Ivan's hammer

Ivan's Hammer is the idea to use a natural asteroid or meteoroid as a weapon of mass destruction in a first-strike role. The concept can be traced back to the 1960s. At the annual meeting of the American Astronautical Society, in January, 1962 Dandridge M. Cole warned that as early as 1970 the Soviets could develop the technology to divert a near earth asteroid to impact a target on earth.

A RAND Corporation study from 2002 also discusses the method and feasibility of such an application. The American astronomer Carl Sagan warned about the possibility of asteroid deflection technology being used as a weapon in several works, describing a "deflection dilemma" for projects seeking to address the asteroid impact hazard.

In popular culture

 * The 1955 movie This Island Earth where the planet Metaluna is at war with the Zagons who use spaceships that bombard with guided flaming meteors.
 * During the late 1960s and early 1970s a number of science fiction writers used the concept in story ideas, most notably Robert Heinlein in The Moon is a Harsh Mistress (1966) where a rebellious Lunar colony uses large payloads of mined ore to bombard Earth from the Moon; Rendezvous with Rama by Arthur C. Clarke (1972); and Lucifer's Hammer by Larry Niven and Jerry Pournelle (1977).
 * The 1992 videogame Assault suit valken featured a level in which an asteroid colony is used to target a city on earth during re-entry.
 * Modified concepts that utilized large man-made constructions can be seen in Mobile Suit Gundam and its derivative series, where large space colonies were dropped onto Earth, sometimes right onto population centers.
 * In the last mission of the 2001 video game Ace Combat 4, a group of rogue Erusean officers defy their country's surrender and attempt to use the superweapon Megalith to rain meteorites upon the Usean continent in a final attempt to defeat ISAF.
 * In one of the story arcs in Fate/Grand Order, a magically-empowered Professor Moriarty intends to direct the asteroid 101955 Bennu to impact with the planet as part of a convoluted scheme to destroy the Earth.