|Radar picture of 1620 Geographos. The white dot on the heart of the picture marks the axis of rotation, which factors towards the viewer. Dots alongside the left aspect are a kilometer aside. The picture is a compilation of a number of radar returns. Picture credit score: NASA Jet Propulsion Laboratory.|
The Nationwide Geographic Society-Palomar Observatory Sky Survey (NGS-POSS) imaged the sky from the North Celestial Pole to about 30° south declination between November 1949 and December 1958. The NGS-POSS was not conceived as a seek for asteroids, however inevitably they appeared as streaks on lots of its practically 2000 glass photographic plates.
On 14 September 1951, for instance, NGS-POSS astronomers Rudolph Minkowski and Albert George Wilson found asteroid 1951 RA. By noting its place on plates made as early as 31 August 1951, they have been capable of decide that it travels across the Solar in an inclined orbit that crosses the orbits of Earth and Mars. It completes an orbit each 508 days.
They decided that their new-found asteroid by no means comes very near Mars — when it crosses the Crimson Planet’s orbit concerning the Solar it’s effectively above the orbital aircraft. When it crosses Earth’s orbit, however, it is extremely close to the orbital aircraft. Consequently, it could move very near Earth. Quickly after it was found, astronomers decided that 1951 RA would move close to Earth in 1969.
1951 RA was of enough curiosity to be made the 1620th named asteroid. In 1956, it was dubbed 1620 Geographos in honor of the Nationwide Geographic Society, which funded the NGS-POSS. The title Geographos means “geographer” in Greek.
1620 Geographos grew to become a topic of particular curiosity for College of California at Los Angeles astronomer Samuel Herrick. Following the 1969 shut flyby, throughout which he refined information of the parameters of its orbit, Herrick calculated that 1620 Geographos would move near Earth in 1994. He believed that its “ominous” orbit meant it stood an excellent probability of putting Earth someday throughout “the Third Millennium” (that’s, within the interval between the years 2001 and 3001).
Herrick offered his outcomes on the Worldwide Astronomical Union’s Bodily Research of the Minor Planets colloquium held at Kitt Peak Observatory in March 1971. His contribution didn’t, nevertheless, seem within the colloquium proceedings NASA revealed later that yr. Herrick subsequently handed away at age 62 on 24 March 1974.
In accordance with Dutch-American astronomer Tom Gehrels, editor of the proceedings of the 1971 assembly, Herrick turned his contribution right into a proposal to make use of 1620 Geographos as a planetary engineering software which may infuse Earth’s crust with new mineral wealth. This led Gehrels and the referees of the 1971 proceedings to declare Herrick’s contribution to be “untimely” and “outrageously progressive” and reject it.
Earlier than the last decade was out, Gehrels had an obvious change of coronary heart. In 1979, he edited the primary Asteroids compilation quantity. Printed by The College of Arizona Press, it included greater than 50 papers summing up the sphere of asteroid research. Amongst them was the overview draft of Herrick’s 1971 paper.
Herrick proposed a two-phase plan spanning about 5 years which might, he declared, generate a lot better public enthusiasm than the Apollo lunar landings. Within the first section, engineers would used unspecified propulsive means to push 1620 Geographos right into a safer orbit and “explosive cleaving” to separate a portion of the asteroid and push it towards Earth.
The second section would see the separated portion guided towards an affect on the Isthmus of Panama. Herrick painted a goal on the Atrato River in Colombia, which, he defined, had been proposed within the yr 1540 as the location for a canal linking the Caribbean Sea and the Pacific Ocean.
On 25 March 1994, the impactor would streak by way of midnight skies over the cities of Quito, Bogota, and Medellin on its method to a “rendezvous” with the “jungle wasteland of northwestern Colombia.” The resultant affect crater would type a “new canal from sea to sea.” The “interocean Crater-Canal” would come with no locks — it might be a sea-level passage by way of the isthmus that may allow the blending of Caribbean and Pacific waters.
Herrick assumed that 1620 Geographos can be manufactured from “nickel and the heavier parts which might be largely locked within the earth’s core: rhenium, osmium, iridium, platinum, gold, and so on.” The affect would, he estimated, deposit on Earth extraterrestrial minerals price $900 billion. They might be collected from the water-filled crater as Earth’s provide of those priceless minerals grew to become depleted.
Herrick acknowledged that potential regional and international ecological results of the 1994 affect must be rigorously studied. He additionally acknowledged that 1620 Geographos won’t be manufactured from helpful metals. He steered that the methods developed to deflect a lot of the asteroid away from Earth and excavate the canal in 1994 may, if mandatory, be utilized to a different, extra mineralogically appropriate Earth-approaching asteroid. Looking for a brand new candidate impactor may additionally reveal future threats to Earth.
In 1994, 20 years after Herrick’s passing, 1620 Geographos orbited nearer Earth than it had in two centuries. It didn’t, nevertheless, pose a menace — at its closest method it handed about 5 million kilometers away (about 12 occasions the gap between the Earth and the Moon). The asteroid won’t move as shut once more till the twenty sixth century. Earth is secure from 1620 Geographos on a time-scale of thousands and thousands of years.
On 25 January 1994, the Clementine spacecraft lifted off from Vandenberg Air Power Base, California, certain for the Moon and 1620 Geographos. The spacecraft was supposed to gather scientific information whereas demonstrating sensor and miniaturized spacecraft applied sciences that might be utilized to ballistic missile protection techniques. After a leisurely one-month switch, Clementine orbited over the poles of the Moon for about two months (it was the primary lunar polar orbiter).
On 3 Might 1994, Clementine started a circuitous switch to 1620 Geographos. Had it succeeded, it might have change into the primary spacecraft to fly by a near-Earth asteroid. Sadly, a pc malfunction on 7 Might precipitated Clementine to fireplace considered one of its thrusters repeatedly, expending most of its remaining propellant provide and imparting a spin charge enough to render most of its devices ineffective.
In the course of the 1994 shut method Earth-based radar research confirmed that 1620 Geographos is 5 kilometers lengthy by about two kilometers huge. It’s most likely a “rubble pile” made up of many small asteroids loosely certain by mutual gravitational attraction. Earth-based research have additionally revealed that it’s a primarily stony asteroid not particularly wealthy in metals.
“Voyage to the Planets,” Kenneth F. Weaver, Nationwide Geographic, Quantity 138, Quantity 2, August 1970, pp. 174-178.
“Exploration and 1994 Exploitation of Geographos,” Samuel Herrick, Asteroids, Tom Gehrels, editor, The College of Arizona Press, 1979, pp. 222-226.
Dictionary of Minor Planet Names, Lutz D. Schmadel, Springer-Verlag, 1992, p. 211.
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A number of Asteroid Flyby Missions (1971)
Earth-Approaching Asteroids as Targets for Exploration (1978)
“A Imaginative and prescient of the Future”: Army Makes use of of the Moon and Asteroids (1983)