In March, 1998, there was major press coverage of newly a discovered asteroid near Earth, catalogued under the name 1997XF11. What happened is that early calculations of its orbit showed that it could come extremely close to Earth in the year 2028, and possibly could collide with Earth. Some reports had it within 30,000 kilometers of Earth -- one eighth the distance to the Moon.
After the initial press reports, the asteroid's orbit was recalculated with greater precision and found to come within a million kilometers, making an impact with Earth unlikely. At the very least, it will be observable by the human eye, and probably bright.
Nonetheless, near-misses of asteroids are not new, and the press missed many more alarming events. 1997XF11 benefitted largely from the Hollywood movies Deep Impact and Armageddon. Another difference is that all the past asteroids were discovered after they had already passed Earth -- we never saw them coming. This is the first asteroid whose orbit we calculated to make a close approach in the future of our generation.
In the first four years after the non-defense Spacewatch Telescope was put into operaton in the early 1990s using a state of the art sensor with a moderately sized telescope in Arizona, four asteroids were detected passing closer to the Earth than the Moon -- much closer than 1997XF11 is likely to come. The asteroid 1989FC, discovered shortly after it passed perilously close to the Earth, would have had the impact power of 1000 one megaton bombs.
Large asteroids have hit Earth as recently as 1908, when an asteroid rich in ices only 50 meters wide exploded in the upper atmosphere 5 kilometers above Tunguska, Siberia, scorching trees out to 14 km from the center, flattening the forest out to 30 km, and blowing things around up to 100 km away. The explosive power was greater than the Hiroshima and Nagasaki bombs. Fortunately, it was just grazing rather than a more vertical impact, and it hit a remote northern territory.
As one researcher put it: "[I]f the same object had exploded over New York City, the scorched area would have reached nearly to Newark, New Jersey. Trees would have been felled beyond Newark... The man knocked off his porch could have been in suburban Philadelphia. 'Deafening bangs' might have been heard in Pittsburgh, Washington, D.C, and Montreal."
If instead it had been a nickel-iron asteroid and a little bit larger, and hit the ocean (which covers 70% of Earth's surface), it could cause a tsunami wave giant enough to smash into numerous modern 20th century coastal cities with no warning.
An asteroid impact could make Cold War weapons look like child's play.
What we need is a defense against asteroids. A liberal space development program would give us this capability. It would be a way to save the world by making money in space.
This page was last updated: 21 June 1999
Copyright © 1983-1999 by Mark Prado, All Rights Reserved except where specifically stated otherwise.
Projects to Employ Resources of the Moon and Asteroids Near Earth in the Near Term