SANTA CRUZ — Folded up inside its rocket like origami, the James Webb Space Telescope lies in wait.
The $10 billion instrument is set to launch as early as Christmas Eve to a gravitational sweet spot nearly a million miles from Earth, where it will tag along with us in orbit around the sun. During its journey, the telescope will slowly unfurl and peer deep into the universe, looking for signs of life in faraway galaxies.
UC Santa Cruz astronomers will be eagerly watching. Their labs are poised to analyze data from the new telescope, which will study faint objects in the cosmos such as exoplanets — worlds orbiting stars that are not our sun.
“Everything we see will be something we’ve never seen before,” said Jonathan Fortney, director of UCSC’s exoplanet program.
Mirrors are key
Webb’s array of 18 hexagonal mirrors can capture six times more light than its predecessor, the Hubble Space Telescope. Named after NASA’s second administrator, the Webb telescope is also equipped with infrared vision, allowing it to see through clouds of gas and dust with unprecedented clarity.
“It’s going to be quite a transformation in our knowledge of exoplanets,” said Andrew Skemer, a UCSC exoplanet researcher who oversees one of the labs that will be analyzing the first wave of data streaming from the telescope.
The first exoplanet circling an ordinary star was observed in 1995. Since then, astronomers have discovered nearly 5,000 of these distant worlds, some of them Earth-sized and orbiting within the “Goldilocks Zone” – a not-too-cold, not-too-hot distance away from their suns where liquid water could exist.
Equipped to capture infrared light from its position four times as far away from Earth as our moon, the new telescope will be able to look directly at exoplanets and gather information about the gases that make up their atmospheres.
“We really know almost nothing about their physical properties,” Fortney said. “James Webb is really our first opportunity to know. We’ve been discovering exoplanets for over 20 years now, but we really haven’t had much of an opportunity to understand what they’re like.”
UCSC, an astronomy powerhouse, is home to two exoplanet labs that will have special access to the first wave of data from Webb, led by Skemer and Natalie Batalha, a professor of astronomy and astrophysics. They will be prepared to process the data with custom-made analytics software carefully crafted over the past several months.
“We want to be completely ready,” Skemer said. “That means knowing exactly what the data is going to look like before we get it, so that we just have to run ‘Go’ on a computer program.”
Two ways to study
There are two main ways to study exoplanets. One, used in Batalha’s lab, is to watch exoplanets pass in front of their suns, creating temporary changes in brightness that telescopes can measure. The second, used in Skemer’s lab, looks at the exoplanets as their own points of light, like stars.
UCSC’s exoplanet researchers are especially keen to understand what exoplanet atmospheres are made of using a technique called spectroscopy. Webb’s instruments will tease out the light that passes through an exoplanet’s atmosphere, then spread it out into a rainbow known as a spectrum.
Because of the different absorption properties of each gas, the spectrum shows a unique pattern that serves as a chemical fingerprint. Looking at these spectra can help astronomers identify gases such as water vapor, methane, carbon dioxide and ammonia.
“The public is used to seeing beautiful images from Hubble, but these are going to be graphs — wiggly lines that show details about the chemical fingerprints,” Batalha said.
While those wiggly lines may not look exciting to the casual observer, they could reveal which exoplanets are home to gases we recognize as signs of life.
The quest to find signs of life on Earth-sized planets is one of the driving forces behind exoplanet research, but it wasn’t part of Webb’s original mission.
When the telescope was first being planned in the early 1990s, exoplanets hadn’t even been observed yet. The original motivation for building the telescope was to look back in time at very distant galaxies to learn how they first formed. The telescope will be able to collect infrared light that passes through clouds of gas and dust in space, providing a clear view into the nebula where stars are born.
But as Webb was burdened by delays and its mission adapted to new data, exoplanets became a major focus, especially as more Earth-like worlds were discovered.
“Earth-sized planets are relatively common in the galaxy, which means that there could potentially be environments like Earth that could serve as cradles of life,” Batalha said.
Webb is a collaboration between NASA, the European Space Agency and the Canadian Space Agency. It will take off from the European Spaceport in French Guiana in South America.
“I’ll probably be up all night watching the preparations,” Batalha said.
The telescope will take about a month to unfurl its tennis court-sized sunshield and 18 hexagonal mirrors as it journeys to its destination, a point behind Earth where the gravitational forces save fuel. Once there, the telescope will take another five months to finish unfolding, cool down, settle into its orbit and test and align its instruments.
There are about 340 single points of failure in this delicate unfolding process that could derail the mission before it truly begins. If everything goes smoothly, Webb will begin sending data to NASA as early as June.
“I’m expecting the unexpected,” Skemer said.
Unlike Hubble, which has now been operating for 30 years, Webb will last only five years to 10 years before running out of fuel. Every moment of Webb’s powerful infrared gaze will be precious.
“When you put a new piece of technology into space, there’s this moment where you open the eyes of the telescope for the first time,” Batalha said. “I can’t wait to see what that looks like.”