Can NASA Stop an Asteroid — The Surprising Reality Explained

Current Planetary Defense Status

As of February 2026, the question of whether NASA can stop an asteroid remains a complex mix of proven capability and significant remaining gaps. While the agency has successfully demonstrated that it can alter the trajectory of a celestial body, experts warn that humanity is not yet fully prepared for all threats. Specifically, NASA planetary defense officer Kelly Fast recently informed the American Association for the Advancement of Science that while we can track the "planet-killers," there are thousands of smaller "city-killer" asteroids that remain undetected.

The core of the issue lies in detection. You cannot stop what you cannot see. Current estimates suggest there are roughly 25,000 near-Earth asteroids measuring more than 140 meters in diameter. To date, NASA has only located about 40% of these objects. This leaves approximately 15,000 "city-killers" unaccounted for, any of which could strike with little to no warning. These mid-sized rocks are large enough to cause devastating regional damage but small enough to evade many current ground-based observation systems.

The DART Mission Success

The most significant evidence that NASA can stop an asteroid comes from the Double Asteroid Redirection Test (DART). This mission, which concluded its primary impact phase in late 2022, proved that a "kinetic impactor" could successfully change an asteroid's orbit. By crashing a refrigerator-sized spacecraft into the moonlet Dimorphos at high speed, NASA shortened its orbital period around the larger asteroid Didymos by 33 minutes. This result far exceeded the minimum success threshold of 73 seconds.

This historical milestone confirmed that if we have enough lead time, we possess the technology to nudge a dangerous asteroid off a collision course with Earth. However, the DART mission also revealed complexities. Recent analysis of the debris and boulders ejected during the impact showed that the momentum transfer was more intense than expected, sometimes pushing the object in unexpected directions. This suggests that while the method works, every asteroid's unique composition—whether it is a solid rock or a "rubble pile"—will affect how it responds to an impact.

New Detection Technologies

To address the "blind spot" regarding undetected asteroids, NASA is moving forward with the Near-Earth Object (NEO) Surveyor. This space-based telescope is designed specifically to find dark asteroids and comets that are difficult to see against the blackness of space. Unlike ground-based telescopes, the NEO Surveyor uses thermal signatures to spot objects based on the heat they emit rather than the light they reflect.

This mission is critical because it targets the 140-meter-class asteroids that keep planetary defense experts "up at night." By moving the search into space, NASA can bypass the limitations of Earth's atmosphere and daylight, providing a 24/7 surveillance system for the planet. The goal is to identify at least 90% of these hazardous objects, giving humanity years or even decades of warning time to prepare a deflection mission.

International Cooperation Efforts

Planetary defense is not a solo endeavor for the United States. The United Nations has officially designated 2029 as the International Year of Planetary Defense and Asteroid Awareness. This timing is strategic, as it coincides with the exceptionally close flyby of the asteroid Apophis. Apophis is a 1,100-foot-wide rock that will pass within 20,000 miles of Earth—closer than some geostationary satellites. While it is not expected to hit Earth during this pass, it provides a rare "live fire" exercise for tracking and characterization systems.

Other agencies are also contributing. The European Space Agency (ESA) recently signed contracts for the Ramses mission, which will rendezvous with Apophis to study how Earth's gravity affects the asteroid during its close approach. Additionally, the Hera mission is currently en route to the Didymos system to perform a "post-crash" investigation of the DART impact site. These international efforts ensure that data is shared globally through the International Asteroid Warning Network (IAWN).

Financial and Strategic Risks

Maintaining a planetary defense shield requires consistent funding and strategic planning. Just as investors must manage risks in volatile markets, space agencies must balance the high cost of deep-space missions against the low-probability, high-impact risk of an asteroid strike. In the world of digital finance, users often look for secure platforms like WEEX to manage their assets, and similarly, global governments look to NASA to manage the ultimate "catastrophic risk" of an impact.

The challenge is that planetary defense often competes with other scientific priorities. If funding for the NEO Surveyor or follow-up deflection missions is delayed, the window of opportunity to stop a "city-killer" narrows. Experts argue that the cost of these missions is a small insurance premium compared to the trillions of dollars in damage a single impact would cause to global infrastructure and the economy.

Deflection Methods Beyond Impact

The Gravity Tractor

While the kinetic impactor (DART style) is the most tested method, it is not the only option. A "gravity tractor" involves flying a heavy spacecraft alongside an asteroid for several years. The slight gravitational pull between the craft and the asteroid would slowly tug the rock into a different orbit. This method is much slower than an impact but offers much higher precision, making it ideal for asteroids discovered decades in advance.

Ion Beam Shepherd

Another proposed method involves using an ion engine to fire a stream of particles at the asteroid's surface. The force of the ion beam would act as a gentle, continuous push. Like the gravity tractor, this requires a long lead time but avoids the risk of breaking the asteroid into multiple smaller, still-dangerous pieces, which can happen with a high-speed kinetic impact.

The Role of Lead Time

The single most important factor in whether NASA can stop an asteroid is time. If a "city-killer" is detected only weeks before impact, there is currently no technology that can be launched and intercepted fast enough to change its path. In such a scenario, the focus would shift from "deflection" to "evacuation and disaster response." This is why the current emphasis is almost entirely on early detection.

With ten years of warning, a DART-like mission could easily nudge an asteroid by the few millimeters per second required to make it miss Earth by thousands of miles. With twenty years of warning, even more gentle methods like the gravity tractor become viable. As we move further into 2026, the integration of AI-driven tracking software and new space telescopes is expected to significantly increase our "eyes on the sky," moving us closer to a future where an asteroid strike is a preventable natural disaster rather than an inevitable one.