The James Webb Space Telescope (JWST) has completed its million-mile journey. NASA reported on the afternoon of January 24th that Webb successfully fired its thrusters to enter a “halo” orbit around the Earth-Sun L2 Lagrange point. It is from this vantage that the Webb telescope will observe the cosmos in greater detail than has ever been possible before, but don’t expect pretty pictures right away.
NASA began work on the JWST back in the 1990s in the wake of the Hubble Space Telescope’s deployment and repair. Construction started in earnest in the early 2000s, but a series of redesigns and budget constraints slowed the project. Now, 20 years of work is about to pay off. Not only did the ESA-operated launch go perfectly, every stage of Webb’s complex unfolding procedure went off without a hitch.
The Earth-Sun L2 Lagrange point is a region of gravitational equilibrium between Earth and the sun. By taking Webb to this location, NASA is able to keep it in position with very little energy input. The telescope will use a little fuel to adjust its attitude and for so-called “station keeping” to remain in orbit of L2. NASA says the process went so well that Webb has enough fuel for 20 years of operations. Because of the distances involved, there are currently no plans to conduct servicing missions for Webb. To do so would require a new class of spacecraft that does not currently exist. That said, 20 years is a long time—maybe we’ll have the right hardware to pay Webb a visit someday.
Being out past the moon’s orbit allows Webb to get extremely frosty. With the sunshield deployed, NASA expects Webb to cool to 50 Kelvin (−223 C or −370 F). This is necessary because Webb operates mainly in the mid-infrared, and its instruments need to be frigid to work correctly. NASA will have to wait for the temperature to drop, but the team will be busy with calibration in the meantime. It will take about three months to get the mirrors aligned with nanometer-level precision.
NASA currently expects Webb to be fully operational by this summer, at which time we will probably see the first images from the telescope. These images might not look like you’d expect, though. Hubble operated mainly in the same visual spectrum as the human eye, but Webb will be able to see through clouds of dust and gas via the infrared spectrum. It will give us a new view of the universe, and the sheer size of the mirror will allow Webb to look at the most distant (and therefore oldest) objects in the universe.