Where would you point the world’s most powerful space telescope? It’s not an easy question. The James Webb Space Telescope (JWST), which launched in December 2021, has been wowing astronomers since it began transmitting its first scientific data in July 2022. Observing breathtaking near-dawn galaxies and examining exoplanet atmospheres in unprecedented detail. And it has brought an amazing new worldview to our solar system. But it’s just the beginning. Last week, May 10, astronomers learned whether the telescope’s proposal for a second scientific year was a success. The competition was fierce, there were many winners and great science was due to be implemented, but there were many who could not participate in “Cycle 2” of his JWST starting next month. “The response from the scientific community has been extraordinary,” said Nancy Levenson, interim director of the Space Telescope Science Institute (STScI) in Maryland, which runs the JWST.
In total, astronomers submitted about 1,600 proposals to STScI for observation time on the NASA-led JWST. However, only 249 were selected. This means that JWST has an “oversubscription” of almost 7:1, similar to the Hubble Space Telescope. To minimize the potential for bias, JWST’s program selection process is completely anonymous, with hundreds of astronomers from multiple subdisciplines involved in the decision process. That said, the winners and losers were clear. Some astronomers, such as Nathan Adams of the University of Manchester, UK, have submitted multiple proposals, which have been rejected. “He had four proposals, but he didn’t have time for any of them,” says Adams. “Obviously, we’re a little disappointed.” Others, such as Mary Ann Limbach of Texas A&M University, have been far more successful. Limbach approved three proposals. “I’m thrilled to have the time,” she says.
Limbach’s proposal focuses on white dwarfs. A white dwarf is the remnant of an Earth-sized core that remains after a Sun-like star swells into a red giant, expelling its outer layers. After this dramatic event, it is thought that these stellar corpses may still harbor intact planets, which could be studied and discovered by Earth 5 billion years after the Sun enters the red giant stage. It may provide us with an opportunity to learn more about the fate that will befall us. Limbach will try to confirm two worlds suspected of being white dwarfs, but he plans to look elsewhere in the sky for up to six more planets. “The JWST can see if any nearby white dwarfs appear brighter than they should be,” she says. “If so, it could indicate there are planets out there. JWST is the only observatory that can actually confirm them.”
A major area of JWST Cycle 1, which received about 1,200 proposals, was the search for the oldest known galaxies in the universe, which formed just a few hundred million years after the Big Bang. The same is true for cycle 2, where both galaxies and exoplanets get the most telescopic hours. Harvard’s Daniel Eisenstein’s proposal has been accepted and is expected to push the JWST to its limits by exploring galaxies perhaps up to 200 million years after the Big Bang. The distance to distant galaxies is measured by redshift, or how much the light seen from them has been shifted to the red end of the spectrum by the expansion of the universe. Eisenstein will look for galaxies beyond redshift 15, farther than any galaxies identified so far. “There is still no convincing case for galaxies above redshift 15,” he says. “It’s really exciting to be able to continue the quest that started this first year.”
Massachusetts Institute of Technology’s Rohan Naidu also plans to explore the distant universe, but not the galaxies with the strongest redshifts. Instead, his program, which he co-led with Jorit Massey of the Swiss Federal Institute of Technology Zurich (ETH Zurich), uses a huge cluster of galaxies called Abell 2744 to pull the light of several small objects through gravity. It is planned to magnify up to 750 times. Millions of years after the big bang. The goal is to find clumps of primordial gas. Among them may be clusters of cluster III, the first generation of stars thought to have illuminated the universe. Although these long-theorized objects have not yet been observed directly, they are expected to be composed almost entirely of pure hydrogen and helium, which makes them enormous, each weighing as much as the sun. should be hundreds of times greater than “We are pushing his JWST through and through,” he says. “We intend to bring back some very promising regions that may be hosting these clusters.”
A key interest of JWST’s cycle 1 is TRAPPIST, which places seven Earth-sized worlds (some of which are potentially habitable) around a red dwarf star about 40 light-years from Earth. It was -1 system. However, in Cycle 1 he was selected for three of his TRAPPIST-1 programs, but this time only his one program, headed by Michael Gillon at the University of Liege, Belgium, was selected. He plans to search the atmospheres of his TRAPPIST-1b and c, his two innermost planets in the system. Early studies of TRAPPIST-1b suggested that the planet has no atmosphere, but Giron says his technique, which measures temperature differences between the planet’s day and night sides, confirms it. says he understands. It could have important implications for other, more benign worlds in TRAPPIST-1, where life could possibly exist. “If he can demonstrate that one of these two planets has an atmosphere, he will be in a very good position to commission the JWST for an ambitious program to investigate other planets. he says.
Closer to home, Christopher Grain of the Southwest Research Institute in Texas (SWRI) will use the JWST to probe Saturn’s moon Enceladus. Enceladus may have a habitable ocean beneath its icy surface. Observations from NASA’s Cassini spacecraft, which orbited Saturn from 2004 to 2017, showed that the moon occasionally ejects water from this ocean via an Antarctic plume. There are currently no spacecraft orbiting Saturn, but JWST is the next best thing. Incredibly, Glein says, it will be possible to “look for evidence of ocean chemistry” on Enceladus’ surface. It will also be sensitive to certain substances, such as ammonia and various organic molecules, that could inform scientists about the habitability of the Moon’s hidden oceans. In 2040, Enceladus’ Antarctic will plunge into a long dark winter that will last until 2055, making future Antarctic landings unlikely to hunt for life. But with JWST, Glein hopes to show that the lunar polar plume is raining icy spray across the surface. All the way to the sunlit equator, where landing is probably more feasible. “JWST can act as a bridge between the Cassini era and the Enceladus lander,” he says.
Not all research fields have been so lucky. David Kipping of Columbia University submitted two of his proposals to use JWST to search for satellites orbiting exoplanets (exomoons). JWST is “the first machine humans have ever built that can actually run this experiment,” Kipping says. However, both proposals were rejected. “We are definitely disappointed,” he says. “We really felt that this was a complete discussion.”
JWST should be able to find an exomoon up to the size of Europa, but even if it doesn’t, the results would be “pretty deep,” Kipping said. The failure to find expected exo-moon populations “means that the model we are using for our solar system is not universal,” he said, suggesting that locally abundant lunar satellites It could be a clue to a strange deviation from the cosmic norm. Given that JWST is the only telescope that can search for exo-satellites now, or in the near future, time is of the essence. “JWST he could last 10 years, or longer,” said Kipping. “I would really regret it if I didn’t search for Exomons with this. It’s such a shame.”
Mr. Levenson knows there will be some disappointment in the programs that aren’t selected. “There are a lot of great ideas that we don’t observe during this cycle,” she says. For those who missed it, she has October to try again and apply for Cycle 3. “We have to keep trying,” Kipping said. “The JWST will not exist forever.” Scientific riches will come to the lucky few who survive. “There are a wide variety of sciences that JWST is best suited for,” says Levenson. “We are not finished yet.”
