Can we really deflect an asteroid by hitting it? Nobody knows, but we’re excited to try

NASA Double Asteroid Redirection Test (DART) The spacecraft is designed to be one of the wonders of the world. Its days will end with a collision with an asteroid at 24,000 kilometers per hour on September 26. Launched from Earth in November 2021, the Dart is roughly the size of a bus and was created to test and prove our ability to defend Earth from asteroid threat.

It’s not easy to hit a target from 11 million kilometers away. But while that sounds far off, the asteroid was actually chosen by NASA because it is relatively close to Earth. This will give engineers the opportunity to test the spacecraft’s ability to operate on its own in the final stages before impact, as it crashes independently.

The asteroid is called the target Dimorphos, an object with a diameter of 163 meters and orbiting an asteroid 780 meters wide called Didymus. This “binary asteroid system” was chosen because Demorphos is in orbit around Didymus, making it easier to measure the outcome of the collision due to the resulting change in its orbit. However, Dimorphos currently pose no threat to Earth.

Regardless, NASA is trying nothing short of a full-scale planetary defense experiment to alter the asteroid’s path. The technique used is called the “kinetic effect,” which changes the asteroid’s orbit by colliding with it. This is basically what’s known as a safety shot in snooker, but it’s played on a planetary level between the spacecraft (like the main ball) and the asteroid.

The tiny deflection could be enough to show that this technology can indeed alter the trajectory of an asteroid on a collision course with Earth.

But the spacecraft DART will explode completely due to the collision because it will explode An effect equivalent to about three tons of TNT. In comparison, the atomic bomb dropped on Hiroshima was equal to 15,000 tons of TNT.

So, with this level of destruction and distance, how will we be able to see the breakdown? Fortunately, the DART spacecraft does not travel alone on its quest, but rather carries it LICIACube, a small, shoebox-sized spacecraft known as a cubesat, developed by the Italian space agency and aerospace engineering company Argotec. This little companion recently separated from the DART spacecraft and is now traveling alone to witness the impact at a safe distance of 55 km.

Illustration of how Dart affected changing Demorphos’ orbit around Didymus. Image credit, Johns Hopkins University Applied Physics Laboratory.

A cube launcher has never worked around asteroids, so this offers potential new avenues for future space exploration. The effect will also be observed from Earth using telescopes. Combined, these methods will enable scientists to confirm whether the process has been successful.

However, it may take weeks for LICIACube to send all the images back to Earth. This period will be quite nerve-wracking – waiting for good news from the spacecraft is always an emotional time for an engineer.

what happened after that?

An investigation team will look into the repercussions of the accident. These scientists will aim to measure changes in the motion of Demorphos around Didymus by observing the orbital period. This is the time Demorphos passes in front of and behind Didymus, which will happen every 12 hours.

Ground-based telescopes aim to capture images of the Demorphos eclipse as it is happening. To cause a sufficiently large deflection, the Dart must create At least 73 seconds orbital period change After Impact – Visible as changes in eclipse frequencies.

These measurements will ultimately determine how effective the “kinetic impact” technique is at deflecting the path of a potentially dangerous asteroid – we simply don’t know yet.

This is because we actually know very little about the formation of asteroids. The great uncertainty about how powerful Dimorphosis is has made designing a spacecraft with a bullet a truly formidable engineering challenge. Based on ground observation, the Didymos system is suspected to be a rubble pile It is made up of many different rocks, but its internal structure is unknown.

There are also great doubts about the outcome of the effect. Substances that are then ejected will contribute to the impacts of the collision, providing additional strength. We don’t know if the crater will be formed by the impact or if the asteroid itself will suffer significant deformation, which means we can’t be sure how much force the impact will release.

futuristic missions

Our exploration of the asteroid system does not end with Dart. The European Space Agency is set to launch Hera’s mission In 2024, reach Didymus in early 2027 for a closer look at the impact’s remaining effects.

By observing the distortions caused by the Dart effect on Demorphos, the Hera spacecraft will gain a better understanding of its formation and composition. Knowing the internal properties of things like Didymus and Demorphos will also help us better understand the danger they might pose to Earth in the event of a collision.

Ultimately, the lessons learned from this mission will help investigate the mechanisms of the high-velocity impact. While lab experiments and computer models can indeed help validate scientists’ predictions of impact, large-scale experiments in space like Dart are the closest to the full picture. Discovering as much information as possible about asteroids will help us understand the force we need to hit to keep them away.

The Dart mission has led to a global collaboration between scientists hoping to address the global issue of planetary defense, and with my colleagues on the Dart investigation team, we aim to analyze the effects of the impact. My special focus will be on studying the motion of matter kick out of influence.

The spacecraft impact is scheduled for September 26 at 19:14 EDT (00:14 BST on September 27). You can follow Impact on NASA TV.