NASAs NEO Surveyor mission will protect Earth from asteroids

NASA is building the first spacecraft specifically to identify large numbers of asteroids and comets that can impact the planet in the future. The Near Earth Object (NEO) Surveyor spacecraft will scan the Solar System using sensitive infrared detectors to track the most elusive objects in the neighbourhood of the Earth. Dark asteroids and comets do not reflect much of the light from the Sun in optical frequencies, but shed the excess heat, which is visible as infrared radiation. No large asteroids are comets are expected to strike the Earth for centuries into the future, but even smaller, denser objects can cause significant local damage on impact. 

Particularly problematic are asteroids that approach the Earth from the direction of the Sun. The light from the Sun saturates detectors in this direction, making in challenging to spot the dark rocks hidden in the glare of Sunlight. The spacecraft will use a large sunshade to protect the detectors from saturation, and block light from the Sun while still being able to observe within 45° of the Sun. NASA is aiming to deploy the NEO Surveyor spacecraft at the first Lagrange point in the Sun-Earth system, a region of stable galaxy between the Earth and the Sun where the spacecraft can remained stationed with minimal expenditure of fuel. 

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The NEO Surveyor instrument enclosure has shiny black and white surfaces to manage the temperature of the spacecraft, and to prevent the heat produced by the spacecraft itself from interfering with the pair of sensitive infrared detectors. The telescope has an aperture of nearly 50 centimetres. The three-mirror anastigmat telescope uses a set of curved mirrors to focus light onto the infrared detectors in a way that minimises optical aberrations. The NEO Surveyor project is being developed by the Jet Propulsion Laboratory in California, with NASA aiming to launch the mission in late 2027.