He Asteroid 2024 YR4 He has aroused unusual interest since his discovery on December 27. Although the probability of impact with the earth remains very low, has risen from 1 to 2% As new observations are obtained. However, astronomers are having difficulty measuring their size and have decided to resort to the most powerful space telescope in history to get out of doubt.
There is a problem in how an asteroid is measured. Until now, the size estimates of 2024 YR4 have oscillated between 40 and 90 meters in diameter, a too wide range to assess the danger that would represent an eventual impact with our planet.
This lack of precision has a reason and is that The size of the asteroid is calculated from the reflected visible lighta method that depends on the reflectivity of its surface. 2024 YR4 could be an object of 40 meters very reflective or an object of 90 meters very dark. As well as any intermediate option.
The James Webb space telescope to the rescue. Unlike other observatories, The 10,000 million dollar telescopeoperated by NASA, ESA and the Canadian space agency, does not observe the visible spectrum, but the infrared spectrum, and with an unprecedented sensitivity.
Astronomers will allocate hours of webb use to analyze the infrared light emitted by the asteroid to obtain a more precise measurement of its size and temperature. With luck, it will allow them to discern whether 2024 YR4 is at the lower or upper end of the estimated range, crucial information to better evaluate the consequences of their unlikely but possible impact.
Two rounds of observation are planned. Space agencies have foreseen Two rounds of crucial observations With the Webb Telescope. The first will take place in early March, when the asteroid is at its point of greatest brightness and visibility for the telescope.
The second round, scheduled for May, will allow scientists to study how the object temperature varies as it moves away from the sun, in addition to continuing to obtain data on its trajectory when the object has ceased to be visible by terrestrial telescopes.
Why fluctuate the probability of impact. The 2% estimate is the most up -to -date ES has provided so far (NASA publishes a 2.1% estimate). The figure varies constantly because the calculations have been incorporating new observations that reduce the uncertainty of their trajectory. These fluctuations are, in fact, typical behavior in the estimation of the impact risk of newly discovered objects.
NASA planetary defense equipment and ESA are based on orbital dynamic systems (such as Scout, Sentry, Meerkat and Aegis) that generate multiple possible trajectories for the asteroid. As less likely orbits are discarded, targeting on Earth may increase the fraction of possible impacts, although, over time, additional observations allow the threat to definitively discard.
If this were not the case with 2024 YR4, we would be talking about a meteorite that could fall in countries as populated as Colombia, Nigeria or India on January 22, 2032. Then we would start talking about a mission to divert it, a task in the that We already have some practice.
Image | Two of the 18 mirrors of the Webb Telescope (NASA/C. GUNN)