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  • Asteroids impacting Earth can be devastating, just ask the dinosaurs.

  • Oh wait, you can’t because theyre all dead.

  • But even the asteroids that aren’t mass-extinction huge can be a serious threat.

  • We get hit with an asteroid about the size of the Great Pyramid of Giza every few thousand years,

  • and when the next one hits it could cause massive damage to an entire region.

  • So when we spot the next one coming, what’s the plan?

  • Now if it were up to me, plan A would be to train a crew of oil rig drillers led by Bruce Willis and Ben Affleck

  • to be astronauts so they can plant a nuclear bomb inside the murder space rock,

  • splitting it up so its two halves dramatically just miss the Earth...

  • I think that’s a pretty obvious and not at all dumb solution to the problem.

  • But NASA has a whole Planetary Defense Coordination office,

  • whose task is coming up with ways to protect the planet from threats from outer space,

  • and my plan isn’t on that list, somehow.

  • However, one of their ideas is to smack a spacecraft head on with an oncoming asteroid

  • to see if it can be slowed down and deflected.

  • Members of NASA, the European Space Agency, and others are informally collaborating

  • with a pair of missions that together are known as the Asteroid Impact and Deflection Assessment, or AIDA.

  • NASA is up first with a mission called the Double Asteroid Redirection Test, or DART.

  • The launch window opens July 22, 2021,

  • and the goal is to nail an asteroid by late September or early October the following year.

  • The target DART is aiming at is one of a pair of binary asteroids called Didymos B.

  • Didymos is Greek for twin, hence the Double part of DART.

  • While it’s not on a trajectory to hit Earth,

  • it is an ideal candidate to see just how much of an impact will affect it.

  • That’s because Didymos B is a moonlet 160 meters across

  • that’s orbiting the much larger asteroid Didymos A, and as luck would have it,

  • from our perspective it passes in front and behind the larger body,

  • causing changes in the system’s brightness that we can measure.

  • When DART hits Didymos B at 6.6 kilometers per second,

  • the asteroid’s speed will change by a fraction of a percent,

  • but that’s enough to change the time it takes to orbit Didymos A by several minutes.

  • Enough to be detected by telescopes roughly 11 million kilometers away here on Earth.

  • Just because DART’s fate is to go out in a dusty blaze of glory doesn’t mean that any old spacecraft will do.

  • It’s not like were flinging a rusty tow truck at Didymos.

  • No, the DART spacecraft will be equipped with the latest in ion engines, NASA’s NEXT-C,

  • and rollout solar panels to power the electric propulsion system.

  • It will also use an autonomous guidance system called SMART Nav

  • that will use the spacecraft’s onboard camera to identify its target

  • and steer DART in for a nearly head-on collision.

  • Huh.. an electric powered self driving vehicle is getting launched into space.

  • Why am I having Deja Vu?

  • About five days before impact, DART will release an Italian-made CubeSat

  • that will record images of the collision,

  • basically a high tech space version of the guy who records you on his phone

  • right before youre about to do something dumb and hurt yourself and become a gif on the internet.

  • If all goes as planned, the second part of AIDA, the ESA’s Hera mission, will launch in 2023,

  • arriving at Didymos a few years later to take more detailed measurements of DART’s impact on the moonlet.

  • While Didymos can be seen by Earth’s telescopes,

  • DART might kick up dust that makes seeing its effect more difficult.

  • So Hera will use data from visual, lasar, and radio science mapping

  • that will make DART go from an ambitious experiment to a repeatable planetary defense technique.

  • AIDA is the first step in the process towards having a viable defense for planet Earth

  • in case we spot the next disasteroid heading our way.

  • It’s not only a way to test the technology needed to hit a moving target in space,

  • it will also foster cooperation between members of different space agencies.

  • Teamwork is crucial when the world is at stake.

  • Here’s hoping DART hits its mark, then finally the dinosaurs will be avenged.

  • Didymos B has a cute little nickname, Didymoon.

  • Fun fact, that’s also my rap name.

  • If you want to learn more about asteroids, check out this video on NASA’s Psyche mission

  • that’s headed to a metal asteroid.

  • Make sure you subscribe to Seeker to keep up to date will all your space news,

  • and as always, thanks for watching.

Asteroids impacting Earth can be devastating, just ask the dinosaurs.

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B2 中高級

美國宇航局計劃將航天器撞向小行星。 (NASA Plans to Slam a Spacecraft Into an Asteroid)

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    林宜悉 發佈於 2021 年 01 月 14 日
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