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Voyager 1
A space probe with squat cylindrical body topped by a large parabolic radio antenna dish pointing upwards, a three-element radioisotope thermoelectric generator on a boom extending left, and scientific instruments on a boom extending right. A golden disk is fixed to the body.
Voyager spacecraft
Organization NASA
Mission type Flyby
Flyby of Jupiter & Saturn
Launch date September 5, 1977 (&0000000000000032.00000032 years, &0000000000000193.000000193 days ago)
Launch vehicle Titan IIIE/Centaur
Mission duration undefined
Home page 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 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.

Contents

Current activities

Voyager 1 is currently the farthest man-made object from Earth, traveling away from both the Earth and the Sun at a speed that corresponds to a greater specific orbital energy than any other probe.[2]

  • Though its twin space-probe, Voyager 2, was launched 16 days earlier, Voyager 2 will never pass Voyager 1 as its end trajectory speed is lower.
  • The New Horizons space probe will never pass Voyager 1, 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).[3] During its flight, Voyager 1 benefited from a number of gravity-assisted speed boosts.

As of August 28, 2009, Voyager 1 was about 110.94 AU (16.596 billion km, or 10.312 billion miles) from the Sun, and has passed the termination shock, entering the heliosheath, with the current goal of reaching and studying the heliopause, which is the known boundary of the solar system.

At this distance, signals from Voyager 1 have a Round Trip Light Time of 30:53:20 (hh:mm:ss) -- versus 24:56:14 for Voyager 2 (as of 2009-09-25).

If Voyager 1 is still functioning when it finally completes the passage through the heliopause (effectively becoming the first human-made object to leave the solar system), scientists will get their first direct measurements of the conditions in the interstellar medium, which may provide clues relevant to the origin and overall nature of the Universe.

With respect to the solar system Voyager 1 is on a hyperbolic trajectory, i.e. its speed (17 km/s) is higher than the local escape velocity. The speed is much less than the escape velocity with respect to the Milky Way (≥ 525 km/s = 326 miles/sec).[4] Thus it will not return to the inner solar system, but stay in the Milky Way.[5][6]

Along with Pioneer 10, Pioneer 11, Voyager 2, and the New Horizons, Voyager 1 is an interstellar probe. If Voyager 1 were traveling in the direction of the nearest star, it would arrive in about 75,000 years.

Voyager 1 had as its primary targets the planets Jupiter and Saturn and their associated moons and rings; its current mission is the detection of the heliopause and particle measurements of solar wind and the interstellar medium.

Both of the Voyager space probes have long outlasted their originally planned lifespan. Each space probe gets its electrical power from three radioisotope thermoelectric generators (RTGs), which are expected to continue to generate enough electric power to let the probes keep communicating with Earth at least until the year 2025.[7]

Mission profile

A rocket launching
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 called the Grand Tour.

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

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.

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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.

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.[8]

view of Saturn lit from the right. Saturn's globe casts its shadow over the rings to the left. Part of the lower hemisphere can be seen through the rings. Some of the spoke-like ring features are visible as bright patches.
Voyager 1 image of Saturn from 5.3 million km, four days after its closest approach. 
orange coloured area at bottom right is separated from black space at upper left by diagonal series of blue bands
Layers of haze covering Saturn's satellite Titan
Cream-colored section of a disk is separated from the black space above by a fuzzy blue curve
Titan's thick haze layer is shown in this enhanced Voyager 1 image. 
black area with white partly layered fuzzy line curving from top to bottom right
Voyager 1 image of Saturn's F ring. 

Interstellar mission

a set of grey squares trace roughly left to right. A few are labeled with single letters associated with a nearby coloured square. J is near to a square labeled Jupiter; E to Earth; V to Venus; S to Saturn; U to Uranus; N to Neptune. A small spot appears at the centre of each coloured square
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,[9] which includes the famous image known as "Pale blue dot". It is estimated that both Voyager crafts have sufficient electrical power to operate their radio transmitters until at least after 2025, which will be over 48 years after launch. Voyager 1 is the most distant functioning space probe to receive commands and transmit information to Earth.

Year End of specific capabilities as a result of the available electrical power limitations
2007 Termination of plasma subsystem (PLS)
2008 Power off Planetary Radio Astronomy Experiment (PRA)
2010 Terminate scan platform and Ultraviolet spectrometer (UVS) observations
2015 Termination of Data Tape Recorder (DTR) operations (limited by ability to capture 1.4 kbit/s data using a 70 m/34 m antenna array. This is the minimum rate at which the DTS can read-out data.)
2016 approx Termination of gyroscopic operations
2020 Start shutdown of science instruments (as of 2008-03-18 the order is undecided but the Low-Energy Charged Particles, Cosmic Ray Subsystem, Magnetometer, and Plasma Wave Subsystem instruments are expected to still be operating)
2025 or after Can no longer power any single instrument.

Heliopause

orange area at left labeled Bow Shock appears to compress a pale blue oval-shaped region labeled Heliosphere extending to the right with its border labeled Heliopause. A central dark blue circular region is labeled Termination Shock with the gap between it and the Heliosphere labeled Heliosheath. Centred in the blue region is a concentric set of ellipses around a bright spot with two white lines curving away from it: the upper line labeled Voyager 1 ends outside the dark blue circle; the lower line labeled Voyager 2 appears inside
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.

Scientists at the Johns Hopkins University Applied Physics Laboratory believe that Voyager 1 entered the termination shock in February 2003.[10] Some other scientists have expressed doubt, discussed in the journal Nature of November 6, 2003.[11] 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 with the data from the other instruments on board Voyager I.

However, in May 2005 a NASA press release said that consensus was that Voyager 1 was now in the heliosheath.[12] 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

yellow spot surrounded by three concentric light-blue ellipses labeled from inside to out: Saturn, Uranus and Neptune. A grey ellipse labeled Pluto overlaps Neptune's ellipse. Four colored lines trails outwards from the central spot: a short red line labeled Voyager II traces to the right and up; a green and longer line labeled Pioneer-11 traces to the right; a purple line labeled Voyager traces to the bottom right corner; and a dark blue line labeled Pioneer 10 traces left
Location and trajectories of Pioneer and Voyager spacecraft, as of April 4, 2007

As of 29 January 2010 (2010 -01-29), Voyager 1 was at a distance of 112.816 AU (approximately 16.89 billion kilometers, 10.48 billion miles, or 0.0017 light years) from the Sun, which makes it the most distant human-made object from Earth.[13] At this distance, it is farther away from the Sun than any known natural solar system object, including Eris and 90377 Sedna, but excluding long-period comets. (Although Sedna has a highly-eccentric orbit that takes it 975 AU away from the Sun at aphelion, as of 2006 it is less than 90 AU away from the Sun and approaching its perihelion at 76 AU.[14][15])

At the above distance, light or radio waves, both of which are forms of electromagnetic radiation and propagate at 299,792.5 kilometers per second (the speed of light), take over 14.6 hours to reach the Earth from Voyager 1. As a basis for comparison, the Moon is about 1.4 light-seconds from Earth; the Sun is approximately 8.5 light-minutes away; Pluto is about 5.5 light-hours away; Trans-Neptunian object 2006 SQ372 at aphelion is about 12.3 light-days away; and the nearest star is 4.22 light-years away.

As of 9 October 2009, Voyager 1 was traveling at a speed of 17.078 kilometers per second relative to the Sun (3.6 AU per year or 61,600 km/h or 38,400 miles per hour), about 10% faster than Voyager 2. As of 10 October 2008, Voyager 1 was traveling at a speed of 17.097 kilometers per second relative to the Sun (a reduction of 19 m/s within a single year, due to the attraction of the sun).

On November 19, 2015, Voyager 1 will be 133.15 Astronomical Units from the Sun. Reasonably accurate information concerning its location can be found in this NASA paper with heliocentric coordinates of both space probes extrapolated up to 2015.

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 moving to the Solar System at about 119 kilometers per second.[16]

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.[17] This is believed to be the first such tracking of Voyager 1.

As of May 2008, 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 by measuring the round-trip time delay of radio signals to and from Voyager 1. Then, halving that time delay, and multiplying by the well-known speed of light gives the one-way distance.

Gallery

See also

References

  1. ^ The term "visit" is used here in the sense of "approach".
  2. ^ Speed of the Voyager Space Probes
  3. ^ "New Horizons Salutes Voyager". New Horizons. August 17, 2006. http://pluto.jhuapl.edu/news_center/news/081706.php. Retrieved 2009-11-03. 
  4. ^ [1]
  5. ^ This applies even if the Voyager travels in the same direction as the Sun in its orbit around the center of the Galaxy, in which case the velocities of 220 km/s and 17 km/s are added.
  6. ^ If the Voyager experiences a strong interaction with something there is a small chance that it will return to the inner solar system, or is ejected from the Milky Way.
  7. ^ "Voyager – Spacecraft – Spacecraft Lifetime". NASA Jet Propulsion Laboratory. 2008-03-15. http://voyager.jpl.nasa.gov/spacecraft/spacecraftlife.html. Retrieved 2008-05-25. 
  8. ^ Voyager - Frequently Asked Questions
  9. ^ http://nssdc.gsfc.nasa.gov/photo_gallery/caption/solar_family.txt
  10. ^ Kate Tobin (November 5, 2003). "Spacecraft reaches edge of solar system". CNN.com. http://edition.cnn.com/2003/TECH/space/11/05/voyager.solar.boundary/. Retrieved 2007-08-07. 
  11. ^ L A Fisk (2003). "Planetary Science: Over the edge?". Nature 426 (6962): 21–22. doi:10.1038/426021a. 
  12. ^ "Voyager Enters Solar System's Final Frontier". NASA. May 24, 2005. http://www.nasa.gov/vision/universe/solarsystem/voyager_agu.html. Retrieved 2007-08-07. 
  13. ^ Heavens Above: Spacecraft escaping the Solar System May 20, 2008, Week Ending May 25, 2008
  14. ^ CNN: "NASA: Voyager I enters solar system's final frontier", May 25, 2005
  15. ^ CNN: "NASA: Voyager II detects solar system's edge", May 23, 2006
  16. ^ Voyager - Mission - Interstellar Mission
  17. ^ AMSAT-DL article in German; ARRL article in English

External links

Media related to Voyager 1 at Wikimedia Commons


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