The new system will improve the capabilities of NASAs JPL’s Center to monitor asteroids and their impact risks as they approach earth. Astronomers have discovered close to 30,000 near-earth asteroids to date and continue to discover more at a rate of roughly 3,000 new objects each year. As technology advances so does our instrumentation and ability to detect more asteroids. Scientists anticipate that 3,000 discoveries per year is just the beginning. As a result, NASA has developed a monitoring algorithm called Sentry-II to aid in the monitoring and assessment of near-earth asteroids and their potential impact risks.

The new system will be managed by the Center for Near Earth Object Studies (CNEOS), located at NASA’s Jet Propulsion Laboratory in Southern California. CNEOS calculates every known near-earth asteroid and it’s orbit to improve the the abitity of managing earth impact assessments.

“SENTRY-II was based on some very smart mathematics: In under an hour, you could reliably get the impact probability for a newly discovered asteroid over the next 100 years – an incredible feat, ” said Javier Roa Vicens who led the development of Sentry-II who also worked at JPL as a navigation engineer.

The Unpredictability of the Yarkovsky Effect

As an asteroid travels through our solar system, its path is dictated by its speed and gravitational force of our sun; the trajectory is also influenced by planet gravitational forces. Sentry-II can model the movement of these asteroids and the forces acting on it to a high degree of accuracy. Incredibly, it can also predict for non-gravitational forces such as the Yarkovsky Effect, which was not possible in the old Sentry-I system.

The Yarkovsky effect is the movement of asteroids as a result of the sun heating up the object. As the asteroid moves closer to the sun, the sunlight heats up the side of the object facing the sun. As the asteroid spins, the hotter surface will then rotate to become the shaded side. As the heated side cools, infrared energy is released and produces a very tiny amount of thrust which is very unpredictable and constant.

“The fact that Sentry-I couldn’t automatically handle the Yarkovsky effect was a limitation,” said Davide Farnocchia, a navigation engineer at JPL who also aided in the development of Sentry-II. “Every time we came across a special case – like asteroid Bennu, we had to do complex and time-consuming manual analyses. With Sentry-II, we don’t have to do that anymore.”

Sources:

Astronomical Journal – Dec. 1, 2021. https://iopscience.iop.org/article/10.3847/1538-3881/ac193f

NASA.goc – Asteroids & Comets – Dec 6, 2021 https://www.jpl.nasa.gov/news/nasas-next-generation-asteroid-impact-monitoring-system-goes-online