Voyager
Voyager.
If the stars had not aligned two of the most remarkable space craft,
would never have been launched.
In this case the stars were actually planets, the four largest in the solar system.
Some sixty years ago they were slowly wheeling into a array,
that last occurred in the early 19th century.
For a while the rare planetary phenomena went unnoticed.
Gary Flandro, a doctoral student at the California institute of technology,
first drew attention to it in 1965.
The era of space exploration was barely underway.
The soviet union had launched Sputnik 1, the first artificial satellite, only 8 years earlier.
Flandro, who was working part-time for NASA, had been tasked with finding,
the most efficient way to send a space probe to Jupiter, or perhaps even out to Saturn,
Uranus, or Neptune.
Using a favoured precision tool of engineers at that time, a pencil,
he charted the orbital paths of those giant planets.
He discovered something intriguing.
In the late 1970’s and early 1980’s, all four would be strung like pearls,
on a celestial necklace, in a long arc with Earth.
This coincidence meant that a space vehicle could get a speed boost,
from the gravitational pull of each giant planet it passed.
Flandro calculated that the repeated gravity assists would cut the flight time,
between Earth and Neptune from 30 years to 12 years.
There was one catch.
The alignment happened only once every 176 years.
To reach the planets while the lineup lasted,
a space craft would have to be launched by the mid 1970’s.
NASA built two space vehicles, Voyager 1 and Voyager 2,
to take advantage of this unique opportunity.
Voyager 1 and Voyager 2 were identical in every detail.
They were launched within 15 days of each other in the summer of 1977.
After 45 years in space, they are still functioning, sending data back to Earth,
everyday from beyond the solar system’s most distant known planets.
They have travelled further and lasted longer than any other spacecraft in history.
They have crossed into interstellar space,
of the boundary between the Sun’s sphere of influence, and the rest of the galaxy.
They are the first human made objects to do so,
a distinction they will hold for at least another few decades.
It was a pretty good record, considering that the voyager mission,
was originally planned to last for just 4 years.
In their early travels the voyagers gave astonished scientists,
the first closeup views of the moons of Jupiter and Saturn.
It revealed the existence of active volcanoes and fissured ice fields,
on what scientists thought would be inert like our own moon.
In 1986, voyager became the first space craft to fly past Uranus.
3 years later it passed Neptune.
Now as pioneering interstellar probes more than 12 billion miles from Earth,
they are delighting and confounding scientists of unexpected discoveries,
about the uncharted region.
Their remarkable odyssey is finally winding down.
Over the past three years NASA has shut down heaters, and other non essential components.
This was done to stretch the remaining energy stores,
to extend their unprecedented journey, to about 2030.
To the voyager’s scientists, many of them who have worked on the mission,
since its inception, it is a bitter sweet time.
They are now confronting the end of the project, that far exceeded all their expectations.