Abstract
RECENT observations with the Spacewatch telescope indicate that the flux of Earth-crossing objects with diameters below about 50 m is some 10-100 times higher than predicted by simple extrapolation from the known main-belt asteroid population1,2. This might seem to imply3 a significantly greater terrestrial hazard from atmospheric explosions such as those that occurred over Revelstoke or Tunguska4,5. Here I show that explosions due to Spacewatch objects with diameters less than 50 m (having kinetic energies below about 10 megatonnes high-explosive equivalent) typically occur too high in the atmosphere to cause substantial surface damage. Exclusive of relatively rare iron objects, no comet or asteroid with an energy below ∼2 megatonnes threatens the Earth's surface. The high flux of small Earth-crossing objects identified by Spacewatch therefore does not imply a greater terrestrial hazard.
Original language | English (US) |
---|---|
Pages (from-to) | 701-703 |
Number of pages | 3 |
Journal | Nature |
Volume | 363 |
Issue number | 6431 |
DOIs | |
State | Published - Jun 24 1993 |
Externally published | Yes |
All Science Journal Classification (ASJC) codes
- General