The Webb’s skill set will also include observation of planets—some possibly like Earth—that orbit stars in other galaxies. One Webb target is the Andromeda galaxy, the closest to our Milky Way, which reveals far more of its nature in the infrared spectrum than in visible light. The telescope also has multiple forms of spectrograph imaging to study the composition of stars and planets.
But before any of this research can happen, Webb must arrive on station. First, the launch itself must be successful. Then the telescope must execute a daunting series of manoeuvres, with the first 13 hours of flight including two critical tasks. Roughly 33 minutes after liftoff, Webb must deploy its solar array to begin generating power. Then about 12 hours later, the craft must initiate a course-correction rocket burn to fine-tune its trajectory toward its final destination.
Both must happen precisely on cue, long before Webb completes the 29-day trip to its post.
The telescope’s workstation is called the second Lagrange point,“behind” the Earth as viewed from the sun. The spot is one of five such points where the gravity of the sun and Earth balance to allow a spacecraft to move along with them. This reduces the amount of propellant needed for the craft to maintain its orbit.
The dark and cold of space are integral to Webb’s infrared work. After rolling out its solar array, the Webb must accomplish additional “unfoldings”. The craft will need to deploy a large scaffold structure to support a sunscreen that shields it from heat and light, followed by a five-layer Kapton sunscreen. The telescope, operating at temperatures below -229 C, will always point away from Earth, the sun and moon.
Following those manoeuvres, the spacecraft will then unfold 18 small, hexagonal mirrors that fit together down to the nanometer, together comprising the telescope’s 6.5 metre mirror. After assembly and arrival at the Lamgridge point, the Webb will have six months of mirror alignment, instrument calibration and other testing before it begins its mission.
If successful, the Webb’s ascent will undoubtedly cheer thousands of scientists who have watched in despair as multiple miscues, soaring costs and slipped deadlines bedevilled the project, which Congress nearly scuttled 10 years ago due to the steep budget overruns. The main contractor is Northrop Grumman Corp.
The Webb is likely to have its earliest “wins” in the area of exoplanet observations, planets that orbit stars in galaxies far from our own, said Alex Ji, a near-field cosmologist and assistant professor at the University of Chicago.
“I think this is going to have an impact on the same level as Hubble,” Ji said, noting the iconic images that telescope collected, capturing the public’s imagination. “What speaks to the power of this telescope across the entire span of astrophysics is how many people are excited about it.”