Spring 2020

Surveying for Near-Earth Objects

University researcher provides leadership for asteroid-hunting space mission.

The University of Arizona is spearheading work that will begin efforts to construct a space-based infrared telescope that could provide the capabilities NASA needs to search for asteroids and comets that pose impact hazards to Earth, called near-Earth objects, or NEOs.

Professor Amy Mainzer of the university’s Lunar and Planetary Laboratory will provide technical leadership for the projected mission, which will be a partnership with NASA’s Jet Propulsion Laboratory in Pasadena, California. The Near-Earth Object Surveillance Mission, or NEOSM, consists of a spacecraft, the NEO Surveyor, that will be designed to continuously collect infrared images of near-Earth space, along with an investigation team to process, analyze and archive the data from the craft.

Amy Mainzer

The spacecraft will use highly sensitive heat-sensing cameras to detect the infrared glow from asteroids and comets that are warmed by the sun as they get close to the orbit of Earth. Searching for asteroids by sensing their heat emission allows astronomers to not only detect their position and movement in space but also measure their sizes and identify even the darkest asteroids that may have primitive, carbon-rich surfaces.

The goal of the mission is to answer a fundamental question: “Are there asteroids or comets out there that can cause harm to the Earth over the next century?” says Mainzer, who also leads NASA’s Near-Earth Object Wide-field Infrared Survey Explorer mission, or NEOWISE. That mission uses an older spacecraft that has been reactivated to hunt for NEOs. The NEO Surveyor builds on the success of NEOWISE, which celebrated its 10th anniversary in December 2019.

“We’ve learned a lot from NEOWISE about how many asteroids are dark versus bright, and it’s been a valuable precursor mission, but it has now operated long past its expected life span. With the NEO Surveyor spacecraft, we can use what we’ve learned from NEOWISE to build a more highly capable and long-lasting spacecraft that will greatly complement the existing network of ground-based telescopes searching the skies for hazardous objects.”

The NEO Surveyor infrared space telescope will begin surveying by 2025 and will survey the skies for at least five years. It will greatly increase the catalog of asteroids larger than 460 feet (140 meters). Its projected design is optimized to carry two 16-megapixel infrared cameras capable of searching the twilight and dawn skies, which are much harder to observe with Earth-based telescopes. The plan is to place the telescope at a gravitationally stable point between Earth and the sun called the Lagrange 1, or L1, point. The L1 location will help the telescope cool to minus 390 degrees Fahrenheit (40K) without cryogenic coolant, as it will be well away from the heat emissions from Earth.

As the survey director, Mainzer will be responsible for all aspects of mission success, with flight project management provided by the Jet Propulsion Laboratory. The NEOSM is an element of NASA’s Planetary Defense Program managed by its coordination office, which is tasked to detect, assess and lead efforts in response to any threat of asteroid and comet impacts.

“More than half of all known potentially hazardous asteroids were discovered by the Catalina Sky Survey and Spacewatch telescopes operated by the University of Arizona over the past two decades,” says University of Arizona President Robert C. Robbins. “We have a longstanding tradition as a pioneer in planetary defense, and we are very proud to bring this history to the next level to help protect our planet from impact hazards.”