NASA’s Near-Earth Object Surveyor space telescope is starting to build and calibrate its mirrors, and work on other spacecraft components is accelerating rapidly. NASA’s new asteroid-hunting spacecraft is taking shape at NASA’s Jet Propulsion Laboratory in Southern California. Called NEO Surveyor, the cutting-edge infrared space telescope will search for the most elusive asteroids and comets that could pose a threat to our planet. In fact, it’s the agency’s first space telescope specifically designed to protect the planet.

Targeted for launch in late 2027, the spacecraft will travel a million miles to a region of gravitational stability between Earth and the Sun called the L1 Lagrange point. From there, the large sunshield will block the glare and heat of sunlight, allowing the mission to detect and track near-Earth objects approaching Earth from the Sun in a way that other observatories have struggled to do. The space telescope could also detect asteroids called terrestrial Trojans, which lead and trail our planet’s orbit and are difficult to see from the ground or Earth’s orbit.

NEO Surveyor relies on advanced detectors that observe two bands of infrared light that are invisible to the human eye. Objects around Earth, no matter how dark, glow brightly in the infrared range when heated by the sun. This will allow the telescope to find dark asteroids and comets that don’t reflect much visible light. It will also measure these objects, which can be a challenge for visible-light telescopes, which have a hard time distinguishing small, highly reflective objects from large, dark ones.

“NEO Surveyor is optimized to help us do one specific thing: allow humanity to find the most dangerous asteroids and comets early enough so we can do something about them,” said Amy Meinzer, NEO Surveyor research director and University Professor in Los Angeles, California. “We aim to build a spacecraft that can find, track and characterize the objects most likely to hit Earth. In the process, we learn a lot about their origin and evolution.”

Comes to focus

A spacecraft’s only instrument is its telescope. About the size of a washing machine and dryer, the telescope’s blocky aluminum body, called an optical bench, was built in a JPL cleanroom. Known as a three-mirror anastigmatism telescope, it will rely on curved mirrors to focus light onto infrared detectors in a way that minimizes optical aberrations.

“We carefully managed the fabrication of the spacecraft’s telescope mirrors, and all were delivered to JPL’s clean room by July,” said Brian Monacelli, JPL’s principal optical engineer. “The mirrors are diamond-lathed and polished from solid aluminum. Each one exceeds mission performance requirements.”

Monacelli examined the mirror surfaces for debris and damage, and then a team of JPL optical mechanics and engineers attached the mirrors to the telescope’s optical stage in August. They will then measure the telescope’s performance and adjust its mirrors.

Complementing the mirror are the telescope’s mercury-cadmium-telluride detectors, similar to those used on NASA’s recently launched NEOWISE mission (short for Near-Earth Object Wide-field Infrared Survey Explorer).

These detectors have the advantage that they do not necessarily require cryogenic coolers or cryogens to lower their operating temperature in order to detect infrared waves. Cryocoolers and cryogens can limit the life of a spacecraft.

Instead, NEO Surveyor will stay cool by using its large sunfinder to block sunlight from heating the telescope and by orbiting outside the Moon’s orbit, minimizing heating from Earth.

The telescope will eventually be housed inside an instrument enclosure assembled in JPL’s historic High Bay 1 clean room, where spacecraft such as Voyager, Cassini and Perseverance were built for NASA missions. The enclosure, made of a dark composite material that conducts heat, will help cool the telescope and prevent its own heat from blurring observations.

Once that is complete in the coming weeks, the body will be tested to make sure it can withstand the rigors of space exploration, then it will be fitted with rear sunshades and the electronics that will power and control the spacecraft.

“The entire team has worked hard over a long period of time to get to this point, and we are excited to see the contributions from the hardware as well as our corporate and industry collaborators across the country,” said Tom Hoffman, NEO Surveyor project manager at JPL.

“From the panels and wiring for the instrument housing to the detectors and mirrors for the telescope and the components needed to build the spacecraft, the hardware is being fabricated, shipped and assembled to create this incredible observatory.”

The NEO Surveyor assembly can be imaged 24 hours a day, seven days a week using the JPL camera.