The Asteroid Hunter

In 2005, Congress told NASA to find the asteroids that could wipe out a city. Twenty-one years later, the machine designed to do that job is finally being assembled.

There are roughly 25,000 near-Earth objects larger than 140 metres, big enough to devastate a region if one struck. Fewer than half have been found, according to Universe Today. The rest are out there, dark and hidden, some drifting through the glare of the Sun where ground telescopes simply cannot see.

NEO Surveyor is the first space telescope built specifically to hunt these objects, with launch set for September 2027. Unlike ground telescopes that detect light reflected off an asteroid's surface, NEO Surveyor detects the heat the asteroid radiates as the Sun warms it, an infrared approach that works even on objects as dark as coal and can peer close to the Sun where conventional telescopes are blind. The spacecraft will travel about 1.5 million kilometres from Earth to the Sun-Earth L1 Lagrange point, a gravitationally stable region between our planet and the Sun. There, a 6-metre sunshade blocks solar glare while solar panels on its Sun-facing side generate electricity, according to the NASA Science Blog and NASA JPL News.

The camera aboard NEO Surveyor uses two 16-megapixel infrared detector arrays, each tuned to a different infrared wavelength. By imaging the same patch of sky through both, scientists can measure an asteroid's temperature and, from that, calculate its size. All data flows back to Earth via NASA's Deep Space Network for processing and cataloguing into planetary defence calculations.

Amy Mainzer, the mission's lead at the University of California, Los Angeles, heads the science team. Jim Fanson, the missions project manager at NASA's Jet Propulsion Laboratory in Southern California, oversees assembly. The development cost baseline is $1.2 billion, with total mission cost estimated between $500 million and $600 million, according to Wikipedia.

The goal is finding 90 percent of near-Earth objects larger than 140 metres within a decade of launch. The mission's predecessor, a space telescope called NEOWISE, detected more than 34,000 previously unknown asteroids and over 3,000 near-Earth objects before its mission concluded in 2024, according to The Independent.

The delay has a pattern. In December 1941, the SCR-270 radar at Opana on Oahu detected a large group of aircraft approaching from the north 50 minutes before the attack on Pearl Harbor. Lieutenant Kermit Tyler assumed they were American B-17 bombers expected from the mainland and dismissed the report, as covered in Wikipedia's account of the radar warning. The detection system worked. Nobody acted on the output. The same structural failure appears in pre-COVID disease surveillance, where the signals existed but the institutional capacity to respond was never built until an outbreak made it unavoidable. Congress mandated asteroid tracking in 2005 without funding a space telescope to do it, a NASA independent review found, and five consecutive NEOCam proposals were rejected before NEO Surveyor was finally approved, per Wikipedia. The 2019 near-miss of asteroid 2019 OK, which passed within 65,000 kilometres of Earth undetected until the day before closest approach, may have been the forcing function that finally broke the logjam. There is no confirmed record of that direct connection in the sources reviewed, but the timing is tight.

The telescope changes the equation. Once NEO Surveyor begins its survey, it is projected to identify 200,000 to 300,000 new near-Earth objects down to 10 metres in diameter. That catalogue will arrive before any decision has been made about what to do with it. NASA's Office of the Inspector General noted in a 2025 review that management structures for the Near-Earth Object Observations Program needed improvement and that maintenance backlogs at ground observatories were a continuing problem, according to The Independent. Deflection technology, the other half of planetary defence, has received a fraction of the funding that detection has. Detection without a response plan is a catalogue of future disasters. That gap is where the next policy fight will be.