Why did it take so long to share the first images of Webb?
Going into space on Christmas Day last year was just the first step for the James Webb Space Telescope.
The spacecraft has been orbiting the second Lagrange point, or L2, about a million miles from Earth since January 24. At L2, the gravitational pull of the sun and Earth keeps Webb in motion around the sun. synchronized with the motion of the Earth.
Before getting there, the telescope pieces had to be carefully unwrapped: a sunshade that kept the instruments cold so it could accurately capture faint infrared light, 18 pieces of gold-plated hexagonal mirrors.
For astronomers, engineers and observers on Earth, deployment is a stressful time. There were 344 single failures, meaning that if any of the actions failed, the telescope would end up as a useless piece of space junk. They all worked.
The telescope’s four scientific instruments must also be turned on. In the months after the telescope arrived at L2, its operators carefully aligned 18 mirrors. In April, the Medium Infrared Instrument, or MIRI, which requires the coldest temperatures, was cooled down to minus 447 degrees Fahrenheit. Once these and other steps are taken, the science can begin.
How does Webb compare to the Hubble telescope?
The Webb telescope’s main mirror is 6.5 meters in diameter, compared to Hubble’s 2.4 meters, giving Webb seven times more light-gathering capacity and thus the ability to see farther in space. time and deeper into the past.
Another important difference is that Webb is equipped with cameras and other devices that are sensitive to infrared, or “thermal” radiation. The expansion of the universe causes light of normally visible wavelengths to be converted to longer infrared wavelengths that are invisible to the human eye.
