But scientists stress that a single experimental success does not equate to an operational planetary defense system.
“We don’t have [another] Dart just lying around,” said Nancy Chabot, a planetary scientist at Johns Hopkins University who led the DART mission. “If something like YR4 had been headed towards the Earth, we would not have any way to go and deflect it actively right now.”
Chabot was referring to asteroid 2024 YR4, which briefly triggered global concern last year when initial calculations showed a 3.2% chance of impacting Earth in 2032. NASA later downgraded that probability to zero after additional observations refined its trajectory. However, the episode served as a stark reminder of how rapidly a potentially serious threat can emerge — and how limited current defensive readiness remains.
Although the risk of an Earth strike has been eliminated, asteroid 2024 YR4 is still being closely monitored. The James Webb Space Telescope is tracking the object, as there remains roughly a 4% chance it could strike the moon. Such an impact would produce a flash visible from Earth but would pose no direct danger to the planet.
