The Webb Space Telescope left Earth safe and sound on Christmas morning, and astronomers across the world breathed a sigh of relief. But the weeks ahead contain a series of hurdles that must be cleared for the $10 billion telescope to begin its scientific duties. On Monday night, Webb officially passed the orbital distance of the Moon, traveling over half a mile per second on its journey to its final destination.
At time of writing, the telescope is over 305,000 miles from Earth, about a third of the way to its destination, a point in space called L2. (You can check the location of Webb here.) The telescope’s current deployment step is what NASA calls its “second mid-course correction burn,” meaning the second use of fuel to correct the spacecraft’s trajectory toward its destination. Next up today is the beginning of the deployment of the all-important sunshield, which will protect the astronomical data Webb collects from heat. According to NASA, this will be “one of the most challenging spacecraft deployments NASA has ever attempted.”
The sunshield pallets will be unfurled in the coming days, like the wings of a butterfly emerging from a chrysalis. In a week’s time, the sunshield will be fully deployed, followed by the mirrors and mirror wings. The entire spacecraft will be unfolded by the end of the first week of January, but there’s plenty that still can go wrong with these steps, even though the most nail-biting part of the operation (the launch) is now complete.
The destination, Lagrange point 2 or simply L2, is perfect for a telescope that is trying to see some of the oldest stars in the universe. As noted by NASA, L2 is good for astronomy because it’s relatively close to Earth and can keep Earth, the Moon, and the Sun behind it for an unobstructed view of the cosmos. L2 is about a million miles from Earth, so it’ll take the telescope a month to get there.
The first images from Webb are expected in June 2022, assuming all goes well in these next few weeks. Scientists are hoping to use the telescope’s observations to learn more about the earliest era of the universe, to find potentially habitable exoplanets, and to better understand how galaxies form and evolve.