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Contact from the Outer Solar System

Is Anyone There?

It’s always a thought in the back of everyone’s mind: Are We Alone? One of the ways that humanity has attempted to answer this question is by trying to tell them that we’re here.

One inventive way we have done this is by sending a pictographic message, using not language, but the art of imagery (something which has been successful on our own planet, in the form of the spread of the Ancient Egyptian language around Europe, to morph into what we now know as Latin and Arabic alphabets [1]). It was in the form of a radio broadcast (the Arecibo Message) from the Arecibo Radio Telescope’s 305 metre antenna, in the north west of the US island, Puerto Rico, in the far east of the Caribbean Sea. This was the most powerful (‘equivalent to a 20 trillion watt omnidirectional broadcast’[2]) radio broadcast ever to be beamed deliberately into the voids of space.

It was made up of 1679 bits (numbers -1s & 0s- of code) put into 73 lines (23 bits per line), making a graphic starting with the Arecibo telescope , before having a representation of the solar system, a figure of a human, some DNA and biochemicals of primitive life on Earth. At 10 bits/second, it took just under 3 minutes to transmit, but its message in our culture has stayed for 46 years (having been transmitted in 1974). [2]

The Arecibo Message

The Arecibo Message. Credit: Arne Nordmann, CC BY-SA 3.0

The Whole of Humanity in a Disc

The Golden Record is, by far, the most impressive method yet to contact alien life. Two copies were made, with one put on Voyager 1 and the other on Voyager 2. It was a 12 inch (~30cm) phonographic record, made of copper, but gold plated, with an aluminium cover electroplated with uranium-238 [3].

This may all sound a bit crazy and over-the-top, but every part of the design had a purpose. The cover was engraved with lots of information on everything from how to play the disc, to where humanity are in the universe compared to everything else, using universal units like the time associated with a fundamental transition of an atom of hydrogen, and binary code. The radioactive cover may seem dangerous, but with a half life of 4.51 billion yeas, and a 2cm diameter on the cover, aliens could measure its diameter or radioactivity, and find how long it has been since the uranium was put on the cover [4].

Then, there’s the record itself, with 55 greetings in different languages, lots of music (from the Brandenburg Concerto to a Peruvian wedding song [6]), some earthly sounds (from a train to a volcano [7]), and 115 images in analog form (from X-ray scans of hands to the double helix of DNA [8]).

This postcard from Earth is something that is certainly an amazing feat of design, but, apart from being a cultural icon, will it ever fall into the hand of aliens, and if so, will we, as a species, be gone by then [5]?

The Sounds of Earth Golden Record

The Golden Record (The Sound of Earth). Credit: NASA

A Journey to the Edge

The records themselves were on board two spacecraft, bound for the outer edges of the solar system, to also send back images never before taken. They set off in 1977, taking now iconic images like “The Pale Blue Dot”, images of much less pale blue Neptune, and the giant that is Saturn.

Then, in 2004 (Voyager 1) and 2007 (Voyager 2), they crossed the shock; an area around the Sun where the solar wind abruptly slows down, welcoming the interstellar wind, heating up the spacecraft. Following this, 2013 (Voyager 1) and 2018 (Voyager 2) marked the entry into Interstellar Space; the place which marks the edge of the heliosphere (the reach of the Sun’s magnetic fields) [9].

Fast-forward to today, and Voyager 1 in 151.7AU (151.7x the average distance from the Earth to the Sun) from the Earth, and Voyager 2 is 125.9AU from Earth [10]. Then, from all that distance away, on 29th October, NASA contacted Voyager 2 for the first time since March (the longest it has been offline in over 30 years), from an antenna in Canberra, Australia (part of a network of antennas to contact satellites past the Moon, including ones in Madrid and California), after upgrades to the deep space network dish at the Canberra site [11]. Due to the distance, it took nearly 17.5 hours to contact the spacecraft, and another 17.5 hours to get a response (imagine trying to talk to a friend and it taking over day to hear a response to something you said!) [12].

It is amazing that such a far-flung object is still in contact with humanity, but such is human engineering that we can indeed do so, and will be able to for many years more.

Model of Voyager Spacecraft

Model of Voyager Spacecraft. Credit: NASA

Are You Receiving?

As the aliens pick up on of the bright signals sent by Earth, there is still a barrier to interpreting what the alien reply will mean? How will they communicate? What will their linguistic code mean? Will we be able to communicate if there were an intelligence barrier between our two species? All questions which sadly cannot be easily answered, with our knowledge of life being focused on a grand total of 1 planet with life: Earth [13].

And then, there’s the question of whether they will even understand or see our signals in the first place. Indeed, Claudio Grimaldi, a French astronomer, published a paper on how it’s likely for an alien civilisation to be long gone. This is partly due to the fact that light has a speed (~300000 km/s), meaning that anything we look at, whether it be a star or an alien civilisation’s message, will be history (it takes 2 years for the light of our nearest star other than the Sun to get to us). It depends on how fast the civilisation can evolve and how long it lasts for as to whether we can see there signals, or if they can see our signals so they know where to direct their’s [14].

Then, if the unlikely event arises that an alien civilisation detects these signals, it could still take 100s or even 1,000s of years to have a conversation (with humans having only been around for ~3.2 million years [15]).

However unlikely contact with another intelligent civilisation is in this truly massive universe, our human wonder for if anyone else is out there will still live on regardless, and maybe, one day, we will find intelligent life, but until then, I guess we’ll just have to watch E.T. and Doctor Who.

The Arecibo Observatory

The Arecibo Observatory. Credit: JidoBG, CC BY-SA 4.0

By George Abraham, ADAS member

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  1. "The Secret History of Writing: From Pictures to Words". BBC. Archived from the original on 14th November 2020.

  2. "Arecibo Message". SETI Institute. Archived from the original on 14th November 2020.

  3. "The Golden Record". JPL, NASA. Archived from the original on 14th November 2020.

  4. "The Golden Record Cover". JPL, NASA. Archived from the original on 14th November 2020.

  5. "What are the contents of the Golden Record?". JPL, NASA. Archived from the original on 14th November 2020.

  6. "Music from Earth". JPL, NASA. Archived from the original on 14th November 2020.

  7. "Sounds of Earth". JPL, NASA. Archived from the original on 14th November 2020.

  8. "Images on the Golden Record". JPL, NASA. Archived from the original on 14th November 2020.

  9. "NASA's Voyager Timeline". JPL, NASA. Archived from the original on 14th November 2020.

  10. "Mission Status". JPL, NASA. Archived from the original on 14th November 2020.

  11. "NASA Contacts Voyager 2 Using Upgraded Deep Space Network Dish". NASA. Archived from the original on 14th November 2020.

  12. "'First human' discovered in Ethiopia". BBC. Archived from the original on 14th November 2020.

  13. "If Aliens Contact Us, We Wont Understand". Archived from the original on 14th November 2020.

  14. "Space aliens could have died out long ago, scientist says". NBC News. Archived from the original on 14th November 2020.

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