In an ambitious pursuit to unravel the mysteries of the cosmos and explore the potential for life beyond Earth, NASA has allocated $5.7 million to an interdisciplinary team of scientists led by Arizona State University.
NASA's Nexus for Exoplanet System Science Program
This funding comes from NASA's Nexus for Exoplanet System Science (NExSS) program, aimed at providing critical expertise in developing space telescopes specifically designed to detect signs of life on distant exoplanets.
Since the groundbreaking discovery of the first exoplanet in 1992, astronomers have identified thousands of distant worlds orbiting stars similar to our sun.
Among these exoplanets, many have attributes that resemble our Earth-sharing comparable masses and sizes, suggesting they might be rocky planets with metallic cores.
With the recent NExSS grant, the interdisciplinary team will embark on a crucial mission to examine the geochemical cycles on the surfaces of exoplanets. Their primary focus is determining the presence and abundance of vital elements in these remote celestial bodies, such as carbon, nitrogen, sulfur, and phosphorus.
Such critical data will serve as the foundation for future measurements aimed at detecting signs of life, aligning precisely with the core objective of the Tracing Rocky Exoplanet Compositions (TREC) team. Yet, unraveling the surface compositions of planets situated light-years away presents its own set of challenges.
Direct observational methods like the radial velocity technique, which measures the gravitational pull of the star caused by the planet's motion, or the transit technique, which measures the dimming of starlight as a planet passes in front of its star, offer only limited information about an exoplanet's mass and radius.
Although this data can provide insights into a planet's general composition, whether it is predominantly rocky and metallic, icy and rocky, or gas-dominated, it falls short of providing detailed information about the elements on the planet's surface.
Elemental Compositions of Host Stars
The TREC team plans to take a holistic approach to overcome these limitations. By measuring the elemental compositions of exoplanet host stars, which are often similar to our sun, they aim to establish baseline data for rocky exoplanets.
However, despite their similarities, they are mindful that Earth exhibits variations in the abundance of certain key elements compared to the sun. Additionally, some vital elements are sequestered within Earth's core or mantle and do not actively participate in the planet's geochemical cycles.
"The TREC team will start with measuring elements in exoplanet host stars. Earth is close in composition to the sun, and exoplanets should be similar to their stars," said Steve Desch, principal investigator of the project and professor in the School of Earth and Space Exploration.
"But Earth does not appear to have formed proportionally as much carbon or other key elements as the sun. Moreover, many key elements it acquired are trapped in Earth's core or mantle and are not involved in geochemical cycles on Earth's surface," he added.
The TREC team will utilize advanced models and lab measurements to study the formation of Earth and other rocky planets in our solar system.
They will then apply these models to exoplanetary systems to assess the presence of carbon, nitrogen, and other elements on rocky exoplanet surfaces. This data will aid future searches for life on these distant planets.
