Shortly after Valentine’s Day, an asteroid estimated to be between 440 and 990 meters will pass by Earth. Some media outlets have reported on this with sensational headlines, sparking social media attention, but experts at NASA’s Near-Earth Object Research Center say we are not in danger.
In the long run, the possibility that the Earth will be affected by NEOs cannot be ignored, but we should not worry too much about the impact of asteroids or comets on Earth.
The asteroid will pass about 5.8 million kilometers from Earth, less than 15 times the distance of the Earth’s moon. The asteroid, known as 2002 PZ39, has been tracked since it was discovered in August 2002, according to NASA’s website. On 11 February, the Arecibo Observatory in Puerto Rico began observing this particular asteroid flyby, which will continue until 17 February.
According to NASA, the Asteroid Center has classified the 2002 PZ39 as a “potentially dangerous asteroid” (PHAs). This applies to any object larger than 150 meters that approaches the Earth within a range of 7.4 million km. However, according to the orbit of asteroid 2002 PZ39, it will not be closer to Earth than expected.
Coincidentally, February 15 is also the seventh anniversary of the 2013 attack on an asteroid in Chelyabinsk, Russia. The asteroid that exploded in the air at the time released a huge amount of energy, 20 to 30 times more than the first atomic bomb, and even brighter than the sun. The impact destroyed more than 7,000 buildings, injured more than 1,000 and shattered windows more than 90 kilometers away.
In addition to tracking potentially threatening near-Earth objects, NASA and other agencies are currently studying near-Earth asteroid missions in the hope of reducing the risk of them hitting Earth. Understanding the size and orbit of asteroids is a major part of these missions, as these data make it possible to predict NEOs.
Ed Lu, a former NASA astronaut and executive director of the Asteroid Institute, said the Large Integrated Sky Telescope (LSST) will be operational in the next few years and will be able to detect tens of thousands of asteroids closer to Earth in orbit.
“This is an exciting time for planetary defense because we’re about to get a lot of new observations that will allow us to track 10 times more asteroids than we did in the past,” Luger said. In its first year, it will discover and track tens of thousands of asteroids. “
Currently, NASA’s OSIRIS-REx probe and Japan’s Osprey 2 probe are exploring asteroids in the solar system and plan to send samples back to Earth in the coming years. As part of nasa’s NEO Cam program, NASA will detect asteroids that are close to Earth and could pose a threat.
Other missions are also planned, such as NASA’s Dual Asteroid Redirect Test (DART), a planetary defense mission designed to prevent an asteroid from hitting Earth. DART’s launch window will open in July 2021, when it will visit a dual asteroid system called 65803 Didymos. The system consists of a main asteroid with a diameter of about 800 meters and an asteroid with a diameter of about 150 meters, two asteroids orbiting each other, and the Target of the DART probe will be targeted at the smaller asteroid in it. NASA believes the asteroid’s size is more in line with our expectations of an asteroid that could threaten Earth.
The European Space Agency’s Hera mission will complement the DART mission, which will accurately measure how the latter changes the speed of larger asteroids and study the Impact Crater of the DART probe on another asteroid.
The Center for Near-Earth Object Research (CNEOS) has been monitoring potentially dangerous asteroids in the sky. In fact, CNEOS currently lists about 20 asteroids that will pass safely through Earth next month. Only one asteroid, a relatively small asteroid, estimated to be about 50 meters in diameter, is known as the asteroid 2018 GY and is expected to reach within 1.6 million kilometers of Earth.
Threats from NEOs
According to CNEOS on NEOs, about a hundred tons of interstellar matter “drifts” to the Earth’s surface every day. Most of the interstellar particles that reach the Earth’s surface come from comets, and as they pass near the sun, their ice evaporates and releases tiny dust particles. The vast majority of large interplanetary material reaching the Earth’s surface is made up of debris from collisions between asteroids several hundred million years ago.
Rock or iron asteroids larger than 100 meters reach the Earth’s surface at an average interval of about 10,000 years, causing locally catastrophic events or tidal waves that can flood low-lying coastal areas. On average, asteroids larger than a kilometer each year can cause global catastrophe. In this case, debris from the impact is scattered into the Earth’s atmosphere, causing acid rain to form, sunlight partially obscured, and flame storms from impacting high temperatures, which eventually fall back to the Earth’s surface. Since NEOs often intersect with Earth orbits and have had multiple impactevents in the past, we should be alert to the possibility of future NEOs approaching the Earth, be more careful to detect and study them, describe their size, composition and structure, and pay close attention to their future trajectories.
However, we should not worry too much about the impact of asteroids or comets on Earth. Auto accidents, diseases, natural disasters and other problems are much more threatening to human beings than NEOs. Of course, in the long run, the possibility that the Earth will be affected by NEOs cannot be ignored. At the moment, the best guarantee for this is the efforts of NEO scientists, who first find these objects and then track their future motion.