How to protect the Earth from asteroids, if they are not visible?

Chelyabinsk meteorite was only 17-20 meters inacross the river, however, caused considerable damage on the spot, poked the windows and crippled people during an explosion in the Earth’s atmosphere in February 2013. To prevent another such collision, Amy Mainzer and her colleagues use a simple but tricky way to detect the tiny near-earth objects (NEO) that threaten our planet.

Amy is a senior research scientist at NASA's Asteroid Hunt at NASA's Jet Propulsion Laboratory in Pasadena, California. How is she trying to protect our planet from asteroids?

Planetary defense

"If we find an object that threatensa collision in a few days, this greatly limits our choices, so in our search we are focused on finding near-Earth objects when they are farther from Earth so that we can choose and we have time for that, ”says Mainzer.

But the task is difficult - how to catch a smoldering ember inthe night sky. Such objects are very dim, because they are small and far from us. In addition, some of them are darker than black toner for a printer, and it is very difficult to find them against the background of black space.

Instead of finding objects in the visiblelight range, the Mainzer team at JPL decided to use the heat of the object as a meaningful signature. Asteroids and comets are heated by the sun and glow in the thermal range (infrared), so they are easy to detect using the NEOWISE telescope, specifically designed to search for near-Earth objects in the infrared range.

“With the help of the NEOWISE mission, we can detect objects regardless of the color of their surfaces and use it to evaluate their size and other surface properties.”

Study of the surface properties of NEO objectsallows Mainzer and her colleagues to determine the size of objects and their composition - both of these parameters are important in determining a defensive strategy against bodies threatening the Earth.

For example, one of the defense strategiesis to physically “lead” NEO from the Earth, change the trajectory of the collision. But to calculate the energy required for a push, you need information about the mass, size and composition of the object. Astronomers also believe that studying the composition of asteroids will help to understand how the solar system was formed.

“Such objects are interesting in themselves, because some believe that their age is comparable with the age of the solar system. Their composition is also quite diverse. ”

Perhaps one day the work of these scientists will save the life of our planet. And what method would you suggest? Tell us in our chat in Telegram.