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NASA is set to launch its infrared space telescope, the Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer (SPHEREx), this week. This groundbreaking mission aims to conduct a comprehensive mapping of the sky, gathering data that will address fundamental questions about the universe, including the moments immediately following the Big Bang, the formation of the first galaxies, and the origins of life’s building blocks.
Optimized Design
The SPHEREx telescope, constructed by Ball Aerospace with contributions from Caltech and NASA’s Jet Propulsion Laboratory (JPL), weighs approximately 1,100 pounds (500 kilograms) — comparable to a grand piano — yet operates on less energy than a standard refrigerator. Its design is both compact and powerful, promising to deliver significant scientific insights.
With a structure resembling an oversized bullhorn, the telescope measures 8.5 feet (2.6 meters) in height and spans 10.5 feet (3.2 meters) at its widest point. It features three nested photon shields that protect its sensitive optics from thermal interference caused by the Sun, Earth, and the electronic systems onboard.
“The shields are relatively lightweight and constructed in layers,” explained Sara Susca, deputy payload manager for SPHEREx. “The outer layers consist of aluminum sheets, while the inner layers feature an aluminum honeycomb design that is robust yet light.”
Heat management is critical for SPHEREx; its design incorporates gaps between the shields and special conical mirrors known as V-groove radiators. These allow for efficient heat expulsion, keeping the telescope at temperatures lower than –350 degrees Fahrenheit (–210 degrees Celsius) to ensure that its infrared sensitivity is not compromised by its own emissions.
Challenges Overcome
The journey to launching SPHEREx has been fraught with delays. Initially proposed for NASA’s Small Explorer (SMEX) program in 2014, the project was not selected until it was resubmitted as a Medium-Class Explorer (MIDEX) mission in 2016, eventually being approved in 2019 with a launch planned for 2023. However, challenges such as the COVID-19 pandemic caused substantial setbacks, affecting supply chains and necessitating remote work adaptations to build engineering models.
“Our team has become like a family,” noted Jennifer Rocca, a project systems engineer. “The pandemic and other challenges, such as the LA fires, have brought us closer together as we navigated these hurdles.”
A Collaborative Launch
SPHEREx will be launched aboard a SpaceX Falcon 9 rocket, a decision made in 2021 at a cost of $98.8 million. Notably, due to its relatively low weight, SPHEREx will share the launch with another NASA mission, the Polarimeter to Unify the Corona and Heliosphere (PUNCH), which will study the Sun’s corona and solar wind using four compact satellites. This collaborative effort optimizes resources and space on the launch vehicle.
SPHEREx is scheduled to enter a near-polar orbit approximately 430 miles (700 kilometers) above Earth, with PUNCH targeting a slightly lower altitude. The launch is set for February 27 at 7:09 P.M. PST from California’s Vandenberg Space Force Base, and conditions permitting, the launch should be visible from the coastline.
In preparation, SPHEREx underwent rigorous environmental testing at the Korea Astronomy and Space Science Institute (KASI), ensuring that its optics were aligned to extremely precise specifications — critical for its performance once in orbit.
Aiming for the Stars
Upon reaching space, SPHEREx will operate in a Sun-synchronous orbit, allowing its instruments to map vast portions of the sky while avoiding sunlight interference. The mission is designed to complete four all-sky maps over a 25-month observational period, significantly differing from traditional telescopes that focus on individual celestial objects.
SPHEREx aims to accomplish three primary scientific objectives. It will investigate cosmic inflation, examining evidence of the rapid expansion that occurred shortly after the Big Bang. Additionally, the telescope will gauge the collective light from galaxies, including those too faint or distant for other observatories to detect, thus providing a clearer understanding of early galaxy formation.
Lastly, the mission will analyze our own Milky Way, searching for vital ingredients such as water and carbon dioxide in regions where new stars and planets form. These insights will assist in unraveling the complexities of planetary formation and the presence of life-sustaining compounds.
Mapping the Universe
Unlike previous infrared telescopes that required cryogenic fluids for cooling, SPHEREx employs a passive cooling system, enhancing its operational longevity beyond the initial 25-month mission. The findings from this mission are anticipated to provoke widespread interest in the astronomical community, as SPHEREx’s vast coverage will identify significant areas for further exploration with more focused telescopes.
According to Beth Fabinsky, the deputy project manager, SPHEREx represents a comprehensive survey of the cosmos, analogy drawn to conducting a census: “It’s about understanding the universe from a broad perspective that supports and complements detailed observations made by other missions.”
Source
www.astronomy.com