How far we have gone in space? This is a question which is of deep interest to many and also a benchmark of human scientific endeavor.
The answer has many layers. A human being has gone no further than the moon which is less than 400,000 kilometre. Of course, other animals have done no better. In 1968, two tortoises and some insects were the first earth born’s to circle the moon. Recently in 2007, the 0.5 mm long tardigrade became the first Earth species to be able to survive in open space without any protection suit.
The ruggedness to survive in extreme space travel environment was also shown by nematodes and roundworms when a group of them in a petri dish survived the tragic 2003 Columbia Space Shuttle accident. Perhaps making them the first species to survive a spaceship crash. Beyond living beings, our technology has fared much better. In 1946, the first radio signal sent towards the Moon, carrying the sound of a church bell is still traveling away from us at the speed of light. The farthest edge of this wave is now 73 light-years away (Comparatively our nearest star Proxima Centuri is 4.2 light-years away).
But, perhaps the most exciting piece of our presence in space are Voyager 1 and 2 probes which were launched on September 5, 1977, and August 20, 1977, respectively and are traveling at a speed of about 55,000 kilometers per hour away from us. Interestingly, Voyager 2 was launched before Voyager 1 as they went on different paths – with Voyager 2 having a longer journey to cover. They are now at a distance of about 21.8 billion kilometers away from us and have escaped the boundaries of the solar system and traveling deep into space towards the next star.
Interestingly, these two probes who have visited Jupiter, Saturn, Uranus and Neptune are still communicating with us, sending sights from distinct space. A lot of what we know about our solar system and its planets and their moons are credited to the idea of Voyagers.
But Voyager was not just about our desire to know more about space. It was about our unflinching hope to find a different and perhaps a new life form somewhere beyond the Earth. That hope was translated into action in the form of the Voyager Golden Record.
What if one day, these spacecraft were found by some advanced spacefaring species? Scientists felt that it was necessary to communicate the story of humanity through them.
The Golden Record is a 1977 state-of-art piece of technology. It is a 12-inch gold plated copper disk. It also includes a needle and a phonograph cartridge, along with the symbolic instructions about how to put all the three items together to play the record. The contents of the record were selected by a committee chaired by famous astronomer Carl Sagan.
The critical question was how and what to communicate to an alien species which doesn’t speak our language, doesn’t understand our symbols and doesn’t use the same reference point to depict places and measurements of space, mass and time. So, the selection committee took almost one full year to come up with the sounds and sights of planet Earth – our welcome present to the species which would be just startled to find us alive in the cosmic arena. Sagan and his associates brought together 115 images and a variety of natural sounds, including those made by surf, wind, thunder and animals.
The record also contains musical selections from different cultures and eras, spoken greetings in 55 ancient and modern languages, including 10 Indian languages, namely – Hindi, Bengali, Urdu, Oriya, Telugu, Gujarati, Marathi, Punjabi, Kannada and Rajasthani.
It also has other human sounds, like footsteps and laughter (Sagan’s own), and printed messages from U.S. President Jimmy Carter and U.N. Secretary-General Kurt Waldheim. The record also includes the inspirational message Per aspera ad astra which is a popular Latin phrase meaning “through hardships to the stars”in Morse code.
What’s special about the cover?
On the upper left-hand of the record is drawing of the phonograph and the needle it carries with it. The needle is shown in the correct position to play the record from the beginning. Written around is the binary equivalent of the time taken by the record to complete on rotation i.e. 3.6 seconds. Of course, you can’t tell an alien species about an hour, minutes and seconds. So, we had to find a new way to express time. This was achieved by using the unit of time as the time period corresponding to the fundamental transition (ground state to first excited state) which is also equal to 0.70 billionths of a second. This interval of time is consistent on every planet and every star as Hydrogen is the most abundant element in the universe itself.
The drawing on the upper-right hand side of the cover depicts how pictures are to be constructed from the signals expressed in a waveform. Immediately below this is the image of a circle enclosed in a rectangle. This is actually the first image on the record and it is placed on the cover to ensure that the signals are being decoded correctly.
On the lower left-hand corner of the cover appearing like a web or a scratch is the most fascinating piece of the design. It is the address of the Earth. It shows the position of our solar system with respect to 14 pulsars. Pulsars are extremely rare in the universe. They are the tombstones of dead massive stars in a powerful explosion of a supernova and reduced to a fast rotating star generating strong detectable electromagnetic beams which can be easily spotted. It is like telling the direction in an ocean using well-spaced lighthouses.
Will extra-terrestrials life able to understand the message?
As of now, we simply don’t know enough about the universe to be able to think of extra-terrestrial life. So, we don’t know whether they exist or not? Even if they do, we are not sure of the possibility that the Golden Records would reach them. Will they be able to access the content of the record? Although we have written instructions to access the content, still the instructions are mostly very technical which even an advanced spacefaring civilization might find difficult to crack. Understanding the content is a completely different matter altogether. But our hope lives on, at some day an extra-terrestrial being or an alien will come visiting us using the guidance of Golden Records.
Will we eventually lose communication with the Voyagers?
Each probe is armed with a radioisotope thermoelectric generator which generates fewer watts of electrical power every year as the radioactive plutonium decays. The team of scientists working on Voyagers prioritizes over the instruments which remain on as the available power is diminishing continuously. At this rate, both Voyagers are expected to continue operating with at least one scientific instrument on till 2025. However, they will remain in the radar of Deep Space Network till about 2036. Beyond it, their ability to transmit signals back to Earth will fade away and these outstanding yet lonely wanderers will disappear from observable human space.
Where Are They Heading?
There is still time before the spacecraft will make a close approach to any other solar system. Voyager 1 is heading towards the Ophiuchus constellation covering 3.5 times the distance between earth and sun every year. It will fly past an obscure star now in the constellation Ursa Minor called Gliese 445 at a distance of 1.7 light-years in about 38,000 years. While Voyager 2 is heading towards the Pavo and Sagittarius constellations. This way, it would take another 40,000 years to pass within 1.7 light-years of a small star Ross 248 of the Andromeda constellation.
If you are reading this article in the Month of August in India and want to know the direction in which the Voyager twins are heading to, just step out of your houses and face towards the sky.
Today (20th August) in India around 9 pm face the Southern direction. At about 60 degrees from the ground would be Sagittarius. That where Voyager 2 is moving towards. And at about 15 degrees towards your right that is towards the South West direction. There is the Constellation Ophiuchus about 45 degree from ground level. This is the direction in which Vogayer 1 is heading to. Of course, you’ll not be able to spot any of spacecraft in the sky but they are right there as the silent ambassadors of humanity from Earth to a distant species.
And while you look at them, you can wish Voyager 2 a very happy birthday.
As published in India Today on August 20, 2019.