The observatory will map the entire sky to study the rapid expansion of the universe after the big bang, the composition of young planetary systems and the history of galaxies.
NASA’s upcoming space telescope, the Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer, or SPHEREx, is one step closer to launch. The mission has officially entered Phase C in NASA language. This means that the agency has approved preliminary design plans for the observatory, and work can begin on creating a final, detailed design, as well as building the hardware and software.
SPHEREx is managed by NASA’s Jet Propulsion Laboratory in Southern California, and it is planned that SPHEREx will start no earlier than June 2024 and no later than April 2025. Its instruments will detect near-infrared light or wavelengths several times longer than the light visible to the human eye. During its two-year mission, it will map the entire sky four times and create a massive database of stars, galaxies, nebulae (clouds of gas and dust in space) and many other celestial objects.
Approximately the size of a sub-compact motor, the space telescope will use a technique called spectroscopy to refract near-infrared light into its individual wavelengths, or colors, just as a prism refracts sunlight into its component colors. Spectroscopy data can reveal what an object is made of, because individual chemical elements absorb and emit specific wavelengths of light. It can also be used to estimate the distance of an object from the earth, which means that the SPHEREx map will be three-dimensional. SPHEREx will be the first NASA mission to build a full-sky near-infrared spectroscopy map, and it will detect a total of 102 near-infrared colors.
“It’s like going from black and white images to color; it’s like going from Kansas to Oz,” said Allen Farrington, SPHEREx project manager at JPL.
Before Phase C began, the SPHEREx team successfully completed a preliminary design review in October 2020. During the multi-day process, the team had to demonstrate to NASA leadership that they could realize their intricate, latest mission design. The review is usually done in person, but with the COVID-19 safety measures, the team had to adjust their presentation to a new format.
“It felt like we’re making a movie,” said Beth Fabinsky, SPHEREx’s deputy project manager at JPL. “There was just a lot of thought given to the production value, like making sure the animations we wanted to show would work over limited bandwidth.”
Three important questions
The SPHEREx science team has three overarching goals. The first is to look for evidence for something that could have happened in less than a billionth of a billionth of a second after the big bang. In that second, space itself could have expanded rapidly in a process that scientists call inflation. Such sudden ballooning would have affected the distribution of matter in the cosmos, and evidence of the influence would still exist today. With SPHEREx, scientists will map the position of billions of galaxies across the universe relative to each other, looking for statistical patterns caused by inflation. The patterns can help scientists understand the physics that drove the expansion.
The second goal is to study the history of galaxy formation, starting with the first stars that ignite after the big bang and extend to the current galaxies. SPHEREx will do this by studying the faint glow created by all the galaxies in the universe. The glow, which is why the night sky is not completely dark, varies through space as galaxies clump together. By making maps in many colors, SPHEREx scientists can find out how light was produced over time and begin to discover how the first galaxies initially formed stars.
Finally, scientists will use the SPHEREx map to search for water ice and frozen organic molecules – the building blocks of life on earth – around newly formed stars in our galaxy. Water ice comes on dust grains in cold, dense gas clouds throughout the galaxy. Young stars form within these clouds, and planets form disks of remaining material around the stars. Ice on these disks can seed planets with water and other organic molecules. In fact, the water in Earth’s oceans most likely started as interstellar ice. Scientists want to know how often life-sustaining materials such as water are absorbed into young planetary systems. This will help them understand how common planetary systems like ours are throughout the cosmos.
Several mission partners are starting to build different hardware and software components for SPHEREx. The telescope that will collect near-infrared light is being built by Ball Aerospace in Boulder, Colorado. The infrared cameras that capture the light will be built by JPL and Caltech (which runs JPL for NASA). JPL will also build the awnings that keep the telescope and cameras cool, while Ball will build the spacecraft bus, which includes subsystems such as the power supply and communications equipment. The software that will manage the mission data and make it accessible to scientists around the world is being built at IPAC, a science and data center for astrophysics and planetary science at Caltech. Critical ground support equipment for testing the instruments will be built by the Korea Astronomy and Space Science Institute (KASI), a science partner for the mission in Daejeon, South Korea.
The SPHEREx team is expected to spend 29 months on the mission components before entering the next mission phase, when the components are assembled, tested and introduced.
SPHEREx is managed by JPL for the Astrophysics Division of NASA within the Directorate of Science Mission in Washington. The chief investigator of the mission, James Bock, has a joint position between Caltech and JPL. The scientific analysis of the SPHEREx data will be done by a team of scientists in ten institutions across the USA and in South Korea.
For more information on the SPHEREx mission visit:
https://www.jpl.nasa.gov/missions/spherex/
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Calla Cofield
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