NASA’s Wide-field Infrared Survey Explorer (WISE) has returned to the hunt for asteroids after more than a two-year hiatus. WISE was reactivated into service back in August of this year. The spacecraft has now been renamed Near-Earth Object Wide-field Infrared Survey Explorer or NEOWISE for short.
WISE was launched by NASA in 2009 spending more than a year mapping-out our sky by using infrared light. In this spectrum of light, galactic dust glows allowing WISE to have taken many stunningly images of space. WISE was then shut down in 2011 when the satellite ran out of coolant. Now reborn as NEOWISE, the satellite was turned back on in September to hunt for near-Earth asteroids.
Asteroids are active emitters of light in the infrared spectrum and NEOWISE didn’t waste any times spotting any. The satellite took a series of images of 872 Holda as the red dots of the asteroid tracked through the night sky. Holda orbits at a safe distance from Earth, orbiting the Sun between Jupiter and Mars. The asteroid is a huge 26 miles across.
Although Holda was spotted by NEOWISE, it is not one of the main targets of the project. The satellite’s main purpose is to spot objects near Earth that pose serious threats to colliding with our own planet. The principal investigator for NEOWISE, Amy Mainzer, said that all on-board is looking good and the satellite should start to find previously known asteroids in the next few months. Mainzer said that it’s nice to know that NASA is taking asteroid threats to our planet seriously.
By operating NEOWISE, Mainzer and her colleagues are better understanding how to operate a Near-Earth Object Camera, or NEOCAM. The team have been working on the design of the next generation of NEOWISE technology. This time the NEOCAM will be designed from the ground up to specifically hunt for asteroid threats.
NASA will return to hunting asteroids from satellite based telescopes as they offer many advantages over ground-based telescopes here on Earth. NEOWISE is able to better detect faint or dimmer asteroids and it does make it easier to determine the asteroids size.
When observing an asteroid in visible light, the asteroid’s size will be based on how far away the asteroid is and how bright it shines. Estimates made in the visible spectrum of light were previously inaccurate due to the observations being affected by the objects reflective properties. The visible light spectrum makes small shiny asteroids look the same size as bigger darker asteroids. NEOWISE will see through the visible light signatures of the asteroids and base the asteroid’s size estimates on the heat signatures instead.
NEOWISE is just one of NASA’s recent moves to learn more about identifying, capturing and the relocation of asteroids. They hope to land an astronaut on the surface of an asteroid by year 2025. This is a move to open doors for privately funded space companies to return to asteroids to mine them for their rich and rare resources. For now NEOWISE will continue to hunt for asteroids by simply spotting and tracking them, until its newer sibling is put into orbit.
By Brent Matsalla