Finding life beyond our solar system goes beyond measuring an exoplanet’s size, as rocky, Earth-sized worlds might not have the conditions for life as we know it. While exoplanets can be directly imaged by blocking their star’s glare, these images are fuzzy and lack resolution to provide enough details about the habitability. Therefore, astronomers are limited to studying an exoplanet’s atmosphere, and this has proven to be quite beneficial in teaching scientists about an exoplanet’s formation and evolution, and whether it contains the necessary ingredients for life as we know it.
Now, researchers at the Carnegie Institute of Science are developing a new tool called the Henrietta Infrared Spectrograph with the goal of advancing exoplanet atmosphere science by providing greater detail than possibly ever before. While several ground-based telescopes are currently used to study exoplanet atmospheres, including the Very Large Telescope, Keck Observatory, and Gemini Observatory, just to name a few, those telescopes are designed to perform several types of science, including galaxy evolution and black holes. In contrast, Henrietta will be the first to specialize in exoplanet atmosphere research in near-infrared light, providing crucial details about exoplanets that go beyond physical attributes.
“Mass and size only tell you so much,” said Dr. Jason Williams, who is a postdoctoral fellow at Carnegie Observatories and the scientific and technical lead of the Henrietta project. “If you measured Earth and Venus that way, you’d think they were almost the same planet. But we know their atmospheres—and their conditions—are completely different.”
To study exoplanet atmospheres, Henrietta will take advantage of the transit method, which is a common method for identifying exoplanets and studying their atmospheres. The transit method occurs when an exoplanet passes in front of its host star, temporarily blocking starlight, with this dip in starlight being used to detect a new exoplanet and measure its size. This method has also been used to study exoplanet atmospheres, as astronomers examine the starlight that passes through the exoplanet’s atmosphere through a technique called spectroscopy. Through this, astronomers have been able to identify common biomarkers like carbon, oxygen, and hydrogen in several exoplanet atmospheres.
Henrietta will study exoplanet atmospheres in infrared light, which is invisible to the human eye, but is where molecules are best observed. Additionally, Henrietta will accomplish this science with enhanced precision combined with the dry environment in Chile. Through this, Henrietta is proposed to be able to accomplish levels of exoplanet atmosphere science long thought only possible from space-based telescopes.
With Henrietta slated to see its first light in late April, Dr. Williams will be presenting a paper at the SPIE Astronomical Telescopes + Instrumentation in Copenhagen, Denmark in July 2026 titled “From assembly to first light: integration, testing, and commissioning of the Henrietta Exoatmosphere spectrograph”. This paper will discuss Henrietta’s journey and scientific capabilities, specifically how Henrietta will study exoplanet atmospheres in a wide range of wavelengths, including optical to near-infrared.
Another paper titled “Control architecture for Henrietta spectrograph on the Swope Telescope” will be presented by Dr. William Schoenell, who is an Instrumentation Software Developer for the Carnegie Institute of Washington, at the same conference. This paper will discuss Henrietta’s integration and operational properties with the Swope Telescope, including challenges and scientific impact. Both scientists are co-authors of each paper, along with several other scientists at Carnegie Observatories and across academia.
The spectrograph is named after American astronomer, Dr. Henrietta Hill Swope, whose research focused on variable stars. However, her greatest contribution to science was calculating the distance to the Andromeda Galaxy at 2.2 million light-years away, which is very close to the current measured distance of 2.5 million light-years away. Currently, the spectrograph is being installed on the Swope Telescope (named in her honor in 1976) located at the Carnegie Science’s Las Campanas Observatory in Chile.
What new insight into exoplanet atmospheres will the Henrietta Infrared Spectrograph teach scientists in the coming years and decades? Only time will tell, and this is why we science!
As always, keep doing science & keep looking up!