2023-06-25 16:40:54
International Asteroid Day is celebrated on June 30, a date that aims to raise awareness of the importance of studying and tracking these celestial bodies, a source of valuable scientific information, but which also represent a threat to our planet.
Image provided by ESA of the Gaia space telescope, which has made it possible to create a three-dimensional map of the Milky Way. PHOTO THAT.
HIGHLIGHTED
The United Nations approved celebrating Asteroid Day in December 2016 and chose the date in memory of the so-called “Tunguska event”, recorded on June 30, 1908, when an asteroid about 40 meters in diameter violently impacted Siberia, destroying 2,000 square kilometers of forest mass.
Said asteroid entered the Earth’s atmosphere at a speed of about 54,000 kilometers per hour, producing a fireball that, according to the US space agency, NASA, released an amount of energy equivalent to 185 Hiroshima bombs.
Another major and more recent impact was recorded on February 15, 2013, when an asteroid measuring 18 meters in diameter and weighing 13,000 tons exploded in the atmosphere over the city of Chelyabinsk in Russia, releasing about half a megaton of energy (equivalent to to 35 Hiroshima bombs). The shock wave damaged thousands of buildings and injured about 1,500 people.
This event marked a before and after in the perception of the risk posed by asteroids and the need for preventive actions. That same year, 2013, the International Asteroid Warning Network (IAWN) was created on the recommendation of the UN.
The Dimorphos asteroid 160 meters in diameter compared to the Colosseum in Rome. Photomontage provided by ESA
MORE THAN ONE MILLION KNOWN ASTEROIDS
Asteroids are rocky remains left over from the initial formation of our Solar System about 4.6 billion years ago and most of them are found in the asteroid belt, a region between the orbits of Mars and Jupiter, although there are also some that They have entered the interior of the Solar System and are crossing Earth’s orbit. Those are the dangerous ones and the ones that deserve more attention.
NASA counts more than 1.2 million known asteroids, of which some 30,000 are close to Earth, and around 1,500 are classified as potentially dangerous.
Most of the asteroids have irregular shapes, although some are almost spherical, and their size is very varied. More than 150 asteroids have a small companion moon, or even two. There are also binary asteroids, in which two rocky bodies of similar size orbit each other; and triple asteroid systems.
The first discovered asteroid was Ceres, in 1801, by the astronomer Giuseppe Piazzi. Ceres was considered the largest asteroid with about 1,000 km in diameter, but in 2006 it was recognized as a dwarf planet, so now the largest are Pallas and Vesta, both with diameters of just over 500 km.
Recent data from the European Space Agency’s (ESA) Gaia space telescope have made it possible to create a 3D map of the Milky Way, revealing that there are many more asteroids than previously thought.
INFORMATION SOURCES
Asteroids, being composed of materials left over from the formation of the planets, are very valuable from a scientific point of view, since they could contain molecular precursors of life and give clues to the birth of the Solar System.
Image obtained by the Japanese spacecraft Hayabusa of the Itokawa asteroid. EFE
Two missions have been launched in recent years to collect asteroid samples and bring them back to Earth. In the first, from the Japanese Aerospace Exploration Agency (JAXA), the Hayabusa-2 probe traveled to the Ryugu asteroid, from which it returned in 2020. The other is NASA’s Osiris-Rex mission, which sampled the asteroid Bennu and Now it travels back to Earth, where it will arrive on September 24.
The importance of the samples taken at Ryugu and Bennu is that they are material that has not been exposed to any terrestrial contamination, as can happen with pieces of asteroids that have fallen on our planet. So far, the samples from Ryugu have already found vitamin B3 and uracil, which is one of the basic components needed to form RNA.
PLANETARY DEFENSE
Scientists have long tracked “potentially hazardous” asteroids to protect Earth from impacts similar to the one that wiped out the dinosaurs 66 million years ago. But if we discover an asteroid heading our way, how can we deflect or destroy it before it arrives?
The cinema already posed this challenge to us 25 years ago and put fear into our bodies with films like “Armageddon” or “Deep Impact”, in which, suddenly, a threat appeared from space and a few heroes improvised solutions to to save the planet.
In reality, however, there are currently planetary defense programs capable of identifying potential threats, and devising and rehearsing plans to deal with them.
The Solar System is full of asteroids and small rocky bodies. Photo courtesy of ESA
NASA and ESA, for example, collaborate on the AIDA (Asteroid Impact and Deflection Assessment) project, within which NASA leads the DART (Double Asteroid Redirection Test) mission, which achieved significant success in September 2022, when he caused a probe to impact the surface of the asteroid Dimorphos and diverted its trajectory (reduced the orbit by 32 minutes). Dimorphos is a rock only 160 meters in diameter, which orbits another larger asteroid called Didymos, 780 meters, forming a binary system that is located 11 million kilometers from Earth.
DART, the first planetary defense drill to deflect asteroids, is followed up by ESA’s Hera (name of the Greek goddess of marriage) mission, which will study in detail the effects of the impact against Dimorphos. The European spacecraft is scheduled to take off in 2024 to reach the Didymos-Dimorphos system in 2026.
NASA also launched the Lucy space probe in 2021 for a 12-year mission to the so-called Trojan asteroids, a region hitherto unexplored. In May 2023 Lucy adjusted her trajectory to meet the small asteroid Dinkinesh.
And there are also other countries with ongoing projects related to asteroids.
China, for example, will launch its own mission in 2025 and its target will be the 2020 PN1 asteroid, only 40 meters in diameter, but classified as potentially dangerous.
The United Emirates Space Agency, for its part, plans to send a probe in 2028 to explore seven asteroids and land on the last one, called Justitia, in 2034.
In addition, last April NASA presented its planetary defense plan for the next 10 years, which includes the preparation of a complete catalog of all near-Earth objects (NEOs) that pose a danger , and the development of technologies to prevent a possible impact.
Among the asteroids listed as at greatest risk, NASA cites Bennu, which could hit Earth in the year 2182, although the probability is very low, 0.037%.
Teresa Sanchez-Bermejo.
Source: EFE
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