September 5th is 30th anniversary of NASA Voyager 1

William Atkins
Monday, 03 September 2007 19:50

Science - Space

On September 5, 1977, Voyager 1 lifted off from Cape Canaveral, Florida, to explore the outer solar system. Originally a five-year mission, in 2007, the interstellar space probe is still functioning and is expected to be the first spacecraft to exit the solar system and enter interstellar space.            

The 1,615-pound (733-kilogram) spacecraft contains sixteen rocket motors that use nuclear power in the form of plutonium-238, a radioactive isotope of plutonium, to make small adjustments in its flight. The three nuclear power devices are called radioisotope thermoelectric generators (RTGs).

When Voyager 1 was launched the RTGs generated about 470 watts of 30 volt direct current power. By 1997, that amount had dropped to 335 watts. Scientists with the Voyager program estimate that the RTGs aboard Voyager will continue to provide electrical power until about 2020.

The probe Voyager 1 also contains a 12-foot (3.66-meter) diameter radio dish antenna, which extends out about 13 meters, that is used to communicate with scientists back on the Earth.

Voyager 1 is the sister craft to Voyager 2. Both contain a 12-inch gold-plated copper disk (“Golden Record”) on which sounds and images of Earth are recorded. Sounds include greetings in fifty-five languages, thirty-five natural and human-made sounds, and twenty-seven excerpts from musical songs.

In February 1998, Voyager 1 became the most distant space probe sent from Earth, when it surpassed Pioneer 10 in distance away from the Earth. December 2004, scientists estimated that Voyager 1 left the termination shock and entered the heliosheath (the volume of space that contains all of the material ejected from the Sun)—at a distance of about 94 astronomical units (AU), or, about 8.7 billion miles (14 billion kilometers).

The termination shock is a boundary point in the heliosphere where the Sun’s solar wind is slowing down in speed due to being increasingly buffeted by winds from the interstellar medium. The heliosheath is a further point in the heliosphere where the solar wind and interstellar wind are roughly equal in strength.

Two years, seven months later, in July 2007, Voyager 1 had made it to 103.2 AU, or about 9.6 billion miles (15.5 billion kilometers). At this distance, signals from the space probe takes approximately thirteen hours to reach the control center at the NASA Jet Propulsion Laboratory in California. Its speed is about 3.5 AU per year, or about 325 million miles (524 million kilometers) each year.

Hopefully before 2020, when Voyager 1 is expected to cease functioning, it will leave the heliosheath and move into the heliopause, which is considered the outer edge of the heliosphere.

Scientists conjecture that the heliopause will be reached some where around 2015. At this point, scientists contend that the solar system ends and interstellar space begins. Also, at this point, Voyager 1 will become the first interstellar spacecraft of the human race. During this point in its travels scientists hope that Voyager 1 will be able to send back information of the heliopause from plasma wave experiments onboard so a better estimate can be made on the size of the solar system.

The NASA Voyager program website is: http://voyager.jpl.nasa.gov/.

The relative positions of Voyager 1, Voyager 2, Pioneer 10, and Pioneer 11 is found at: http://www.heavens-above.com/solar-escape.asp.

Additional information from NASA, along with external links: http://www.nasa.gov/vision/universe/solarsystem/voyager_agu.html.