NASA really wants its spacecraft to hit an asteroid


While Dimorphos is similar to many other near -Earth asteroids, the DART team chose it as a target because it is the junior member of a binary asteroid. It’s called the “moonlet,” and it orbits Didymos, its larger companion, like a clock every 11 hours and 55 minutes. DART will hit Dimorphos at an angle of about 17 degrees relative to its orbit, and scientists plan to measure how much shift in its orbit. In other words, they can easily compare its movement to another body nearby. If they choose to attack a lone asteroid, the slight deviation in its orbit will not be visible for many years, until it passes through Earth. But thanks to the proximity of its companion, any changes in Dimorphos ’orbit can be determined within days.

“It’s a smart and intelligent approach, and it’s cost effective. And it’s safe too: You push this moon pretty close to the asteroid that is already orbiting it, ”Chabot said. He and his team expect DART to shorten the asteroid’s orbit by five to 15 minutes, to take only 11 hours and 45 minutes to orbit Didymos. NASA would consider a deviation of 73 seconds or more a successful mission.

The asteroid pair will be too close for accurate measurements using Earth’s telescopes until March 2023. After that, they will travel and farther, rather than part of their orbit around the sun that transcends Mars ’orbit. While asteroids look like a point of light from this distance, scientists will be able to measure how often the reflected sunlight bounces off the Didymos module — a proxy for duration in the orbit of Dimorphos.

These asteroids, like many others and some meteors — rocks in space that enter the Earth’s atmosphere — are not as dense and solid as billiard balls. These can be chunks of rock, gravel, and ice grouped together in an arrangement called a “rubble pile,” with a rocky composition similar to asteroids. Ryugu and Eros, and in meteor that exploded over Chelyabinsk, Russia, in 2013. In fact, the Dimorphos moonlet was probably formed simply by rotating the side of Didymos. If Dimorphos is dirty, the DART effect will be a crater, instead of throwing debris and meaningfully pushing the asteroid. But uncertainty is one of the reasons for doing the mission.

For a more detailed inspection of the crash scene, the European Space Agency’s Hera next mission. The spacecraft is scheduled to launch in 2024. When it arrives with the asteroidal duo in 2026, its optical camera, lidar tool, infrared scanner, and two CubeSat sidekicks will produce detailed maps of Dimorphos ’surface and structure.

If a dangerous asteroid is constantly heading for Earth, hitting a spacecraft — or a “kinetic impactor” —it is just a tool available to man. NASA, ESA, and other space agencies are also exploring other methods, such as placing a spacecraft nearby as a “gravity tractor” to pull it in another direction, or detonating a nuclear explosion. near to force it away. (Nuking the asteroid itself is in danger of failing, because it could be possible more rocks that don’t change their course much.) “The kinetic impactor is the most mature of these techniques,” Lori Glaze, director of NASA’s Planetary Science Division, said at a media briefing Sunday.



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