Deflecting an asteroid with a nuclear blast depends on which side the X-rays hit

What happened

• A study in the journal Icarus examined deflecting an asteroid with a nuclear explosion that releases X-rays, which heat the surface and push the object onto another path.
• Physicist Nathan Moore of Sandia National Laboratories led the work.
• The authors found that changing the direction of the burst gives very different results on the same asteroid.
• In one simulation the object changed its speed by 3.9 millimeters per second when irradiated from one side, against only 0.8 from another.
• For another simulated asteroid the change in spin rate varied by a factor of 17 depending on direction.
• ScienceDaily circulated the study on 8 November 2026.

Why it matters

Planetary defense models often use smooth, round objects. Real asteroids are irregular, and shape differences alter how much energy is absorbed and where the object is pushed. Picking the wrong side can leave a deflection almost five times smaller. Moore said they expected aim to matter but not this much, which for a real mission means knowing the asteroid’s shape first.

The number

3.9 versus 0.8 mm/s. The deflection speed difference for the same asteroid depending on the side of irradiation: almost fivefold.

Context

Radiation deflection works because X-rays vaporize a thin layer of surface, and the expansion of that material acts as a push. The figures come from simulations, not tests on real asteroids, and no nuclear mission is under way. What the study adds is that knowing the shape matters as much as the power. Related coverage: A compact X-ray laser driven by plasma acceleration is simulated end to end, A physical model of the Webb telescope multiplies its sensitivity up to 15 times, Modified gravity reduces the missing mass in clusters but does not remove it, The Sun may have stripped between 1.7 and 5.2 meters of surface from interstellar comet 3I/ATLAS.

What’s next

• Researchers can repeat the calculation with more asteroid shapes and rotations.
• Reconnaissance missions that measure real shape would precede any deflection plan.
• Validation with real asteroid data, not only models, is still missing.

Bottom line

Planetary defense is pictured as a blow of power, but these figures suggest aim decides as much as energy.

Sources

• ScienceDaily, “A nuclear blast could save Earth from an asteroid, but there’s a catch”, 8 November 2026, on a study by Nathan Moore and colleagues at Sandia National Laboratories in Icarus. The Icarus paper was not read.
• Cover image: ESO. Acknowledgement: JAXA, CC BY 4.0, via Wikimedia Commons

Edited by Rodrigo Cornejo. How we select and verify: who writes these notes.