DA14 closest asteroid on record to surface of the planet.
If you weren’t glued to binoculars or a telescope last Friday you missed the closest recorded asteroid to Earth in recent history, the 2012 DA14. Just 27,600 kilometers above the surface of the Earth the asteroid was closer to the planet than many artificial satellites.
The asteroid is fifty meters wide; equivalent in size to an Olympic swimming pool, and with an estimated weight of 143,000 tons it would have caused major damage if it had made an impact on the Earth. Scientists predicted that if impact had occurred it would affect an area of approximately 2000 square kilometers.
Telescopes around the world focused in as the fast moving space rock travelled by, at a rapid pace of 7.82 kilometers per second relative to the Earth. Moving from the southern to northern hemisphere throughout the day the DA14 was visible in some areas of Australia, Asia and Europe with the aid of telescopes or binoculars. Astronomers around the world recorded this historical event with a wide array of astronomical photography. A variety of webcasts are available online of the close brush with the asteroid.
The next astronomical event with a similar proximity to Earth is not predicted to occur until 2029, but even that event will not come quite as close to the planet. Since the records of systematic surveys of the sky began in the mid-1990s this is the largest event that astronomers have known about in advance. This event could be the last close pass for this asteroid because the force of the Earth’s gravitational field will alter the orbit of DA14 further away from the planet. A Spanish observatory a year ago discovered the asteroid, and its path has been closely monitored since that time. DA14 avoided impact with Earth by a mere fifteen minutes.
The use of radar enabled scientists to learn more precise data about the composition and structure of the asteroid during its flight. The resources on similar asteroids are the motivation behind space mining companies like Deep Space Industries and Planetary Resources.
Deep Space estimated the economic value of DA14 to be close to $195 billion, including water and metals. Critics, including a spokesperson from the National Radio Astronomy Observatory, say that Deep Space had greatly exaggerated the accessibility of the nearby resources. Plans for commercial mining of asteroids include harvesting the metals found in the rock as well as using the water in asteroids to refuel spacecraft efficiently. The DA14 asteroid is not accessible and the company has no plans to harvest it, rather they are using the near miss as an example of the relative abundance of similar asteroids passing near Earth.