How will Nasa’s SPHEREx telescope change our understanding of the cosmos?

Nasa is preparing to launch its latest space telescope, SPHEREx (Spectro-Photometer for the History of the Universe, Epoch of Reionisation, and Ices Explorer).

Scheduled for liftoff aboard a SpaceX Falcon 9 rocket from Vandenberg Space Force Base in California on Friday, February 28, this cutting-edge observatory is set to embark on a two-year mission that will significantly enhance our understanding of the cosmos.

Designed with a budget of $488 million, SPHEREx will conduct a 3D survey of the entire sky, capturing data across a wide range of wavelengths that are invisible to the human eye.

🚀LAUNCH UPDATE

NASA and SpaceX are now targeting NET Sunday, Mar. 2 for the launch of the SPHEREx and PUNCH missions.https://t.co/Ry65lFP9kY pic.twitter.com/cq0wuzt2A9

— ARCHIVED: NASA LSP (@NASA_LSP) February 26, 2025

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By mapping more than 450 million galaxies and over 100 million stars in the Milky Way, the telescope will create an unparalleled cosmic catalog, providing critical insights into the universe’s formation, evolution, and the distribution of essential molecules necessary for life.

Why the SPHEREx telescope is unique

Mapping the universe in unprecedented detail

Unlike the James Webb Space Telescope (JWST), which focuses on deep-space observations in specific regions, SPHEREx will scan the entire sky twice a year.

The observatory’s unique spectrophotometer splits light into 102 distinct colours, enabling it to detect faint cosmic structures and pinpoint icy molecules across space.

Shaped like a megaphone, the SPHEREx mission will map the entire sky in infrared light to answer big questions about the universe. 📣

Here are 6 things to know about NASA's newest space telescope, set to launch Feb. 27: https://t.co/mx8vlvqBfk pic.twitter.com/Z6Qjyaeu87

— NASA JPL (@NASAJPL) January 31, 2025

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“SPHEREx is a testament to doing big science with a small telescope,” Beth Fabinsky, deputy project manager at Nasa’s Jet Propulsion Laboratory, told reporters last month.

One of the mission’s primary objectives is to investigate cosmic inflation — a period of rapid expansion that occurred a fraction of a second after the Big Bang.

Scientists aim to use SPHEREx’s data to track statistical patterns in the large-scale distribution of galaxies, which will provide deeper insights into how minuscule fluctuations in matter shaped the cosmos.

Unlocking the origins of water & life-forming molecules

Water is a fundamental component for life, and scientists have long speculated about its presence in interstellar clouds and how it travels to planets.

SPHEREx is designed to locate frozen water and biogenic molecules — such as carbon, hydrogen, oxygen, nitrogen, and sulfur — across the Milky Way.

These elements, crucial to life as we know it, are embedded in icy dust particles within massive molecular clouds, where stars and planets eventually form.

The telescope will perform more than 9 million line-of-sight observations to track the distribution and abundance of these icy compounds.

By determining their location and concentration, researchers hope to unravel the processes that delivered water and organic molecules to developing planetary systems, including our own.

“I expect the unexpected to come out of the data for this mission,” James Fanson, the project manager for SPHEREx told NPR.

Investigating molecular clouds & building blocks of planets

SPHEREx will conduct large-scale surveys of molecular clouds—vast regions of gas and dust where stars and planetary systems take shape.

Unlike traditional telescopes that capture two-dimensional images, SPHEREx will collect three-dimensional data, allowing scientists to see how ice and molecular compositions vary across different environments.

Nasa’s past missions, such as the Submillimeter Wave Astronomy Satellite (SWAS) in 1998, revealed far less water in gas form than anticipated, suggesting that much of it was locked in icy dust grains deep within molecular clouds.

Scientists believe that cosmic radiation could break apart these molecules if they weren’t shielded within these dense regions. SPHEREx will further investigate this phenomenon and determine how these frozen compounds survive and accumulate over time.

“This puzzled us for a while,” said Gary Melnick, a senior astronomer at the Center for Astrophysics | Harvard & Smithsonian. “We eventually realised that SWAS had detected gaseous water in thin layers near the surface of molecular clouds, suggesting that there might be a lot more water inside the clouds, locked up as ice.”

SPHEREx will also examine newly formed stars and the protoplanetary disks surrounding them to understand how their chemical compositions influence planet formation.

By studying these disks, scientists hope to uncover how water and biogenic molecules transition from interstellar clouds into developing planetary systems.

How SPHEREx will help others in space discovery

While SPHEREx is designed to conduct broad surveys, its findings will complement those of targeted telescopes like JWST, which provides high-resolution observations of specific celestial objects.

“If SPHEREx discovers a particularly intriguing location, Webb can study that target with higher spectral resolving power and in wavelengths that SPHEREx cannot detect,” Melnick said.

In addition to SPHEREx, the Falcon 9 rocket will carry another Nasa mission, PUNCH (Polarimeter to Unify the Corona and Heliosphere).

☀Our Sun creates a solar wind that fills the solar system!

NASA will take a PUNCH at solving how solar wind is created with four small satellites. PUNCH will launch as a rideshare with SPHEREx no earlier than Feb. 27! pic.twitter.com/f69HFqmwVz

— ARCHIVED: NASA LSP (@NASA_LSP) February 13, 2025

PUNCH consists of four satellites that will observe how the Sun’s outer atmosphere, or corona, transitions into the solar wind — a stream of charged particles that flows throughout the solar system and influences space weather.

Despite its immense scientific potential, SPHEREx is relatively compact. Weighing about 1,100 pounds (500 kilogrammes) — comparable to a grand piano — it operates with only 270 to 300 watts of power, less than a standard household refrigerator. It generates its power through a thick solar array, similar to those found on residential rooftops.

Once in orbit, the telescope will conduct a precise series of maneuvers, targeting specific sections of the sky for a few days at a time.

This meticulous scanning process will allow it to complete two full-sky surveys per year, building a comprehensive dataset that scientists can analyse for years to come.

With inputs from agencies