Voyager 2 completes 43 years: Know about NASA's space probe with our message to aliens

In the late summer of 1977, NASA launched two space probes—Voyager 1 and Voyager 2—as part of a mission to better understand the gaseous giants, Jupiter and Saturn. After making some remarkable discoveries and giving astronomers some new insights about some of the biggest mysteries of our solar system, the mission was extended.

Interestingly, Voyager 2 was launched before Voyager 1 due to some technical reasons. Starting its journey on August 20, 1977, Voyager 2 went on to explore the ice giants, Neptune and Uranus and to date remains the only spacecraft to have visited those outer planets. In fact, a lot of what we know about the outer planets and their moons is credited to these siblings.

While Voyager 2 was busy ing outer planets, Voyager 1 did something even more significant which gave us a new perspective about our place in the universe. In 1990, about 6 billion km away from us, it turned around and snapped a photo of our planet, Earth. This iconic image, known as “The Pale Blue Dot” shows our home planet as a tiny outpost of life in an incomprehensibly vast cosmos.

Travelling at a speed of around 55,000 kilometers per hour, they are now the longest-operating and most distant spacecraft in history. They have escaped the boundaries of the Solar System and are now at a distance of over 22 billion km from us.

But the Voyager mission was not just about our desire to explore and understand more about our Solar System. Hidden aboard, space crafts also houses humanity’s message in a bottle to anybody and everybody out there — The Golden Record.

The Golden Record

The Golden Record is a 12-inch gold plated copper phonograph containing sounds and sights of our planet and its diverse inhabitants. Designed as a gift from Earth to extraterrestrial beings, the contents of the record were curated by a team led by the famous astrophysicist Carl Sagan.

The biggest challenge before the team was to figure out a way to communicate to a civilization that neither understands our symbols nor speaks our language. Sagan and his associates took almost a year to assemble 115 images and a variety of natural sounds, such as those made by wind, birds, thunder and animals.

The record also has musical selections from different eras and cultures, spoken greetings in 55 ancient and modern languages, including 10 Indian languages -- Hindi, Urdu, Telugu, Bengali, Oriya, Punjabi, Gujarati, Marathi, Rajasthani and Kannada.

It also contains electronically encoded images which includes a woman with a microscope, a mother nursing her baby, an astronaut in space, children studying in a classroom. It also includes printed messages from then-US president Jimmy Carter and then-UN Secretary-General Kurt Waldheim.

The record also has a popular Latin phrase, ‘Per aspera ad astra’ which means "through hardships to the stars" encoded in Morse code.

What’s special about the cover?

The upper left-hand side of the record has a drawing of the record and the needle it carries along with it. The drawing shows the correct position of the needle to play the record from the beginning. Around this drawing, there are binary markings which denotes the time taken by the record to complete one rotation is 3.6 seconds.

Alien species won’t be able to understand seconds, minutes and hours. So, we had to devise a new way to express time. This was done using the fundamental transition (ground state to first excited state) of the Hydrogen atom that is also equal to 0.70 billionths of a second. This time interval is consistent on every planet and star.

The lower left-hand corner of the cover has some scratches. However, this scratchy looking diagram is actually the most interesting part of the cover. These scratches actually show the ‘address’ of our planet in the Solar System. The diagram depicts the position of our solar system with respect to the 14 pulsar stars. Pulsar stars are essentially 'tomb stones' of massive stars that died. They are fast rotating stars that generate strong detectable electromagnetic beams which can be easily spotted. This is similar to telling direction in an ocean using well-spaced lighthouses.

Will we eventually lose communication with the Voyagers?

Each spacecraft houses a radioisotope thermoelectric generator. This generator produces few watts of electrical power every year as the radioactive plutonium inside the generator decays. A team of scientists is constantly working to prioritize the instruments which will stay on considering the diminishing power situation.

At the current rate, Voyager siblings are expected to continue operation till 2025 with at least one scientific instrument on. However, they are expected to remain active in the Deep Space Network till 2036.

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, and someday an extra-terrestrial being or an alien will come visiting us using the guidance of Golden Records.

Where are they heading?

Voyager 1 is covering 3.5 times the distance between Earth and Sun each year and is heading towards the Ophiuchus constellation. While Voyager 2 is moving towards the Pavo and Sagittarius constellations.

If you are reading this article in the month of August 2020 in India and want to know the direction in which the Voyager 2 are heading to, just step out of your houses and face towards the sky.

Today (August 20) in India, at around 8 pm, look up and face the Southern direction. At about 60 degrees from the ground you’ll find Sagittarius. This is where Voyager 2 is heading. You’ll not be able to spot the spacecraft in the sky but it is right there, functioning as the silent ambassadors of humanity from Earth to a distant species.

And while you look at it, you can wish Voyager 2 a very happy birthday. Of course, even if your greetings travel at the speed of light, they would take 21 hours to reach Voyager 2.

(Written by Srijan Pal Singh. He is an IIM Ahmedabad graduate and was the Advisor for Policy and Technology to Dr. A.P.J. Abdul Kalam, 11th President of India. He co-authored the book Reignited along with Dr Kalam and is the author of Reignited 2. He is the CEO of Kalam Centre.)