Asteroid Apophis 2029: Why Scientists Fear Space Junk Could Ruin the Flyby

What if the closest asteroid flyby in modern history got ruined, not by the asteroid itself, but by a random piece of human space junk? That’s the strange, very real worry hanging over asteroid Apophis 2029, one of the most anticipated close encounters in the history of planetary science.

Mark your calendar: asteroid Apophis 2029 arrives on April 13. That’s the day a 370-meter chunk of rock named 99942 Apophis will scream past Earth, closer than many satellites orbit right now. Scientists insist there’s no danger of impact. But they’re genuinely worried about something else entirely.

Quick Facts

• Apophis will pass within 32,000 km (20,000 miles) of Earth on April 13, 2029
• That’s closer than many geostationary satellites, which orbit around 36,000 km out
• Two spacecraft, ESA’s RAMSES and NASA’s OSIRIS-APEX, will be watching the encounter up close
• A new study warns there’s a real, if small, chance the asteroid could collide with human-made space debris beforehand

What Is Apophis, and How Close Will It Actually Come?

Apophis isn’t small. At roughly 370 meters long, it’s about the length of three football fields. When astronomers first spotted it back in 2004, early calculations briefly suggested it might actually hit Earth. Follow-up observations ruled that out completely. Scientists have now crunched the numbers so many times, they’re about as confident as they can be: Apophis poses zero impact risk in 2029.

But “no risk of impact” doesn’t mean “far away.” Quite the opposite. The asteroid will pass within about 32,000 kilometers of Earth’s surface, well inside the ring of geostationary satellites that orbit roughly 36,000 kilometers out. For an object this size, that’s an astonishingly close shave. Encounters like this, where a rock big enough to devastate a region skims this near to Earth, happen only once every few thousand years.

A Brief History of the Asteroid Apophis 2029 Scare

Asteroid Apophis 2029 wasn’t always just a fascinating flyby. Back in December 2004, early tracking data briefly suggested a genuinely alarming 2.7% chance that Apophis could slam into Earth in 2029. For a short, tense window, it topped every asteroid risk scale scientists had. Headlines called it a “doomsday rock.” NASA and other observatories scrambled to gather more precise measurements.

Additional observations quickly ruled out any 2029 impact entirely. A smaller, more distant concern lingered for a few more years, a possibility that the 2029 flyby itself could bend Apophis’s path through a narrow “gravitational keyhole,” setting up a potential impact in 2036. Later tracking data eliminated that risk too. As of today, scientists consider an Apophis impact, in 2029, 2036, or any foreseeable future pass, essentially ruled out.

That history is exactly why the 2029 flyby matters so much now. A rock once treated as a serious planetary threat has turned into one of the best natural experiments scientists have ever had the chance to observe up close.

What Would Happen If a Rock This Size Actually Hit?

It’s worth understanding why Apophis earned its fearsome reputation in the first place. An asteroid roughly 370 meters across, striking Earth at typical asteroid speeds, would release energy equivalent to well over a thousand megatons of TNT, thousands of times more powerful than the atomic bomb dropped on Hiroshima. An impact like that wouldn’t be a global extinction event, Apophis is far smaller than the object blamed for the dinosaurs’ extinction, but it could flatten a region the size of a small country, and an ocean impact could trigger tsunamis capable of devastating coastlines thousands of kilometers away.

That’s the scenario asteroid Apophis 2029 has already safely avoided. It’s also exactly why scientists are so eager to study the flyby closely: understanding how gravity reshapes an asteroid this size helps refine planetary defense strategies for the next object that might not miss.

Why Scientists Care So Much About This Flyby

This isn’t just a spectacle. It’s a genuine scientific opportunity. As Apophis swings past, Earth’s gravity will tug on it hard enough to potentially reshape it, alter its spin, trigger landslides across its surface, and possibly even set off small “asteroid quakes.” Researchers may finally get a rare, close-up look at what’s hiding just beneath an asteroid’s surface, information that’s nearly impossible to gather any other way.

Two spacecraft are racing to be in position for it. The European Space Agency’s RAMSES mission and NASA’s OSIRIS-APEX (a repurposed version of the spacecraft that previously returned samples from asteroid Bennu) both plan to observe the flyby in extraordinary detail, some instruments potentially even placed directly on Apophis’s surface.

The Real Worry: Space Junk

Here’s where the story takes an unexpected turn. Physicist Giulia Schettino and astrodynamicist Alessandro Rossi, both researchers at Italy’s National Research Council, decided to check something nobody had seriously modeled before: could Apophis run into any of the enormous amount of human-made debris cluttering the region around geostationary orbit?

Rossi expected what scientists call a “null result,” basically, nothing to see here. Instead, the simulations turned up a real, if small, possibility that something in that debris field could actually strike the asteroid before its closest approach. “I was struck by the possibility to have some objects potentially coming to less than a few kilometers from the asteroid,” Rossi said.

What Could Actually Happen

To be clear, this isn’t a doomsday scenario. A stray piece of debris wouldn’t meaningfully change Apophis’s trajectory. In fact, a small impact crater or debris plume might even hand scientists bonus data to study. The real concern is more subtle than that.

If something hits Apophis shortly before its closest pass, researchers might struggle to tell which changes were caused by Earth’s gravity, the thing they actually want to study, and which were caused by the random collision beforehand. It’s the scientific equivalent of someone jostling your camera right before you take the photo of a lifetime.

Rossi was careful to note that any impact wouldn’t trigger a runaway chain reaction either. Unlike the crowded chaos of low-Earth orbit, debris around geostationary altitude is comparatively sparse, so the odds of a collision cascading into something bigger, a scenario known as Kessler syndrome, remain low.

Why This Matters Beyond Apophis

Maybe the most important takeaway from this study has nothing to do with Apophis at all. It’s a reminder of just how little we actually know about the smaller debris quietly orbiting far above Earth. Large, trackable objects get monitored routinely. Countless smaller fragments simply don’t.

Rossi hopes the upcoming flyby pushes agencies to fix that gap before 2029 arrives. New tracking systems, including telescopes being rolled out under the EU’s Space Surveillance System, are specifically designed to improve visibility into this poorly understood region of space. It’s a small but genuine silver lining: even the possibility of an asteroid getting photobombed by space junk is helping motivate better bookkeeping of what we’ve left orbiting up there. If you’re curious how spacecraft like RAMSES and OSIRIS-APEX actually get positioned for missions like this, our explainer on how rockets and spacecraft escape Earth’s gravity covers the engineering that makes flybys like this possible in the first place.

Frequently Asked Questions

Will asteroid Apophis hit Earth in 2029?
No. Scientists have thoroughly confirmed Apophis poses no impact risk during its April 13, 2029 flyby. It will pass within about 32,000 kilometers of Earth, but that’s still a safe distance.

What’s the real concern about asteroid Apophis 2029?
Researchers are worried that human-made space debris near geostationary orbit could collide with Apophis before its closest approach, potentially complicating scientific measurements of how Earth’s gravity reshapes the asteroid.

How big is asteroid Apophis?
Apophis measures roughly 370 meters (1,210 feet) long, making it one of the larger near-Earth asteroids to pass this close to our planet in recorded history.

Which spacecraft will study the Apophis flyby?
ESA’s RAMSES mission and NASA’s OSIRIS-APEX spacecraft are both being positioned to observe the April 2029 encounter up close, potentially placing instruments directly on the asteroid’s surface.

Final Thoughts

Asteroid Apophis was once feared as a genuine impact threat. Now it’s shaping up to be one of the best scientific opportunities in decades, assuming nothing bumps into it first. Either way, April 13, 2029 is worth marking on the calendar. It isn’t every day a rock the length of three football fields swings by close enough to study up close, and safely.

Sources:

• NASA: Asteroid Apophis
• ESA: RAMSES Mission to Asteroid Apophis
• The Planetary Science Journal: Original Study