Legendary Arecibo Telescope will close forever. (History of its accomplishments)
After more than a half-century of supporting breakthrough scientific work—and providing
a scenic backdrop for Contact, GoldenEye and other blockbuster Hollywood films—the iconic
Arecibo Observatory in Puerto Rico is going dark.
Engineers cannot find a safe way to repair it after two cables supporting the structure
broke suddenly and catastrophically, one in August and one in early November.
It is the end of one of the most iconic and scientifically productive telescopes in the
history of astronomy — and scientists are mourning its loss.
“I don’t know what to say,” says Robert Kerr, a former director of the observatory.
“It’s just unbelievable.”
The Arecibo telescope, which was built in 1963, was the world’s largest radio telescope
for decades and has historical and modern importance in astronomy. It was the site from
which astronomers sent an interstellar radio message in 1974, in the hope that any extraterrestrials
might hear it, and where the first confirmed extrasolar planet was discovered, in 1992.
It has also done pioneering work in exploring many phenomena, including near-Earth asteroids
and the puzzling celestial blasts known as fast radio bursts. All those lines of investigation
have now been shut down for good, although limited science will continue at some smaller
facilities on the Arecibo site.
“Follow me on this journey to get to know better how the Arecibo radiotelescope worked
and which were the most important discoveries made by the Arecibo Observatory during the
years!”
The Arecibo Observatory had its origins in an idea of Professor William E. Gordon, from
Cornell University, who was interested in the study of the Ionosphere. Gordon's research
during the fifties led him to the idea of radar backscatter studies of the Ionosphere.
Gordon's persistence culminated in the construction of the Arecibo Observatory which began in
the summer of 1960. With its 305m (1000ft) diameter dish constructed in 1963, the Arecibo
Observatory continuously provided valuable data for the scientific community and the
world.
We would like to celebrate Arecibo's closing reporting some of Arecibo Observatory accomplishments
in history.
1965 In 1965 Arecibo Radiotelescope established
the rotation rate of Mercury, which turned out to be 59 days than the previously estimated
88 days. This discovery, one of the earliest major
achievements of planetary radar astronomy, astounded astronomers, who sought to explain
the new, correct rotational rate. The finding of a value for the rotational period of Mercury
which differs from the orbital period is unexpected and has interesting theoretical implications.
It indicates either that the planet has not been in its present orbit for the full period
of geological time or that the tidal forces acting to slow the initial rotation have not
been correctly treated previously. Working with Giuseppe "Bepi" Colombo, an astronomer
from the University of Padova visiting the Smithsonian Astrophysical Observatory, Shapiro
began to develop an explanation for the new rotational period. Colombo, Shapiro recalled,
"realized almost immediately that 58.65 days was exactly two-thirds of 88 days. Mercury
probably was locked into a spin such that it went around on its axis one-and-a-half
times for every once around the planet. The same face did not always face the Sun. That
meant that near Mercury's perihelion, that is, when its orbit is closest to the Sun,
Mercury tends to follow the Sun around in its orbit. Near perihelion, then, the orbital
motion and spin rotation of Mercury were very closely balanced, so that Mercury almost presented
the same face to the Sun during this period.
1968 Sporadic radio pulses from the direction of
the Crab Nebula supernova remnant found at Green Bank were shown by Arecibo to come from
a 33-ms period pulsar situated at the centre of the nebula.
The Crab pulsar s a relatively young neutron star located in the centre of the Crab Nebula,
the remnant of the supernova SN 1054. Discovered in 1968, it was the first pulsar to be
related to a supernova remnant, a breakthrough for the interpretation of pulsars as fast-spinning
neutron stars.
1974 The first pulsar in a binary system was discovered,
leading to important confirmation of Einstein's theory of general relativity and a Nobel Prize
1993 for astronomers Russell Hulse and Joseph Taylor.
But what is a binary pulsar? A binary pulsar is a pulsar with a binary
companion, often a white dwarf or neutron star.
Binary pulsars are one of the few objects which allow physicists to test general relativity because
of the strong gravitational fields in their vicinities. Although the binary companion
to the pulsar is usually difficult or impossible to observe directly, its presence can be deduced
from the timing of the pulses from the pulsar itself, which can be measured with extraordinary
accuracy by radio telescopes.
While Hulse was observing the newly discovered pulsar PSR B1913+16 (weird name, I know!),
he noticed that the rate at which it pulsed varied regularly. It was concluded that the
pulsar was orbiting another star very closely at a high velocity and that the pulse period
was varying due to the Doppler effect: as the pulsar was moving towards Earth, the pulses
would be more frequent; and conversely, as it moved away from Earth fewer would be detected
in a given time period. One can think of the pulses like the ticks of a clock; changes
in the ticking are indications of changes in the pulsars speed toward and away from
Earth. Hulse and Taylor also determined that the stars were approximately equally massive
by observing these pulse fluctuations, which led them to believe the other object was also
a neutron star.
Also, on 16 November 1974, the “Arecibo message” was broadcast into space toward
the globular star cluster M13 25,000 light-years away. The message was designed by Frank Drake
with the help of Carl Sagan among others, and though its main purpose was to demonstrate
the capabilities of newly installed equipment in the upgraded radio telescope, it also constitutes
an attempt to contact extraterrestrial intelligence. The message consists of 1679 bits, arranged
into 73 lines of 23 characters per line (these are both prime numbers, and may help the aliens
decode the message). The "ones" and "zeroes" were transmitted by frequency shifting at
the rate of 10 bits per second. It consists, among other things, of the Arecibo telescope,
our solar system, DNA, a stick figure of a human, and some of the biochemicals of earthly
life. Although it's unlikely that this short inquiry will ever prompt a reply, the experiment
was useful in getting us to think a bit about the difficulties of communicating across space,
time, and a presumably wide culture gap.
1981 Using the radar technique, Arecibo Observatory
mapped the geologic surface of Venus. Radar images of Venus have revealed geological
structures on the planet, such as steep-sided domes and rugged highland terrain, which geologists
think could feature mineral-rich materials, such as felsic rocks.
The discovery of felsic rocks on Venus would add support to the idea that the planet was
once more Earth-like, as most of these materials on Earth formed in a water environment. However,
other processes that don’t require the presence of water may also produce felsic rocks.
1982 The discovery of milliseconds pulsars, which
rotate several hundred times per second. This was a huge discovery because it demonstrated
the existence of two classes of pulsars: the millisecond pulsars and the slower-rotating
pulsars, which rotate about once per second.
1992 Ice was discovered in shadowed craters at
Mercury's north pole. Later observations showed ice in south pole craters as well.
The radar observations of Mercury showed numerous “radar‐bright” features, areas with
high radar reflectivity, and also a high same‐sense to opposite‐sense circular polarization
ratio, distinctive traits associated with ice on the Galilean satellites and the polar
caps of Mars The radar‐bright features showed a correlation
with the interiors of craters, which were suggested to contain permanently shadowed
regions with low enough temperatures to sustain the long‐term stability of water ice.
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2003 Evidence for hydrocarbon lakes on the Saturn
satellite Titan is established using Observatory Planetary Radar. Later, in 2004, Cassini
spacecraft arrived in orbit around Saturn. Cassini observed many lakes and seas on Titan
and showed that the moon has an active weather system based on liquid hydrocarbons. Methane
and ethane fall from the sky as rain, course down river systems and pool in lakes and seas,
some of which are bigger than North America's Great Lakes.
Titan remains the only cosmic body beyond Earth known to harbour bodies of stable liquid
on its surface.
2007 Previously undetected radio lines of the molecule
hydrogen cyanide and the presence of the molecule methenamine were discovered in the distant
galaxy Arp 220. Arp 220, a “starburst galaxy” in which
massive stars are being born at a rate one hundred times that within our Milky way, lies
250 million light-years away! Both methenamine and hydrogen cyanide are
considered to be pre-biotic, which is to say that they are among the fundamental building
blocks for the production of more complex molecules with relevance to the origins of
life in the Universe. The occurrence of these pre-biotic molecules
in such a distant galaxy is surely telling us much of importance concerning how the ingredients
for life may have arisen in the first place, and of how widespread they are likely to be
in the cosmos.
2012 Arecibo joins with telescopes in Europe and
with the Russian Radio Astron satellite to form the largest telescope ever – 20 times
the size of the Earth!
And now, after more than a half-century of supporting breakthrough scientific work, Arecibo
Observatory is going dark: The U.S. National Science Foundation (NSF), which owns the observatory,
announced on November 19 that it will begin the process of planning for “controlled
decommissioning” of the 305-meter telescope. Over the past several months the instrument
has suffered two catastrophic failures of cables that support its 900-ton (817-metric-ton)
central receiving platform. Could the observatory have been saved? Scientists
and historians will likely debate the circumstances of Arecibo’s death knell for years to come.
It should be noted that one thing is indisputable, however: Arecibo is a very unique facility,
and its capabilities are not going to be reproduced anywhere else quickly!
"This video ends here! Thanks for watching everyone! We are sad about hearing Arecibo's
last new. How do you feel about it? Don't you think it had a huge positive impact on
the Astrophysics world? Let us know in the comments below!
See you next time on the channel!