European Space Agency (ESA) announced about a rare «time-critical» decision that will direct James Webb Space Telescope. At least two missions are planned for the next two months to study the potentially dangerous asteroid 2024 YR4.
2024 YR4 — is a near-Earth asteroid belonging to the Apollo group (i.e., its orbit crosses the Earth’s orbit), which was discovered in December 2024 and «went viral in the news» after NASA announced the probability of its collision with our planet in 2032. This probability is small, but recently the American space agency has updated its forecasts and doubled it to 2.3% (1 to 43).
According to astronomers, the diameter of 2024 YR4 reaches 40-50 meters, so it’s ramming is unlikely to lead to mass extinction, as was the case with the 10-kilometer asteroid that formed the Chicxuluba crater 66 million years ago. However, the fall of an object can cause chaos and panic in a particular region — as it actually happened with the Tunguska meteorite, which damaged about 80 million trees in Siberia in 1908.
However, it is worth clarifying that the current size of 2024 YR4 — is only an estimate based on data from ground-based telescopes, and they may be limited. So now an international group of astronomers, according to ESA, has received permission to «emergency» use the currently most powerful James Webb Space Telescope (JWST) for detailed observation of the asteroid over the next two months and adjust its size.
«In general, the brighter an asteroid is, the larger it is, but this relationship is highly dependent on how the asteroid’s surface reflects light», — ESA writes. «2024 YR4 can have a diameter of 40 m and a high reflectivity, or 90 m and a low reflectivity. It is important to clarify this estimate, as these sizes carry different levels of hazard».
JWST, unlike Earth-based telescopes, will not record reflected sunlight, but will use its own infrared instruments to study the heat emitted by the asteroid itself (in addition to its size, this will help to estimate its composition).
The first mission is scheduled for March — when 2024 YR4 reaches its maximum brightness, and the second — in May, when the asteroid is moving away from the Sun (this is the last opportunity for observation in the coming years, as the next close approach is expected in 2028).
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