34 Years Ago, On September 5, Voyager 1 launched from Cape Canaveral aboard a Titan-Centaur (TC-6) rocket

The twin spacecraft Voyager 1 and Voyager 2 were launched by NASA in separate months in the summer of 1977 from Cape Canaveral, Florida. As originally designed, the Voyagers were to conduct closeup studies of Jupiter and Saturn, Saturn’s rings, and the larger moons of the two planets.

 

Voyager 1 Launched Sept. 5th, 1977 onboard a Martin Marrietta Titan III-E + General Dynamics Centaur-D-1TR Rocket from SLC-41 CCAFS, FL. The Rockets internal name - TC-6.

To accomplish their two-planet mission, the spacecraft were built to last five years. But as the mission went on, and with the successful achievement of all its objectives, the additional flybys of the two outermost giant planets, Uranus and Neptune, proved possible — and irresistible to mission scientists and engineers at the Voyagers’ home at the Jet Propulsion Laboratory in Pasadena,California.

As the spacecraft flew across the solar system, remote-control reprogramming was used to endow the Voyagers with greater capabilities than they possessed when they left the Earth. Their two-planet mission became four. Their five-year lifetimes stretched to 12 and is now near thirty years.

Interstellar Mission. The twin Voyager 1 and 2 spacecraft continue exploring where nothing from Earth has flown before. In the 34th year after their 1977 launches, they each are much farther away from Earth and the Sun than Pluto. Voyager 1 and 2 are now in the "Heliosheath" - the outermost layer of the heliosphere where the solar wind is slowed by the pressure of interstellar gas. Both spacecraft are still sending scientific information about their surroundings through the Deep Space Network (DSN).

 

Eventually, between them, Voyager 1 and 2 would explore all the giant outer planets of our solar system, 48 of their moons, and the unique systems of rings and magnetic fields those planets possess.

Had the Voyager mission ended after the Jupiter and Saturn flybys alone, it still would have provided the material to rewrite astronomy textbooks. But having doubled their already ambitious itineraries, the Voyagers returned to Earth information over the years that has revolutionized the science of planetary astronomy, helping to resolve key questions while raising intriguing new ones about the origin and evolution of the planets in our solar system.

NASA placed an ambitious message aboard Voyager 1 and 2-a kind of time capsule, intended to communicate a story of our world to extraterrestrials. The Voyager message is carried by a phonograph record-a 12-inch gold-plated copper disk containing sounds and images selected to portray the diversity of life and culture on Earth. The contents of the record were selected for NASA by a committee chaired by Carl Sagan of Cornell University, et. al. Dr. Sagan and his associates assembled 115 images and a variety of natural sounds, such as those made by surf, wind and thunder, birds, whales, and other animals. To this they added musical selections from different cultures and eras, and spoken greetings from Earth-people in fifty-five languages, and printed messages from President Carter and U.N. Secretary General Waldheim. Each record is encased in a protective aluminum jacket, together with a cartridge and a needle. Instructions, in symbolic language, explain the origin of the spacecraft and indicate how the record is to be played. The 115 images are encoded in analog form. The remainder of the record is in audio, designed to be played at 16-2/3 revolutions per minute. It contains the spoken greetings, beginning with Akkadian, which was spoken in Sumer about six thousand years ago, and ending with Wu, a modern Chinese dialect. Following the section on the sounds of Earth, there is an eclectic 90-minute selection of music, including both Eastern and Western classics and a variety of ethnic music. Once the Voyager spacecraft leave the solar system (by 1990, both will be beyond the orbit of Pluto), they will find themselves in empty space. It will be forty thousand years before they make a close approach to any other planetary system. As Carl Sagan has noted, "The spacecraft will be encountered and the record played only if there are advanced spacefaring civilizations in interstellar space. But the launching of this bottle into the cosmic ocean says something very hopeful about life on this planet." The definitive work about the Voyager record is "Murmurs of Earth" by Executive Director, Carl Sagan, Technical Director, Frank Drake, Creative Director, Ann Druyan, Producer, Timothy Ferris, Designer, Jon Lomberg, and Greetings Organizer, Linda Salzman. Basically, this book is the story behind the creation of the record, and includes a full list of everything on the record. "Murmurs of Earth", originally published in 1978, was reissued in 1992 by Warner News Media with a CD-ROM that replicates the Voyager record. Unfortunately, this book is now out of print, but it is worth the effort to try and find a used copy or browse through a library copy.

 

History Of The Voyager Mission

The Voyager mission was designed to take advantage of a rare geometric arrangement of the outer planets in the late 1970s and the 1980s which allowed for a four-planet tour for a minimum of propellant and trip time. This layout of Jupiter, Saturn, Uranus and Neptune, which occurs about every 175 years, allows a spacecraft on a particular flight path to swing from one planet to the next without the need for large onboard propulsion systems. The flyby of each planet bends the spacecraft’s flight path and increases its velocity enough to deliver it to the next destination. Using this “gravity assist” technique, first demonstrated with NASA’s Mariner 10 Venus/Mercury mission in 1973-74, the flight time toNeptunewas reduced from 30 years to 12.

While the four-planet mission was known to be possible, it was deemed to be too expensive to build a spacecraft that could go the distance, carry the instruments needed and last long enough to accomplish such a long mission. Thus, the Voyagers were funded to conduct intensive flyby studies of Jupiter and Saturn only. More than 10,000 trajectories were studied before choosing the two that would allow close flybys of Jupiter and its large moon Io, and Saturn and its large moon Titan; the chosen flight path for Voyager 2 also preserved the option to continue on to Uranus and Neptune.

From the NASA Kennedy Space Center at Cape Canaveral,Florida, Voyager 2 was launched first, on August 20, 1977; Voyager 1 was launched on a faster, shorter trajectory on September 5, 1977. Both spacecraft were delivered to space aboard Titan-Centaur expendable rockets.

The prime Voyager mission to Jupiter and Saturn brought Voyager 1 to Jupiter on March 5, 1979, and Saturn on November 12, 1980, followed by Voyager 2 to Jupiter on July 9, 1979, and Saturn on August 25, 1981.

Voyager 1’s trajectory, designed to send the spacecraft closely past the large moon Titan and behind Saturn’s rings, bent the spacecraft’s path inexorably northward out of the ecliptic plane — the plane in which most of the planets orbit the Sun. Voyager 2 was aimed to fly by Saturn at a point that would automatically send the spacecraft in the direction of Uranus.

After Voyager 2’s successful Saturn encounter, it was shown that Voyager 2 would likely be able to fly on to Uranus with all instruments operating. NASA provided additional funding to continue operating the two spacecraft and authorized JPL to conduct a Uranus flyby. Subsequently, NASA also authorized theNeptuneleg of the mission, which was renamed the Voyager Neptune Interstellar Mission.

Voyager 2 encountered Uranus on January 24, 1986, returning detailed photos and other data on the planet, its moons, magnetic field and dark rings. Voyager 1, meanwhile, continues to press outward, conducting studies of interplanetary space. Eventually, its instruments may be the first of any spacecraft to sense the heliopause — the boundary between the end of the Sun’s magnetic influence and the beginning of interstellar space.

Following Voyager 2’s closest approach toNeptuneon August 25, 1989, the spacecraft flew southward, below the ecliptic plane and onto a course that will take it, too, to interstellar space. Reflecting the Voyagers’ new transplanetary destinations, the project is now known as the Voyager Interstellar Mission.

Voyager 1 has crossed into the heliosheath and is leaving the solar system, rising above the ecliptic plane at an angle of about 35 degrees at a rate of about 520 million kilometers (about 320 million miles) a year. Voyager 2 is also headed out of the solar system, diving below the ecliptic plane at an angle of about 48 degrees and a rate of about 470 million kilometers (about 290 million miles) a year.

Both spacecraft will continue to study ultraviolet sources among the stars, and the fields and particles instruments aboard the Voyagers will continue to explore the boundary between the Sun’s influence and interstellar space. The Voyagers are expected to return valuable data for at least another decade. Communications will be maintained until the Voyagers’ power sources can no longer supply enough electrical energy to power critical subsystems.

Launch

Voyager 2 launched on August 20, 1977, from Cape Canaveral, Florida aboard a Titan-Centaur rocket. On September 5, Voyager 1 launched, also from Cape Canaveral aboard a Titan-Centaur rocket.

Planetary Tour

Between them, Voyager 1 and 2 explored all the giant planets of our outer solar system, Jupiter, Saturn, Uranus and Neptune; 48 of their moons; and the unique system of rings and magnetic fields those planets possess.

Closest approach to Jupiter occurred on March 5, 1979 for Voyager 1; July 9, 1979 for Voyager 2.

Closest approach to Saturn occurred on November 12, 1980 for Voyager 1; August 25, 1981 for Voyager 2.

Closest approach to Uranus occurred on January 24, 1986 by Voyager 2.

Closest approach to Neptune occurred on August 25, 1989 by Voyager 2.

Most Distant Spacecraft

The Voyager spacecraft will be the third and fourth human spacecraft to fly beyond all the planets in our solar system. Pioneers 10 and 11 preceded Voyager in outstripping the gravitational attraction of the Sun but on February 17, 1998, Voyager 1 passed Pioneer 10 to become the most distant human-made object in space.

The Golden Record

Both Voyager spacecrafts carry a greeting to any form of life, should that be encountered. The message is carried by a phonograph record – -a 12-inch gold-plated copper disk containing sounds and images selected to portray the diversity of life and culture on Earth. The contents of the record were selected for NASA by a committee chaired by Carl Sagan of Cornell University. Dr. Sagan and his associates assembled 115 images and a variety of natural sounds. To this they added musical selections from different cultures and eras, and spoken greetings from Earth-people in fifty-five languages.

Present Status

As of March 2010, Voyager 1 was at a distance of 16.9 billion kilometers (~ 113 AU) from the Sun.

Voyager 2 was at a distance of 13.7 billion kilometers (~ 92 AU).

Voyager 1 is escaping the solar system at a speed of about 3.6 AU per year.

Voyager 2 is escaping the solar system at a speed of about 3.3 AU per year.

There are currently five science investigation teams participating in the Interstellar Mission. They are:

1. Magnetic field investigation
2. Low energy charged particle investigation
3. Cosmic ray investigation
4. Plasma Investigation (Voyager 2 only)
5. Plasma wave investigation

Five instruments onboard the Voyagers directly support the five science investigations. The five instruments are:

1. Magnetic field instrument (MAG)
2. Low energy charged particle instrument (LECP)
3. Cosmic ray instrument (CRS)
4. Plasma instrument (PLS)
5. Plasma wave instrument (PWS)

One other instrument is collecting data but does not have official science investigation associated with it:

6. Ultraviolet spectrometer subsystem (UVS), Voyager 1 only

Termination Shock

Voyager 1 crossed the termination shock in December 2004 at about 94 AU from the Sun while Voyager 2 crossed it in August 2007 at about 84 AU. Both spacecraft are now exploring the Heliosheath.

The Heliopause

While the exact location of the Heliopause is not known, it has been estimated that Voyager could reach this entry into interstellar space 10 years after crossing the Termination Shock.

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