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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Voyager 1 | 3/7 | https://en.wikipedia.org/wiki/Voyager_1 | reference | science, encyclopedia | 2026-05-05T13:27:04.653048+00:00 | kb-cron |
The Voyagers found aurora-like ultraviolet emissions of hydrogen at mid-latitudes in the atmosphere, and auroras at polar latitudes (above 65 degrees). The high-level auroral activity may lead to the formation of complex hydrocarbon molecules that are carried toward the equator. The mid-latitude auroras, which occur only in sunlit regions, remain a puzzle, since bombardment by electrons and ions, known to cause auroras on Earth, occurs primarily at high latitudes. Both Voyagers measured the rotation of Saturn (the length of a day) at 10 hours, 39 minutes, 24 seconds. Voyager 1's mission included a flyby of Titan, Saturn's largest moon, which had long been known to have an atmosphere. Images taken by Pioneer 11 in 1979 had indicated the atmosphere was substantial and complex, further increasing interest. The Titan flyby occurred as the spacecraft entered the system to avoid any possibility of damage closer to Saturn compromising observations, and approached to within 6,400 km (4,000 mi), passing behind Titan as seen from Earth and the Sun. Voyager's measurement of the atmosphere's effect on sunlight and Earth-based measurement of its effect on the probe's radio signal were used to determine the atmosphere's composition, density, and pressure. Titan's mass was also measured by observing its effect on the probe's trajectory. The thick haze prevented any visual observation of the surface, but the measurement of the atmosphere's composition, temperature, and pressure led to speculation that lakes of liquid hydrocarbons could exist on the surface. Because observations of Titan were considered vital, the trajectory chosen for Voyager 1 was designed around the optimum Titan flyby, which took it below the south pole of Saturn and out of the plane of the ecliptic, ending its planetary science mission. Had Voyager 1 failed or been unable to observe Titan, Voyager 2's trajectory would have been altered to incorporate the Titan flyby, precluding any visit to Uranus and Neptune. The trajectory Voyager 1 was launched into would not have allowed it to continue on to Uranus and Neptune, but could have been altered to avoid a Titan flyby and travel from Saturn to Pluto, arriving in 1986.
=== Exit from the heliosphere ===
On February 14, 1990, Voyager 1 took the first "family portrait" of the Solar System as seen from outside, which includes the image of planet Earth known as Pale Blue Dot. Soon afterward, its cameras were deactivated to conserve energy and computer resources for other equipment. The camera software has been removed from the spacecraft, so it would now be complex to get them working again. Earth-side software and computers for reading the images are also no longer available. On February 17, 1998, Voyager 1 reached a distance of 69 AU (6.4 billion mi; 10.3 billion km) from the Sun and overtook Pioneer 10 as the most distant spacecraft from Earth. Traveling at about 17 km/s (11 mi/s), it has the fastest heliocentric recession speed of any spacecraft. As Voyager 1 headed for interstellar space, its instruments continued to study the Solar System. Jet Propulsion Laboratory scientists used 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. As of 2013, the probe was moving with a relative velocity to the Sun of about 61,197 kilometers per hour (38,026 mph).With the velocity the probe is currently maintaining, Voyager 1 is traveling about 523 million km (325 million mi) per year, or about one light-year per 18,000 years.
==== Termination shock ====
Scientists at the Johns Hopkins University Applied Physics Laboratory believe that Voyager 1 entered the termination shock in February 2003. This marks the point where the solar wind slows to subsonic speeds. Some other scientists expressed doubt and discussed this in the journal Nature of November 6, 2003. The issue would not be resolved until other data became available, since Voyager 1's solar-wind detector ceased functioning in 1990. This failure meant that termination shock detection would have to be inferred from the data from the other instruments on board. In May 2005, a NASA press release said that the consensus was that Voyager 1 was then in the heliosheath. In a scientific session at the American Geophysical Union meeting in New Orleans, Louisiana, on May 25, 2005, Ed Stone presented evidence that the craft crossed the termination shock in late 2004. This event is estimated to have occurred on December 15, 2004, at a distance of 94 AU (8,700 million mi) from the Sun.