The next SPHEREx mission of the POT will be able to scan the entire sky every six months and create a map of the cosmos like never before.
Scheduled to launch no later than April 2025, will investigate what happened in the first second after the Big Bang, how galaxies form and evolve, and the prevalence of molecules critical to the formation of life, such as water, locked up as ice in our galaxy. Achieving these goals will require state-of-the-art technology, and NASA this month approved final plans for all components of the observatory.
“We are in the transition from doing things with computer models to doing things with real hardware,” Allen Farrington, SPHEREx project manager at NASA’s Jet Propulsion Laboratory, which manages the mission, said in a statement. “The design of the spacecraft, as it stands, is confirmed. We have shown that it is feasible even in the smallest details. So now we can really start building and putting things together.”
To answer big questions about the universe, scientists need look at the sky in different ways. Many telescopes, like NASA’s Hubble Space Telescope, are built to focus on individual stars, galaxies, or other cosmic objects and study them in detail. But SPHEREx (which stands for Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer) belongs to another class of space telescopes that rapidly survey large portions of the sky, examining many objects in a short period of time.
SPHEREx will scan more than 99% of the sky every six months; by contrast, Hubble has observed about 0.1% of the sky in more than 30 years of operations. Although survey telescopes like SPHEREx can’t see objects in the same level of detail as dedicated observatories, they can answer questions about the typical properties of those objects throughout the universe.
For example, NASA’s recently launched James Webb Space Telescope will target individual exoplanets (planets outside our solar system), measuring their size, temperature, weather patterns, and composition. But do exoplanets, on average, form in environments conducive to life as we know it? With SPHEREx, scientists will measure the prevalence of life-supporting materials, like the water that resides in the icy dust grains in galactic clouds from which new stars and their planetary systems are born. Astronomers believe that the water in Earth’s oceans, which is thought to be essential for life beginning on Earth, originally came from such interstellar material.
“It’s the difference between knowing a few individual people and taking a census and learning about the population as a whole,” said Beth Fabinsky, deputy project manager for SPHEREx at JPL. “Both types of studies are important and complement each other. But there are some questions that can only be answered through that census.”
SPHEREx and Webb differ not only in their approach to studying the sky but also in their physical parameters. Webb is the largest telescope ever flown in space, with a 6.5-meter primary mirror to capture the highest resolution images of any space telescope in history. The observatory Protect your sensitive instruments from the sun’s blinding light with a tennis court-sized sunshade. SPHEREx, on the other hand, has an 8-inch main mirror and a hood that is only 3.2 meters wide.
But both observatories will collect infrared light, wavelengths outside the range that the human eye can detect. Infrared is sometimes called heat radiation because it is emitted by hot objects, which is why it is used in night vision equipment. The two telescopes will also use a technique called spectroscopy to break down infrared light into its individual wavelengths or colors, much like a prism breaks down sunlight into its component colors. Spectroscopy is what allows both SPHEREx and Webb to reveal what an object is made of, because individual chemical elements absorb and radiate specific wavelengths of light.
To answer general questions, the SPHEREx team first had to answer more practical questions, such as whether the onboard instrument could survive the environment in space and whether all of its components could be packaged and operated as a system. Last month, the team’s final plans were approved by NASA, a step the agency calls critical design review, or CDR. This marks a important milestone for the mission on its way to launch.