Asteroid impacts and solar storms are low-probability but high-consequence events, and Earth is taking them seriously. A global network of telescopes, spacecraft, and emergency planners now works in concert to spot hazardous objects, test ways to nudge them off course, and prepare for worst-case scenarios. Recent missions have demonstrated that deflection is possible, while new surveys promise to find threats earlier. At the same time, space-weather forecasters are improving warnings that protect satellites, power grids, and aviation. Planetary defense has moved from science fiction into practical policy.
The first line of defense is finding hazardous objects early. Dedicated surveys such as Pan-STARRS in Hawaii, the Catalina Sky Survey in Arizona, ATLAS, and the reactivated NEOWISE mission scan the sky for near-Earth asteroids and comets. Planetary radar—most notably the Goldstone Solar System Radar working with the Green Bank Telescope—sharpens orbits and reveals sizes, shapes, and spin states. The Vera C.
Rubin Observatory’s wide-field survey, coming online in the mid-2020s, and NASA’s planned NEO Surveyor infrared mission later this decade are expected to boost discovery rates and reduce blind spots. Most kilometer-scale objects are now cataloged, but many smaller, city-damaging bodies remain to be found. Proving we can change an asteroid’s path was a turning point. In 2022, NASA’s DART spacecraft intentionally struck Dimorphos, measurably shortening its orbital period by 33 minutes and validating the kinetic-impactor technique.
ESA’s Hera mission is set to turn that experiment into a well-calibrated playbook by surveying the impact site and the binary system in detail, with arrival planned for 2026. Engineers are also studying slow-push concepts like gravity tractors and, for last-resort scenarios involving very large objects, nuclear options under international legal and policy frameworks. The right tool depends on warning time and the target’s properties, which is why characterization matters as much as detection. Preparedness is increasingly organized at the international level.
NASA’s Planetary Defense Coordination Office works with the International Asteroid Warning Network and the Space Mission Planning Advisory Group to share data and align response plans under United Nations-endorsed frameworks. Regular tabletop exercises with emergency managers, including FEMA in the United States and partners abroad, stress-test timelines for evacuations, messaging, and decision-making. Risk communication tools such as the Torino and Palermo scales help convey changing probabilities as measurements improve. The goal is to move from ad hoc reactions to rehearsed, science-based responses.
Cosmic threats are not limited to rocks. Space-weather hazards from solar flares and coronal mass ejections can disrupt satellites, GPS, aviation, and power grids, so agencies track the Sun around the clock. NOAA’s Space Weather Prediction Center and ESA’s space-weather services issue watches and warnings informed by spacecraft such as SOHO, STEREO, DSCOVR, Parker Solar Probe, and Solar Orbiter. Operators can place satellites in safe mode, reroute polar flights, and adjust grid operations to ride out severe storms.
Long-period comets—fast and often discovered late—remain a special challenge, making wide-field surveys and rapid follow-up crucial. Building resilience on Earth complements the search and deflection efforts in space.
