Bumping asteroids off course

This exercise is a part of Educator Guide: NASA’s DART Mission Is a Success / View Guide

Directions for teachers: Project and play the Science News TikTok “Crashing into an asteroid on purpose?!” for your class. Then ask students to read the online Science News article “NASA’s DART mission successfully shoved an asteroid” and answer the following questions. A version of the article, “NASA’s DART mission is a success,” appears in the November 5, 2022 issue of Science News.

1. In your own words, describe the goal of NASA’s DART mission. What does DART stand for?

The goal of NASA’s Double Asteroid Redirection Test, or DART, mission was to knock an asteroid off course by smashing a spacecraft into it. If successful, the tactic could be used to divert a potentially dangerous asteroid from colliding with Earth. 

2. What was the DART spacecraft’s target? Is the target a threat to Earth? Explain.

DART’s target was the asteroid Dimorphos, which orbits a slightly larger asteroid called Didymos. Dimorphos and Didymos are approximately 11 million kilometers from Earth and are not threats to us.

3. How fast was DART traveling through space when it hit its target? Don’t forget to include appropriate units of measure.

DART was traveling about 22,500 kilometers per hour when it smashed into Dimorphos.  

4. What was the result of the impact on the asteroid’s orbit? How did the result compare with scientists’ expectations?

DART shortened the orbit of Dimorphos by 32 minutes, which is more than 30 minutes longer than the minimum 73-second shift that scientists had anticipated. Before the impact, Dimorphos orbited Didymos every 11 hours and 55 minutes. After the impact, the small asteroid completed an orbit every 11 hours and 23 minutes.

5. What do scientists think contributed to the difference between their expectations and the results?

The impact itself moved the asteroid a little bit, but the debris that the spacecraft kicked up when it crashed acted like a rocket engine and gave the asteroid an additional boost.

6. How did scientists figure out that the DART mission was successful?

Four telescopes in Chile and South Africa that watched the asteroids after the impact detected periodic changes in brightness as the asteroids eclipsed each other. The observations were confirmed by direct radar measurements of the asteroids’ orbits.

7. What do the results suggest about the success of a future planetary defense program? If a large asteroid were headed toward Earth, how far in advance would a spacecraft need to crash into it to avert disaster?

The results suggest that crashing a spacecraft into a potentially hazardous asteroid could nudge it out of the way before it hits Earth. For such a mission to be successful, scientists would want to know that the space rock is coming years before it gets close to our planet.