It is the largest – and most expensive – space telescope in space history. James-Webb, a telescope of all superlatives, was successfully launched on December 25, 2021. He is in a way the heir of the iconic Hubble, designed according to the scientific results delivered by the latter in order to be able to go further in understanding the Universe. We take stock of the key steps that still need to be taken before starting the observations.
Why it matters. The Hubble telescope, placed in low orbit in 1990, has already enjoyed more than 30 years of loyal service. Obviously, in 30 years, the state of knowledge – and outstanding scientific questions – has evolved considerably. Hubble thus observes the Universe in the visible and ultraviolet domains. James-Webb, for his part, will mainly work in the infrared spectral domain. It was developed by the European Space Agency (ESA), NASA and by the Canadian Space Agency.