Not only did Webb launch, but its Ariane 5 rocket performed the flight with such precision that the spacecraft was able to save precious fuel for maneuvering, thereby extending its lifetime. Over the next two weeks, engineers and scientists executed hundreds of steps to unfold and fully extend the telescope and its massive sunshield. And then, finally, on Monday, the spacecraft performed one final major burn of its thrusters, falling into a halo orbit around the L2 point.
This means that the Webb space telescope has reached its final destination, a 180-day orbit around this L2 point, which keeps the telescope in line with the Earth as both the instrument and planet orbit around the Sun. Here, while using a minimum amount of fuel to hold its position, Webb can use its sunshield to keep the infrared telescope and its instruments cold.
The work is not done. The telescope has 18 primary mirror segments, which are moved by 132 actuators. These actuators have already been tested and shown to work. Now, over the next three months, telescope operators will fine-tune the alignment of these mirrors. During this process, scientists will use a Sun-like star named HD84406 to focus the mirrors. This star is located about 240 light years from Earth and can be found in Ursa Major near the bowl of the Big Dipper.
At the same time, in the wake of the sunshield, these mirrors and their scientific instruments will continue to cool in order to be able to detect the weak, ultra-distant signals of heat from the Universe’s oldest galaxies.
At times, it remains difficult to believe that this is really happening. But all of the unprecedented stuff for this large space science project is complete, and now the commissioning of the instruments should be fairly routine. Webb won’t be ready for science operations until June, but the odds are very high that it will get there.
I have only been a very outside observer of this process over the last five years—knowing enough to be concerned about the fate of this $10 billion telescope but not facing any serious consequences should it fail. Even so, I have worried continuously about the fate of Webb. At times I have despaired about it ever making a science observation. So I have felt elated over the last couple of weeks as everything has fallen neatly into place.
I can only imagine the utter delight of astronomers, physicists, and scientists who have worked directly on this project. Bravo to you all.