humanity would see in real time whether it could change the path of a celestial body
On the evening of September 26, 2022, humanity attempted something it had never done before — reaching out across millions of miles of space to nudge the cosmos itself. NASA's DART spacecraft, traveling at over 14,700 miles per hour, was aimed deliberately at Dimorphos, a small asteroid moon, not out of necessity but out of foresight: a rehearsal for the day when such an act might mean the difference between catastrophe and survival. It was, in its quiet way, a species practicing the art of its own protection.
- For the first time in history, a spacecraft was intentionally aimed at a celestial body to test whether human technology could alter its path through space.
- The collision — 1,260 pounds of spacecraft meeting a 525-foot asteroid at over 14,700 mph — was expected to shorten Dimorphos's orbital period by several minutes, a change precise enough to measure from Earth.
- Italy's LICIACube satellite, released from DART two weeks prior, raced to arrive just three minutes after impact, its twin cameras poised to capture the crater, the debris plume, and the immediate aftermath.
- Scientists were watching not just for proof of impact, but for data on surface composition and ejected material — the raw ingredients for models that could one day guide a real planetary defense mission.
- Live coverage began at 6 p.m. Eastern, with the world watching to learn whether kinetic force alone could move a world — however slightly — off its course.
On the afternoon of September 26, 2022, NASA prepared to do something unprecedented: deliberately crash a spacecraft into an asteroid to see if the impact could alter its trajectory. The target was Dimorphos, a rocky moon roughly 525 feet across orbiting the larger asteroid Didymos. The collision was set for 7:14 p.m. Eastern time, and a small Italian satellite would be watching from close range.
The Double Asteroid Redirection Test — DART — had been years in the making. Launched in November 2021, the 1,260-pound spacecraft carried a straightforward but audacious purpose: to prove that humanity could deflect an asteroid by ramming into it. Neither Dimorphos nor Didymos posed any threat to Earth; they were chosen precisely because scientists could afford to use them as a proving ground. If the experiment succeeded, it would validate kinetic impact as a real planetary defense strategy for the day astronomers might spot something genuinely dangerous.
The expected result was subtle but measurable — a shortening of Dimorphos's orbital period by several minutes, detectable by Earth-based telescopes. But NASA wanted more than orbital data. Italy's LICIACube satellite, tucked inside DART and released two weeks before impact, was designed to arrive at Dimorphos roughly three minutes after the collision to photograph the crater, the debris plume, and the reshaped surface. Its images would reveal what the asteroid was made of, how large the crater had grown, and how much material had been thrown into space — all critical inputs for future deflection modeling.
As live coverage began at 6 p.m. Eastern, the world prepared to witness, in real time, whether a species could move a piece of the solar system through sheer force of will — and whether a small Italian satellite could document the moment it happened.
On the afternoon of September 26, 2022, NASA was about to conduct an experiment that had never been attempted before: deliberately crashing a spacecraft into an asteroid to see if the impact would change its course through space. The target was Dimorphos, a small rocky moon about 525 feet across that orbits a much larger asteroid called Didymos. The collision would happen at 7:14 p.m. Eastern time, and a small Italian satellite called LICIACube would be watching.
The Double Asteroid Redirection Test, or DART, had been in development for years. NASA launched the 1,260-pound spacecraft in November 2021 with a straightforward but audacious goal: to demonstrate that humanity could alter an asteroid's trajectory by ramming something into it. If this works, the reasoning goes, it becomes a viable defense strategy if astronomers ever spot a genuinely dangerous space rock headed toward Earth. The asteroid system chosen for the test posed no actual threat to our planet—it was selected precisely because scientists could afford to use it as a proving ground.
Dimorphos, the target, orbits its larger companion Didymos, which measures 2,560 feet across. When DART struck Dimorphos at over 14,700 miles per hour, the impact was expected to shorten the smaller moon's orbital period by several minutes—a change subtle enough that Earth-based telescopes would be able to measure it with precision. That measurement would confirm whether the kinetic impact had worked as theory predicted.
But NASA wanted more than just orbital data. That's where LICIACube came in. The Italian Space Agency had built this small satellite—its name stands for Light Italian CubeSat for Imaging Asteroids—and tucked it inside the DART spacecraft. On September 11, about two weeks before impact, LICIACube separated and began its independent journey through space. It was designed to arrive at Dimorphos roughly three minutes after DART struck, positioning it to photograph what happened next: the impact crater, the plume of debris thrown up by the collision, and the immediate aftermath.
The Italian team had already released calibration images from LICIACube as it prepared for its moment. One showed Earth as a partially shadowed crescent from a distance of 8.6 million miles. Another captured stars in the Pleiades cluster. These were dress rehearsals. The real work would begin when DART's cameras went dark and LICIACube's twin optical cameras took over, documenting the destruction of the spacecraft and the violent reshaping of an asteroid's surface.
Scientists hoped the debris plume would tell them crucial things: what the asteroid's surface was actually made of, how large the impact crater had grown, and how much material had been ejected into space. All of this would feed into computer models designed to predict what would happen if humanity ever needed to deflect a genuinely threatening asteroid. The stakes were not immediate—Dimorphos posed no danger—but the knowledge gained could matter enormously someday.
NASA began streaming live coverage at 6 p.m. Eastern time, with still images from DART's cameras available starting at 5:30 p.m. The collision itself would occur at 7:14 p.m. For the first time, humanity would see in real time whether it could change the path of a celestial body through sheer kinetic force. And an Italian satellite would be there to document whether the experiment worked.
Notable Quotes
NASA scientists want to find out if it is possible to change an asteroid's path through space by ramming something into it—a maneuver that has never been tried before.— NASA mission objectives
The Hearth Conversation Another angle on the story
Why does it matter that LICIACube arrives three minutes after impact rather than at the same moment?
Because DART will be destroyed on contact. Its cameras will go dark the instant it hits. LICIACube needs to arrive after, when the debris is still rising and the crater is fresh, so we can actually see what happened.
And the debris plume—why is that so important to photograph?
The plume tells us what the asteroid is made of and how much energy was released. Different materials eject differently. By studying the plume, we learn whether our impact models are accurate, which matters if we ever need to do this for real.
This asteroid isn't a threat, though. So why risk it?
Exactly—it's not a threat, which is why it's safe to use as a test. If we wait until we find a dangerous asteroid, it might be too late to develop and launch a deflection mission. This proves the concept works before we need it.
What happens if the impact doesn't change Dimorphos's orbit as much as expected?
Then we learn that kinetic impact is less effective than we thought, and we need to rethink planetary defense strategy. Either way, we get crucial data.
How will scientists measure whether the orbit actually changed?
Ground-based telescopes will track Dimorphos before and after. If its orbital period around Didymos shifts by even a few minutes, we'll see it. The change will be small but measurable.
And if this works, what's next?
We'll have proven the concept. But there's still a lot to learn about how to apply it to different asteroid types, sizes, and compositions. This is the first step of a much longer process.