From time to time, we hear the disturbing news that a big asteroid passes near the Earth. And often, we also learn that the rock was discovered just before the flyover. Close calls are a reminder of the real vulnerability of our planet.
We now know what NASA intends to do about it. The new plan of the agency describes how he will defend himself against asteroid attacks.
The plan focuses on detection, which means telescopes and software. Asteroids have predictable orbits, so once one is spotted, scientists can quickly tell if this will pose a threat and when is the best time to try to deflect it.
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And if a threat is found? Some options for deflecting an asteroid are subtle, like gravity tractors, where a spaceship uses its own small gravitational field to push an asteroid into a different orbit.
Others are less subtle, like crushing a spaceship into the asteroid at high speed to make it take off. And yes, blowing an asteroid with a nuclear weapon is a real option.
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Space asteroids
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IN SPACE – JULY 10: This image provided by the European Space Agency, transmitted by the Rosetta spacecraft, shows the asteroid Lutetia at the closest approach on the 10th July 2010 between Mars and Jupiter in space. Lutece, of which little is known, although discovered in 1852, is thought to have a diameter of 134 kilometers. The Rosetta, which was launched in 2004, flew tonight by Lutetia at a distance of 1900 miles (3,200 kilometers). (Photo by MPS ESA 2010 for the OSIRIS team via Getty Images)
This image of Dawn's Asteroid Vesta Framing Camera (FC) shows the crater Licinia, which is the big crater in the center of the image. Licinia has a fresh, pointed edge that is scalloped in shape. Around the crater Licinia, many trails of dark and shiny materials cascade to the center of the crater. This image is located in the Floresta quadrilateral of Vesta, in the northern hemisphere of Vesta. The NASA Dawn spacecraft got this image with its framing camera on October 11, 2011. (Photo by: Universal History Archive / UIG via Getty Images)
The large asteroid Vesta is shown in this image taken by NASA's Dawn spacecraft. Astronauts and scientists are training in the waters off Key Largo, Florida, as part of NASA's Extreme Mission (NEEMO) operations to test equipment and human responses to an asteroid . (Miami Herald / MCT via Getty Images)
IN SPACE – JULY 10: This photo illustration provided by the European Space Agency, transmitted by the Rosetta spacecraft, shows the final sequence of images before the approach. Closer to the asteroid Lutetia on July 10, 2010 between Mars and Jupiter in space. Lutece, of which little is known, although discovered in 1852, is thought to have a diameter of 134 kilometers. The Rosetta, which was launched in 2004, flew tonight by Lutetia at a distance of 1900 miles (3,200 kilometers). (Photo by MPS ESA 2010 for the OSIRIS team via Getty Images)
The NASA Dawn spacecraft got this image with its framing camera on July 17, 2011. It was taken at a distance of about 9,500 miles (15,000 kilometers) from the Vesta protoplanet. Each pixel in the image corresponds to about 0.88 miles (1.4 kilometers). (Photo by: Universal History Archive / UIG via Getty Images)
Image of the asteroid Vesta. This Vesta Dawn (FC) framing camera image shows linear grooves and ridges in the Vesta Regolith. These linear entities are generally diagonally arranged on the image, from the upper left to the lower right. They have a width less than 1 kilometer (0.6 mile) and some have lengths that extend over the entire image. This image is located in the Tuccia quadrilateral of Vesta, in the southern hemisphere of Vesta. NASA's Dawn spacecraft got this image on April 8, 2012. (Photo by: Universal History Archive / UIG via Getty Images)
As NASA's Dawn spacecraft takes off for its next destination, this mosaic synthesizes some of the best views that the spacecraft has from the giant Vesta asteroid. Dawn studied Vesta from July 2011 to September 2012. The towering mountain at the South Pole – more than twice the height of Mount Everest – is visible at the bottom of the picture. The set of three craters known as "snowman" can be seen at the top left. (Photo by: Universal History Archive / UIG via Getty Images)
The 2015 TB145 asteroid is represented on eight individual radar images collected on October 31, 2015 between 5:55 am PDT (8:55 am EDT) and 6:08 pm PDT (9:08 am EDT). (Photo via NASA / JPL-Caltech / GSSR / NRAO / AUI / NSF)
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The report also states that NASA is now convinced that all the larger asteroids – ones that are big enough to cause damage on a global scale – have already been found and that no one is dangerous. .
And for smaller asteroids, early detection could give years to prepare for an impact if it can not be deflected.
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