That’s the finding of a new study by researchers who looked not at the Webb telescope’s optics, but at the models scientists use to interpret the findings after the telescope has made an observation. In particular, the models scientists use to understand opacity, how easily light passes through an atmosphere, are not accurate enough, according to MIT graduate student Prajwal Niraula, co-author of a new paper published in Thursday in Nature Astronomy. And since Webb studies exoplanets—planets around stars other than our Sun—by measuring the wavelengths of light passing through a planet’s atmosphere using its spectroscopic instrument, the less accurate models could mean the telescope’s observations Webb is unreal by an order of magnitude. “Currently, the model we use to decipher spectral information does not match the accuracy and quality of the data we have from the James Webb telescope,” Niraula said in a press statement. “We need to up our game and tackle the problem of opacity together.” Webb’s spectrometer acquires a “spectrum,” a collection of wavelengths of light shining through an exoplanet’s atmosphere. Since different molecules absorb light at different wavelengths, the unique pattern of a spectrum can tell scientists which compounds are present in what amounts in a planet’s atmosphere, including gases and organics that could indicate signs of biological activity. So not solving the opacity model problem could, in practice, mean that scientists miss signs of life on an exoplanet or get false positives for possible signs of alien life in an exoplanet atmosphere. “There is a scientifically significant difference between the presence of a compound like water at 5 percent versus 25 percent that current models cannot differentiate,” said Julien de Wit, assistant professor in the Department of Earth, Atmospheric and Planetary Sciences. of MIT. author, said in a press statement. In their study, the researchers created alternative opacity models that changed some assumptions about how light and matter would interact in an exoplanet atmosphere. They then fed the Webb spectra through these models and each produced very different results from each other, but also that each model seemed to fit the data very well. It would be hard for scientists looking at this data to know it was wrong, in other words, unless they knew what to look for. “We found that there are enough parameters to tweak, even with the wrong model, to get a good fit, which means you won’t know that your model is wrong and that what it’s telling you is wrong,” said Dr de Wit . The researchers suggest several ways to improve the opacity models so they can match the accuracy of Webb’s optics, starting with more laboratory experiments on ground models, model refinement, and a central database with a standardized format to help astronomers update the models them from spectral data and experiments. “There is so much that could be done if we knew perfectly how light and matter interact,” said Mr Niraula. “We know that pretty well around Earth conditions, but once we move into different types of atmospheres, things change and it’s a lot of data, with increasing quality, that we risk getting misinterpreted.”
