Teachable Moments | October 20, 2022
The Science Behind NASA's First Attempt at Redirecting an Asteroid
Find out more about the historic first test, which could be used to defend our planet if a hazardous asteroid were discovered. Plus, explore lessons to bring the science and engineering of the mission into the classroom.
Update: Oct. 20, 2022 – The DART spacecraft successfully impacted the asteroid Dimorphos on September 26, reducing the period of the asteroid's orbit by 32 minutes. Scientists considered a change of 73 seconds to be the minimum amount for success. This article has been updated to reflect the latest data and images from the impact.
In a successful attempt to alter the orbit of an asteroid for the first time in history, NASA crashed a spacecraft into the asteroid Dimorphos on Sept. 26, 2022. The mission, known as the Double Asteroid Redirection Test, or DART, took place at an asteroid that posed no threat to our planet. Rather, it was an ideal target for NASA to test an important element of its planetary defense plan.
Read further to learn about DART, how it worked, and how the science and engineering behind the mission can be used to teach a variety of STEM topics.
Why It's Important
The vast majority of asteroids and comets are not dangerous, and never will be. Asteroids and comets are considered potentially hazardous objects, or PHOs, if they are 100-165 feet (30-50 meters) in diameter or larger and their orbit around the Sun comes within five million miles (eight million kilometers) of Earth’s orbit. NASA's planetary defense strategy involves detecting and tracking these objects using telescopes on the ground and in space. In fact, NASA’s Center for Near Earth Object Studies, or CNEOS, monitors all known near-Earth objects to assess any impact risk they may pose. Any relatively close approach is reported on the Asteroid Watch dashboard.
NASA's Planetary Defense Coordination Office runs a variety of programs and initiatives aimed at detecting and responding to threats from potentially hazardous objects, should one be discovered. The DART mission is one component and the first mission being flown by the team. Image credit: NASA | + Expand image
While there are no known objects currently posing a threat to Earth, scientists continue scanning the skies for unknown asteroids. NASA is actively researching and planning for ways to prevent or reduce the effects of a potential impact, should one be discovered. The DART mission was the first test of such a plan – in this case, whether it was possible to divert an asteroid from its predicted course by slamming into it with a spacecraft.
Eyes on Asteroids is a real-time visualization of every known asteroid or comet that is classified as a near-Earth object, or NEO. Asteroids are represented as blue dots and comets as shown as white dots. Use your mouse to explore the interactive further and learn more about the objects and how we track them. Credit: NASA/JPL-Caltech | Explore the full interactive
With the knowledge gained from the demonstration, similar techniques could be used in the future to deflect an asteroid or comet away from Earth if it were deemed hazardous to the planet.
How It Worked
With a diameter of about 525 feet (160 meters) – the length of 1.5 football fields – Dimorphos is the smaller of two asteroids in a double-asteroid system. Before DART's impact, Dimorphos orbited the larger asteroid called Didymos (Greek for "twin"), every 11 hours and 55 minutes.
The sizes of the two asteroids in the Didymos system relative to objects on Earth. Image credit: NASA/Johns Hopkins APL | + Expand image
Neither asteroid poses a threat to our planet, which is one reason why this asteroid system was the ideal place to test asteroid redirection techniques. At the time of DART's impact, the asteroid pair was 6.8 million miles (11 million kilometers) away from Earth as they traveled on their orbit around the Sun.
The DART spacecraft was designed to collide head-on with Dimorphos to alter its orbit, shortening the time it takes the small asteroid to travel around Didymos. Compared with Dimorphos, which has a mass of about 11 billion pounds (five billion kilograms), the DART spacecraft was light. It weighed just 1,210 pounds (550 kilograms) at the time of impact. So how did such a light spacecraft affect the orbit of a relatively massive asteroid?
You can use your mouse to explore this interactive view of DART's impact with Dimorphos from NASA's Eyes on the Solar System. Credit: NASA/JPL-Caltech | Explore the full interactive
DART was designed as a kinetic impactor, meaning it transferred its momentum and kinetic energy to Dimorphos upon impact, altering the asteroid's orbit in return. Scientists were able to make predictions about some of these effects thanks to principles described in Newton's laws of motion.
Newton’s first law told us that the asteroid’s orbit would remain unchanged until something acted upon it. Using the formula for linear momentum (p = m * v), we could calculate that the spacecraft, which at the time of impact would be traveling at 3.8 miles (6.1 kilometers) per second, would have about 0.5% of the asteroid’s momentum. The momentum of the spacecraft may seem small in comparison, but calculations suggested it would be enough to make a detectable change in the speed of Dimorphos' orbit. However, mission planners felt that changing Dimorphos’ orbit by at least 73 seconds would be enough to consider the test a success.
But there was more to consider in testing whether the technique could be used in the future for planetary defense. For example, the formula for kinetic energy (KE = 0.5 * m * v2) tells us that a fast moving spacecraft possesses a lot of energy.
When DART hit the surface of the asteroid, its kinetic energy was 10 billion joules! A crater was formed and material known as ejecta was blasted out as a result of the impact. Scientists are still studying the data returned from the mission to determine the amount of material ejected out of the crater, but estimates prior to impact put the number at 10-100 times the mass of the spacecraft itself. The force needed to push this material out was then matched by an equal reaction force pushing on the asteroid in the opposite direction, as described by Newton’s third law.
This animation shows conceptually how DART's impact is predicted to change Dimorphos' orbit from a larger orbit to a slightly smaller one that's several minutes shorter than the original. Credit: NASA/Johns Hopkins APL/Jon Emmerich | Watch on YouTube
How much material was ejected and its recoil momentum is still unknown. A lot depends on the surface composition of the asteroid, which scientists are still investigating. Laboratory tests on Earth suggested that if the surface material was poorly conglomerated, or loosely formed, more material would be blasted out. A surface that was well conglomerated, or densely compacted, would eject less material.
After the DART impact, scientists used a technique called the transit method to see how much the impact changed Dimorphos' orbit. As observed from Earth, the Didymos pair is what’s known as an eclipsing binary, meaning Dimorphos passes in front of and behind Didymos from our view, creating what appears from Earth to be a subtle dip in the combined brightness of the pair. Scientists used ground-based telescopes to measure this change in brightness and calculate how quickly Dimorphos orbits Didymos. By comparing measurements from before and after impact, scientists determined that the orbit of Dimorphos had slowed by 32 minutes to 11 hours and 23 minutes.
The green circle shows the location of the Dimorphos asteroid, which orbits the larger asteroid, Didymos, seen here as the bright line across the middle of the images. The blue circle shows where Dimorphos would have been had its orbit not changed due to NASA’s DART mission purposefully impacting the smaller asteroid on Sept. 26, 2022. The images were obtained from the NASA Jet Propulsion Laboratory’s Goldstone planetary radar in California and the National Science Foundation’s Green Bank Observatory in West Virginia. Image credit: NASA/Johns Hopkins APL/JPL/NASA JPL Goldstone Planetary Radar/National Science Foundation’s Green Bank Observatory | + Expand image | › DART image gallery
One of the biggest challenges of the DART mission was navigating a small spacecraft to a head-on collision with a small asteroid millions of miles away. To solve that problem, the spacecraft was equipped with a single instrument, the DRACO camera, which worked together with an autonomous navigation system called SMART Nav to guide the spacecraft without direct control from engineers on Earth. About four hours before impact, images captured by the camera were sent to the spacecraft's navigation system, allowing it to identify which of the two asteroids was Dimorphos and independently navigate to the target.
A composite of 243 images of Didymos and Dimorphos taken by the DART spacecraft's DRACO camera on July 27, 2022, as the spacecraft was navigating to its target. Image credit: JPL DART Navigation Team | + Expand image | › DART image gallery
DART was not just an experimental asteroid impactor. The mission also used cutting-edge technology never before flown on a planetary spacecraft and tested new technologies designed to improve how we power and communicate with spacecraft.
Learn more about the engineering behind the DART mission, including the innovative Roll Out Solar Array and NEXT-C ion propulsion system, in this video featuring experts from the mission. Credit: APL | Watch on YouTube
One such technology that was first tested on the International Space Station and was later used on the solar-powered DART spacecraft, is the Roll Out Solar Array, or ROSA, power system. As its name suggests, the power system consisted of flexible solar panel material that was rolled up for launch and unrolled in space.
The Roll Out Solar Array, shown in this animated image captured during a test on the International Space Station, is making its first planetary journey on DART. Image credit: NASA | + Expand image
Some of the power generated by the solar array was used for another innovative technology, the spacecraft's NEXT-C ion propulsion system. Rather than using traditional chemical propulsion, DART was propelled by charged particles of xenon pushed from its engine. Ion propulsion has been used on other missions to asteroids and comets including Dawn and Deep Space 1, but DART's ion thrusters had higher performance and efficiency.
Follow Along
In the days following the event, NASA received images of the impact from a cubesat, LICIACube, that was deployed by DART before impact. The cubesat, which was provided by the Italian Space Agency, captured images of the impact and the ejecta cloud.
This image from LICIACube shows plumes of ejecta streaming from Dimorphos after DART's impact. Each rectangle represents a different level of contrast to better see fine structure in the plumes. By studying these streams of material, scientists will be able to learn more about the asteroid and the impact process. | + Expand image | › DART image gallery
Meanwhile, the James Webb Space Telescope, the Hubble Space Telescope, and the Lucy spacecraft observed Didymos to monitor how soon reflected sunlight from the ejecta plume could be seen. Going forward, DART team members will continue observing the asteroid system to measure the change in Dimorphos’ orbit and determine what happened on its surface. And in 2024, the European Space Agency plans to launch the Hera spacecraft to conduct an in-depth post-impact study of the Didymos system.
This animation, a timelapse of images from NASA’s James Webb Space Telescope, covers the time spanning just before DART's impact at 4:14 p.m. PDT (7:14 p.m. EDT) on Septtember 26 through 5 hours post-impact. Plumes of material from a compact core appear as wisps streaming away from where the impact took place. An area of rapid, extreme brightening is also visible in the animation. Image credit: Science: NASA, ESA, CSA, Cristina Thomas (Northern Arizona University), Ian Wong (NASA-GSFC); Joseph DePasquale (STScI) | + Expand image | › DART image gallery
Continue following along with all the science from DART, including the latest images and updates on the mission website.
Teach It
The mission is a great opportunity to engage students in the real world applications of STEM topics. Start exploring these lessons and resources to get students engaging in STEM along with the mission.
Educator Guides
Expert Talks
Student Activities
Articles
-
Teachable MomentsHow NASA Studies and Tracks Asteroids Near and Far
Here’s how NASA uses math and science to track the movements of asteroids and find out what they’re made of – and students can, too.
-
Meet JPL InternsFrom Island Life to Spotting Asteroids for NASA
Meet a JPL intern whose journey took her from the remote island of Saipan to a team helping track asteroids at NASA.
Resources for Kids
Check out these related resources for kids from NASA Space Place:
- Article for Kids: Asteroid or Meteor: What's the Difference?
- Article for Kids: What Is an Asteroid?
- Article for Kids: Why Does the Moon Have Craters?
- Article for Kids: What Is an Impact Crater?
Explore More
- Facts & Figures: Didymos In Depth
- Facts & Figures: DART Mission
- Website: DART Mission
- Gallery: DART Mission Images and Videos
- Facts & Figures: Asteroid Watch
- Gallery: Next Five Asteroid Approaches
- Articles: Asteroid News and Images from JPL
- Eyes on Asteroids
- Eyes on the Solar System - DART Impact
- Quiz: Are You a Planetary Defnder?
- Center for Near-Earth Object Studies
TAGS: Asteroids and Comets, DART, near-Earth objects, planetary defense, Science, K-12 Education, Teachers, Educators, Parents, Teachable Moments, Asteroid TM
Meet JPL Interns | September 20, 2018
From Island Life to Spotting Asteroids for NASA
When Lean Teodoro was growing up on the remote island of Saipan in the middle of the Pacific Ocean, her dream of one day working for NASA always seemed a bit far-fetched to those around her. Now, a geophysics student on the premed track at the University of Hawaii and a summer 2018 intern at NASA’s Jet Propulsion Laboratory, Teodoro is making her dream a reality. This summer, she took a short break from her internship searching for asteroids with NASA’s NEOWISE team to tell us about her career journey so far, what inspired her to study STEM and how she hopes to play a role in human space exploration of the future.
What are you working on at JPL?
I work with the NEOWISE team, the Near-Earth Object Wide-field Infrared Survey Explorer. My focus is on near-Earth asteroids. I do a lot of image analysis and processing. Not all of the time do asteroids get detected through our automated system, so my job is to look at archives to find previously undetected asteroids.
What is a near-Earth object and how do you look for them?
Near-Earth objects are objects [such as asteroids and comets] that are very near to Earth's orbit. There are other asteroids that are located roughly between the orbits of Mars and Jupiter, but my focus is on those that are closer to Earth. The way that we detect them is we have this [space telescope called NEOWISE] that surveys the sky in two wavelengths. It senses the heat of asteroids. So I look at images from NEOWISE and, if I see a red dot that is bright, then that's usually an asteroid. But I go through several search techniques to see if the signal-to-noise ratio is good. So there are several processes that work.
NASA's asteroid-hunting NEOWISE mission uses infrared to detect and characterize asteroids and comets. Since the mission was restarted in December 2013, NEOWISE has observed or detected more than 29,000 asteroids in infrared light, of which 788 were near-Earth objects. Credit: NASA/JPL-Caltech | Watch on YouTube
What is the ultimate goal of the project?
My ultimate goal is to try to increase the number of known near-Earth objects so that, in the future, we can get more precise measurements for their positions and movements -- just in case they pose a risk to Earth.
What's an average day like for you?
I go through, I'd say, hundreds of images per day. I also took part in a side project where I had to get the measurements of an asteroid that was observed 39 years before it was officially discovered. We looked at this astronomical plate from the 1950s. You can see a very small arrow pointing to an asteroid. Positions for the asteroid hadn’t been discovered yet, so my job was also to find those. It had a lot to do with coding and I had very little experience with coding, so it was nice.
What other skills have you been able to pick up at JPL?
My major is geophysics, so I had little knowledge about astronomy. My whole research team exposed me to an exciting world of astronomy, so that was really nice. They were very encouraging. I've learned so much more about astronomy this summer than I did throughout my whole undergrad career. I mean, there is some connection between geophysics and astronomy, in a way, but this summer, I really learned so much.
Meet JPL Interns
Read stories from interns pushing the boundaries of space exploration and science at the leading center for robotic exploration of the solar system.
You grew up on the remote island of Saipan in the Northern Mariana Islands. How did you get exposed to STEM and what got interested in pursuing it as a career?
When I was young, my dad would always make us go fly kites at night on the beach. There was this one night where I was just looking at the Moon. I was like, "Oh my god, I really want to learn more about astronomy.” I think since then, I've been interested in STEM. But when you're coming from a really small island, you feel very limited. So I didn't have that strong foundation in STEM. And that's the reason why I wanted to move off the island -- because I knew that I couldn't get the opportunities if I stayed. That's the reason I moved to the University of Hawaii. They have a strong geology and geophysics program, and it's a great research university. Since I started there, I've been doing research related to NASA -- like the NASA Hawaii Space Grant Consortium. I feel like if I didn't move to the University of Hawaii, I wouldn't be where I am today, interning at JPL.
So you moved from one island to another?
[Laughs.] Yeah, I couldn't leave the island vibe, I guess. I think it's just a little closer to home. I feel more at home when I'm in Hawaii. Not only that, but also they have a great program, so that was a plus, too. And they have close affiliations with NASA, so that was really great, because my goal was to work for NASA.
Was it a challenge to move away from the island where you grew up?
It was definitely a challenge leaving family and friends behind. I was there on my own. The reason why I chose the University of Hawaii is because of their program. I had a really hard time choosing my major because I was interested in health, but I was interested in geology as well. I'm doing premed as well [as geology and geophysics]. I'm really interested in how humans or organisms can adapt to extreme environments and in learning about geology – for example on Mars – and health, and seeing how we can combine those two fields to contribute to future human space exploration.
Teodoro's first mentor at the University of Hawaii, Heather Kaluna (middle), helped connect her with JPL scientist Joseph Masiero (left) for an internship at the laboratory. Photo courtesy Lean Teodoro | + Expand image
What do your family and people back home think of your career path?
It's so funny because I remember, in middle school, I would always tell my friends and family how I wanted to work for NASA, and they would laugh about it because I don't think anyone back home has ever done something big like that. Having them see me working here -- it just kind of opened their eyes, like, “Wow, it's possible,” you know? Most of the time, people back home just stay for financial reasons. It was really expensive moving to Hawaii. But I really wanted to do it. So here I am, and I'm so happy.
Did you know that we have a group of student teachers from the Northern Mariana Islands that has come to NASA’s MUREP Educator Institute at JPL the past couple summers?
Yeah! So three weeks ago, I was walking to my office, and I saw a few friends from back home. I was like, “Oh my god, what are you guys doing here?” We all went to the same high school and everything! They were telling me about that whole program. I was like, “Oh my god, I feel so happy. That's so great.” The chances -- it was mind-blowing. I'm so happy for them. I'm really excited for the future of Saipan and the whole Northern Mariana Islands.
What's the most JPL- or NASA-unique experience you've had so far?
Of all the internships I've had in the past, JPL is really unique because everyone is just so passionate about the work that they do, so it really rubs off on you. Not only that, but also the intern community here is just amazing. And not only the interns, but also my mentors and the other scientists and engineers I've met. I've made so many friends throughout my summer here from all over the nation and all over the world, which is nice because I'm from this small island, and it just makes me realize how big the world is.
I feel like interning at JPL builds a foundation for me. And with my mentors here at JPL and in Hawaii, I do feel more confident in being a minority and a woman in STEM. I feel more driven to be successful and to inspire people from back home to go and pursue what they want to do. Don't let the confinements of your environment stop you from what you want to do.
What’s your ultimate career goal?
My ultimate goal is to try and contribute to future human space exploration. That's what I really want to do. I'm still trying to figure out how I can pave my path by combining health and geosciences. We'll see how it goes.
Explore JPL’s summer and year-round internship programs and apply at: https://www.jpl.nasa.gov/edu/intern
The laboratory’s STEM internship and fellowship programs are managed by the JPL Education Office. Extending the NASA Office of Education’s reach, JPL Education seeks to create the next generation of scientists, engineers, technologists and space explorers by supporting educators and bringing the excitement of NASA missions and science to learners of all ages.
TAGS: Women in STEM, Internships, Higher Education, Science, Astronomy, Asteroids and Comets, NEOWISE, Asian Pacific American Heritage Month, Asteroids, Women at NASA
