The universe as we know it is getting a new, unprecedented map. After a successful launch and positioning in low Earth orbit, NASA's newest astrophysical space telescope, known as SPHEREx, has begun its revolutionary mission of mapping the entire sky. What makes this mission particularly significant is the fact that the data is shared with the world almost instantly. Every week, a new set of data from the space survey arrives in the public archive, opening the doors of the cosmos to scientists and enthusiasts across the planet. This practice of transparency enables a collective exploration of the universe's greatest secrets, from its very beginnings to the search for the prerequisites of life.

The full name of the mission, Spectro-Photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer, precisely describes its ambitious goals. During its two-year primary mission, SPHEREx will fly over and capture the entire sky twice a year, thus creating four comprehensive maps of the celestial sphere. These data will allow the science team, as well as the global community, to explore everything from the physical laws that governed the expansion of the universe immediately after the Big Bang, to the distribution of water ice and organic molecules within our galaxy, the Milky Way.

A revolution in 102 infrared colors

Although previous missions, such as NASA's celebrated WISE (Wide-field Infrared Survey Explorer) telescope, also mapped the entire sky, SPHEREx brings a technological leap that changes the rules of the game. While WISE observed the universe in four infrared bands, SPHEREx does so in as many as 102 different infrared wavelengths. This seemingly technical difference is the foundation of the new mission's power. Viewing the same celestial object in 102 "colors" allows scientists to apply a powerful technique known as spectroscopy.

Spectroscopy works like a cosmic fingerprint. Every chemical element and molecule absorbs and emits light at unique, specific wavelengths. By analyzing the spectrum of light coming from a distant star, nebula, or galaxy, scientists can precisely determine its chemical composition. With 102 wavelengths, SPHEREx can identify the signatures of specific molecules with incredible precision. Technically speaking, the telescope has a 20-centimeter diameter mirror and uses advanced detectors cooled to a temperature below 80 Kelvin (-193 °C) to reduce its own thermal noise and enable the detection of extremely faint signals from the deep universe.

Echoes of the Big Bang and the cosmic dawn

One of the three primary science goals of the SPHEREx mission is to peer into the earliest moments of the universe's existence. Specifically, the mission is designed to study cosmic inflation – a theoretical, extremely rapid expansion of the universe that occurred in the first trillionth of a trillionth of a second after the Big Bang. Although it cannot directly observe that moment, SPHEREx will look for its consequences in the present-day structure of the universe.

The mission will create the largest three-dimensional map of the universe to date, precisely recording the positions of hundreds of millions of galaxies. The theory of inflation predicts subtle but recognizable statistical patterns in the way these galaxies are distributed on vast scales. By analyzing these patterns, or the way galaxies cluster together, scientists can test different models of inflation and gain insight into the fundamental physical processes that shaped our universe. The second part of the mission's name, "Epoch of Reionization," refers to the period several hundred million years after the Big Bang, when the first stars and galaxies began to emit enough energy to ionize the neutral hydrogen that filled the universe, making it transparent to light. By measuring the total brightness of all galaxies throughout cosmic history, SPHEREx will also help illuminate this crucial evolutionary phase.

The search for the ingredients of life in the Milky Way

The second key pillar of the SPHEREx mission's research is the search for the basic ingredients necessary for life as we know it. The focus is on mapping the distribution of water ice and organic molecules within our galaxy. These molecules, such as carbon dioxide, methanol, and carbon monoxide, are frozen onto the surface of tiny dust grains within dense and cold molecular clouds. It is precisely these clouds that are the "nurseries" of stars and planets.

When a new star forms within such a cloud, a disk of gas and dust – a so-called protoplanetary disk – is created around it, from which planets are born. It is believed that ice and organic molecules from the cloud are key ingredients of these disks. Later, during the formation of a planetary system, comets and asteroids, which are actually remnants of this process, can deliver these molecules to the surface of young planets, potentially bringing water and the "building blocks of life." SPHEREx will create the first comprehensive "ice map" of the Milky Way, showing where these vital resources are most abundant and helping scientists understand the chemical processes that precede the formation of planets.

Open Science: Data available to the whole world

NASA's commitment to open science and transparent data sharing is fully realized through SPHEREx. All data collected by the telescope becomes publicly available through the NASA/IPAC Infrared Science Archive (IRSA) within just 60 days. This short delay period is necessary for the mission team to process the raw data – remove instrumental artifacts, correct for detector effects, and precisely align the images with astronomical coordinates. Along with the data itself, detailed descriptions of the processing procedures are also published, allowing other researchers full control and understanding of the material.

This approach fosters scientific collaboration on a global scale. "By releasing the data, we are enabling the entire astronomical community to use SPHEREx to work on all other areas of science," said Rachel Akeson, head of the SPHEREx Science Data Center. The mission team alone could not explore everything the data offers; this way, thousands of scientists can use this treasure trove of information for their own, often unexpected, projects and discoveries.

Synergy with other space giants

The value of the SPHEREx mission is further multiplied when its data are used in combination with other powerful observatories. Its role is often described as a "target finder." Because it maps the entire sky, SPHEREx is ideal for identifying the most astronomically interesting objects or phenomena.

Once SPHEREx spots something promising, telescopes with a much narrower field of view but higher resolution, such as the James Webb Space Telescope (JWST), can be pointed at that target for detailed study. The mission's data will also help to more accurately determine the parameters of exoplanets discovered by the TESS (Transiting Exoplanet Survey Satellite). Furthermore, in combination with the European Space Agency's Euclid mission and NASA's upcoming Nancy Grace Roman Space Telescope, SPHEREx's comprehensive maps will provide crucial context for studying dark matter and dark energy, the mysterious forces that dominate the universe. The mission is managed by NASA's Jet Propulsion Laboratory (JPL), while the spacecraft and telescope were built by BAE Systems, with the participation of an international science team from the USA, South Korea, and Taiwan. For more information about the mission, visit the official website at https://nasa.gov/SPHEREx.

The original article was published on the NASA Jet Propulsion Laboratory portal.
Source: How NASA’s SPHEREx Mission Will Share Its All-Sky Map With the World
Author: Lauren Leese | NASA/JPL-Caltech