NASA has begun construction on a space telescope that is specifically designed to detect asteroids. Called the NEO Surveyor, it will watch for asteroids that might pose a danger to Earth.
“NEO” stands for Near-Earth Object. Many near-Earth objects like asteroids and comets might regularly cross Earth’s orbit and could smash into Earth eventually. Most of them are small enough to burn up harmlessly in the atmosphere and just show up as “shooting stars.”
A few of them may pose a danger. Scientists suspect that a comet that exploded in Earth’s atmosphere caused the Tunguska event of 1908, which flattened about 2,000 square kilometers of forest and left charred and fallen trees behind.
A large asteroid caused a mass extinction event that wiped out most of the dinosaurs. Skywatchers and astronomers say that, if it can happen once, it can happen again.
Dangerous asteroids can be deflected, but first scientists need to find them.
Earlier this year, NASA tested a long-proposed method for deflecting asteroids with the DART mission. This mission sent a small robotic probe to slam into a small asteroid orbiting a bigger asteroid to change the course of its orbit.
The test succeeded. In fact, it changed the asteroid’s orbit slightly more than expected, though scientists say that part of the “extra” change might be caused by some of the asteroid’s material spraying off when the spacecraft hit it. The European Space Agency plans to send a follow-up mission called HERA in October 2024 to make closer observations of DART’s effect.
Before asteroids can be deflected, mission planners have to know they exist. NASA’s Planetary Defense Coordination Office (PDCO) intends NEO Surveyor to watch for these potentially dangerous asteroids. This new telescope will help NASA fill objectives outlined in the NASA Authorization Act of 2005, which ordered NASA to discover and categorize at least 90% of near-Earth objects over 140 meters in diameter that come within 30 million miles of Earth’s orbit.
“NEO Surveyor represents the next generation for NASA’s ability to quickly detect, track, and characterize potentially hazardous near-Earth objects,” said Lindley Johnson, NASA’s Planetary Defense Officer at PDCO.
The NEO Surveyor will include infrared sensors capable of finding asteroids that are hard to spot using visible wavelengths. Ground-based telescopes have difficulty finding these asteroids because most infrared light is filtered out as it passes through Earth’s atmosphere.
NEO Surveyor can also detect asteroids that might approach Earth from the direction of the Sun or have orbits that lead or follow Earth as it orbits the Sun. Scientists discovered the first known Earth Trojan that accompanies Earth in its orbit in 2011. These asteroids are hard to spot because the sun’s glare can drown them out.
Mission developers and manufacturers are already working on the instruments and some of the components of NEO Observer, including composite struts that will separate the instruments from the main body of the spacecraft to protect them from excess heat from the electronics. This helps the infrared detectors avoid returning false readings that might be caused by the waste heat generated by the rest of the spacecraft. Manufacturers also plan to fabricate the mirror from a solid block of aluminum using a custom-built diamond-turning machine to shape it.
“The project team, including all of our institutional and industrial collaborators, is already very busy designing and fabricating components that will ultimately become flight hardware,” said Tom Hoffman, NEO Surveyor project manager at JPL. “As the mission enters this new phase, we’re excited to be working on this unique space telescope and are already looking forward to our launch and the start of our important mission.”