Mapping the past from space

Animation of the sun shields of SPHEREx

NASA’s high-powered satellite telescope SPHEREx, equipped with dilemma/survey planning software built by Arizona State University researchers, will help unlock the mysteries of the universe.

On a crisp, clear night, we may find ourselves gazing up at the sky. As we stand in our present, we sometimes forget that we are reveling in the sky’s past. We’re captivated by starlight whose age can be measured not in minutes or days but in years — traveling trillions of miles just to be witnessed by planet Earth.

With billions of stars in our galaxy and billions of galaxies across the universe, what can be seen with the naked eye or a high-powered ground-based telescope is only a drop in the bucket. These mysteries happening behind the visible ancient light have intrigued scientists for generations.

Sparked by this desire to see further into the past, scientists at NASA and Arizona State University are moving one step closer to launch with the Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer, or SPHEREx a high-powered satellite telescope.

SPHEREx’s mission is to map the entire sky creating an unprecedented new database of galaxies, stars and other celestial objects. It will collect data that will reach far into the past to see the formation of planetary systems, the history of galaxies and perhaps the origins of the Big Bang. 

Several new technologies will be used on this space observatory’s powerful infrared telescope. The system measures the infrared spectrum of the entire sky in each of 102 wavelength bands separately, detecting spectral features in each observed galaxy to determine its redshift (changes in the light’s wavelength). It will use these measurements to build an unprecedented 3D map of galaxies.

As a Phase C project at NASA, the SPHEREx team can begin work on creating the detailed design and building all the hardware and software systems needed to get to launch.

Sean Bryan, an associate research scientist in the School of Electrical, Computer and Energy Engineering, one of the six schools in the Ira A. Fulton Schools of Engineering at ASU, began working on the project as a post-doctoral researcher in 2015. His involvement with SPHEREx ebbed and flowed over the years, but the chance to resume working on the observing schedule [MC3] brought him back on board a little over a year ago.

Bryan, along with Professor Philip Mauskopf, Regents and Foundation Professor Rogier Windhorst and Assistant Research Scientist Seth Cohen, all from the ASU School Of Earth and Space Exploration, are working in partnership with NASA’s Jet Propulsion Laboratory, or JPL. They are tasked with building the survey planning software, a significant part of the SPHEREx mission. As the telescope scans the sky collecting images and data of the entire sky from low-Earth orbit, only a limited area of the sky is observable because it must avoid excess heat and light from Earth, the moon or the sun. The telescope also needs time to pause to downlink information. Mapping the entire sky while meeting all of these constraints, in conjunction with a tight 25-month time frame, means that scheduling every data collection point is crucial.

The multidisciplinary team also includes undergraduate computer science student Cody Roberson, earth and space exploration undergraduate student Julian Mena and physics graduate student Pao-Yu Wang.

SPHEREx is a global initiative with teams from all over the world contributing to its success.

“The SPHEREx mission will be NASA’s exquisite all-sky eye in the infrared,” says Windhorst. “The telescope will find millions of targets ranging from ices in the solar system and our own Galaxy to galaxies, galaxy clusters, and some of the most distant quasars.”

Although the observatory launch is still several years away, the ASU team’s software system is getting close to a viable product. A significant upcoming milestone will be shipping the software for testing on JPL’s Mission Operations computer systems.

“We’re looking forward to real-world testing and integration with JPL,” Bryan says. “We will be an active partner and support the software from testing all the way through the mission.”

The SPHEREx telescope will be roughly the size of a compact car and will reside in low-Earth orbit. Its mission is expected to last 26 months, but the team hopes it will remain functioning long after that.

Top image: Animation showing the preliminary sun shield design for SPHEREx.
Photo credits: NASA/JPL-Caltech