What do you do when your advanced space telescope turns out to be too big for an available rocket? If you are from NASA and the instrument in question is the James Webb space telescope, you make it a masterpiece of technological origami so that it can fold like a butterfly in the planned Ariane 5 rocket to put it into orbit.
It is the largest and most complex space telescope developed to date, and when opened, its large sun visor will measure more than 66 feet by 46 feet. NASA completed its assembly in August 2019 and, since then, has carried out tests on mirrors and scientific instruments.
Webb actually consists of two main parts. On the one hand, there is the telescope itself, which is a conical assembly that can be aimed at distant galaxies. Its optical telescope element consists of eighteen 52-inch hexagonal mirror segments, each made of beryllium and gold-plated. They combine to form a mirror 21 feet in diameter, significantly larger than that of the Hubble Space Telescope.
To be able to correctly observe the infrared spectrum, however, it must be kept cool. This is where the second part comes in, the huge sun visor that will help keep it below -370 degrees Fahrenheit. Its five layers are each as thin as a human hair and are made from a polyamide film with aluminum and silicon coatings.
To squeeze into the Ariane 5 rocket, the sun visor will have to fold twelve times in total. This will bring the Webb telescope back to something that fits in the 15-foot by 53-foot payload shroud, like a moth in a chrysalis.
Then, with the telescope successfully collapsed, engineers from NASA, ESA and the Canadian Space Agency can perform their final acoustic and vibration tests. Assuming it succeeds, it will be deployed one last time before being dispatched to Guyana for its launch in ten months.
It has not been an easy road here. Engineers encountered problems with tears in the delicate sun visor, which delayed the project, and previous cost overruns made it controversial in political circles. Once in space, it will be positioned near the Lagrangian point EarthSun L2, also helping to keep the instrumentation cold. Designed to last five years, but with at least ten objectives, it will give astronomers an unprecedented glimpse of the light of the first stars in the universe, formed after the Big Bang.
He will also study how galaxies form and evolve, as well as the birth and death of stars and planetary systems. The designers hope that his near infrared vision will allow him to identify the origins of life and other planets where conditions could also be conducive to the formation of life. However, it is a risky project and the team on Earth must absolutely succeed before Webb takes off. The telescope is not designed to be usable once in space and, unlike Hubble’s past, if something goes wrong, the instrumentation cannot be repaired or replaced.