We tell why outer space is dangerous and after how many years can humanity die of an asteroid collision with Earth
At the end of the Cretaceous, a meteorite fell to the ground and destroyed the dinosaurs. More than 66 million years have passed, but the cosmos is still unpredictable, even though humans have made great strides in terms of innovation and made space travel almost possible for everyone.
However, the situation with a meteorite that fell many years ago may repeat itself. On the surface of the earth, about 20 craters from meteorites have been preserved, similar in scale to those that destroyed the dinosaurs. It is impossible to calculate exactly what day a space object will fall to the ground. But the frequency of meteorites falling, such as the one that killed the dinosaurs, is already known – 100 million years. If the last one fell 64 million years ago, then humanity has formally still had about 40 million years left, but that does not mean at all that this will happen in reality. Vladimir Surdin – astronomer, senior researcher at the State Astronomical Institute named after PK Sternberg, associate professor at Moscow State University, told how scientists try to prevent space objects from colliding with Earth and which of them can fly to our planet in the near future.
Vladimir Surdin – about whether humanity will die from a collision with an asteroid
Collision with Earth: how scientists determine the risk level for asteroids
The Earth’s collision with dangerous space objects does not occur when they move along the same orbit, but at different times. Now space scientists are noting the four most dangerous asteroids, whose orbits cross the earth:
- 1950 DA (an earth impact possible);
- Bennu (1999 RQ36) (78 collisions possible);
- Apophis (2004 MN4) (possibly 12 collisions);
- 200 SG344 (101 collisions possible).
Astronomers rank asteroids on the Palermo scale, a special danger scale. Until 2021, Apophis (2004 MN4) was considered the most dangerous, with a diameter of about 325 m. Its average approach to the earth is about 31 thousand km from the planet’s surface (about 1/10 of the distance from the earth to the earth’s surface). Moon). Scientists managed to find out that the asteroid is not dangerous for the next 100 years – it will most likely fly by.
Dangerous space objects: from asteroids to interstellar objects
Asteroids are not the most dangerous space objects. They can be counted, and because they move in a limited area of the solar system (in the main asteroid belt, between Mars and Jupiter’s orbits) in almost circular orbits, they are also easy to observe. To date, more than 1 million asteroids have been discovered: all are larger than one kilometer in diameter. Telescopes of the new generation with a wide field of view make it possible to follow these space objects.
Comets are more dangerous and unpredictable. They come from the most remote areas of the solar system, where the sun’s rays no longer penetrate, so it is impossible to notice comets. They move around the sun in an elongated orbit, and as they approach it, it develops a tail that is millions of kilometers long. The moment the comet is discovered, it will have been two or three years since it flew past Earth: it is impossible to secure its motion for the planet’s surface in such a short time. The comet turned out to be the well-known Tunguska meteorite, which collided with the surface of our planet in the area of the Podkamennaya Tunguska river in 1908. The Tunguska meteorite struck trees in an area similar to that in Moscow.
The most dangerous space object is interstellar. It is not bound by gravity to any star. An interstellar object was first discovered in 2017: a body from another (unknown to us) planetary system was discovered in space near the sun. It swept near the earth at high speed and was named 1l / Oumuamua (C / 2017 U1), meaning “the first herald from afar” in the Haitian language. The shape of the interstellar object resembles a huge elongated cigar. Some have speculated that the interstellar object may even be an alien ship.
Another object that was potentially dangerous because it unexpectedly flew close to Earth is the comet Borisov (Borisov), discovered using a homemade telescope by Gennady Borisov, an engineer at the Crime Laboratory at the State Astronomical Institute named after PK Sternberg Moscow State University. It is the first known interstellar comet.
Other space objects are meteors and meteorites. Meteors flicker and burn up in the Earth’s atmosphere. Meteorites fall to the surface of the earth.
How to prevent an asteroid from colliding with Earth: spraying dangerous objects and the Yarkovsky effect
The first thing humanity needs to do is build telescopes and observatories. A large telescope can see a space object long before it approaches the Earth’s orbit. The ground-based telescope must be equipped with a very large segment of mirrors with a diameter of 39.3 m.
There are several ways to avert an asteroid attack, but astronomers cannot handle it alone – they must mobilize forces to create a powerful technical invention: for example, a laser gun or a rocket gun that would be loaded with nuclear bombs that turn a space object into dust.
So far, calculations show that the current battle arsenal of Earthlings can not prevent a collision of a large asteroid with the planet. Space objects with a diameter of less than one kilometer (500-900 m) could be sprayed. Up to 5 km – break into separate parts, but even these pieces will fall and cause significant damage. In any case, scientists will not destroy asteroids, they want to gently “turn away” from Earth with a rocket to attack asteroids (like SpaceX Starship) or sunlight reflectors (sun sails) – this can change the orbit of space objects. To do this, you need to anticipate when they will fly close to Earth.
Unfortunately, when observing outer space through a telescope, it is impossible to determine exactly where the target is: through a thick layer of air, it looks like a blurred luminous spot. One way to prevent an asteroid from colliding with Earth is to mark the space object with a marker (such as a radio beacon) that allows you to notice it and track its movement. Radio astronomers aim their telescopes much more precisely than optical astronomers.
radio astronomy examines the electromagnetic radiation from space objects.
Optical astronomy observes space objects with telescopes that can receive visible light.
Several thousand asteroids are known, which means that it is necessary to launch several thousand rockets that will fly up to them and fix radio beacons. They did so a few years ago. In 2014, the Japanese space agency launched the Hayabusa-2 spacecraft to orbit the Ryugu asteroid, and two years later, the United States launched the OSIRIS-Rex automatic interplanetary station to the Bennu orbit (1999 RQ36), which landed on the asteroid in 2019.
Bennu is potentially one of the most dangerous space objects. Its diameter is 560 m. For comparison, the height of the Empire State Building is 443 m, and the Eiffel Tower is 324 m. Bennu will probably approach the earth 2175-2199, but its orbit can still be changed with the help of nuclear charges. The probability of an asteroid colliding with Earth earlier, in 2023, is 0.04%.
The sun’s rays are one of the options for affecting the asteroid. Of course, they have little effect on space objects, but even such a force for many years can gradually divert the asteroid from a dangerous orbit. The strongest effect of the sun’s rays was discovered in 1900 by the engineer and natural scientist Ivan Yarovsky in Moscow. He found that thermal radiation gives the asteroid an extra acceleration force. Imagine: sunlight warms the earth’s surface during the day, but the warmest condition of the earth’s surface is in the evening. When the planet cools down, it emits infrared radiation into space, which acts as a jet engine (in science fiction novels it is called a photon rocket). The Yarkovsky effect affects bodies up to ten meters in diameter. It turns out that if a dark-colored asteroid is sprinkled with chalk, which will reflect the rays and prevent its surface from heating up, it is possible to increase the absorption of sunlight and weaken the Yarkovsky effect. If it is sprinkled with coal dust, the asteroid will absorb sunlight – the pressure will decrease, but the Yarkovsky effect will increase.