The 1980s were both exhilarating and puzzling for those grasping at the nature of space and time. Astronomers knew the universe was vast and expanding, but fundamental mysteries remained unsolved. They did not know, for instance, when or how the universe began, nor what most of it was made of. Worlds beyond our solar system were largely out of reach, left to scientists’ imagination.
Then NASA launched its first great fleet of observatories, beginning with the Hubble Space Telescope in 1990. And the heavens were cast anew.
“Now we take it for granted,” said Michael Turner, a cosmologist at the University of Chicago. But “it was bold to put a telescope in space,” he said. “They were reaching for the stars, literally.”
On Sunday, NASA plans to extend that reach further with the launch of its Nancy Grace Roman Space Telescope, which promises to chart a view of the universe so wide and so deep it would take over half a million high-definition TVs to display just one image in full. With a gaze up to a thousand times faster and at least a hundred times wider than Hubble’s, Roman will use its crisp infrared vision to capture billions of galaxies and stars, as well as discover an estimated 100,000 new exoplanets.
Astronomers will use this data to shed light on the nature of dark matter and dark energy, two mysterious entities that make up about 95 percent of the universe, and complete the census of planets in our Milky Way. Part of the appeal also lies in whatever “unknown unknowns” Roman might uncover.
Like those that came before it, Roman is equipped with “foundational new capabilities that are going to open new discovery space,” said Julie McEnery, who leads Roman’s science team. “And that discovery space has had a return every single time.”
Ideas for putting a telescope in space emerged during the first half of the 20th century. Astronomers were uncovering much about the stars from ever larger observatories on the ground, but were limited by the veil of Earth’s atmosphere, which distorts and blocks many wavelengths of light. In space, however, light could be collected across the entire electromagnetic spectrum.
“It was an enormous expansion of what astronomers could hope to examine,” said Robert Smith, a space historian at the University of Alberta in Edmonton, Canada.
NASA began experimenting with orbiting astronomical observatories alongside its Apollo program in the 1960s, and by the end of the next decade, Congress had approved funding for what would become known as the Hubble Space Telescope. That was in large part due to efforts by Nancy Grace Roman, NASA’s first chief astronomer, who played a pivotal role in building out the agency’s space astronomy program.
But Hubble was just one kind of telescope that NASA planned to launch to space. The agency was pushing for more, which together could explore the universe across infrared, visible, ultraviolet, X-ray and gamma ray wavelengths.
A colorful report published by NASA in 1986 argued for a fleet of Great Observatories that would allow astronomers to sojourn across the stars, learning about the birth and the fate of our universe, how stars and galaxies grow, the prevalence of black holes and whether life was unique to Earth.
“If we succeed, we will leave a legacy to rank us with the great civilizations of the past,” the report read.
Four years later, NASA launched the Hubble. Then came the Compton Gamma Ray Observatory in 1991, the Chandra X-ray Observatory in 1999 and the Spitzer Space Telescope in 2003.
“They all have their own stories,” said John Mather, an astrophysicist at NASA’s Goddard Space Flight Center. “And they all gave us big surprises.”
Together, these observatories transformed humanity’s perception of the universe. Hubble provided a precise measurement of just how fast the cosmos is expanding outward, which helped scientists compute its age. (The estimate we have today is 13.8 billion years old.)
The telescopes have detected black holes throughout the cosmos, including massive ones at the hearts of galaxies like our own, and recorded some of nature’s most violent, energetic events. They have also expanded knowledge about the existence and characteristics of planets beyond our solar system.
NASA’s Great Observatories became precursors for a suite of other telescopes launched by the agency, including Kepler, which pushed the number of known exoplanets into the thousands, and James Webb, which has peered back to nearly the beginning of time, when the seeds of early galaxies were first sprouting.
There is more to the cosmos than meets the human eye, and space telescopes have allowed scientists to grasp at the parts they otherwise could not see. Many questions about how it began, how it matured and what it consists of have been answered.
But despite that broader view, or in some ways because of it, the universe has only gotten stranger.
Scientists have since discovered that cosmic expansion is not constant, but is accelerating with time, driven by a repulsive force called dark energy. (A newer result hints, even more mysteriously, that the behavior of this force may ebb and flow with time.) And while they have cinched down one measurement of how fast this expansion is occurring, more recent calculations using another technique have come up with a different result.
Those values disagree by about 9 percent — a seemingly small discrepancy that has staggering consequences for scientists’ understanding of the history of the cosmos, as well as its eventual fate.
Dark matter also continues to evade direct detection, decades after astronomers confirmed its existence. The invisible substance, thought to drive the motions of galaxies and shape the very structure of the universe, remains out of reach.
And though more than 6,000 exoplanets have been found, life elsewhere has not.
Roman will join a fleet of next-generation telescopes — bigger, faster, with sharper resolution and higher precision than their predecessors — already attempting to tackle these questions, though they all see with slightly different eyes. In addition to being NASA’s latest telescope, it is part of a lineage of observatories on the ground and in space that have captured wider swaths of the sky, with no specific target in mind.
Such a survey will allow astronomers to use Roman’s data to explore the interiors of stars, bright galactic jets, feasting black holes and other exotic phenomena that go bump in the night.
“When it launches, it’s going to do things that currently are impossible,” Shawn Domagal-Goldman, the head of NASA’s astrophysics division, said of Roman at a news conference in July. “In many ways, the astronomical target that Roman is chasing, is designed to study, is the universe itself.”
