"The WFC3 camera on Hubble is a very sensitive instrument, not initially designed to observe bright stars, and the instrument would overexpose like your cell-phone camera held towards the sun would," Waldmann said. "In 2012, the scanning mode was introduced to address this. Essentially we now quickly move Hubble across the star and ‘smear' the spectrum across the detector. This helps the overexposure issue, but makes the data analysis very difficult."
An additional challenge came from 55 Cancri e's close distance. It is orbiting a sun-like star that is only about 40 light-years away. Because the star is so bright, Waldmann said, the scan speed had to be much faster than what was used before. The team studied the situation and developed a method that can extract a viable signal from the data, a signal that was strong enough to detect elements in the small planet's atmosphere.
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"If we can do this with Hubble, we are very confident that we can significantly improve with future instruments," Waldmann said, pointing to the future James Webb Space Telescope (JWST), Transiting Exoplanet Survey Satellite (TESS) and PLAnetary Transits and Oscillations of stars (PLATO) telescope as examples. "These next-generation facilities will blow the field of exoplanet spectroscopy wide open and allow insight that, to date, we cannot even imagine. In other words, we really are on the threshold of taking planetary science from our solar system into the galaxy."