2024 Gruber Cosmology Prize

Marcia Rieke has been at the forefront of infrared astronomy throughout her career. 

She was there in the early 1980s as part of a team at the University of Arizona’s Steward Observatory that designed an infrared camera producing images the size of a kilopixel—32 by 32 pixels. “We thought we’d died and gone to heaven,” she says.

She was there at the forefront of infrared astronomy as a co-investigator for the Multi-band Imaging Photometer aboard the infrared Spitzer Space Telescope, which was operational from 2003 to 2020. 

She was there as deputy principal investigator for the Near Infrared Camera and Multi-Object Spectrometer on the Hubble Space Telescope.

And she was there when an ad hoc committee, in the late 1990s, was conceiving in detail the mission that would become the James Webb Space Telescope. In that capacity, and then as the chair of the telescope’s interim Science Working Group from 2000 to 2003, she oversaw numerous decisions about the design of the infrared instruments. Her reward: In 2002 NASA selected Rieke as the Principal Investigator for JWST’s Near-Infrared Camera (NIRCam)—a position she held for the next two decades, through the 2021 launch and the July 2022 scientific commissioning.

Astronomers have known since the mid-twentieth century that light from the universe beyond the narrow sliver of the electromagnetic spectrum that our eyes can see—the visible portion—contains an alternative view of the cosmos. The brightness of the infrared sky seen from Earth prevents observing faint sources so astronomers wanting to explore that portion of the electromagnetic spectrum have to confine their investigations to space telescopes. Rieke’s career coincided with the onset of infrared astronomy from space.

Seeing in the infrared offers two advantages to astronomy. First, it pierces through dust that obscures much of the evolutionary processes in the universe—the violent assemblies of gas and dust attending the formation of stars in our galaxy as well as their emerging planets. The second advantage of seeing in the infrared, though, is especially suitable to performing the science of cosmology—the study of the growth and structure of the universe—on the earliest time-scales.

When light left the first galaxies, in a period 100 million to 1 billion years after the Big Bang, it occupied the visible and ultraviolet sections of the electromagnetic spectrum. In the 13.7 to 13 billion years since then, the expansion of the universe—the expansion of space itself—has stretched those light waves, lengthening them, shifting them not just toward the red end of the visible spectrum but into the infrared. There they reside beyond the reach of even the Hubble Space Telescope—but within the grasp of JWST.

In the brief period since JWST entered scientific mode in July 2022, NIRCam has already challenged conventional wisdom about the early universe. The instrument has repeatedly identified galaxies in the early universe that developed earlier, grew larger, and spawned a richer array of elements than previous theories had predicted. Rieke herself has joined with numerous collaborators in making many of those crucial observations. That evidence is, in turn, pushing theorists to refine their models for galaxy formations, and therefore the evolution of the universe.

All of which means that Marcia Rieke is still at the forefront of infrared astronomy.