Voyager 1

Voyager 1

Voyager spacecraft
Operator	NASA
Mission type	Flyby
Flyby of	Jupiter & Saturn
Launch date	September 5, 1977 (&000000000000003300000033 years, &0000000000000162000000162 days ago)
Launch vehicle	Titan IIIE/Centaur
Mission duration	undefined
Homepage	NASA Voyager website
Mass	721.9 kg (1,592 lb)
Power	420 W

The Voyager 1 spacecraft is a 722-kilogram (1,592 lb) robotic space probe of the outer Solar System and beyond, launched by NASA on September 5, 1977. It still receives commands from, and transmits information to Earth, currently pursuing its extended mission to locate and study the boundaries of the solar System, including the Kuiper belt and beyond. Its original mission was to visit^[1] Jupiter and Saturn; and it was the first probe to provide detailed images of the moons of these planets.

Mission profile

Voyager 1 lifted off with a Titan IIIE/Centaur

Voyager 1 was originally planned as Mariner 11 of the Mariner program. From the outset, it was designed to take advantage of the then-new technique of gravity assist. Luckily, the development of interplanetary probes coincided with an alignment of the planets making possible a mission to the outer Solar System called the Grand Tour.

The Grand Tour was a linked series of gravity assists that would enable a single probe to visit all four of the Solar System's gas giant planets (Jupiter, Saturn, Uranus, and Neptune) with only the minimal fuel needed for course corrections.

The nearly identical Voyager 1 and Voyager 2 space probes were designed with the possibility of a Grand Tour in mind, and their launches were timed to enable the Grand Tour to be carried out if things went well. However, the two Voyagers were only funded by Congress as Jupiter-Saturn probes. At one time, the program was called the "Mariner Jupiter-Saturn" project.

Because of this remarkable planetary alignment, a Voyager-class spacecraft could visit each of the four outer planets mentioned above in just twelve years, instead of the approximately thirty years that would usually be required otherwise.

The Voyager 1 probe was launched on September 5, 1977, by the National Aeronautics and Space Administration from Cape Canaveral, Florida, aboard a Titan IIIE/Centaur carrier rocket, two weeks after its twin space probe, Voyager 2 had been launched on August 20, 1977. Despite being launched after Voyager 2, Voyager 1 was sent off on a somewhat shorter, quicker trajectory, so that it reached both Jupiter and Saturn before its sister space probe did.

For details on the Voyager space probes' identical instrument packages, see the separate article on the overall Voyager Program.

Jupiter

Voyager 1 began photographing Jupiter in January 1979. Its closest approach to Jupiter was on March 5, 1979, at a distance of about 349,000 kilometres (217,000 miles) from the planet's center. Due to the greater photographic resolution allowed by a closer approach, most observations of the moons, rings, magnetic fields, and the radiation belt environment of the Jovian system were made during the 48-hour period that bracketed the closest approach. Voyager 1 finished photographing the Jovian system in April 1979.

The two Voyager space probes made a number of important discoveries about Jupiter, its satellites, its radiation belts, and its never-before-seen planetary rings. The most surprising discovery in the Jovian system was the existence of volcanic activity on the moon Io, which had not been observed either from the ground, or by Pioneer 10 or 11.

The Great Red Spot as seen from Voyager 1.	View of lava flows radiating from the volcano Ra Patera on Io.
False color detail of Jupiter's atmosphere, as imaged by Voyager 1.	Valhalla crater on Callisto. Image taken by Voyager 1 in 1979.

Saturn

The gravitational assist trajectories at Jupiter were successfully carried out by both Voyagers, and the two spacecraft went on to visit Saturn and its system of moons and rings. Voyager 1's Saturnian flyby occurred in November 1980, with the closest approach on November 12, 1980, when the space probe came within 124,000 kilometers (77,000 mi) of Saturn's cloud-tops. The space probe's cameras detected complex structures in the rings of Saturn, and its remote sensing instruments studied the atmospheres of Saturn and its giant moon Titan.

Because Pioneer 11 had one year earlier detected a thick, gaseous atmosphere over Titan, the Voyager space probes' controllers at the Jet Propulsion Laboratory elected for Voyager 1 to make a close approach of Titan, and of necessity end its Grand Tour there. (For the continuation of the Grand Tour, see the Uranus and Neptune sections of the article on Voyager 2.)

Its trajectory with a close fly-by of Titan caused an extra gravitational deflection that sent Voyager 1 out of the plane of the Ecliptic, thus ending its planetary science mission. Voyager 1 could have been commanded onto a different trajectory, whereby the gravitational slingshot effect of Saturn's mass would have steered and boosted Voyager 1 out to a fly-by of Pluto. However, this plutonian option was not exercised, because the other trajectory that led to the close fly-by of Titan was decided to have more scientific value and less risk.^[2]

Voyager 1 image of Saturn from 5.3 million km, four days after its closest approach.  Layers of haze covering Saturn's satellite Titan.  Titan's thick haze layer is shown in this enhanced Voyager 1 image.  Voyager 1 image of Saturn's F Ring.

Interstellar mission

The "family portrait" of the Solar system taken by Voyager 1

On February 14, 1990, Voyager 1 took the first ever "family portrait" of our solar system as seen from outside,^[3] which includes the famous image known as "Pale blue dot". It is estimated that both Voyager craft have sufficient electrical power to operate their radio transmitters until at least 2025, which will be over 48 years after launch.

On November 17, 1998, Voyager 1 overtook Pioneer 10 as the most distant man-made object from Earth, at a distance of 69.419 AU. It is currently the most distant functioning space probe to receive commands and transmit information to Earth. Provided Voyager 1 does not collide with any stellar objects, the New Horizons space probe will never pass it, despite being launched from Earth at a faster speed than either Voyager spacecraft.

The current speed of New Horizons is slightly greater than Voyager 1 but when New Horizons reaches the same distance from the sun as Voyager 1 is now, its speed will be about 13 km/s (8 miles/sec) compared to Voyager's 17 km/s (10.5 miles/sec).^[4] The close flyby of Saturn and Titan gave Voyager 1 a massive advantage with its extra gravity assist.

Heliopause

Voyager 1 is in the heliosheath.

As Voyager 1 heads for interstellar space, its instruments continue to study the solar system; Jet Propulsion Laboratory scientists are using the plasma wave experiments aboard Voyager 1 and 2 to look for the heliopause, the boundary at which the solar wind transitions into the interstellar medium.

Scientists at the Johns Hopkins University Applied Physics Laboratory believe that Voyager 1 entered the termination shock in February 2003.^[5] Some other scientists have expressed doubt, discussed in the journal Nature of November 6, 2003.^[6] In a scientific session at the American Geophysical Union meeting in New Orleans on the morning of May 25, 2005, Dr. Ed Stone presented evidence that Voyager 1 crossed the termination shock in December 2004.

The issue will not be resolved until other data becomes available, since Voyager 1's solar-wind detector ceased functioning in 1990. This failure has meant that termination shock detection must be inferred from the data from the other instruments on board.

However, in May 2005 a NASA press release said that consensus was that Voyager 1 was now in the heliosheath.^[7] Scientists anticipate the craft will reach the heliopause in 2015.

Golden record

Included in the spacecraft is one of the two Voyager Golden Records. This phonograph record contains sounds and images selected to portray the diversity of life and culture on Earth. It is intended for any intelligent extraterrestrial life form, or for future humans, that may find it.

Current status

Location and trajectories of Pioneer and Voyager spacecraft, as of April 4, 2007. Note Voyager 2 is further than Pioneer 11 and only appears closer here due to its -55 degree declination, and that Voyager 1's position is drawn too far away.

As of July 27, 2010 (2010 -07-27)^[update], Voyager 1 was about 113.478 AU (16.976 billion km, or 10.549 billion miles) or 0.002 of a light-year from the Sun. Its current relative velocity is 17.07 km/s, or 61,452 kilometres per hour (38,185 mph). This calculates as 3.6 AU per year, about 10% faster than Voyager 2.

NASA extrapolated the location and heliocentric coordinates of both Voyager space probes up to 2015.^[8] On November 19, 2015, Voyager 1 will be approximately 133.15 Astronomical Units from the Sun.

Voyager 1 is not heading towards any particular star, but in about 40,000 years it will pass within 1.6 light years of the star AC+79 3888 in the constellation Camelopardalis because AC+79 3888 is generally moving towards our Solar System at about 119 kilometers per second.^[9]

As of May 2008^[update], Voyager 1 is at 12.45° declination and 17.125 hours right ascension, placing it in the constellation Ophiuchus as observed from the Earth. NASA continues its daily tracking of Voyager 1 with its Deep Space Network. This network measures both the elevation and azimuth angles of the incoming radio waves from Voyager 1, and it also measures the distance from the Earth to Voyager 1.

On March 31, 2006, the amateur radio operators from AMSAT in Germany tracked and received radio waves from Voyager 1 using the 20-meter (66 ft) dish at Bochum with a long integration technique. Its data was checked and verified against data from the Deep Space Network station at Madrid, Spain.^[10] This is believed to be the first such tracking of Voyager 1.

Gallery

Trajectory of Voyager 1 using Celestia

Voyager spacecraft structure

See also

References

External links

Media related to Voyager 1 at Wikimedia Commons