We have all watched the doomsday movies like ‘Mars attacks’, ‘Independence day’ where aliens attack earth and try to destroy it. Movies like ‘Armageddon’ where an asteroid is on collision course with earth or, movies on mega natural disasters with the ability to wipe of human existence. Such movies are high voltage drama and make a good entertainment. But such movies have also shown the possibility of one of the incident happening in reality though the chances of it may be very remote.
But if such a situation happens then there will be some information available in the cosmos that will carry the proof that we once existed. Just as we hear stories of sealed bottles with messages from long time back found floating in the ocean, only to be retrieved by someone. Though un-intentionally, we have been sending to out radio and TV signals to outer space for about a 100 years. The furthest these signal have reached is 200 light years in diameter. Though 200 light years may seem a lot by our standards but it is actually a very miniscule distance in galactic measurement. Also these radio bubbles thin out very fast and therefore will require a very strong receiver to catch them at extreme distances.
Then there was the 'Arecibo message' which was transmitted towards the M13 cluster of stars in 1974. It also contains some information of earth in binary terms. But it would take 25000 years to reach that cluster of stars in. If someone receives it and decodes it and sends a reply then it would again take another 25000 years to receive it back on earth. A lot would have changed on earth by then.
Next is creating a time capsule or plaque with some essential information of earth and us. But keeping the time capsule on earth may not be a good idea as the purpose of that time capsule is to survive even if earth gets destroyed. So the next best option is to keep it in a satellite rotating the earth. The same was done with a satellite named ‘Lageos 1’ sent out in 1976. Its primary role was to make precise measurements of location on earth. It also carries a plaque on which is written number 1 to 10 in binary and diagram of earth’s continents and oceans as it was 250 million years ago, the present day as well as what it may appear 8.4 million years from now. The satellite is expected to last 8.4 million years even though it will fall back to earth due to drag at some point of time.
Further away from earth comes the geo stationary orbits where at present about 450 satellites are encircling the earth. These orbits are far enough from earth to get affected by earth atmosphere and its disturbances and will last much longer in the atmosphere than the lower orbit ones like the Lageos. So these satellites can be our technological pyramids in space which when discovered by aliens if ever will give them a glimpse of us. When these satellites complete their life cycle there orbit is pushed away from the main orbit to what is called the graveyard orbit. In this graveyard orbit these now defunct satellites will keep orbiting the earth as tombs. A few of these satellites contains such information which we want the aliens to know. One such is ‘Echostar XVI’, which carries a silicone disk containing 100 images of earth. These geo stationary satellites are expected to last billions of years so there chances of discovery by aliens is more.
But if our solar system gets destroyed or the aliens don’t plan to visit earth, in that case we have to bank on the interstellar satellites which have truly crossed the boundary of our solar system and are moving in outer space. At present there are 11 human made objects flying outside the solar system. Out of these the 5 probes are Pioneer 10, Pioneer 11, Voyager 1, Voyager 2 and New Horizon. These objects are the farthest from earth and are our technological emissaries for the next billions and billions of years. These probes are the most likely candidates to be found by aliens when it passes close to other star cluster or even planets.
The Pioneer 10 and Pioneer 11 have plaques attached to it containing the diagram of hydrogen atoms (because it is the most abundant element in the universe), the picture of a male and a female standing in front of the probe to give an idea about the heights, and the location in the milky way and also our location in the solar system.
The Voyager 1 is currently the farthest from earth and currently moving at the speed of 17 kms per second. In another 40000 years both these Voyagers will pass about 2 light years distance away from other stars. It is then that it is hoped that some form of intelligent life forms may get inkling about us. Both the Voyagers have a gold plated copper disc with some Uranium 238 so that by studying it these aliens can make out how old it is. This record contains 116 images of earth and also audio and video recording of humans animals and songs. It also has engraving of how to use the record; our location in space and that of a hydrogen atom. It also contains a message from Jimmy Carter the then President of USA.
We are throwing a stone in the darkness and across time with the hope that it will bear our proof of existence. Information that will last billions of years, lost or found, but will bear a testimony of our civilization and its advancement. Maybe some intelligent life form will get it; some may try to contact us, ignore us, and conquer us. Or they may not be developed enough to reach back to us as we are incapable of it now.
But it will last for a very long long time as a proof – ‘we exist’ or’ we existed’ at some corner of this universe.
Thank you Telesfor sir.