NASA's Asteroid Collision Detection System Just Got a Powerful New Upgrade

Bringing next-gen precision to bear against the end of the world.
Chris Young
An diagram of thousands of NEOsNASA/JPL-Caltech

The probability of an asteroid 6.2 miles (10 km) wide and with the potential to end civilization impacting Earth is calculated to be 0.000001% every year, though that may be about to change. 

That's because NASA's second-generation asteroid detection system, Sentry-II, has just gone online, a blog post from the U.S. space agency explains.

The new system, outlined in a paper in the Astronomical Journal, will allow astronomers to calculate the orbits as well as the impact probability of asteroids in our solar system with far greater accuracy.

NASA bolsters its planetary defense capabilities

Even smaller asteroids than the 6.2 mile wide rock that killed the dinosaurs have a lot of potential for damage. As New Atlas points out, the meteor that flew and exploded over Chelyabinsk, Russia in 2013 injured almost 1,500 people, and it was estimated to be only 20 meters (66 ft) wide. 

That's why NASA is working on developing methods for asteroid collision prevention. One example is the space agency's Double Asteroid Redirection Test (DART) mission, which launched on Nov. 24. That mission is sending a spacecraft crashing into an asteroid at speeds of approximately 15,000 mph (24,000 km) to test if we can successfully alter the trajectory of a space rock in the event that we discover one that's Earthbound.

NASA's Asteroid Collision Detection System Just Got a Powerful New Upgrade
An artist's illustration of NASA's asteroid-bound DART spacecraft. Source: NASA/Johns Hopkins APL

In order to detect an asteroid on a collision course with Earth in the first place, the Center for Near Earth Object Studies (CNEOS) calculates the orbit of every near-Earth object (NEO) that has been detected so far — the number is roughly 28,000. Then, NASA's software, Sentry, is trained on these orbits to calculate if and when any of these NEOs may pose a risk to humanity. Incredibly, in under an hour, the software could calculate the impact probability for a newly-discovered NEO over the next century. 

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Sentry-II: a truly next-gen experience

The first iteration of Sentry was in operation for almost two decades, and, as impressive as it was, the time has come for an upgrade. Using complex mathematical equations, Sentry was incredibly accurate at calculating the orbital paths of asteroids based on the gravitational pull of the Sun and planets of our solar system. 

However, there are some effects that the first iteration of Sentry did not account for. For example, the Yarkovsky effect, which is when the Sun heats part of the surface of an asteroid as it nears the center of the solar system, creating thermal forces that can produce thrust and alter its trajectory. Though this effect has little impact on an asteroid's trajectory in the short term, it can vastly influence its paths over decades and centuries. 

NASA's astronomers have been aware of the Yarkovsky effect for years and they have manually corrected trajectories when necessary, though this is an incredibly time-consuming process, especially given the number of NEOs in the near universe.

Sentry-II will account for the Yarkovsky effect as well as a number of other effects that can similarly snowball to alter the course of an NEO's trajectory over many years. The newest version uses a revised algorithm that models many different scenarios for an asteroid, allowing it to calculate a greater number of low-probability impact scenarios.

"Sentry-II is a fantastic advancement in finding tiny impact probabilities for a huge range of scenarios," says Steve Chesley, a senior research scientist at JPL who works on the Sentry program. "When the consequences of a future asteroid impact are so big, it pays to find even the smallest impact risk hiding in the data."

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