). However, this warning signal has long been picked up by international authorities.

sky watchers

In the late 1990s, NASA was commissioned by the government to find all asteroids larger than 1 kilometer within 20 years. In 2005, he accepted an order to reduce this size to 140 meters.

On the European side, since 2002 the European Space Agency (ESA) has been studying space missions to deflect asteroids. There have been systems on both sides of the Atlantic since the turn of the century to monitor the impacts of these space rocks, such as the one implemented at ESA’s NEO Coordination Centre.

It should be noted that the NEO population has an exponential distribution. This means that although there are few very large objects, their number increases very quickly as the size decreases. In total, according to our estimates, there are about 900 objects larger than 1 kilometer and about 25,000 objects larger than 140 meters. When we reduce the size to 50 meters, we will talk about 200,000-300,000 NEOs, and if we refer to objects like the one that hit Chelyabinsk, we will get from 5 to 10 million.

The good news is that humanity has managed to detect almost all objects larger than one kilometer that can cause global catastrophes. In the range up to 140 meters, we found about 40%, and as we continue to reduce detection levels, they decrease significantly. Today we know just over 31,000 NEOs.

Risk that can be prevented

While NEO detection and monitoring systems have been in place since the turn of the century, the Chelyabinsk event has led to a greater degree of awareness of the need to take action to help us protect our societies from the threat; a threat that, on the other hand, can be prevented.

In this sense, it is worth highlighting the various initiatives taken in recent years to improve our level of protection. On the one hand, compliance with NASA’s mandate to detect all asteroids larger than 140 meters in a reasonable amount of time is enhanced through the development of the NEO Surveyor space telescope, due to be launched by mid-2028. For its part, ESA has embarked on an additional mission called NEOMIR. which are being studied.

At the global level, the United Nations Office for Outer Space Affairs (UNOOSA) also commissioned two supranational institutions in 2013 to advise the international community on these issues: IAWN and SMPAG.

The International Asteroid Warning Network (IAWN) is tasked with developing a NEO risk response strategy using well-defined communication plans and protocols to assist governments in analyzing the impact of an asteroid impact and planning for response. This network also brings together all the observatories and observation centers that monitor the danger posed by asteroids.

On the other hand, the mission of the Space Mission Planning Advisory Group (SMPAG) is to prepare for an international response to asteroid risk by sharing information and developing options for joint research and mission capabilities. NEO threat mitigation planning activities.

DART and Hera companion missions

In terms of preparing for the threat, the first planetary defense demonstration mission in the last decade has become a reality: NASA’s DART mission strikes the Dimorph moon of the binary asteroid Didymus.

DART is in addition to the ESA Hera mission, which will be launched in October 2024 to study the results of the collision in detail. Through these two missions, we will be able to better understand the required technologies and the effects that can be obtained after a high-speed satellite-asteroid collision. All this is necessary to prepare for the future response to threats.

Unlikely, but very destructive

As I have tried to explain in this article, while the Chelyabinsk event was a global wake-up call, the community of scientists and engineers who collaborate internationally on planetary defense have been working on it for several decades. In the last decade, the results of all this work have become visible.

The risk of NEO is very unlikely, but the consequences can be devastating. Fortunately, it also falls into the category of predictable threats (unfortunately, this is not the case for many others, as we recently saw with the earthquakes in Turkey and Syria).

Therefore, actions are required that are not expensive, but that allow continued investment over time to gradually discover all the objects that we have yet to discover and prepare space missions that will allow us to eliminate the risk, if the opportunity arises. event that we have detected an object heading towards Earth.

So, at both ESA and NASA, we have specific programs in place to understand and deal with this danger and to enable our society to be prepared to face any threat that comes our way from the solar system’s environs in the future.

Juan Luis Cano González, NEOCC Information Service Coordinator, European Space Agency

This article was originally published on The Conversation. Read the original.

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