Voyager 1 is about to have its 44th birthday. It was launched in 1977, and we should celebrate an extraordinary achievement. The fact that it is still travelling and still sending back data is a tribute to NASA’s ability to maintain a system that should have been obsolete (in modern computer terms) about 1980, when it flew past Saturn, its last planetary stop before leaving our solar system.
Now, Voyager 1 is over 22 billion kilometres from Earth and flying through interstellar space. Light, and Voyager’s signals, take almost a day to travel back to Earth.
Voyager 1 has altered several theories over its lifetime. Scientists, in 1977, believed that the edge of the solar system, the heliopause, was about 10 AU (the distance between Earth and the Sun) beyond Saturn.
It turns out it is 120 AU.
Voyager 1 is still transmitting, still measuring the density of the atmosphere around it. And still feeling – generally gentle – magnetic bursts from our Sun. This against a gentle hum that seems to be the background noise of deep space.
That Voyager 1 is still feeling the sun from that far away makes you wonder about the forces at work in the Universe. Compared to some of the monstrous caldrons of boiling chaos, our sun is pretty small compared to some of the stars that scientists have examined.
So, when will Voyager 1 begin to feel their effects if some of them are that much larger than our own?
The other issue is that Voyager 1 is now transmitting its signals in interstellar space and who knows who is picking them up, apart from NASA. Could it be that Voyager 1 becomes a trigger for some alien civilisation to think that we have now grown up enough to pay us a visit – if they haven’t already?
The good news on that front is that our technology has come on leaps and bounds since 1977. That year, the Apple II was introduced, the Atari games console appeared, the Commodore Personal Electronic Transactor was launched, and Industrial Light and Magic briefed people on how the Death Star worked. Mobile phones were still in the future, and smartphones were still far, far away.
The bad news is that Voyager 1 will not last forever, about another 40 years, scientists calculate, as its plutonium fuel cells have a half-life of about 80 something years. This is sad because they calculate it will take another 80 something years to reach the rather fascinating Oort Cloud.
It is also sad because Voyager 1 will, well, die.
It is perhaps a vain hope but maybe some aliens will be kind and bring it home.