NASA’s newest astrophysics observatory, SPHEREx, is on its way to study the origins of the universe and the history of galaxies and to search for the ingredients of life in our galaxy.
Short for Spectro-Photometer for the History of the Universe, Epoch of Reionisation and Ices Explorer, SPHEREx lifted off on March 12, 2025 (AEDT) aboard a SpaceX Falcon 9 rocket from Vandenberg Space Force Base.
Riding with SPHEREx aboard the Falcon 9 were four small satellites that make up the agency’s PUNCH (Polarimeter to Unify the Corona and Heliosphere) mission, which will study how the Sun’s outer atmosphere becomes the solar wind.
“Everything in NASA science is interconnected, and sending both SPHEREx and PUNCH up on a single rocket doubles the opportunities to do incredible science in space,” said NASA Science Mission Directorate Associate Administrator Nicky Fox.
Ground controllers at NASA’s Jet Propulsion Laboratory in Southern California, which manages SPHEREx, established communications with the space observatory. The observatory will begin its two-year prime mission after a roughly one-month checkout period, during which engineers and scientists will make sure the spacecraft is working properly.
The PUNCH satellites successfully separated about 53 minutes after launch. Now, PUNCH begins a 90-day commissioning period where the four satellites will enter the correct orbital formation, and the instruments will be calibrated as a single ‘virtual instrument’ before the scientists start to analyse images of the solar wind.
The two missions are designed to operate in a low Earth, Sun-synchronous orbit over the day-night line (also known as the terminator) so the Sun always remains in the same position relative to the spacecraft. This is essential for SPHEREx to keep its telescope shielded from the Sun’s light and heat (both would inhibit its observations) and for PUNCH to have a clear view in all directions around the Sun.
To achieve its wide-ranging science goals, SPHEREx will create a 3D map of the entire celestial sky every six months, providing a wide perspective to complement the work of space telescopes that observe smaller sections of the sky in more detail, such as NASA’s James Webb Space Telescope and Hubble Space Telescope.
The mission will use a technique called spectroscopy to measure the distance to 450 million galaxies in the nearby universe. Their large-scale distribution was subtly influenced by an event that took place almost 14 billion years ago known as inflation, which caused the universe to expand in size a trillion-trillionfold in a fraction of a second after the big bang. The mission also will measure the total collective glow of all the galaxies in the universe, providing new insights about how galaxies have formed and evolved over cosmic time.
Spectroscopy can also reveal the composition of cosmic objects. SPHEREx will survey our home galaxy for hidden reservoirs of frozen water ice and other molecules, like carbon dioxide, that are essential to life as we know it.
NASA’s PUNCH will make global, 3D observations of the inner solar system and the Sun’s outer atmosphere, the corona, to learn how its mass and energy become the solar wind, a stream of charged particles blowing outward from the Sun in all directions. The mission will explore the formation and evolution of space weather events such as coronal mass ejections, which can create storms of energetic particle radiation that can endanger spacecraft and astronauts.
“The space between planets is not an empty void. It’s full of turbulent solar wind that washes over Earth,” said Principal Mission Investigator Craig DeForest. “The PUNCH mission is designed to answer basic questions about how stars like our Sun produce stellar winds and how they give rise to dangerous space weather events right here on Earth.”
