Two NASA missions finally launched from the California coast and soared toward the stars late Tuesday night, overcoming a week of delays to get to orbit. Both aim to unravel mysteries about the universe — one by peering far from Earth, the other by looking closer to home.
The rocket’s chief passenger is SPHEREx, a space telescope that will take images of the entire sky in more than a hundred colors that are invisible to the human eye. Accompanying the telescope is a suite of satellites known collectively as PUNCH, which will study the sun’s outer atmosphere and solar wind.
The launch has been postponed several times since late February for mission specialists to perform additional checks on the SpaceX Falcon 9 rocket and NASA spacecraft. Gloomy weather also contributed to a scrubbed launch on Monday night. But that was forgotten on Tuesday as SPHEREx and PUNCH lifted off from the Vandenburg Space Force Base against the black expanse of clear California sky at 11:11 p.m. Eastern time.
Roughly two minutes later, the rocket’s reusable booster separated from the upper stage and flipped back toward Earth for a controlled landing near the launch site.
Forty-two minutes into the launch, SPHEREx floated away from the rocket’s upper stage. The four PUNCH satellites, released in pairs, followed suit about 10 minutes later. Both mission teams are awaiting signal from the spacecraft, which are orbiting approximately 400 miles above Earth’s terminator, the line separating day and night on our planet, and over the north and south poles. This type of orbit is known as sun-synchronous because it keeps the spacecraft oriented in the same position relative to our sun.
That’s advantageous for both spacecraft. PUNCH will have a clear view of the sun around all times, while SPHEREx will stay pointed away from it, avoiding light from our home star that could mask fainter signals from faraway stars and galaxies.
Charting the cosmos
SPHEREx is short for Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer. The mouthful of a name is fitting for the vastness of its goal: to survey the entire sky in 102 colors, or wavelengths, of infrared light.
“It’s really the first of its kind,” said Olivier Doré, a cosmologist at NASA’s Jet Propulsion Laboratory and the mission’s project scientist. By contrast, NASA’s Wide-field Infrared Survey Explorer, which retired in 2011, mapped the sky in just four hues of infrared.
Scientists will use the data from SPHEREx to study how the total light emitted by galaxies has changed through cosmic time and to chart where frozen water and other ingredients essential for life exist across the Milky Way.
“It’s thought that the oceans on Earth originated from these interstellar ice reservoirs,” said James Bock, a cosmologist at the California Institute of Technology and principal investigator for the mission.
A three-dimensional map charting the uneven clumping of galaxies across the universe today — some parts thick with galactic gas and dust, others more sparse — will also help physicists learn more about inflation, the rapid ballooning of the cosmos that occurred a split second after the Big Bang.
According to Dr. Bock, tiny irregularities emerged as matter spread across the early universe. But inflation “blew them up to cosmic scales,” he said, and the imprint of those irregularities is preserved in the overarching structure of today’s cosmos.
Physicists have long used measurements of the cosmic microwave background — the light left over from the Big Bang — to study inflation. But a galactic survey will allow them to gain an understanding of the physical processes that drove that extreme expansion.
“This is an idea that has been around, but we’re really the first experiment designed to look for this,” Dr. Bock said.
SPHEREx, which looks like a giant megaphone, will record around 600 images each day for more than two years, capturing light from millions of stars in our cosmic backyard and even more galaxies beyond it.
Using a technique called spectroscopy, the telescope will separate the light into different wavelengths, like a glass prism splitting white light into a rainbow of colors. The color spectrum of an object in space reveals information about its chemical makeup and distance from Earth.
At the end of its run, SPHEREx will have sampled the whole sky four times. “We’ll have spectra of every kind of celestial object — planets, stars, comets, asteroids, galaxies,” Dr. Doré said. “And every time we look at the sky in a different way we discover new phenomena.”
Tracking the solar wind
According to Craig DeForest, a heliophysicist at the Southwest Research Institute, hot plasma continuously streaming from our sun washes over everything in the solar system, including us. It is the solar wind.
“We are not separate from our star,” he said. “We are bathed in it.”
Dr. DeForest is the principal investigator for PUNCH, which stands for Polarimeter to Unify the Corona and Heliosphere. Data taken with PUNCH will elucidate the boundary where the sun ends and the solar wind begins. The two-year mission will also help forecasters better predict the potential effects of space weather, from power outages to glittering northern lights.
Many solar missions focus on observing the sun’s outer atmosphere, known as the corona. “It’s like studying human biology with only an electron microscope,” Dr. DeForest said — great for looking at cells, bad for learning about anatomy.
PUNCH is designed to measure both the corona and the broader cocoon of solar wind swaddling our solar system. The mission consists of four 140-pound satellites, each around the size of a suitcase.
One satellite carries a coronagraph, which will take pictures of the sun’s corona. The other three are equipped with cameras to capture wider views of the solar wind as it leaves the corona and permeates the solar system.
Each satellite has three polarizing filters, through which only waves of light aligned in a particular direction can pass. That’s similar to the way polarized sunglasses block glare. By measuring polarized light, scientists will be able to reconstruct the position, speed and direction of the corona and the solar wind in three dimensions.
For the first time, they will also be able to track the evolution of coronal mass ejections, violent blasts of solar material, as they make their way to Earth and induce space weather.
Joseph Westlake, the director of heliophysics at NASA, likened the data that PUNCH will collect to measuring a baseball after it has been thrown by a pitcher. Everything up until the ball leaves their hands, Dr. Westlake explained, is captured by missions like NASA’s Parker Solar Probe and the Solar Dynamics Observatory.
“But actually seeing the ball as it goes from the hand to the home plate is PUNCH,” Dr. Westlake said. “It takes what we see at the sun and connects it to what we experience on Earth.”