Will new telescope Roman help reveal long-kept secrets of the universe? Q&A with an expert

On Sunday, Aug. 30, the Nancy Grace Roman Space Telescope is expected to launch from NASA’s Kennedy Space Center in Florida. The observatory will join the Hubble Space Telescope, launched in 1990, and the James Webb Space Telescope, launched in 2021, in scanning the vastness of space and potentially finding answers to longstanding mysteries of the universe.

Known as Roman, the new telescope will be able to block the starlight that hides distant exoplanets and reveal distant disks of dust and particles that eventually give rise to new planets. Roman’s goals include completing a statistical census of planetary systems in the Milky Way and a historical analysis of how dark matter and energy—particles and forces that aren’t entirely understood—influenced the formation and evolution of the normal matter making up the universe.

In this Q&A, Christopher Palma, teaching professor of astronomy and astrophysics in Penn State’s Eberly College of Science, spoke about Roman, satellites much closer to home and what’s obscuring space observations from Earth’s surface.

Q: What is the Nancy Grace Roman Space Telescope? How does it differ from the James Webb Space Telescope and the Hubble Space Telescope?

The telescope has some similarities to both Webb and Hubble, but it is unique in many ways. Telescopes are described by what type of light they can detect. Hubble is sensitive to ultraviolet, visible and infrared light; Roman to visible and infrared light; and Webb only to infrared light. These different types of light can provide insight into completely different cosmic phenomena and objects because different objects stand out more or less in one type of light versus another.

The size of the observatory’s mirror also determines how sensitive the telescope is to detecting faint objects. Hubble and Roman have identically sized mirrors, about eight feet in diameter, while Webb has a much larger mirror at about 21 feet in diameter.

What really makes Roman stand out is that it is designed for wide-field imaging. The cameras on telescopes can often detect objects in only a very small patch of sky. If we use the size of the full moon in the sky as our guide, Hubble’s field of view is often smaller than that—meaning each picture it takes is of a patch of sky smaller than the full moon.

Webb’s fields of view are often even smaller than Hubble’s. Each picture taken by Roman, however, will be larger than the full moon, allowing it to survey more of the sky much faster than Hubble or Webb.

Q: The Nancy Grace Roman Space Telescope will join Webb in orbiting the sun almost one million miles (1.6 million kilometers) from Earth, but Hubble circles Earth in ‘low Earth orbit.’ What does that mean?

To set the scale, the moon is about 250,000 miles or 400,000 kilometers from Earth. Most folks picture telescopes and satellites quite far from Earth—they often think they are about halfway between Earth and the moon. In reality, they are in low Earth orbit, which is about 0.25% of the way to the moon.

Low Earth orbit often means something like 500 to 2,000 kilometers, or roughly 310 to 1,250 miles, above Earth. In comparison, that’s at least 44 times higher than the cruising altitude for most commercial flights. So, low Earth orbit is much higher than planes fly, but it is much, much closer than the moon.

Q: What else is sent to low Earth orbit? How crowded is this area getting, and how might that impact life on Earth?

There are many satellites in low Earth orbit. These can be for research, communications or military purposes, for example. Other things we launch into space, like expended rocket bodies, wind up in these orbits, too. There is debris like small pieces of destroyed satellites, and there are natural objects like meteoroids that pass through low Earth orbit.

It is already crowded, but many companies want to build and launch from many thousands to a million satellites in the next decade or so. There is a lot of concern among astronomers about how these satellites may negatively impact our ability to see beyond Earth.

Beyond satellites, there are other companies focused on using low Earth orbit for other reasons—one particular project causing significant concerns involves launching space mirrors to light up large swaths of Earth.

While space and the ability to see the sky beyond are areas of significant worry, there is also concern that a catastrophic collision could result as satellites become more prevalent. Such a collision might create a chain reaction that destroys most of the artificial objects in orbit, cutting those on Earth off from space and from each other in terms of telecommunications.

Called Kessler syndrome, the theoretical scenario has been depicted in works of fiction such as the movie “Gravity” but has real scientific analysis underpinning the possibility.

Q: Back on Earth, reports indicate that light pollution has caused the brightness of the night sky—which can obscure stars and planetary bodies—to more than double from 2011 to 2022. What is light pollution? Can it be mitigated?

There is increasing crowding in low Earth orbit, but light pollution on Earth’s surface is what really prevents us from seeing the night sky, and we can blame ALAN: artificial light at night.

All of our upward-pointing lights illuminate the sky, making the night sky much brighter than it would be without them. One way to characterize the scope of the problem in any particular place is to estimate how many stars you can see on a moonless night. Without light pollution, a good human eye can detect a few thousand stars.

However, in downtown New York City, you might see a dozen. In more suburban locations like State College, we may see a few hundred stars on a good, dark night, but that’s a change from a few decades ago, when we used to be able to see the Milky Way.

There are ways to mitigate light pollution: shielding lights, using timers or motion sensors, reducing the amount of light you install, and using lights that give off more orange and red and less blue and white light. Many areas around the world, including France and parts of Australia, have shown that common-sense restrictions on lights can dramatically improve the night sky.

In particular, Flagstaff, Arizona—the home of Lowell Observatory, where Pluto was discovered—has been very successful in reducing its light pollution using these approaches and describes its sky as 90% darker than the similarly sized community of Cheyenne, Wyoming. They claim that you can see the Milky Way within the city limits, which is unheard of in 2026 for most communities larger than a few thousand people.

Who’s behind this story?

Sadie Harley

BSc Life Sciences & Ecology. Microbiology lab background with pharmaceutical news experience in oil, gas, and renewable industries.

Full profile →

Andrew Zinin

Master’s in physics with research experience. Long-time science news enthusiast. Plays key role in Science X’s editorial success.

Full profile →