Voyager program

[1] After the planetary flybys were complete, decisions were made to keep the probes in operation to explore interstellar space and the outer regions of the solar system.

Like a great painting or an abiding institution, it has acquired an existence of its own, a destiny beyond the grasp of its handlers.The two Voyager space probes were originally conceived as part of the Planetary Grand Tour planned during the late 1960s and early 70s that aimed to explore Jupiter, Saturn, Saturn's moon, Titan, Uranus, Neptune, and Pluto.

The mission originated from the Grand Tour program, conceptualized by Gary Flandro, an aerospace engineer at the Jet Propulsion Laboratory, in 1964, which leveraged a rare planetary alignment occurring once every 175 years.

The mission was to send several pairs of probes and gained momentum in 1966 when it was endorsed by NASA's Jet Propulsion Laboratory.

The gravity-assist technique, successfully demonstrated by Mariner 10, would be used to achieve significant velocity changes by maneuvering through an intermediate planet's gravitational field to minimize time towards Saturn.

[17] Two mission trajectories were established: JST aimed at Jupiter, Saturn, and enhancing a Titan flyby, while JSX served as a contingency plan.

[17] The probes would be launched in August or September 1977, with their main objective being to compare the characteristics of Jupiter and Saturn, such as their atmospheres, magnetic fields, particle environments, ring systems, and moons.

After completing their flybys, the probes would communicate with Earth, relaying vital data using their magnetometers, spectrometers, and other instruments to detect interstellar, solar, and cosmic radiation.

Their radioisotope thermoelectric generators (RTGs) would limit the maximum communication time with the probes to roughly a decade.

Voyager 1 and Pioneer 10 are the most widely separated human-made objects anywhere since they are travelling in roughly opposite directions from the Solar System.

[25] In 2010 Voyager 1 reported that the outward velocity of the solar wind had dropped to zero, and scientists predicted it was nearing interstellar space.

[27] In June 2012, Scientists at NASA reported that Voyager 1 was very close to entering interstellar space, indicated by a sharp rise in high-energy particles from outside the Solar System.

[28][29] In September 2013, NASA announced that Voyager 1 had crossed the heliopause on 25 August 2012, making it the first spacecraft to enter interstellar space.

[30][31][32] In December 2018, NASA announced that Voyager 2 had crossed the heliopause on 5 November 2018, making it the second spacecraft to enter interstellar space.

The diagram shows the high-gain antenna (HGA) with a 3.7 m (12 ft) diameter dish attached to the hollow decagonal electronics container.

The scan platform comprises: the Infrared Interferometer Spectrometer (IRIS) (largest camera at top right); the Ultraviolet Spectrometer (UVS) just above the IRIS; the two Imaging Science Subsystem (ISS) vidicon cameras to the left of the UVS; and the Photopolarimeter System (PPS) under the ISS.

The DTR is used to record high-rate Plasma Wave Subsystem (PWS) data, which is played back every six months.

)[46]: 17 Because of the inverse-square law in radio communications, the digital data rates used in the downlinks from the Voyagers have been continually decreasing the farther that they get from the Earth.

Whilst the craft were between Saturn and Uranus the onboard software was upgraded to do a degree of image compression and to use a more efficient Reed-Solomon error-correcting encoding.

In the United States, the Very Large Array in New Mexico was brought into temporary use along with the antennas of the Deep Space Network at Goldstone.

"[51] The main objective of the VIM was to extend the exploration of the Solar System beyond the outer planets to the heliopause (the farthest extent at which the Sun's radiation predominates over interstellar winds) and if possible even beyond.

Passing through the heliopause boundary has allowed both spacecraft to make measurements of the interstellar fields, particles and waves unaffected by the solar wind.

The Voyager 1 scan platform was scheduled to go off-line in late 2000 but has been left on to investigate UV emission from the upwind direction.

Gyro operations are used to rotate the probe 360 degrees six times per year to measure the magnetic field of the spacecraft, which is then subtracted from the magnetometer science data.

The two spacecraft continue to operate, with some loss in subsystem redundancy but retain the capability to return scientific data from a full complement of Voyager Interstellar Mission (VIM) science instruments.

The spacecraft began VIM in an environment controlled by the Sun's magnetic field, with the plasma particles being dominated by those contained in the expanding supersonic solar wind.

According to the researchers, this implies that "the density gradient is a large-scale feature of the VLISM (very local interstellar medium) in the general direction of the heliospheric nose".

[33][29] The record is intended as a combination time capsule and an interstellar message to any civilization, alien or far-future human, that may recover either of the Voyagers.

[62] The Voyager program's discoveries during the primary phase of its mission, including new close-up color photos of the major planets, were regularly documented by print and electronic media outlets.

That's us....The Earth is a very small stage in a vast cosmic arena.... To my mind, there is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world.

A poster of the planets and moons visited during the Voyager program.
The trajectories that enabled the Voyager spacecraft to visit the outer planets and achieve velocity to escape the Solar System
Plot of Voyager 2 ' s heliocentric velocity against its distance from the Sun, illustrating the use of gravity assist to accelerate the spacecraft by Jupiter, Saturn and Uranus. To observe Triton , Voyager 2 passed over Neptune's north pole, resulting in an acceleration out of the plane of the ecliptic and reduced its velocity away from the Sun. [ 14 ]
Interactive 3D model of the Voyager spacecraft .
A space probe with squat cylindrical body topped by a large parabolic radio antenna dish pointing left, a three-element radioisotope thermoelectric generator on a boom extending down, and scientific instruments on a boom extending up. A disk is fixed to the body facing front left. A long triaxial boom extends down left and two radio antennas extend down left and down right.
Voyager spacecraft diagram
RTGs for the Voyager program
Voyager 1 crossed the heliopause, or the edge of the heliosphere , in August 2012.
Voyager 2 crossed the heliosheath in November 2018. [ 3 ] [ 49 ]
This diagram about the heliosphere was released on 28 June 2013 and incorporates results from the Voyager spacecraft. [ 57 ]
The cover of the golden record
Seen from 6 billion kilometers (3.7 billion miles), Earth appears as a " pale blue dot " (the blueish-white speck approximately halfway down the light band to the right).