OK! Just Missing Our Earth
- Elements of Science
- Aug 4, 2019
- 2 min read
Updated: Aug 28, 2019
July 2019
When we ponder about the randomness in our lives, one of the more extreme examples we sometimes jokingly think about is “what if we are hit by a giant asteroid?” To many, this seemed like a farfetched imaginary catastrophe that should never happen in the near future...until three weeks ago.
On July 24, 2019, two groups of independent astronomers reported that an asteroid of nearly 140 feet in radius would fly by Earth on the 25th, and the minimum orbit intersection distance — the closest distance between Earth’s orbit and that of the asteroid’s — would be alarmingly short. According to the report, this extraterrestrial object would miss us by just 0.00048 Astronomical Unit (One astronomical unit is the distance between Earth and the Sun) at a speed of 55000 miles per hour. To put these literally astronomical numbers into perspective, a football field-sized asteroid was just ⅕ of the Moon-Earth distance from colliding with Earth’s surface, and it was shooting across the sky 55 times faster than the cruising speed of a standard long-distance commercial airplane. This hazardous object is classified as a city killer. In other words, the object could wipe out an entire city.
While our hearts are pounding fast, some of us may be wondering: what can we do if an asteroid’s trajectory is estimated to hit Earth? One of NASA’s planetary defense programs is specifically designed to handle missions like deflecting an asteroid. The Double Asteroid Redirection Test, or DART, is attempting to launch a satellite that will intersect the asteroid’s trajectory before it hits Earth. A collision between the satellite and the asteroid will change the momentum of the asteroid and slightly alter its orbit, redirecting it away from our mother planet. The mechanism has many complicated parts, but the gist of the idea can be explained with a simple analogy. Imagine you are trying to throw a basketball into the basket. Your aim is perfect, but a strong wind blows by and gives your ball a push midair; as a result, the basketball misses its target. Here the asteroid is the target, and the satellite is the basketball.
Such thrilling scenarios happen far more often than some of us may expect. Near-extinction events caused by extraterrestrial objects are estimated to happen once every couple of millennia. However, it is emergencies like these that help to drive technology forward. Therefore, while we may be horrified after hearing such near-misses, we should also be glad that these incidents are crucial motivation for scientists to keep developing new and more effective solutions to similar problems, and such advances may benefit our lives in many other areas.
By Peiyao Li
Works Cited
- MOID DATA:
- Speed/Size DATA:
- DART Mission Image
- 2019 OK Image
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