… just by war or climate change.
According to NASA, “DART is the first-ever mission dedicated to investigating and demonstrating one method of asteroid deflection by changing an asteroid’s motion in space through kinetic impact”. This means NASA has DART collide with an asteroid deliberately to change its speed and path i.e., the orbit.
Launched last year, DART targeted the asteroid system “Didymos” which comprises the asteroid Didymos and another asteroid that orbits it called “Dimorphos”. Neither of these objects posed (or poses) any threat to Earth. DART collided with “Dimorphos” and successfully altered its orbit. Initially, NASA had expected to alter Dimorphos’ orbit by around 10 minutes but ended up shortening the orbit by 32 minutes! It created a 10,000 km-long debris tail (that’s 6,200 miles for those of you who don’t understand metric) that can be seen from Earth through a telescope (like a comet as in the image above which was taken by astronomers in Chile).
Let’s just take a minute to really understand that. Humanity changed the orbit of a celestial object! That’s like something out of science fiction. Even the name of the space craft – DART, which stands for Double Asteroid Redirection Test, sounds like it was inspired by acronyms in comic books.
Why, you might ask, did NASA just nudge the asteroid’s orbit rather than blowing it up? That’s because there is always the possibility that the debris might hit Earth.
But there’s still work to do. Now, NASA and space programs around the world must work on early detection systems for celestial bodies headed towards Earth (like this one?). If we want to do this in the future, it will need to happen years in advance and that’s why we need warning time is key to enable this kind of planetary defense strategy. There are likely thousands of space rocks that could potentially impact Earth and fewer than half have been identified. There may also be asteroids near Mecury and Venus but so far, it has been difficult to discover objects that are interior to the Earth’s orbit with our current telescopes, according to Dr. Cristina Thomas, a planetary astronomer at Northern Arizona University.
In the coming months, astronomers will continue to monitor the impact of the DART on the Didymos asteroid system.
Photo credit: https://www.bbc.com/news/science-environment-63140097
