Decades ahead, Europe picks goals for big space missions

doi:10.1126/science.372.6548.1252

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DOI	10.1126/science.372.6548.1252
	Decades ahead, Europe picks goals for big space missions
	Daniel Clery
	2021-06-18
发表期刊	Science
出版年	2021
英文摘要	Big space missions take patience and long planning. And all start with a goal. The European Space Agency (ESA) took that first step last week when it revealed the science themes it wants to pursue in billion-euro missions to be launched between 2035 and 2050. They include taking a close look at ocean-bearing moons around Jupiter and Saturn, dissecting the atmospheres of temperate exoplanets, and using new tools to study the formation of the universe's first stars, galaxies, and black holes. The choices reflect areas most likely to generate “breakthroughs in science on that timescale,” says Linda Tacconi of the Max Planck Institute for Extraterrestrial Physics, who chaired the selection panel. ESA refreshes its slate of science missions every decade or so. The current program, called Cosmic Vision, has three flagship missions that will launch by 2034: a spacecraft to study Jupiter's icy moons, an x-ray telescope, and a gravitational wave detector. Competition for the next round, dubbed Voyage 2050, kicked off in 2019 with almost 100 suggested missions or themes from teams of researchers ( Science , 25 October 2019, p. [410][1]). Dozens of researchers were recruited into committees to winnow down the suggestions into three categories, which ESA's Science Programme Committee approved last week. Although the themes do not specify particular missions, some clearly nod at concepts that researchers have been working on for years. The first calls for looking for life in the Solar System with a visit to one of the moons of Jupiter or Saturn thought to have water oceans hidden beneath their frozen shells, including Europa, Enceladus, Titan, and Ganymede. Such oceans, warm and laden with minerals essential to life, “hold important clues to the emergence of life on Earth,” says Athena Coustenis of the Paris Observatory in Meudon. NASA and ESA both have upcoming missions to swoop past some of these moons, but ESA wants to get closer with a lander or drone. Technology development needs to start now, Coustenis says. “Today, we don't know how to land and drill down into the oceans, how to shield landers from radiation, how to communicate,” she says. A second theme calls for new probes of the early universe. One possibility is a mission that would build on Planck, which mapped the relic microwave radiation from the big bang to learn about the expansion of the universe and how initial clumps of matter seeded the formation of galaxies. Advances in microwave spectrographs could allow the mission to test the standard model of cosmology and look for evidence of primordial black holes or proposed dark matter particles like axions. Another possibility is a successor to the Laser Interferometer Space Antenna (LISA), a fleet of three spacecraft flying in formation, due for launch in 2034. LISA aims to detect gravitational waves with long wavelengths, such as those from the merger of massive black holes—events that detectors on Earth cannot catch. A new mission could probe even longer wavelengths, revealing how quasars—superbright galactic cores in the distant universe—form and whether the supermassive black holes at the centers of galaxies grow by swallowing stars and gas or by merging with other giants. The third theme calls for studying either the Milky Way's stars or planets. If ESA chooses exoplanets, one option would be scrutinizing the midinfrared glow from temperate exoplanets for atmospheric gases that could hold signatures of life. One mission concept in contention is the Large Interferometer for Exoplanets (LIFE), a flotilla of four orbiting telescopes that would combine their light in a fifth craft not only to sharpen their view, but also to cancel out a star's glare, revealing the faint infrared glow of surrounding planets. “This is what we really need to understand exoplanets,” says Sascha Quanz of ETH Zurich, who heads the LIFE team. Tacconi says the exoplanet theme was “very, very compelling,” but acknowledges that many questions hang over such a costly mission, including whether there are enough exoplanets within range to get a good sample. If ESA opts for Milky Way stars instead, one option could be a follow-on to ESA's Gaia telescope, which is mapping the positions and motions of 2 billion stars to understand how the Milky Way evolved. The new mission would shift to near-infrared light, mapping five times as many stars with 10 times the accuracy. “It tells you how the galaxy is moving,” says David Hobbs of Lund University, who wants to use the stars as tracers for the halo of invisible dark matter that helps hold the galaxy together. ESA plans to build the ocean moon mission first, in part because after it launches the Jupiter Icy Moons Explorer next year, teams with relevant expertise will be free to work on a new mission. Fabio Favata, ESA's head of strategy, planning, and coordination, says around the end of the year ESA will form a committee of experts to pick the target moon and decide what is technologically possible within the time and cost constraints. Feasibility studies from contractors will follow, and after as many as 5 years, teams will be invited to propose missions for the slot. A year or two later, the process will start again for the next theme. Building such missions means “finding a compromise between ambition and boundary conditions,” Favata says. “It takes years of work to finally converge.” [1]: http://www.sciencemag.org/content/366/6464/410
领域	气候变化 ; 资源环境
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文献类型	期刊论文
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/330785
专题	气候变化资源环境科学
推荐引用方式 GB/T 7714	Daniel Clery. Decades ahead, Europe picks goals for big space missions[J]. Science,2021.
APA	Daniel Clery.(2021).Decades ahead, Europe picks goals for big space missions.Science.
MLA	Daniel Clery."Decades ahead, Europe picks goals for big space missions".Science (2021).