Webb Will Unlock New Secrets of the Cosmos. 5 Experts Explain What to Expect

They've been waiting a long time for this.
Grant Currin
An artist's rendering of the TRAPPIST-1 system.NASA/JPL-Caltech/R. Hurt (IPAC)

Early on Christmas morning, thousands of scientists across the world held their breath, crossed their fingers, and watched as the James Webb Space Telescope — the most powerful ever built — set off on its million-mile journey. Now that Webb has successfully passed the most treacherous of its 344 single-point failures (pins that had to release, latches to lock into place, and other mechanisms that had to perform as planned), it’s time to shift our attention from the instrument itself and toward the cosmos. After all, Webb was launched to learn where we came from — and to see what else is out there. 

While Webb won’t return useful data until summer, researchers have already published more than 20,000 peer-reviewed articles exploring the instrument itself and discussing how it should be used. Interesting Engineering got in touch with the authors of some of the most highly cited papers and asked them a simple question: What are you most excited to learn? We’re sharing their answers here.

Some responses were edited for length and clarity.

Astrophysicist Jason Kalirai is Mission Area Executive for Civil Space at Johns Hopkins University’s Applied Physics Laboratory. He’s most excited about new research into star clusters.

These are the birthplaces of all stars in the Universe, and Webb’s photometric precision and sensitivity will enable our first views of the entire stellar population in these systems, from small failed stars that never formed to the cinders of stellar evolution that exhausted their fuel 10+ billions of years ago.  Studying these systems, over a range of environments, composition, and ages will provide astrophysics with new insights on the formation of galaxies and their stellar populations that can lead to systems like our own with a rich diversity of planets and life.”

Ioannis Argyriou, a post-doctoral researcher at the Institute of Astronomy at Belgian University KU Leuven is interested in the formation around some of those stars.

The gas and dust in young solar systems evolves under the influence of gravity, producing rocky planets and gas giants in the process. The properties of the primordial disk of matter around the central star is an important constraint to the type of formed exoplanets. Thus, JWST observations of protostars, protoplanetary disks, and debris disks, will be the key to helping us understand which solar systems are suitable to sustain life. 

As an instrument scientist on the MIRI instrument, Argyriou has an intimate understanding of the telescope. His team is partially responsible for helping researchers make sense of the messy data Webb will send back to Earth.

My job is to make sure that we understand what part of the data is linked to the observed celestial sources (exoplanets, stars, distant galaxies), and which part is linked to the telescope and instrument inherent behavior. JWST observations are made noisier by the telescope thermal background (radiation emitted by the telescope itself), by the onboard electronics, and by the optical components that bring the collected light of the telescope to the detectors. Interestingly, we have found that for MIRI the most significant part of the noise is directly linked to how the photons from an observed source (e.g. star, or planetary nebula) bounce around inside the layers of the detectors themselves. Although this effect can be very complicated to remove from the data, if we are able to understand it, it will allow us to take the achievable science with JWST to new heights. This is a very inspiring prospect for me, given that JWST is a once-in-a-generation mission.

NASA researcher Thomas Greene and his colleagues will spend their telescope time learning about a wide range of exoplanets. 

Our team will spend over 200 hours observing the atmospheres of these planets that exist around other stars, using Webb's powerful spectroscopic capabilities to study the molecules in their atmospheres. We will observe 9 exoplanets ranging in size from Earth to as big as Jupiter, over 300 times the mass or weight of Earth. The Hubble Space Telescope has shown that many exoplanets have water in their atmospheres, and JWST will tell us if they have carbon dioxide, methane, ammonia, and other molecules. Unlike water, these other molecules contain carbon and nitrogen, elements that are also important for life. These observations will also give us much more insight into the compositions of these planets, whether they are similar to their parent stars, and what chemical processes occur in their atmospheres. We will also learn about the climate on these planets, including how winds circulate in their atmospheres and where clouds form and dissipate. The smaller exoplanets are particularly interesting, some of which are intermediate in size between Earth and Neptune and are therefore unlike any planets in our own Solar System. Our observations of the Earth-sized planet TRAPPIST-1 b will reveal whether it has carbon dioxide in its atmosphere, as found in Earth, Mars, and Venus in our own Solar System. To top it all off, we are especially excited because we also contributed to designing and testing JWST's NIRCam and MIRI scientific instruments which we will use to make these observations.

Joshua Krissansen-Totton, a NASA Sagan fellow at UC Santa Cruz, is looking forward to seeing the atmospheres of rocky, Earth-sized planets for the first time. 

The Hubble Space Telescope and other existing telescopes simply cannot tell whether rocky planets in the habitable zones of other stars are airless like the moon, possess hellish CO2-rich atmospheres like Venus, or are clement and inhabited like Earth. However, with JWST, we will finally have the technological capability to measure the atmospheric composition of rocky exoplanets, albeit only for a handful of favorable targets such as the seven planets in the TRAPPIST-1 system. It may also take years to do these observations because, even for JWST, they will be pushing the limits of its instruments. But when completed, these observations will be thrilling because we do not know what we will discover! Will rocky planets elsewhere look anything like the solar system planets, or does nature produce more diverse worlds than we can currently imagine? Do habitable zone planets often have atmospheres or are they typically stripped away by harsh stellar radiation? It is even possible that we might discover tentative signs of life in these exoplanet atmospheres, such as abundant atmospheric methane, which is a potential biosignature gas. However, proving that such methane is produced by life and not some non-biological process will require future telescopes and new capabilities. Nonetheless, JWST will provide the first opportunity to test our ideas about how rocky planets work and the first tantalizing glimpse at potentially habitable worlds among the stars.

Victoria Meadows, professor of astronomy at the University of Washington and a principal investigator leading NASA’s hunt for habitable exoplanets, is interested in the atmospheres of far-off planets that — in some ways — resemble Earth. She’ll be looking very closely at data from the TRAPIST-1 system, a solar system approximately 40 lightyears from Earth. 

The seven Earth-sized planets orbiting the tiny star TRAPPIST-1 are our best targets for studying the atmospheres of extrasolar terrestrial planets.  An Earth-sized planet passing in front of TRAPPIST-1 may reveal absorption from atmospheric molecules which dim the starlight at levels that JWST can detect.  The two planets closest to TRAPPIST-1 may have lost oceans, leaving behind steam, oxygen or carbon dioxide-dominated atmospheres---or have lost their atmospheres completely.  JWST may reveal key atmospheric molecules, including water with a heavier form of hydrogen, that indicate early ocean loss.  We can also look for signs of life in the atmospheres of TRAPPIST-1’s three habitable-zone planets.  Although photosynthetic oxygen will be extremely difficult to detect, absorption from carbon dioxide and methane may be easier and could suggest a strong release of methane, a sign of life on Earth. However, given how little we know about these planets, a CO2 and CH4 detection will be difficult to interpret as being definitively due to life.  Still, it will be exciting to start the search for life beyond the Solar System with JWST!

Will Webb find Earth’s doppelganger? Or will it turn up “intriguingly un-Earth-like” planets? Meadows’ research — and work from the thousands of other scientists patiently waiting to see what Webb can do — will help answer some of these questions.

And spark many, many more. 

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