Aboard it was NASA's relatively puny New Horizon's probe, a half-tonne, piano-sized craft equipped with seven science instruments that collectively use less power than a night light.
NASA is using an Atlas rocket, built by Lockheed Martin, one of the largest rockets in the US expendable booster fleet to give as much velocity as possible to the probe and hopefully shave years off the 4.8-billion-kilometre journey to Pluto.
It’s scheduled to blast off from Cape Canaveral at 1824 GMT, Tuesday.
Radioactive energy
Because the probe will travel too far from the sun for solar energy, it will draw power from the decay of radioactive plutonium pellets.
It will also get added punch from an unprecedented five solid-fuel strap-on motor.
By the time New Horizons separates from the Atlas' third and final motor, it will be moving at about 16km per second, or 58,400kph, to become the fastest spacecraft ever launched from Earth.
In fact, if the Apollo astronauts had been launched at that speed, the trip to the moon would have taken about nine hours instead of three days.
Long wait
Even so, New Horizons will still need to bounce off Jupiter's gravity field, in a "slingshot" effect that will give it added velocity, to make it to Pluto in less than a decade.
If the probe cannot be launched by February 2, it will miss its opportunity to bounce off the solar system’s largest planet, and delaying its arrival at Pluto until 2018 at the earliest.
But there are no time complaints from New Horizon's science team, who already have faced decades of delays while NASA and the US Congress faced off over mission approval and funding.
During the five months before New Horizons' closest approach to Pluto and for one month after, scientists hope to collect information about Pluto's surface and its ethereal atmosphere, which is shedding into interstellar space like the tail of a comet.
The probe will be moving too fast to slow down and enter into orbit around Pluto.
Rather, after an extensive study of Pluto, its primary moon Charon and two other recently discovered small moons, New Horizons is expected to position to discover the horizons beyond Pluto.
Is it a planet?
The last discovered planet in our solar system was found in 1930 by US astronomer Clyde Tombaugh, since then there has been debate over whether or not Pluto is a true planet - or if it should be considered as part of the Kuiper Belt.
And some international science boards have questioned whether Pluto should be stripped of its planetary nomenclature, particularly as the number of similar though smaller objects circling beyond
Neptune's orbit are discovered.
The planet appears to be quite similar to the recently discovered planet-like objects called "ice dwarfs".
It is the only unexplored planet of the solar system's original nine.