NASA just shut down a planetary defence mission that tracks asteroids. Now what? Premium

NASA’s NEOWISE mission operated in Earth’s orbit until late last week. It detected more than 3,000 near-Earth objects or NEOs – asteroids or comets whose orbits can bring them close to Earth,

Launched in 2011, NASA’s NEOWISE mission operated in Earth’s orbit until late last week. It detected more than 3,000 near-Earth objects or NEOs – asteroids or comets whose orbits can bring them close to Earth, even with the possibility of a collision. NEOWISE was shut down on August 8.

Surveying the population of NEOs is central to the emerging concept of planetary defence. That is, understanding and mitigating the risk of collision from asteroids large enough to do significant damage to Earth.

NEOWISE has made fundamental contributions to establishing the knowledge base for planetary defence, with more than 200 of the 3,000 objects it studied not known to us previously.

Now at mission end, and commanded by NASA to shut itself down, NEOWISE will re-enter Earth’s atmosphere before the end of this year. Where does that leave us with defending our planet?

NEOWISE started life as a different mission, simply called WISE (Wide-field Infrared Survey Explorer). It was designed to study the infrared radiation from distant galaxies in the universe.

Infrared means “beyond red” – infrared light sits just past the red end of the spectrum of colours humans can see. We know infrared radiation better as the heat from the Sun, for example, or from a radiator keeping us warm in winter.

When the coolant on the WISE mission ran out and these sensitive observations of galaxies couldn’t be carried out any more, NASA granted a mission extension under the NEOWISE name. They realised the telescope system was still sensitive enough to detect asteroids and comets that come close to Earth and the Sun, thereby having a very strong infrared signal.