Revisiting Project Icarus

In the wake of yesterday's Meteorite explosion over Russia's city of
Chelyabinsk shouldn't we be discussing planetary defence once again? Be sure
to read the wonderful Wired article "MIT Saves the World: Project Icarus
(1967) by David S. F. Portree.

Walter Baade used the 48-inch reflecting telescope at Palomar Observatory in
southern California to capture humankind's first image of asteroid 1566
Icarus on 26 June 1949. Icarus, it was soon found, is unusual because its
elliptical orbit takes it from the inner edge of the Main Asteroid Belt
between the orbits of Mars and Jupiter to well within Mercury's orbit.
Icarus needs 1.12 years to circle the Sun once. Every 19 years, always
during the month of June, Icarus and Earth pass near each other at a
relative velocity of about 18 miles per second. Baade detected Icarus during
one of these close encounters.

MIT Professor Paul Sandorff taught the Interdepartmental Student Project in
Systems Engineering in the Spring 1967 term at Massachusetts Institute of
Technology (MIT) near Boston. He noted that Icarus and Earth would pass each
other at a distance of 4 million miles (about 16 times the Earth-Moon
distance) on 19 June 1968. He then asked his students to suppose that,
instead of missing Earth on that date, Icarus would strike in the Atlantic
Ocean east of Bermuda with the explosive force of 500,000 megatons of TNT.
Debris flung into the atmosphere would cool the planet to some unknown
degree and a 100-foot wave would inundate MIT. Sandorff gave his class until
27 May 1967 to develop a plan for averting the catastrophe.

In 1967, the physical characteristics of Icarus were little-known. For
purposes of their study, Sandorff's students assumed that it measures 4,200
feet in diameter and has a density of 3.5 grams per centimeter, yielding a
mass of 4.4 billion tons. For comparison, Earth has an average density of
5.5 grams per cubic centimeter. They acknowledged, however, that, given its
orbit, which resembles that of a short-period comet, Icarus might be a
defunct comet nucleus. In that case, its density and mass would likely be
considerably less. They also assumed that it is a solid body; that is, that
it is not made up of small pieces held together loosely by weak mutual
gravitational attraction.

In March 1967, the MIT students visited Cape Kennedy, Florida, to size up
U.S. space capabilities. At the time, the first manned flight of the Apollo
Command and Service Module (CSM) had been postponed indefinitely following
the Apollo 1 fire (27 January 1967) and the Saturn V moon rocket had yet to
fly. (Apollo 4, the successful first Saturn V test flight, would not occur
until 9 November 1967.) Nevertheless, the students wrote that "the awesome
reality" of the Vertical Assembly Building (VAB), in which the Saturn V and
Apollo spacecraft would be prepared, and the twin Launch Complex 39 pads
(Pads 39A and 39B), from which they would be launched, had "completely
erased" any doubts that they might have had about using Apollo/Saturn
technology in their project.

http://www.wired.com/wiredscience/2012/03/mit-saves-the-world-project-icarus
-1967/