by This February 15th marks the tenth anniversary of the so-called Chelyabinsk event. On that cold morning, and over that Russian city in the foothills of the Urals, an asteroid between 17 and 20 meters in diameter impacted the Earth’s atmosphere, causing an explosion equivalent to 500 kilotons of TNT (about 35 times the energy released by the Hiroshima bomb).
For the first time, an event of this magnitude could be followed and studied in detail thanks to the multitude of cameras available in the vehicles that were driving that morning up to distances of several hundred kilometers from the point of impact.
The air explosion took place at an altitude of about 30 kilometers. When the shock wave reached the ground a few minutes later, it broke a multitude of windows and the roofs of some facilities. Some 1,500 people had to be treated for varying degrees of severity.
The Chelyabinsk event marked a before and after in society’s perception of the risk posed by near-Earth bodies (NEOs). However, this warning signal had long since been picked up by international authorities.
the sky watchers
In the late 1990s, NASA had been instructed by its government to find all asteroids larger than 1 kilometer within 20 years. In 2005, he accepted the commission to reduce that size to 140 meters.
On the European side and since 2002, the European Space Agency (ESA) was already studying space missions to deflect asteroids. On both sides of the Atlantic, there have been systems for monitoring the impact of these space rocks since the beginning of the century, such as the one implemented at ESA’s NEO Coordination Center.
It should be noted that the NEO population follows an exponential distribution. This means that although there are few very large objects, the numbers increase very rapidly as we reduce the size. In total, we estimate that there are around 900 objects larger than 1 kilometer and some 25,000 larger than 140 meters. When we reduce the size to 50 meters, we would be talking about between 200,000 and 300,000 NEO, and if we refer to objects like the one that hit Chelyabinsk, we would be between 5 and 10 million.
The good news is that humanity has managed to detect almost all objects larger than one kilometer, which are the ones that could cause global disasters. In the range up to 140 meters, we have found around 40%, and as we continue to lower the levels of discovery they are much reduced. Today we know of a little more than 31,000 NEOs.
A risk that can be prevented
Although NEO discovery and monitoring systems have existed since the beginning of the current century, the Chelyabinsk event brought 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, is one of the few that can be prevented.
In this sense, it is worth highlighting various initiatives taken in recent years to increase our level of protection. On the one hand, compliance with NASA’s mandate to discover all asteroids larger than 140 meters in a reasonable time is being strengthened through the design of the NEO Surveyor space telescope, which should be launched before mid-2028. For its part, ESA has embarked on a complementary mission called NEOMIR which is beginning to be studied.
At a global level, the United Nations Office for Outer Space Affairs (UNOOSA) commissioned that same year of 2013 the creation of two supranational institutions to advise the international community on these issues: IAWN and SMPAG.
The International Asteroid Warning Network (IAWN) is tasked with developing an NEO risk response strategy using well-defined communication plans and protocols to assist governments in analyzing the consequences of asteroid impact and planning responses. of mitigation. This network also brings together all the observatories and surveillance 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 the risk of asteroids through the exchange of information and the development of collaborative research options and mission opportunities. , and to carry out NEO threat mitigation planning activities.
DART and Hera, companion missions
From the point of view of preparing to face the threat, during the last decade the first planetary defense demonstration mission has become a reality: the impact of the NASA DART mission against the moon Dimorph of the binary asteroid Didymus.
DART is the companion to ESA’s Hera mission, which will be launched in October 2024 to study with in great detail the results of the collision. Thanks to these two missions we will be able to understand much better the technologies required and the effects that can be produced after the hypervelocity impact of a satellite against an asteroid. All of this is needed to prepare for a future response to threats.
Unlikely, but very devastating
As I have tried to explain in this article, although the Chelyabinsk event was a global wake-up call, the community of scientists and engineers who collaborate internationally in planetary defense have been working on it for several decades. In the last decade, the results of all that work have begun to be seen.
NEO risk is very unlikely to occur, but its consequences can be devastating. Fortunately, it also falls into the category of foreseeable threats (unfortunately this is not the case for many others, as we have seen recently with the earthquakes in Turkey and Syria).
Therefore, actions are imposed that do not require large levels of spending but allow continued investments over time to gradually detect all the objects that we still have to discover and have prepared space missions that allow us to eliminate the risk, if the unfortunate event occurs that we detect an object heading towards Earth.
In summary, both at ESA and at NASA we have specific programs to understand and deal with this danger and allow our society to be prepared to face any threat that comes to us from the vicinity of the Solar System in the future.
By: Juan Luis Cano Gonzalez
NEOCC Information Service Coordinator, European Space Agency
Article originally published on The Conversation
