A newly discovered asteroid called 2023 DW has been causing quite a stir for the past week due to an estimated 1 in 670 chance of it hitting Valentine’s Day 2046 an asteroid doomsday on your planner for that date.
Risk assessment has less to do with the probability roll of the cosmic dice than with the uncertainty associated with a limited set of astronomical observations. If the case of 2023 DW plays out as all previous asteroid fears have played out over the course of nearly 20 years, further observations will reduce the risk to zero.
Nonetheless, the hubbub surrounding a space rock that could be as much as 50 meters wide highlights some trends to watch out for: We’re likely to get more of these asteroid warnings in the years to come, and NASA is likely to pay more attention to repel potentially dangerous near-earth objects or NEOs.
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If a 50-meter-wide asteroid were to tumble through Earth’s atmosphere, it could create a blast of air as powerful as a nuclear bomb. One such explosion, known as the Tunguska event, occurred over Siberia in 1908 and destroyed hundreds of thousands of acres of remote woodland. A similar collision in the wrong place could destroy a city. It wouldn’t be as deadly as the cosmic impact that killed the dinosaurs 66 million years ago, believed to have been caused by an asteroid 6 to 10 miles wide, but it could trigger a global emergency.
An asteroid-finding program based in Chile’s Atacama Desert spotted 2023 DW in February, and some of the projections of its trajectory crossed Earth’s orbit on February 14, 2046. Its size – variously described as the size of an Olympic swimming pool, the Leaning Tower of Pisa, or 27 pandas – has been estimated for its brightness.
NASA took the sighting seriously enough to give it a 1 on the Torino scale of 1 to 10, which is used to assess the risks of near-Earth objects. 2023 DW is currently the only property with a non-zero rating. Some went so far as to plot where the asteroid might hit if it hit Earth. (The possibilities span a line stretching from the southern tip of India to the east coast of the US.)
#2023DW. With only 3 arc days, I found a 1 in 400 probability on Feb 14, 2046 (JPL 1/770). Certainly that possibility will soon be eliminated, but as an exercise I calculated where the asteroid might fall if that possibility occurred. pic.twitter.com/ldlSYJMvMz
– PS (@Piero_Sicoli) March 2, 2023
Astronomers stressed that the risk rating, which stands at 1 in 670 today, is based on a very limited amount of data on the asteroid’s orbit around the Sun. This uncertainty is visualized as an “error ellipsoid,” with the Earth located somewhere within the elongated ovoid zone of uncertainty.
“When new objects are first discovered, weeks of data are often required to reduce uncertainties and adequately predict their orbits years into the future,” NASA said in a series of tweets.
The more observations you collect, the smaller the error ellipsoid becomes. And it often turns out that astronomers can identify a newly discovered asteroid in archived observations, providing more data points to refine their orbital projections. What usually happens is that the error ellipsoid eventually shrinks to a size that Earth misses.
If the risk assessment changes significantly in the coming weeks, we will update this point to reflect the change. In the longer term, expect asteroid alerts of this level to become routine.
When the Vera C. Rubin Observatory in Chile begins a wide-angle survey of the sky in 2024, it is expected to identify thousands of potentially dangerous asteroids. NASA’s NEO Surveyor mission, scheduled to launch in 2028, will also significantly increase the number of asteroids. A cloud-based data analysis technique developed at the University of Washington with support from the Asteroid Institute and the B612 Foundation could streamline the tracking process — and make it easier to distinguish near misses from real threats.
What if a real threat is detected? NASA and the European Space Agency are already exploring ways to deflect a more than potentially threatening asteroid. Last year, NASA’s Double Asteroid Redirection Test showed that an impacting spacecraft could alter an asteroid’s orbit, and a subsequent ESA mission called Hera will more accurately quantify the effect.
When DW 2023 comes out for Valentine’s Day 2046, the world’s space agencies and policymakers should know what to do if the close encounter threatens to get heated and violent.
While serving as MSNBC.com Science Editor in 2011, Alan Boyle was part of the Near-Earth Objects Media/Risk Communications Working Group for a report prepared by the Secure World Foundation and the Association of Space Explorers and provided to the UN became Committee on the Peaceful Uses of Outer Space.