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Around the sunrise of February 15, 2013, an extremely bright object from another world was seen crossing the skies over Russia before exploding at about 97,000 feet above sea level. above the surface of the Earth. The ensuing explosion damaged thousands of buildings and injured around 1,500 people in and around Chelyabinsk. Although it sounds like the first scene of a sci-fi movie, this invader was not an alien spacecraft attacking humanity, but a 20-meter-wide asteroid that had entered collision with the Earth.
What is disturbing is that no one knew that this 20-meter asteroid existed before entering the Earth's atmosphere that morning.
As an astronomer, I study objects in the sky that change brightness over short periods. observations that I use to detect planets around other stars. Much of my research is to understand how we can better design and operate telescopes to monitor an ever-changing sky. This is important because the same telescopes that I use to explore other star systems are also designed to help my colleagues discover objects in our own solar system, such as asteroids on a trajectory. collision with the Earth.
Near-Earth Objects
A meteor is a piece of matter that enters the Earth's atmosphere. Before Chelyabinsk's meteor knew of his disappearance on Earth, he was in orbit around our sun like an asteroid. These rocky objects are normally considered limited to the asteroid belt between Mars and Jupiter. However, there are a lot of asteroids throughout the solar system. Some, like Chelyabinsk's meteor, are known as Near Earth Objects (NEO).
The Chelyabinsk meteor is probably from a group of near – Earth objects called Apollo asteroids, named after the 1862 Apollo asteroid. There are more than 1,600 Apollo asteroids known in the JPL Small-Body database that have earth-crossing orbits and are large enough (over 140 meters) to be considered potentially hazardous asteroids (PHAs). with Earth would devastate the affected area.
The scars of these past collisions are prominent on the moon, but the Earth also bears the marks of such impacts. The Chicxulub crater of the Yucatan Peninsula in Mexico was created by the Chicxulub asteroid that led to the extinction of the dinosaurs. The Barringer crater in Arizona is only 50,000 years old. The question is not whether a dangerously large asteroid will collide with the Earth, but when?
In Search of Threat
The US government takes seriously the threat of a collision of asteroids. In Article 321 of the NASA Authorization Act of 2005, Congress asked NASA to develop an NEO search program. NASA has been tasked with identifying 90% of all near-Earth objects over 140 meters in diameter. Currently, they estimate that three quarters of the 25,000 PLWHA have not yet been found.
To achieve this goal, an international team of hundreds of scientists, including myself, is completing the construction of the Large Synoptic Telescope (LSST) in Chile, which will be an essential tool to alert us to PLHIV.
With significant funding from the United States, LSST will look for PLHIV during its ten-year mission by observing the same area of the sky at one-hour intervals in search of objects having changed position. Everything that moves in an hour must be so close that it is in our solar system. Teams led by researchers from the University of Washington and JPL both produced simulations showing that the LSST alone would be able to find about 65% of PLHIV. If we combine the LSST data with other astronomical surveys like Pan-STARRS and the Catalina Sky Survey, we believe we can help achieve this goal of discovering 90% of potentially dangerous asteroids.
Preparing for Disaster [19659005] The Earth and these asteroids are in orbit around the sun, just on different paths. The more the observation of a given asteroid is important, the more its orbit can be mapped and predicted accurately. The biggest priority, then, is to find asteroids that could collide with Earth in the future.
If an asteroid is on a collision course for hours or days before it happens, the Earth will not have many options. It's as if a car is suddenly withdrawing in front of you. There is little you can do. If, however, we find these asteroids years or decades before a potential collision, then we might be able to use the spacecraft to push the asteroid enough to change its path so that it and the Earth does not collide
however, easier said than done, and currently no one really knows how an asteroid can be redirected. There have been several proposals from NASA and the European Space Agency to do this, but so far, they have not taken the initial stages of mission development.
The B612 Foundation, a private non-profit group, is also trying to fundraise privately for an asteroid reorientation mission, and they could be the first to try to do so if the space programs governments do not do it. Pushing an asteroid seems a strange thing to do, but when we someday find an asteroid on a collision course with the Earth, it may well be that this knowledge saves humanity.
Learn more:
Two small asteroids pass the Earth safely this week
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