NASA’s Next Flagship an Important Step Toward Finding Life on Other Planets

Since the Big Bang, 14 billion years ago, the universe has been expanding at an ever-accelerating rate. The culprit is a mysterious force called dark energy.

“If you threw up a ball, gravity would pull the ball back down,” said NASA cosmologist Jason Rhodes in an October 9 lecture at the American Association for the Advancement of Science. “But the effects of the universe, through this dark energy, are as if you threw up a ball, and instead of the ball coming back down, it kept going away from you faster and faster.”

Everything that we can see, including planets, stars, and gases, makes up less than 5% of the universe. Dark matter and dark energy, which neither give off nor absorb light, occupy the remaining space. But these forces can only be measured indirectly, with reference to their gravitational influence on other objects. Our understanding of the phenomena that dominate our universe, therefore, remains extremely limited.

Rhodes’ lecture, the latest installment in AAAS’ monthly series of public seminars, detailed the scientific priorities of NASA’s Wide Field Infrared Survey Telescope. A flagship mission set for launch in 2025, WFIRST will obtain precise measurements of the properties of dark matter and dark energy, while laying the groundwork for future missions that will look for signs of life in distant solar systems.

According to Einstein’s general theory of relativity, matter bends space. Thus, light from faraway galaxies distorts on its path to us, due to the dark matter and dark energy in its way. WFIRST will measure the shapes of hundreds of millions of galaxies and, in doing so, will elucidate coherent changes caused by distortion, allowing us to map the dark matter and dark energy between us and those galaxies.

In addition to measuring the shape of galaxies, WFIRST will measure their positions, as well as the behavior of light given off by exploding stars, or supernovae, across cosmic time. It will be the world’s only mission to use all three of these techniques to measure the properties of dark matter and dark energy. “That’s going to give us a very robust picture of the physics of the universe,” said Rhodes, who is the project scientist for WFIRST at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.

Perhaps even more intriguing than WFIRST’s investigation into the basic composition of the universe will be its census of exoplanets, planets outside of our solar system. To date, astronomers have discovered almost 4,000 exoplanets. WFIRST will uncover thousands more, using microlensing and coronography, techniques that block out starlight and make exoplanets visible.

“Seeing an exoplanet around a star is like trying to see a firefly flying around a spotlight in Los Angeles, when you’re standing here in Washington, D.C.,” said Rhodes. “Seeing an Earth-like exoplanet around a Sun-like star is 1000 times harder.” WFIRST will demonstrate the technology needed to do the latter. Missions in the 2030s will ideally be able to image exoplanets with resolution high enough to capture the presence of biomarkers, elements like oxygen and methane that signal the potential presence of life.

NASA defines its flagship missions — now officially called Large Strategic Science Missions — as those costing more than $1 billion. After the 2021 launch of the James Webb Space Telescope, which will serve as the successor to the renowned Hubble Space Telescope, WFIRST will be the next of this highest class. It is the same size as Hubble, at 2.4 meters in diameter, but is hundreds of times more powerful. Whereas it took 400 discrete images from Hubble to piece together a full picture of the Andromeda Galaxy, our Milky Way’s closest neighbor, WFIRST will need just two images to do the same.

Though the White House budget request for the 2019 fiscal year proposed the termination of WFIRST, Congress fully funded the mission in 2018 and gave a strong recommendation for full funding next year. “We have traditionally had very strong, bipartisan support in both houses of Congress for WFIRST, so we’re cautiously optimistic,” said Rhodes.

If the project continues to receive funding as planned, it will be a boon to the global scientific community. NASA will release all of the data that WFIRST collects to the public in real time, without any proprietary period. Additionally, during its five-year prime mission, 25% of the telescope’s time will be devoted to proposals from scientists and space agencies around the world. In the 10 years that NASA expects the telescope to function following its prime mission, nearly all of its time will be given to this general observance.

“WFIRST is seeking to answer some of the biggest questions in all of science,” said Rhodes. What is the universe made of? … And are we alone?”