Voyager 1 spacecraft

Who would have thought that a spacecraft launched in 1977 to study Jupiter and Saturn would be poised to leave our solar system!

Based on new data from the craft, NASA announced last week that Voyager 1 is nearing the heliopause, the border between our solar system and deep interstellar space. To put in perspective -- Voyager 1 is 11 billion miles from Earth which is nearly 120 times more than the distance between the Earth and the Sun. It takes nearly 17 hours for radio signals from the probe to reach the earth.

Crossing The Bubble

Imagine our solar system as being inside a bubble, known as heliosphere. The boundary of the bubble is where the sun's influence diminishes and the magnetic field of the interstellar space takes over. As you know, our sun emits charged particles -- known as solar wind. This is responsible for the spectacular northern lights display (Aurora) when it collides with the earth's atmosphere.

This boundary of the heliosphere is called the 'termination shock'. Voyager 1 crossed this boundary in December 2004 and is now in the region known as heliosheath. Scientists have been receiving signals from the spacecraft over the past six months, indicating that the speed of the solar wind has reached zero. This means that the spacecraft is close to the outer edges of the heliosheath and is likely to enter interstellar space in a year.

The spacecraft has enough power to last until 2020 or 2025. Electricity is generated by nuclear energy from radioactive plutonium and this is used to communicate with Earth. And when the power sources dry up, Voyager will continue to float through the lonely interstellar space, heading for the unknown.

A Message From Earth!

Voyager 1 has expanded our understanding of the universe from the flybys and close-up images of Europa and Io and Titan and Ganymede. We have come to understand that these worlds are not static from pictures of volcanoes and lava flows on Io, icy sheaths on the surface of Ganymede (both moons of Jupiter), impact craters on Rhea (Saturn's moon) to Saturn's amazing rings.

Voyager 1 carries with it a record disk with images of 20th-century Earth, music from many of its cultures, greetings in dozens of languages and a message that states "This is a present from a small, distant world, a token of our sounds, our science, our images, our music, our thoughts and our feelings. We are attempting to survive our time so we may live into yours".

Perhaps someday, somewhere.. an advanced civilization like ours may pick up this message. This may be the only enduring evidence that life once existed on Earth.