Others occur just once in a blue moon but can impact the entire planet, such as global pandemics and asteroid impacts.
The threat from asteroids however is unique: an asteroid impact is the most predictable natural disaster we face, and given enough warning we have the technology, in principle, to entirely prevent it.But the smaller they get, the more we still have to find, which is why the impact of this year’s asteroid, 2021 PDC, provided such an important lesson: we can only prevent what we can predict.
It all began on April 19, 2021, when a new asteroid was discovered by the Pan-STARRS near-Earth object survey project.It soon became clear that this asteroid was worryingly likely to strike Earth in just six months.
As would be the case if a real asteroid were on collision course, the International Asteroid Warning Network (IAWN) – a network of organizations that detect, track and characterise potentially hazardous asteroids – publicly disseminated weekly updates on the impact probability as the situation progressed.At the same time, the Space Missions Planning Advisory Group (SMPAG) began to consider our options to prevent the impact.At this point, SMPAG concludes that no space missions can be launched in time to deflect or disrupt 2021 PDC from its collision course.
A scenario like this, in which an asteroid impact is predicted with short warning of just a few months, poses challenges for in-space prevention.Had a more sensitive asteroid survey such as NEOSM or the Rubin Observatory (LSST) been in place in 2014, they would almost certainly have detected 2021 PDC on a previous journey round the Sun, and this seven-year warning would have opened up a host of different possible outcomes.Finally, one thing is clear: an asteroid impact, although unlikely, is probably going to happen sooner or later – so it is best to be preparedApril 30, 2021April 29, 2021April 29, 2021April 29, 2021April 29, 2021April 29, 2021
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