Picture this: a ‘city killer’ asteroid is hurtling through space, and its trajectory has it on a collision course. Thankfully, the latest tracking data says it’s going to miss Earth. Phew. But there’s a catch, it now has a pretty good chance of slamming directly into the Moon in 2032, and the fallout could be a serious headache for us back here on Earth.
The rock in question is asteroid 2024 YR4. Discovered in December 2024, it initially caused a stir with a 3.1% chance of impacting Earth. While our planet is now in the clear, the Moon isn’t so lucky, facing a roughly 4% chance of taking the hit. So, what’s the big deal if our celestial neighbour gets a new crater?
A Shower of Cosmic Shrapnel
If an asteroid the size of 2024 YR4 smacks into the Moon, it won’t just be a light show for backyard astronomers. The impact would blast tons of lunar dust and rock (known as “ejecta”) into space. A new, non-peer-reviewed study warns this could crank up the amount of micrometeoroid debris in low Earth orbit by as much as 1,000 times.
Think of it as a massive cloud of cosmic gravel rash. This debris cloud would pose a significant threat to our high-tech hardware in orbit, including satellites and the International Space Station (if it’s still up there). These tiny, “bullet-like” projectiles can puncture spacecraft hulls and astronaut spacesuits, turning a routine spacewalk into a catastrophic failure.
The Planetary Protection Playbook: What Are Our Options?
Faced with this potential mess, scientists are reviewing the playbook, and it reads like something straight out of a Hollywood blockbuster. A new study posted to the preprint server Arxiv explores the options, from a gentle nudge to an all-out demolition job.
1. The Cosmic Nudge (Kinetic Impactor)
Our first thought might be to just push it out of the way. We’ve got some experience here. NASA’s DART (Double Asteroid Redirection Test) mission successfully proved this concept in 2022 when it sent a spacecraft to ram the asteroid moonlet Dimorphos, altering its orbit.
However, the researchers behind the new study say this approach is “impractical” for 2024 YR4. The big problem is we don’t know the asteroid’s exact mass. Trying to nudge it without that crucial data is a massive gamble. A miscalculation could accidentally push the asteroid onto a new path, one that heads directly for Earth. It’s a high-risk manoeuvre with potentially planet-altering consequences.
2. The Sledgehammer Approach (Fragmentation)
If you can’t move it, smash it. Another option is to send a DART-style impactor not to gently push the asteroid, but to punch it into smaller, more manageable pieces. While this is an untested concept, it’s an intriguing one. The launch window for such a mission would be between April 2030 and April 2032, giving engineers time to draw up the blueprints.
3. The Ultimate Option: “Just Nuke It”
When all else fails, go big. The study considers launching a nuclear weapon to detonate on or near the asteroid before its 2032 lunar flyby. This method is also untested in the real world but is theoretically possible and has been a staple of science fiction for decades. A nuclear mission would need to be ready sooner, with a potential launch window between late 2029 and late 2031.
A Cosmic Fire Drill
Before we panic, it’s important to remember there’s a 96% chance that 2024 YR4 will sail harmlessly past both the Earth and the Moon. However, scientists see this as a valuable, real-world fire drill. It’s an opportunity to seriously research and develop our planetary defence technologies before a more serious threat comes knocking on our door.
The researchers are calling on the global scientific community to refine designs and calculate build times for these asteroid-smashing spacecraft. Because when it comes to protecting our planet, we need to be ready to put the pedal to the metal at a moment’s notice.
