Pandora, a keen-eyed satellite built to study exoplanets, readies for launch
After clearing its last hurdle on its way to space, the Pandora satellite mission is awaiting to be launched into orbit, where it will study at least 20 exoplanets and their host stars over long periods of time.
image: Artist's concept of NASA's Pandora mission, which will help scientists untangle the signals from the atmospheres of exoplanets – worlds beyond our solar system – and their stars.
Credit: NASA's Goddard Space Flight Center/Conceptual Image Lab
Pandora, the latest in a long portfolio of University of Arizona's space science missions, has cleared its last major milestone on its journey into space. This week, Pandora – a satellite about the size of a fridge – was mounted inside the launch vehicle, a SpaceX Falcon 9 rocket. Pandora now awaits blast-off from Space Launch Complex 4E at Vandenberg Space Force Base in California. The launch window opens at 6:19 a.m. Arizona time (8:19 a.m. EST) on Sunday, Jan. 11. SpaceX will provide a livestream of the event.
The Pandora satellite will provide in-depth study of at least 20 known planets orbiting distant stars to determine the composition of their atmospheres – especially the presence of hazes, clouds and water. It consists of telescope with an 18-inch mirror and instrumentation that allow it to analyze light spectra and measure brightness to an extreme level of accuracy. Light spectra are like signatures that provide scientists with information about the chemical makeup of a star and the atmosphere of a planet that orbits it, while subtle dips in brightness are tell-tale signs that a planet is crossing in front of its star as seen from the observer.
The first space telescope built specifically for detailed multi-color observations of starlight filtered through the atmospheres of exoplanets, Pandora will help interpret data both from previous missions like NASA's Kepler Space Telescope and ongoing missions such as the James Webb Space Telescope, said Daniel Apai, the U of A lead of the mission and its exoplanet science team, and a professor for astronomy and planetary sciences at the U of A Steward Observatory and Lunar and Planetary Laboratory.
"Pandora opens a new chapter in exoplanet science, and it will guide future projects in their search for habitable worlds," he said.
The Pandora SmallSat was selected as an inaugural NASA Astrophysics Pioneers mission in 2021. NASA Pioneers are fast-paced missions that are uniquely able to respond to exciting, newly emerging science questions, according to Apai. By design, more than half of the Pandora mission leadership roles filled by early-career scientists and engineers, providing an exciting opportunity for emerging leaders in space sciences. After launching into low Earth orbit, Pandora will undergo a month of commissioning before embarking on its one-year prime mission. All the mission's data will be publicly available.
Once the Pandora satellite has reached its orbit and passed all initial tests, the mission will be operated by the U of A's Multi-Mission Operation Center, or MMOC, which is part of the Arizona Space Institute. Through a contract with NASA, the MMOC, housed at the Advanced Research Building on the U of A's main campus, will manage and track the spacecraft's operations in real time, monitor telemetry – data sent down from the satellite – and overall spacecraft health.
"This is the first time an orbiting astrophysics mission is operating from our new Mission Operations Center at the university," said Erika Hamden, director of the Arizona Space Institute. "The PHOENIX Mars Lander and the OSIRIS-REx asteroid sample return mission were operated very successfully from the U of A, and now we're excited to continue that legacy with Pandora. We hope this represents just the first of many transformational NASA missions that ASI will operate out of the Advanced Research Building."
Pandora will stare at each of its 20 target planets and their host stars for 24 hours at a time before moving on to the next and repeat that process for a total of 10 observations for each system. The data will establish a firm foundation for interpreting measurements by NASA's James Webb Space Telescope and future missions aimed at searching for habitable worlds.
"From combining Pandora's observations with data from James Webb, we will better understand the atmospheres of those exoplanets," Apai said. "At this point, our goal is not to assess these planets for life, but to probe their atmospheres for any water vapor and – importantly – understand their host stars."
Until just over three decades ago, no one knew whether there were planets outside our solar system, let alone planets that could potentially be habitable to life forms. The first exoplanet was discovered in 1992, kicking off a hunt for planets hiding elsewhere in our home galaxy, the Milky Way. As of the time of writing, scientists have discovered more than 6,000 worlds orbiting stars other than our sun. Among exoplanets, the search for worlds that could potentially harbor life has naturally attracted outsized attention from researchers and the public alike.
To determine whether a planet even has the potential of sustaining life, scientists look for certain clues in its atmosphere, such as chemical signatures of oxygen or water.
"With the Pandora satellite poised for launch, we stand at the cusp of a new era in cosmic discovery — one in which we will, for the first time, peer deeply into the atmospheres of distant worlds and expand humanity's understanding of what lies beyond our own sky," said Tomás Díaz de la Rubia, senior vice president for research and partnerships. "At the University of Arizona, space missions like Pandora reflect our enduring legacy of excellence in observational astronomy and our commitment to research that deepens human knowledge and serves the public good."
Because of the enormous distances involved – dozens, if not hundreds of light-years from Earth – observing exoplanets directly has proven extremely challenging. Any planet with conditions conducive to life would be too cool to register in telescopic observations. To get around this, astronomers have resorted to zooming in on their host stars and detecting any planets that may be present through indirect means.
One such technique measures the tiny dip in brightness that occurs when a planet passes in front of its star while traveling along its orbit. Taking this so-called transit method a step further, astronomers such as Apai's group use spectroscopy to analyze the star light that is filtered as it passes through the planet's atmosphere, in search for clues about the chemical elements and molecules present in the atmosphere.
The only problem with that approach, Apai explained, is that stars aren't the immaculate, uniform, shiny objects familiar from books and illustrations. Most are swirling balls of roiling gas and plasma, their faces smudgy and dotted with sunspots, and some even have atmospheres with cloud-like features wafting across the bright disk. Depending on whether a transiting planet happens to be backlit by a "clean" section of its star or one that is "smudgy," the light measurements will vary, and all bets are off.
"Pandora is the first mission really designed to study the stars and their planets together," he said. "We will have a much better ability to separate the contribution from the star from that of the planet."
For more information on the University of Arizona's long history and achievements in space science, visit www.arizona.edu/research/space.