NASA’s SPHEREx: By the Numbers

NASA's SPHEREx mission will operate in low Earth orbit, detecting hundreds of millions of stars and galaxies and creating the first all-sky spectroscopic survey in the near-infrared. This artist's concept shows the spacecraft and its distinctive conical photon shields, which protect SPHEREx's telescope from infrared light and heat from the Sun and Earth.
NASA’s SPHEREx mission will operate in low Earth orbit, detecting hundreds of millions of stars and galaxies and creating the first all-sky spectroscopic survey in the near-infrared. This artist’s concept shows the spacecraft and its distinctive conical photon shields, which protect SPHEREx’s telescope from infrared light and heat from the Sun and Earth. Photo credit: NASA/JPL-Caltech

With launch just under 10 minutes away, let’s take a closer look at some important numbers for NASA’s newest space observatory, SPHEREx (Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer), which will help answer big questions about the early universe, the history of galaxies, and the life-sustaining molecules in planet-forming regions of the Milky Way. 

  • 14 billion – SPHEREx will shed light on a cosmic phenomenon called inflation, occurring almost 14 billion years ago, when in the first billionth of a trillionth of a trillionth of a second after the big bang, the universe increased in size by a trillion-trillionfold.
  • 450 million – SPHEREx will map the distribution of more than 450 million galaxies, to help scientists improve our understanding of the physics behind this extreme cosmic event.
  • 11,000 – SPHEREx will complete more than 11,000 orbits over the duration of planned survey operations.
  • 600 – The spacecraft will take up to about 600 exposures per day, allowing it to complete four all-sky spectroscopic surveys during its two-year prime mission. 
  • 404 – The SPHEREx spacecraft will orbit Earth about 404 miles (650 kilometers) overhead. 
  • 360 – Each orbit allows the telescope to image a 360-degree strip of the celestial sky. 
  • 102 – SPHEREx will gather information about the composition of and distance to millions of galaxies and stars in 102 wavelengths of infrared light. 
  • 98 – Each Sun-synchronous orbit of SPHEREx will take approximately 98 minutes. 
  • 91 – By remaining over Earth’s day-night line (or terminator) for the entire mission, the observatory will keep the conical photon shields that surround its telescope pointed at least 91 degrees away from the Sun to avoid its light and heat. 
  • 27 – The baseline mission for SPHEREx covers 27 months, including launch, one month of in-orbit checkout, 25 months of survey operations, and one month of decommissioning activities. 
  • 14.5 – The observatory will circle the Earth about 14.5 times per day. 
  • Six – SPHEREx will complete an all-sky map within six months. 
  • Four – SPHEREx will complete four all-sky maps during its mission.