When We’ll Know if NASA’s Asteroid Impact Test was a Success

Recently NASA’s DART mission succeeded in its primary goal, which was to slam a spacecraft face-first into an asteroid. For science. The intention of the mission was to test if we could actually redirect an asteroid and send it into a different orbit. But how and when will we know if it worked?

The DART (Double-Asteroid Redirect Test) is about as simple as you can get when it comes to orbital mechanics. Find an asteroid. Slam something into it. See if we can move it. Done. The unlucky asteroid in question is Dimorphos, a small satellite of the larger asteroid Didymos. Dimorphos is relatively small when it comes to asteroids, just about 500 feet across and weighing somewhere around 5,500 tons.

The spacecraft, on the other hand, weighs about half a ton. So how could this possibly work?

It works because when it comes to space - if you give something an inch it will take a mile. The goal wasn’t to massively, instantly change the orbit of Dimorphos, but to change it just a little. Over long enough times, it’s hoped, even the tiniest change will add up to big differences.

Imagine you’re driving your car on a perfectly straight road. If you turn your steering wheel even a tiny bit, you’ll still stay on the road but after the miles add up you’ll find yourself on the side. If we hit an asteroid and give it a tiny change in velocity, it’s possible to send it into a completely different orbit.

What we do know now, is that DART slammed into Dimorphos as hard as it could. A combination of onboard cameras, a ride-along CubeSat imager, and Earth-based observatories all confirmed the impact. We won! Or did we? If the changes are going to be very small, how can we possibly tell?

The complete answer will come in a follow-up mission launched by the European Space Agency. The HERA mission will fly to the same asteroid as DART, this time without intentionally trying to hit it. HERA is expected to launch in 2024 and arrive at the Didymos-Dimorphos system about a year later. Once in orbit, it will survey the damage dealt and measure any changes to the orbital characteristic of the system.

We need to wait these few years because the orbital changes will initially be too small to measure. It will take time for the differences to build up to become something measurable, and only then will we truly know if DART was a success.

For now, NASA will be releasing information on the immediate results of the impact this Tuesday.

Next Up

Watch NASA's Asteroid-Crashing DART Mission Make Impact

NASA sent a spacecraft on a mission to crash into an asteroid, so how did it go?Updated 9/26/22

When Did the First Stars Shine?

Our universe is home to up to two trillion galaxies, with each galaxy hosting hundreds of billions of stars. That’s…a lot of stars. Each one a ball of fearsome energies, powered by the nuclear fusion of fundamental elements in their hearts. Each one pouring out light into the empty cosmos, illuminating our universe for our wonder and delight.

Romeo and Juliet: The Story of Galaxy Collisions

Our Milky Way galaxy is on a collision course. With destiny. With destruction. With fate. With our nearest neighbor, Andromeda. You can stream HOW THE UNIVERSE WORKS on discovery+.

What Happens When the Sun Throws a Tantrum?

Sure, the sun looks all calm up there in the sky. Kids even put little smiley faces on the sun when they draw it. But look closer and you’ll find that our sun has a nasty, violent temper.

Astronomers See Flashes from Behind a Black Hole

Want to see what’s behind a black hole? Easy. You just…stare at it. The whole thing is pretty weird to contemplate, but an excellent example of the space-bending (and mind-bending) powers of black holes.

The Milky Way Broke its Arm (But is Totally Okay)

The Milky Way is a giant, magnificent, truly transcendently beautiful spiral arm galaxy. It’s too bad we can’t get a decent picture of it. The problem is that we live inside it, and so astronomers have to work extra-hard to construct an accurate map.

The Cost of Global Satellite Internet: Worse Astronomy

A few billionare-backed companies have ambitious goals: launching tens of thousands of communication satellites to provide global high-speed internet access. Elon Musk’s StarLink, Jeff Bezos’ Project Kuiper, One Web, GuoWang, and more are all competing for this lucrative market. In less than a decade, we can expect over 50,000 new satellites to encircle the Earth. That’s about ten times more than are currently active.

What Screaming Black Holes are Telling Us

In 2002, NASA’s orbiting X-ray observatory, the Chandra telescope, mapped out the movements of hot gas in a cluster of galaxies sitting 250 million light-years away.

Do Giant Water Worlds Host Alien Life?

We all wish we could find an Earth 2.0 – a planet about the size of our own, made of roughly the same chemical mixture, orbiting a sun-like star at just the right distance so that all its water doesn’t evaporate or freeze.

The Nobel Prize Fell Into a Black Hole (and That’s a Good Thing)

The 2020 Nobel Prize in Physics is being awarded to scientists to have dedicated their careers to the study of black holes.

Related To: