NASA's SPHEREx Launches Soon and Will Search For Water in Molecular Clouds
A significant aspect of astrobiological research focuses on the essential requirement for water as a fundamental element for life as we know it. Water plays a pivotal role in cellular functions and biochemistry, rendering its presence on other celestial bodies a crucial factor in assessing their potential habitability. Consequently, NASA is preparing to launch the SPHEREx mission, which aims to investigate the origins of water within molecular clouds.
SPHEREx is an abbreviation for the Spectro-Photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer. Scheduled to launch on February 27, 2025, SPHEREx is equipped with a single instrument dedicated to mapping the sky in near-infrared wavelengths and measuring the spectra of approximately 450 million galaxies. The essence of this mission is to enhance our understanding of the universe's expansion and the formation of galaxies through meticulous spectral analysis.
This image shows a semi-frontal view of the SPHEREx observatory during integration and testing at BAE Systems (Boulder, CO). Image Credit: NASA/JPL-Caltech.
In addition to mapping galaxies, SPHEREx will play an integral role in probing molecular clouds for the presence of water ice and other frozen prebiotic molecules. Within these clouds, critical chemical constituents necessary for life exist as ices bound to the surfaces of dust grains. This process is fundamental for the eventual formation of oceans on planets and is vital for the emergence of life. The mission seeks to answer an essential question: how does ice content evolve from diffuse clouds to dense clouds to planetary disks and eventually to planets?
Research indicates that molecular clouds harbor vast quantities of water in frozen form. Infrared observations have revealed that in these cold and dense regions of space, vital chemicals, including carbon dioxide (CO₂), carbon monoxide (CO), methanol (CH₃OH), and ammonia (NH₃) are trapped, forming an essential foundation for the emergence of life.
The importance of water in molecular clouds cannot be overstated; scientists speculate that the bulk of the galaxy's water, and by extension that of the universe, is ensconced within these frozen grains of dust. These components serve as the progenitors of water for Earth's oceans and potentially for any exoplanets or moons that may possess hospitable conditions.
As outlined in Table 1 below, SPHEREx will conduct a detailed examination of the chemical makeup of molecular clouds, especially focusing on the quantity of water present.
| Parameter | Description | Methodology |
|---|---|---|
| Water Ice Detection | Focused study on ice composition in molecular clouds | Infrared spectroscopy |
| Prebiotic Molecule Analysis | Assessment of critical chemicals | Spectral measurement |
| Galactic Mapping | Mapping the locations of water in the galaxy | Surveying 450 million galaxies |
Another important aspect of the SPHEREx mission is its ability to examine the materials surrounding stars within molecular clouds. The mission intends to analyze the rings of material formed around stars, which represent the early building blocks of planet formation. Figure 1 below illustrates the complex structure of the molecular cloud regions.
This photo by renowned astrophotographer Rogelio Bernal Andreo shows the Orion constellation and the surrounding nebulas of the Orion Molecular Cloud complex. The clouds in the complex hold frozen water and other chemicals critical to life. Image Credit: By Rogelio Bernal Andreo - source.
Probing into molecular clouds allows researchers to gather insights into the distribution and abundance of ices as stars form and evolve. SPHEREx will operate under the hypothesis that a significant relationship exists between the ice content and the prevailing conditions within the molecular clouds. To substantiate this hypothesis, the following parameters will be measured:
| Observational Target | Objective | Expected Outcome |
|---|---|---|
| Molecular Clouds | Calculate water ice constituents | Insight into water formation |
| Stars within Clouds | Study material density | Understanding planet formation phases |
| Planetary Disks | Examine ices in disks | Comprehend distribution patterns |
The evolution from molecular clouds to rocky planets entails numerous transformations and processes that scientists seek to unravel. One central question that persists is the transition of ice from molecular clouds to the surfaces of planets. The SPHEREx mission's unique emphasis on infrared absorption spectroscopy will yield new spectra measurements that will catalyze progress in understanding ices throughout various stages of stellar evolution.
Figure 2 provides a comparative analytical representation of ice spectra observed by earlier missions, underscoring the substantial data acquisition potential that SPHEREx promises.
The black line is the JWST spectrum of a source seen through a thick molecular cloud of interstellar dust, showing the strong features of the interstellar ice species H2O, CO₂, and CO at wavelengths of 3.05, 4.27, and 4.67 microns. Image Credit: NASA/JPL.
The SPHEREx mission is prepped to deliver new data that will not only fill existing gaps in spectroscopic ice data but will catalyze paradigm shifts within the scientific community's understanding of star and planet formation dynamics.
Moreover, the impressive data yield generated by SPHEREx will create ample opportunities for intersectional discussions between the SPHEREx initiative and contemporaneous projects like the James Webb Space Telescope (JWST). The complementary nature of both missions is aimed at enhancing the knowledge base regarding ice distribution and formation on planetary bodies.
The investigative approach taken by SPHEREx comes at a crucial time in astrophysics and cosmology. As steadily mounting evidence indicates that various celestial bodies harbor water, the need for missions dedicated to elucidating the origins and transformations of such fundamental compounds for life is paramount.
SPHEREx is set to announce more in-depth findings in upcoming years and will pave the way for further exploration of molecular clouds and their relation to life-sustaining resources.
