UNITED STATES: NASA’s Near-Earth Object (NEO) Programme Office Manager, Paul Chodas, presented a hypothetical asteroid scenario at the 8th Planetary Defence Conference in Vienna on April 4 to demonstrate the need for planetary defence.
The exercise illustrates how an asteroid threat might evolve over several years and the potential devastation such a strike could cause. Chodas’ hypothetical scenario begins on January 10, 2023, with the discovery of a new asteroid, which NASA names 2023 PDC.
The object is initially designated a “potentially hazardous asteroid” (PHA), which NASA defines as any asteroid that intersects Earth’s orbit at a distance from the planet of around 7.4 million kilometres or less when discovered.
Another criterion for defining an asteroid is when its magnitude is 22.0 and it is only a little brighter than the faintest stars visible to the Hubble Space Telescope.
The probability of the PDC’s 2023 havingan impact with Earth is initially just 1 in 10,000. However, Chodas explained that the impact probability steadily increases as asteroid tracking facilities on Earth continue following the asteroid, better constraining its orbit around the sun.
The hypothetical scenario becomes serious on April 3, 2023, at a point that Chodas refers to as “Epoch 1.” “Today is Epoch 1, and the impact probability has reached 1%,” Chodas says. He determines the impact will be felt in 13 years, so it is not imminent. However, NASA can already predict the date of impact.
The 2023 PDC’s size is between 720 and 2,200 feet (220 and 660 metres), but it could be as wide as 1.3 miles (2 km).
The asteroid’s size is crucial because it determines how much damage it can do. It also determines what measures a planetary defence system must take to divert it or whether this would be possible.
Chodas explains that the 2023 PDC is too close to the sun to use infrared astronomy to help determine its size.
As a result, space-based telescopes that rely mainly on infrared observations, such as the James Webb Space Telescope (JWST) and the Hubble Space Telescope, won’t be able to help NASA observe the rock.
Likewise, the asteroid will be too far away during the early stages of its approach for us to measure it with radar.
According to Chodas, during the 13-year lead time, NASA can dispatch a reconnaissance spacecraft to the 2023 PDC and determine its size.
Not only would this help us better ascertain the size and mass of the asteroid, but such a mission would also help better calculate another crucial aspect of the asteroid vital to mitigating its impact on Earth: its orbit.
Reducing the red “hitbox” in the team’s calculation to less than the size of the Earth means that Chodas’s hypothetical scenario indicates a potentially catastrophic event that could have serious consequences.
Therefore, NASA now has to make crucial decisions to avert this disaster. When an asteroid is on a collision course with Earth, every moment counts, and NASA and other space agencies must act quickly to develop and implement a plan to mitigate the impact.
This hypothetical scenario is a wake-up call for space agencies and underscores the need for continued research on ways to detect, track, and deflect asteroids that pose a risk to our planet.
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