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1963: Arecibo Ionospheric Observatory commissioned for service on November 1 for $ 9.7 million.
1965: One of his first results was to establish Mercury’s rotation rate, which turned out to be 59 days instead of the 88 days previously estimated.
1968: Sporadic radio pulses from the direction of the Crab Nebula supernova remnant found at Green Bank were shown by Arecibo as coming from a 33 ms pulsar located in the center of the nebula.
1974: New high precision surface reflector installed, planetary radar transmitter installed.
1974: The first pulsar in a binary system was discovered, which led to an important confirmation of Einstein’s theory of general relativity and the 1993 Nobel Prize for astronomers Russell Hulse and Joseph Taylor.
1974: On November 16, the “Arecibo message” was sent into space to the globular star cluster M13 25,000 light years away.
The main purpose of the message was to demonstrate the capabilities of the equipment recently installed in the upgraded radio telescope and was an attempt to contact extraterrestrial intelligence.
1979: A large, anomalous traveling ionospheric disturbance (i.e. a wave from the upper atmosphere) moving from southeast to northwest was detected in the early morning, something researchers had never seen before. The data helped define the probable cause as an aerial nuclear explosion over the Indian Ocean.
1981: The first radar maps of the geological surface of Venus are produced.
1982: The discovery of a strong “megamaser” emission from the hydroxyl (OH) molecule in the Starburst Arp 220 galaxy (IC 4553).
1982: The discovery of millisecond pulsars, which rotate several hundred times per second. This demonstrated the existence of two classes of pulsars: millisecond pulsars and slower spinning pulsars, which rotate about once per second.
1989: The first measurement of the escape flow of hydrogen from Earth is presented, based on measurements of the velocity distribution of the emission of the hydrogen glow in the upper atmosphere.
Early 90s: The first planets outside the solar system were discovered around Pulsar B1257 + 12, a rapidly rotating pulsar with three Earth-like planets in orbit.
1992: In October, ice is discovered in the shadowed craters at the north pole of Mercury. Subsequent observations also show ice in the south pole craters.
1996: A layer of helium ions is shown to be a common, but previously unrecognized, feature in the low-latitude ionosphere near 600 km.
1998: On July 28, the Arecibo Observatory “found” the SOHO (Solar and Heliospheric Observatory) space probe, after losing communication with the European Space Agency and NASA. bouncing a radar signal off the satellite. SOHO’s mission has been resumed and continues to produce data today.
May 2000: Radar observations of asteroid 216 Kleopatra reveal a metal-rich object in the shape of a “dog bone”.
September 2000: 2000 DP107 was discovered to be the first near-Earth asteroid identified by radar as a binary system. The primary is roughly spherical with a diameter of half a mile and the smaller secondary, which orbits it in 1.8 days, is about 1000 feet.
2003Tests for hydrocarbon lakes on Saturn’s Titan satellite are established using the Observatory’s planetary radar.
April 2004: Installation of the Arecibo L-band Feed Array, which allows for a wide variety of astronomical investigations including the discovery of pulsars, the mapping of gas in our galaxy and the search for other galaxies.
2005-2012Mars radar images reveal lava flows and near-surface geological features not visible in visible images. This provides new insight into the geology of the surface of Mars.
2006: The search for water ice in the permanent shadow of the lunar Shackleton crater challenges the evidence of water ice on the lunar surface.
October 2006Radar images of the moon’s south pole reveal no evidence of thick ice deposits.
November 2006: Radar images of binary asteroid (66391) 1999 KW4 in May 2001 and again in June 2002 reveal exotic physical and dynamic properties that may be common among near-Earth binary systems.
March 2007Mercury radar images reveal features that will be further studied by the Messenger spacecraft in the coming years.
2007: The near-Earth asteroid 2005 PH5 has been observed to increase in rotation speed, due to uneven absorption and solar radiation emission.
2007: Previously undetected radio lines of the hydrogen cyanide molecule (HCN) and the presence of the methanimine (CH2NH) molecule, have recently been discovered in the distant “starburst galaxy” Arp 220.
February 2008: Discovery of the first triple asteroid system among asteroids near Earth. The asteroid, 2001 SN263, is about 1.5 miles in diameter, with two moons orbiting it.
2008-2012: Observations discover a radio explosion in the nearby galaxy NGC 660, ten times brighter than a radio supernova.
2011: Observations of brown dwarfs find the coldest star to show radio emission.
November 2011: Radar images of the near-Earth asteroid 2005 YU55, which made a very close flyby. This dark, spheroidal asteroid was found to have a diameter of approximately 1,148 feet.
2012: A neutral ionic chemical model is developed to successfully describe thin layers of neutral metal atoms at altitudes greater than 62 miles.
More information: National Astronomy and Ionosphere Center
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