DV Journal

On Oct. 1, 1847, at age 29, Maria Mitchell, a studious and sturdy Quaker who, as a child, began sweeping the sky above Nantucket, Mass., with a telescope, became America’s first scientist to discover a comet.

Mitchell was awarded a gold medal from King Frederick VI of Denmark for discovering the comet, which would be named “Miss Mitchell’s Comet,” and in 1848, she was the first woman elected to the American Academy of Arts and Sciences. Much later in her life, astronomers honored Mitchell by naming a Moon crater for her.

The sky was the limit for Mitchell — and she achieved renown as a professor of astronomy at Vassar College, an activist in the anti-slavery and suffrage movements, and a leader of professional associations for women and a pioneering mixed-gender one.

Of the stars, which were always in her sights, Mitchell said, “Do not look at stars as bright spots only. Try to take in the vastness of the universe.”

That is what NASA’s next-generation space telescope, named after a legendary woman astronomer of the 20th century, Nancy Grace Roman, aims to do when it is launched late next year or early in 2027 — if all goes without delay. Nancy Grace Roman was the first chief astronomer at NASA — and is affectionately known as “the mother of the Hubble Space Telescope.”

On a recent group tour of the work on Roman, managed at NASA’s Goddard Space Flight Center in Greenbelt, Md., I learned that the telescope is “75 percent clear” for launch.

Roman, NASA’s next large flagship mission, will survey the infrared universe from beyond the orbit of the Moon. It will map stars, galaxies and dark matter to explore the formation and evolution of large cosmic structures like galaxies and galaxy clusters.

Roman looks a lot like Hubble. It is about the size of a school bus and features a primary mirror that is 7.9 feet across — the same size as Hubble. Roman’s primary mirror, working with other optics, will send light to its two science instruments: the Wide Field Instrument and Coronagraph technology demonstration.

“The big difference between the two telescopes is that Roman has 40-years-newer technology,” tour guide Joe Foster said.

Roman will have the exact crisp resolution as Hubble, which has reached 35 years in orbit, and the James Webb Space Telescope, launched in December 2021, but its field of view will be at least 100 times larger.

Foster, who joined NASA in 2019 as its first full-time civil servant dedicated to the cloud, said there is already an incredible explosion of data volume from the orbiting telescopes, and it will continue to grow. The tour was arranged by Omar Hatamleh, head of AI at NASA.

The James Webb telescope, in its first five years of operations, is going to produce just shy of 1 petabyte of data per day, Foster said. “Roman, in its first five years, is going to produce 20 petabytes of data per day — a 20 times increase in data volume in just one generation of satellite,” he said.

Every photo that Roman takes will be a 300.8 million-megapixel image of the sky. “There aren’t enough human eyeballs in the world in a day to look at every picture of that size,” Foster said, “So we are investing in computer-vision algorithms to use AI to help us detect changes in those pictures.”

Unlike Hubble and the James Webb, Roman will do “survey campaigns.” During those campaigns, the telescope will focus on the same patch of the sky because it has such a wide view for prolonged periods of time.

The computer-vision algorithms will detect subtle changes in starlight while looking at faraway host stars. Based on those changes, NASA astrophysicists will know whether those host stars have planets orbiting around them, how far from the host star those planets are, the potential composition of the atmosphere of those planets, and whether they have the ability to harbor life.

“With the launch of James Webb, the number of exoplanets we know about has jumped exponentially. Once Roman launches, it is going to go from tens of thousands of exoplanets to millions potentially — and it might be millions in a couple of months that we find,” Foster said.

Roman is a $4 billion flagship telescope, the largest one fully assembled and built at Goddard by a 1,000-strong team.

However, work on Roman almost didn’t get off the ground.

The mission came about as a result of a 90- to 180-day conference, held once every decade, at which NASA and the broader scientific community worldwide submit papers.

“People vote up or down the papers in very Reddit style. Then, they produce what is called a decadal survey.

“So when mission ideas come along, NASA looks at the priorities in the most recent decadal survey,” Foster said.

That survey took place about eight years ago, and in it, the need for a wide-field survey telescope was identified as one of the primary means to discover exoplanets.

At the time, James Webb hadn’t launched and Roman was a concept telescope. NASA wanted Roman to align with the most recent decadal survey and successfully fought the previous Trump administration to get its funding with the help of the Maryland congressional delegation.

Obviously, Foster said NASA telescopes aren’t built in a day. It takes time to incubate the technology before it becomes flight-ready.

Technology isn’t the only thing at work in a NASA space telescope mission.

As Maria Mitchell said, “We especially need imagination in science. It is not all mathematics, nor all logic, but it is beauty and poetry.”