A 320-metre strike may have buried Deimos; a buried blast triples the shove
A Hera-fed simulation has a 320-metre asteroid draping Deimos in debris after a 45-degree strike. A peer-reviewed model finds a 3-megaton warhead delivers at least 30 centimetres per second in a 30-metre crater.
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A 320-metre strike may have draped Deimos in debris
Images Hera took during its March 2025 Mars flyby feed a simulation in which a 320-metre asteroid, striking at about 45 degrees, excavated the 10-kilometre basin near Deimos's south pole and buried the moon under its own debris. The reconstruction, published in Nature Astronomy and led by Sabina Raducan of the University of Bern, combines Hera's Asteroid Framing Camera and TIRI thermal images with impact modelling. The debris blanket reaches more than 200 metres in places.[1]
Older craters still show through the blanket
Older craters stay visible beneath that debris, which the authors link to the porous, fractured interior expected in a rubble-pile body. The reconstruction remains a simulation matched to brightness patterns across the 12-kilometre moon, so it offers a candidate history that further observation would have to confirm. Hera itself is en route to the Didymos system.[1]
A 30-metre burial triples the nuclear shove
In simulations of a 1-kilometre basalt asteroid, a 3-megaton warhead detonated in a shallow surface crater changed the body's velocity by 9.2 centimetres per second, while the same warhead set off in a 30-metre pre-excavated crater delivered at least 30 centimetres per second. The paper by Xiaowei Wang and colleagues appears in Space: Science & Technology and is peer-reviewed. Its own caveat concerns the material: known near-Earth asteroids are mostly loosely bound rubble piles rather than the solid basalt modelled here, and how a buried detonation couples into such a body has not been validated. Every step — arriving, excavating, placing and firing on schedule — adds engineering difficulty on a short-warning timeline. No known asteroid is currently on a collision course with Earth.[2]
