Vandenberg Space Force Base, United States · 11 March 2025 — NASA's SPHEREx (Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer) mission successfully launched aboard a SpaceX Falcon 9 rocket from Space Launch Complex 4 East (SLC-4E) at Vandenberg Space Force Base in California. The observatory was co-manifested with NASA's PUNCH (Polarimeter to Unify the Corona and Heliosphere) mission satellites in a rideshare configuration.
Over its planned two-year mission, SPHEREx will conduct the first all-sky near-infrared spectral survey, collecting data on more than 450 million galaxies and over 100 million stars in the Milky Way to explore the origins of the universe, the history of galaxy evolution, and the presence of water and organic molecules in planetary systems.
A New Kind of Sky Survey
SPHEREx is classified as a "spectro-photometer" — an instrument that combines the capabilities of a spectrometer and a photometer. Rather than capturing images in a few broad color bands (as most all-sky surveys do), SPHEREx will map the entire sky in 102 different color bands across the near-to-mid-infrared spectrum, far exceeding the color resolution of any previous all-sky map.
The mission's spectral resolution, while modest compared to dedicated spectrometers on telescopes like James Webb, is achieved across the entire sky — a trade-off that enables statistical studies of enormous populations of objects rather than detailed examination of individual targets. SPHEREx will also identify promising targets for follow-up observation by future missions, including NASA's James Webb Space Telescope.
Three Core Science Objectives
1. The History of the Universe
SPHEREx will measure the 3D positions of hundreds of millions of galaxies across cosmic time, enabling scientists to study the large-scale structure of the universe and the imprint of cosmic inflation — the exponential expansion of space in the first fraction of a second after the Big Bang. By measuring how galaxies are distributed at different distances (and therefore different epochs), the mission will constrain models of the early universe and the physics of inflation.
2. The Origin of Water and Organic Molecules
Within the Milky Way, SPHEREx will search for water and organic molecules — the essential building blocks of life as we know it — in stellar nurseries, the regions where stars are born from gas and dust, and in protoplanetary disks around young stars where new planets may be forming. By surveying the entire sky in infrared light, the mission can identify these materials across a wide range of environments and quantify their abundance.
3. The Epoch of Reionization
The mission will also study the epoch of reionization, the period in cosmic history when the first stars and galaxies began emitting ultraviolet light that stripped electrons from hydrogen atoms in the intergalactic medium. SPHEREx's large-scale galaxy surveys will help characterize the sources responsible for this transformative period in the universe's evolution.
Technical Design and Partnerships
The SPHEREx observatory is relatively compact by space telescope standards, with a primary aperture of 20 centimeters (approximately 8 inches) and a total mass of approximately 285 kilograms. Its modest size is enabled by the mission's all-sky survey strategy, which does not require the light-gathering power of larger telescopes. The instrument uses technologies adapted from Earth-orbiting satellites and interplanetary spacecraft.
The mission is led by Principal Investigator Dr. Jamie Bock of the California Institute of Technology (Caltech). The SPHEREx payload was developed jointly by Caltech and NASA's Jet Propulsion Laboratory (JPL), with the spacecraft bus supplied by Ball Aerospace. The Korea Astronomy and Space Science Institute (KASI) contributed the non-flight cryogenic test chamber. The science team includes researchers from UC Irvine, Ohio State University, the Harvard-Smithsonian Center for Astrophysics, Arizona State University, the University of Arizona, Rochester Institute of Technology, Argonne National Laboratory, and Johns Hopkins University.
All data from the mission will be made publicly available through the Infrared Processing and Analysis Center (IPAC) at Caltech, ensuring that the broader astronomical community can leverage the survey for a wide range of research.
The PUNCH Co-Manifested Mission
Sharing the Falcon 9 ride to orbit with SPHEREx were four small satellites comprising NASA's PUNCH (Polarimeter to Unify the Corona and Heliosphere) mission. PUNCH is designed to study the Sun's outer atmosphere (the corona) and the solar wind — the stream of charged particles that flows outward from the Sun and interacts with planetary atmospheres and magnetic fields.
Together, the two missions represent a dual investigation: SPHEREx looking outward to the farthest reaches of the observable universe, and PUNCH looking inward at the Sun's influence on the solar system. Both missions contribute to NASA's broader heliophysics and astrophysics programs.
From Launch to Science Operations
Following launch, SPHEREx underwent a period of in-orbit checkout and calibration — verifying that its instruments, pointing systems, and data processing pipelines functioned correctly in the space environment. The observatory operates in a sun-synchronous low Earth orbit, which provides consistent lighting conditions and thermal stability for its infrared detectors.
Once calibration was complete, SPHEREx began its formal science operations, executing the first of four planned full-sky surveys (one every six months over the two-year primary mission). Each survey produces a complete spectral map of the sky, and combining multiple surveys improves sensitivity and enables detection of variable sources.
Sources
- NASA JPL, SPHEREx Mission Page ()
- NASA JPL, SPHEREx Press Kit: Mission Overview ()
- SpaceX, SPHEREx Launch Page ()
- Caltech SPHEREx Mission Website ()
- NASA Science Blogs, SPHEREx ()
- Spaceflight Now, "Falcon 9 launches SPHEREx and PUNCH," March 11, 2025
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