While NASA's NEOWISE telescope ended its journey through space on Nov. 1, 2024, the team at IPAC, a science center at Caltech, was working on one further gift from the prolific mission.
The final data release from NEOWISE was released to the astronomy community just two weeks later, on Nov. 14, encompassing over 26 million images and nearly 200 billion sources detected by the telescope. And today, IPAC is releasing six new images from the mission's archival data as a tribute to this landmark project, available here: https://www.astropix.org/link/3b2x
NEOWISE was launched as the Wide-field Infrared Survey Explorer (WISE) in 2009 and then reactivated in 2013 as NEOWISE, the asteroid-hunting phase of the mission. The infrared space telescope studied the entire night sky and conducted 21 complete sky surveys during more than a decade of operation. The mission focused on identifying and studying small objects in our solar system like asteroids and comets, also known as near-Earth objects (NEOs), but the infrared data collected by the telescope has proven to have countless applications throughout the field of astronomy.
The mission concluded operations in July 2024, and during its 15 years in space, scientists have been able to revisit the same areas of the sky again and again, with most being observed by NEOWISE at least 220 times. This repeated observation helps astronomers search for and study objects that change in brightness or location.
"Being able to watch the changing sky for nearly 15 years has opened a new avenue for time-domain science, for everything from the closest asteroids to the most distant quasars," said Joe Masiero, Research Scientist at IPAC and the Deputy Principal Investigator of the mission.
In recent years, NEOWISE has enabled scientists to study curious objects like brown dwarfs and discover patterns in large populations of comets. Over its mission lifetime, NEOWISE has characterized over 3000 NEOs—approximately 10% of the known population, and something that was only possible due to its long tenure scanning the sky.
The final NEO observed by NEOWISE, known as 2007 LV8, was seen over 100 times in the closing days of the survey since it closely followed the telescope's scan pattern.
"Because of NEOWISE's extensive view of the sky, we get a more complete picture of the asteroids and comets in Earth's orbital neighborhood. The data provide a unique way of understanding factors like the size and rotation period of these NEOs," said Roc Cutri, NEOWISE Task Lead and Project Scientist at IPAC.
The team at IPAC was responsible for the ingestion and processing of raw data, production of final data products, and archiving mission science and engineering data. IPAC also distributes WISE/NEOWISE data to the community through the NASA/IPAC Infrared Science Archive (IRSA) and provides services such as powerful analysis and visualization tools. The IPAC Communications & Education team prepares mission images for public release in the AstroPix image gallery.
Never-before-seen images from NEOWISE
During the original WISE mission, over 100 areas of the sky were highlighted in public image releases, but they revealed only a tiny fraction of the full-sky coverage of the survey.
"The WISE and NEOWISE data releases are built for researchers, but they also embody some of the most amazing images of our infrared sky," said Robert Hurt, IPAC Visualization Scientist. "They are so easy to work with it's almost too easy to make a beautiful image from them! That's why I wanted to revisit the archive to locate some hidden gems we missed before."
To find new interesting areas of the sky, the positions of the previous images were overlaid onto maps of the sky using data from WISE and other missions. The new map revealed many zones that have not been highlighted for the public but contain fascinating regions of cosmic dust where stars are born. Six spots were selected, with many of them spanning large areas of the sky—a distinct advantage of an all-sky survey such as NEOWISE.
One image stands out as particularly meaningful to the IPAC community: NEOWISE's view of the California Nebula.
Named after the dust cloud's resemblance to the California coastline, Masiero says it commemorates the years of hard work and dedication of the NEOWISE data processing team at IPAC, located in Pasadena, California.
"I'm really grateful for all of the people at IPAC who have put so much effort into making this the best dataset possible, for today and for future generations," said Masiero.
The California Nebula is located in the Milky Way, about 1000 light-years away, in the Perseus constellation. It is a dusty region illuminated by the nearby massive star Menkib, born just a few million years ago. The entire California Nebula stretches across 100 light-years and is fully captured in this wide-field view. The dust clouds glow brightly in longer wavelengths of infrared light, displayed here in green and red.
The new images pulled from the archives represent the billions of sources detected by NEOWISE waiting to be studied by future researchers.
"We know there are more things to discover in the NEOWISE data that we just haven't noticed yet," said Masiero. "As astronomers develop new tools and techniques and as new surveys are conducted, we can be sure the NEOWISE archive will be one of the first places we look for the data needed to better understand our universe."
NEOWISE's legacy is only just beginning
As astronomers continue to mine the NEOWISE archive at IRSA, there are many untold stories of comets, asteroids, nebulae, and more waiting in the data.
Yuna Kwon, a solar system astronomer and IPAC archive scientist, first joined as a postdoctoral fellow in 2023. Even though the NEOWISE mission ended not long after, her work with its data is only just beginning.
Along with Masiero, Kwon is leading a project called COSINE, Cometary Object Study Investigating their Nature and Evolution, cataloging and analyzing comets observed by NEOWISE.
"Together with my amazing colleagues at IPAC, we now have the largest-ever consistently analyzed comet database and are preparing publications based on our findings," said Kwon.
Kwon studies comets because they are some of the oldest and most primitive objects in our solar system. Their physical properties could tell us about the conditions during the solar system's formation.
"Comets are like cats — they have tails and do precisely what they want," said Kwon. "Thankfully, NEOWISE has a treasure trove of data to study these idiosyncratic objects."
Before working with NEOWISE data, Kwon said that it was hard to decipher large-scale trends from only a small number of comets. But now with COSINE and NEOWISE data, she is able to understand the big picture.
"I'm truly enjoying this exploration," said Kwon. "My experience with NEOWISE data has broadened my perspective and deepened my understanding of the comet population itself, putting the observations in a broader context of the formation and evolution of the solar system."
Going forward, Kwon hopes to combine the knowledge gained from NEOWISE with new data from upcoming observatories including NEO Surveyor and SPHEREx.
