Home / Science / Earth protection against asteroids has two phases. The greatest risk is from the sun.

Earth protection against asteroids has two phases. The greatest risk is from the sun.

Visualization of dart mission.
Photo: Profimedia.sk

What we have only recently been able to see in Hollywood sci-fi movies is slowly becoming a reality. The U.S. National Aeronautics and Space Administration (NASA) spacecraft, which is to test the protection of planet Earth from a possible collision by hitting an asteroid, successfully launched from Wandenberg’s space force base on the California coast.

The spacecraft has launched the spacecraft’s Falcon 9 rocket as part of a mission called the Double Asteroid Redirect Test (DART).

The spacecraft is scheduled to hit the surface of Dimorph, the moon of the much larger planet Didimos, sometime between September and October next year, to change its orbit. Both objects revolve around the sun together.

The size of the planet Didimos and its moon Dimorphos compared to terrestrial objects.

The size of the planet Didimos and its moon Dimorphos compared to terrestrial objects. Photo: Profimedia.sk

The impact itself will occur on the asteroid Moon Didimos. This will mainly cause a change in the dynamics of the orbiting Dimorphos, which is expected to reduce its large half-life, which will lead to a change in the orbital period of the “Asteroid Didimos. The circulation is now at the level of 11 hours and 55 minutes. After the impact, the period should be shortened by a few minutes, maybe tens of minutes,” said Jiří Šilha, an astronomer from the Department of Astronomy, Earth Physics. And Meteorology at Comenius University.

The collision should change the velocity of the body around Didima by a fraction of a percent, which should be sufficient to be monitored and measured with telescopes on the ground.

The Didimos binary system itself is not a threat to planet Earth. The object is selected in order to test the possibilities of influencing the trajectory of bodies using kinetic energy together – i.e. by impact.

The DART probe has a total weight of 610 kg, which hits the moon at a speed of about 6.6 km / s, which is 23,760 km / h. The high speed and weight of the probe will ensure that the total kinetic energy that will “It should be sufficient to change its trajectory. However, it also depends on the composition and internal structure of the moon itself, which determines how much energy it absorbs and how much material is ejected into space after the collision.” The astronomer explained.

The mission will be explored by experts primarily with telescopes on the ground. However, valuable data will also be provided by the small Italian satellite light Italian CubeSat for asteroid imaging (LICIACube), which will separate from the impact unit in time and will document the entire maneuver.

The goal is to allow Earth astronomers to track the event in “real time,” as well as what will happen after the collision. The collision should occur when the binary asteroid is close to Earth, more than 10 million kilometers. The light from the lightning to the ground will fly for about 35 seconds.

The effects of the impact of the probe on Dimorph in 2024 should also be tested in more detail by the European Space Agency (ESA) mission called Hera.

Two phases of planetary defense

Planetary defense has two phases. The first is to detect as many space objects as possible and then monitor them closely so that scientists can track their trajectories and compare them with the Earth’s orbit long into the future. According to NASA records, they have so far identified 27,000 asteroids, of which nearly 10,000 are larger than 140 meters.

These are the dimensions in which scientists fear that the object could cause great regional damage. Smaller asteroids should decay into the atmosphere and their fragments would no longer have the potential to do much damage.

Click on the image to enlarge.

The largest asteroids in the solar system.

The largest asteroids in the solar system. Photo: Profimedia.sk

“Asteroids with a diameter of one kilometer or more would have catastrophic consequences. At that time, the atmosphere would no longer play a role in its flight and would fall to the surface at full speed. Of course, the angle of impact plays a role However, it is not expected to be perpendicular, which is the worst case scenario, as the objects in the solar system orbit the sun in the same direction, in similar planes, causing small angles to collide with the earth and potential impactors, Says the astronomer.

Scientists do not yet know of any larger object that could hit our planet. If that happened, the second phase of planetary defense would come into play – that is, to do something that would save humanity from the fate that befell the dinosaurs. One of the alternatives to achieve this could be seen in the film Armageddon. However, it is not so simple.

“Breaking the asteroid from within, as it is presented in the film, is an unpredictable phenomenon in which we would not be able to estimate the consequences for the structure and trajectory of the asteroid. It could therefore complicate the situation even further. Another option is a non-contact gravity tractor. This is a slow process that takes several years. A probe is sent to the asteroid in order to become its moon. The probe acts gravitationally on the asteroid, a fact used in this concept. The orbit of the probe changes slowly in such a direction that the center of gravity of the asteroid-probe system passes, until the change is sufficient, the astronomer explained.

So China wants to test how to change the asteroid’s trajectory with rockets. The target should be the asteroid Bennu, whose diameter is about 1.5 times larger than the Moon Dimorphos. The study showed that it would be necessary to fire together around 23 missile impactors, which consist of the largest Chinese missile stages QZ-5.

An image of the asteroid Benn took in 2018 by NASA's OSIRIS-REx spacecraft.

An image of the asteroid Benn took in 2018 by NASA’s OSIRIS-REx spacecraft. Photo: profimedia.sk/AFP/NASA

The greatest risk is from the sun.

An asteroid as big as an SUV set a new record in August 2020. The body flew so close to Earth – at an altitude of 2,950 kilometers above the South Indian Ocean. Astronomers did not notice the new near-Earth object, 2020 QG, until six hours after the incident. He flew to the planet from the sun. And since asteroids are looking for optical telescopes that can observe the sky only at night, astronomers have not noticed this body.

“It is assumed that we already know all the asteroids, more than one kilometer long, that could cause a global catastrophe. However, none of them was in a collision with the Earth for the next 100 years. However, objects with a diameter Of hundreds of meters are problematic. Not all of us have been discovered. One of the reasons is their tricks. If they have perihelion (smallest point at the sun, ed. Note) under one astronomical unit (average distance from the earth of The sun, ed. Note), then they can come to us from the direction of the sun, where we astronomers can not observe them, i.e. discover and measure. One solution is to send a spacecraft into space, a telescope that will be able to observe areas right near the sun, as those observations will not be contaminated by the scattering of sunlight into the Earth’s atmosphere, “Silha added.

Source link