Planetary defense
We can nudge a small asteroid (DART, 2022), but have found fewer than half of the large ones and never tested on a big one.
Open in the interactive tree →On 26 September 2022 NASA's DART spacecraft hit the moonlet Dimorphos and shortened its orbit around Didymos by about 32 minutes, the first deliberate change of a celestial body's motion. A deflection needs years of warning.
As of October 2026
ESA's Hera spacecraft (launched 7 October 2024) imaged Didymos for the first time on 7 October 2026 and is due to arrive in November 2026 to measure DART's crater and the mass of Dimorphos. About 44% of near-Earth asteroids larger than 140 m had been found by January 2024. NASA's NEO Surveyor infrared telescope (planned launch September 2027) aims to find two-thirds of them within five years, and Apophis will pass Earth at close range on 13 April 2029.
What is missing
- A complete catalogue of asteroids above about 140 m, and of long-period comets
- An infrared space telescope for asteroid hunting such as NEO Surveyor (planned for September 2027)
- Tests on larger, loosely bound rubble-pile asteroids
- Ready-to-launch interceptors and an international decision process
- Years to decades of warning time
Becomes possible once solved
- Protection against a civilisation-scale impact
- Knowledge of asteroid structure for mining and exploration
- Practice in precise deep-space navigation and operations
Open steps
- Finding asteroids in survey data High AI leverageLink faint moving dots across nights in huge image archives and new surveys to complete the catalogue above 140 m.
- Fast orbits and impact odds Medium AI leverageCompute orbits and impact probabilities of newly found objects within hours, including non-gravitational forces and poorly observed comets.
- Deflecting a rubble-pile asteroid Medium AI leveragePredict how a kinetic impactor changes the orbit of a loosely bound rubble pile, calibrating impact simulations with DART and Hera data.
- Long-period comet warning Medium AI leverageDetect and predict comets that arrive with only months of warning, too little time for most deflection missions.
- Size and structure of a threat Medium AI leverageEstimate size, density and internal structure of a threatening asteroid from few observations, which sets the deflection strategy.
Where AI could help
Medium AI leverage. Software and AI find more asteroids in survey data, but telescopes, deflection tests and years of warning time are physical and political.
- Link faint moving detections across nights in Rubin and NEO Surveyor data to find asteroids and comets earlier
- Reject image artefacts automatically so human checkers see only real candidates
- Run impact and deflection simulations to choose targets and test interceptor strategies
- Refine orbits and impact probabilities of newly found objects within hours
Shown so far
- In April 2024, the THOR orbit-linking algorithm, run on Google Cloud, found about 27,500 asteroid candidates in archived NOIRLab images, including 100+ near-Earth ones, with manual verification still the bottleneck. source
- In May 2022, citizen scientists plus a deep-learning classifier found 1,701 asteroid trails in archived Hubble images, 1,031 of them unidentified. source
Prerequisites
- Liquid-fuel rocket (V-2)1942
- Deep-space probes (Voyager)1977
- Asteroid Sample Return2020–2023Ryugu and Bennu samples show how rubble-pile asteroids are built, key to deflection
- Rubin and Roman sky surveys2026