Saturday, May 31, 2014

Voyager 1 and 2

Voyager 2 is a 722 kg (1,592 lb) space probe launched by NASA on August 20, 1977 to study the outer Solar System and eventually interstellar space. It was actually launched before Voyager 1, but Voyager 1 moved faster and eventually passed it. Voyager 2 has been operating for 36 years, 9 months and 11 days as of 31 May 2014, and the Deep Space Network is still receiving its data transmissions.
At a distance of 104.44 AU (1.562×1010 km) as of 31 May 2014 from Earth, it is one of the most distant human made objects (along with Voyager 1, Pioneer 10 and Pioneer 11). Voyager 2 is part of the Voyager program with its identical sister craft Voyager 1, and is in extended mission, tasked with locating and studying the boundaries of the Solar System, including the Kuiper belt, the heliosphere and interstellar space.
 The primary mission ended December 31, 1989 after encountering the Jovian system in 1979, Saturnian system in 1981, Uranian system in 1986, and the Neptunian system in 1989. It is still the only spacecraft to have visited the two outer giant planets Uranus and Neptune. The probe is now moving at a velocity of 15.428 km/s relative to the Sun.
Some history
 Conceived in the 1960s, a Grand tour proposal to study the outer planets, prompted NASA to begin work on a mission in the early 1970s. The development of the interplanetary probes coincided with an alignment of the planets, making possible a mission to the outer Solar System by taking advantage of the then-new technique of gravity assist.
It was determined that utilizing gravity assists would enable a single probe to visit the four gas giants (Jupiter, Saturn, Uranus, and Neptune) while requiring a minimal amount of propellant and a shorter transit duration between planets. Originally, Voyager 2 was planned as Mariner 12 of the Mariner program; however, due to congressional budget cuts(a lot of short sight people), the mission was scaled back to be a flyby of Jupiter and Saturn, and renamed the Mariner Jupiter-Saturn probes. As the program progressed, the name was later changed to Voyager as the probe designs began to differ greatly from previous Mariner missions.
Upon a successful flyby of the Saturnian moon Titan, by Voyager 1, Voyager 2 would get a mission extension to send the probe on towards Uranus and Neptune, ultimately realizing the vision of the Planetary Grand Tour. This could happen because one time time history of human all the planet would be on the same side of the Sun. This happen once every 200 to 300 years!(when jupiter and Saturn Uranus and Neptune)
Each space probe has a record with sounds of the Earth and some photos.
Each of them is power by RTGs( radioisotope thermoelectric generators).Each RTG includes 24 pressed plutonium oxide spheres and provides enough heat to generate approximately 157 watts of power at launch. Collectively, the RTGs supply the spacecraft with 470 watts at launch and will allow operations to continue until at least 2020.
 It flyby Planet Jupiter
The closest approach to Jupiter occurred on July 9, 1979. It came within 570,000 km (350,000 mi) of the planet's cloud tops. It discovered a few rings around Jupiter, as well as volcanic activity on the moon Io.
The Great Red Spot was revealed as a complex storm moving in a counterclockwise direction. An array of other smaller storms and eddies were found throughout the banded clouds.
Discovery of active volcanism on Io was easily the greatest unexpected discovery at Jupiter. It was the first time active volcanoes had been seen on another body in the Solar System. Together, the Voyagers observed the eruption of nine volcanoes on Io, and there is evidence that other eruptions occurred between the two Voyager fly-bys.
The moon Europa displayed a large number of intersecting linear features in the low-resolution photos from Voyager 1. At first, scientists believed the features might be deep cracks, caused by crustal rifting or tectonic processes. The closer high-resolution photos from Voyager 2, however, left scientists puzzled: The features were so lacking in topographic relief that as one scientist described them, they "might have been painted on with a felt marker." Europa is internally active due to tidal heating at a level about one-tenth that of Io. Europa is thought to have a thin crust (less than 30 km (19 mi) thick) of water ice, possibly floating on a 50-kilometer-deep (30 mile) ocean.
Two new, small satellites, Adrastea and Metis, were found orbiting just outside the ring. A third new satellite, Thebe, was discovered between the orbits of Amalthea and Io.
Flyby of Saturn

The closest approach to Saturn occurred on August 26, 1981.
While passing behind Saturn (as viewed from Earth), Voyager 2 probed Saturn's upper atmosphere with its radio link to gather information on atmospheric temperature and density profiles. Voyager 2 found that at the uppermost pressure levels (seven kilopascals of pressure), Saturn's temperature was 70 kelvins (−203 °C), while at the deepest levels measured (120 kilopascals) the temperature increased to 143 K (−130 °C). The north pole was found to be 10 kelvins cooler, although this may be seasonal 
After the fly-by of Saturn, the camera platform of Voyager 2 locked up briefly, putting plans to officially extend the mission to Uranus and Neptune in jeopardy. Fortunately, the mission's engineers were able to fix the problem (caused by an overuse that temporarily depleted its lubricant), and the Voyager 2 probe was given the go-ahead to explore the Uranian system.It because of this the camera platform screw up most new space probe they done away from and place the camera on the body of the space probe it self in one location and away from any other thing it could get in the way! and the whole space probe turns, this would be used on new Horizon space probe when it get to Pluto. This would be the first and last time a space probe would flyby Pluto ! Would you take a chance on a platform that might fuck up? Plus there are back up to the PC that would control the probe.
Flyby of Uranus(the only space probe to flyby)
The closest approach to Uranus occurred on January 24, 1986, when Voyager 2 came within 81,500 kilometers (50,600 mi) of the planet's cloud tops. Voyager 2 also discovered the moons Cordelia, Ophelia, Bianca, Cressida, Desdemona, Juliet, Portia, Rosalind, Belinda, Perdita and Puck; studied the planet's unique atmosphere, caused by its axial tilt of 97.8°; and examined the Uranian ring system.
Uranus is the third largest (Neptune has a larger mass, but a smaller volume) planet in the Solar System. It orbits the Sun at a distance of about 2.8 billion kilometers (1.7 billion miles), and it completes one orbit every 84 Earth years. The length of a day on Uranus as measured by Voyager 2 is 17 hours, 14 minutes. Uranus is unique among the planets in that its axial tilt is about 90°, meaning that its axis is roughly parallel with, not perpendicular to, the plane of the ecliptic. This extremely large tilt of its axis is thought to be the result of a collision between the accumulating planet Uranus with another planet-sized body early in the history of the Solar System. Given the unusual orientation of its axis, with the polar regions of Uranus exposed for periods of many years to either continuous sunlight or darkness, planetary scientists were not at all sure what to expect when observing Uranus.
Voyager 2 found that one of the most striking effects of the sideways orientation of Uranus is the effect on the tail of the planetary magnetic field. This is itself tilted about 60° from the Uranian axis of rotation. The planet's magneto tail was shown to be twisted by the rotation of Uranus into a long corkscrew shape following the planet. The presence of a significant magnetic field for Uranus was not at all known until Voyager's 2 arrival.
The radiation belts of Uranus were found to be of an intensity similar to those of Saturn. The intensity of radiation within the Uranian belts is such that irradiation would "quickly" darken — within 100,000 years — any methane that is trapped in the icy surfaces of the inner moons and ring particles. This kind of darkening might have contributed to the darkened surfaces of the moons and the ring particles, which are almost uniformly dark gray in color.
A high layer of haze was detected around the sunlit pole of Uranus. This area was also found to radiate large amounts of ultraviolet light, a phenomenon that is called "dayglow." The average atmospheric temperature is about 60 K (−350°F/−213°C). Surprisingly, the illuminated and dark poles, and most of the planet, exhibit nearly the same temperatures at the cloud tops.
The Uranian moon Miranda, the innermost of the five large moons, was discovered to be one of the strangest bodies yet seen in the Solar System. Detailed images from Voyager 2's flyby of Miranda showed huge canyons made from geological faults as deep as 20 kilometers (12 mi), terraced layers, and a mixture of old and young surfaces. One hypothesis suggests that Miranda might consist of a reaggregation of material following an earlier event when Miranda was shattered into pieces by a violent impact.
All nine of the previously known Uranian rings were studied by the instruments of Voyager 2. These measurements showed that the Uranian rings are distinctly different from those at Jupiter and Saturn. The Uranian ring system might be relatively young, and it did not form at the same time that Uranus did. The particles that make up the rings might be the remnants of a moon that was broken up by either a high-velocity impact or torn up by tidal effects.
 Very little detail was show,This could because at one time in Uranus history it was hit by a large object knock the planet on the side. This could had shut down the power source at the core.

Flyby Neptune
Sense very little detail was show on Uranus NASA thought Neptune wouldn't show much detail but boy was they wrong Neptune unlike Uranus was a active planet.
Voyager 2's closest approach to Neptune occurred on August 25, 1989. Since this was the last planet of our Solar System that Voyager 2 could visit, the Chief Project Scientist, his staff members, and the flight controllers decided to also perform a close fly-by of Triton(the only moon except Titan to have a atmosphere) , the larger of Neptune's two originally known moons, so as to gather as much information on Neptune and Triton as possible, regardless of Voyager 2's departure angle from the planet. This was just like the case of Voyager 1's encounters with Saturn and its massive moon Titan.
Through repeated computerized test simulations of trajectories through the Neptunian system conducted in advance, flight controllers determined the best way to route Voyager 2 through the Neptune-Triton system. Since the plane of the orbit of Triton is tilted significantly with respect to the plane of the ecliptic, through mid-course corrections, Voyager 2 was directed into a path several thousand miles over the north pole of Neptune. At that time, Triton was behind and below (south of) Neptune (at an angle of about 25 degrees below the ecliptic), close to the apoapsis of its elliptical orbit. The gravitational pull of Neptune bent the trajectory of Voyager 2 down in the direction of Triton. In less than 24 hours, Voyager 2 traversed the distance between Neptune and Triton, and then observed Triton's northern hemisphere as it passed over its north pole.
The net and final effect on the trajectory of Voyager 2 was to bend its trajectory south below the plane of the ecliptic by about 30 degrees. Voyager 2 is on this path permanently, and hence, it is exploring space south of the plane of the ecliptic, measuring magnetic fields, charged particles, etc., there, and sending the measurements back to the Earth via telemetry.
While in the neighborhood of Neptune, Voyager 2 discovered the "Great Dark Spot", which has since disappeared, according to observations by the Hubble Space Telescope. Originally thought to be a large cloud itself, the "Great Dark Spot" was later hypothesized to be a hole in the visible cloud deck of Neptune.
Neptune's atmosphere consists of hydrogen, helium, and methane. The methane in Neptune's upper atmosphere absorbs the red light from the Sun, but it reflects the blue light from the Sun back into space. This is why Neptune looks blue.
Voyager 1 is the same but it flyby only Jupiter and Saturn. Both space probe are still working and had pass through the Sun magnetic field and now in interstellar space.They are except to keep on work until 2020 than it power source would stop working.

Friday, May 16, 2014

Hubble shows that Jupiter Red Spot is smaller than every messure!

Recent observations confirm that the Great Red Spot now is approximately 10,250 miles across!
 Jupiter’s trademark Great Red Spot — a swirling anti-cyclonic storm larger than Earth — has shrunk to its smallest size ever measured.

According to Amy Simon of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, recent NASA Hubble Space Telescope observations confirm that the Great Red Spot now is approximately 10,250 miles (16,500 kilometers) across. Astronomers have followed this downsizing since the 1930s.

Historic observations as far back as the late 1800s gauged the storm to be as large as 25,500 miles (41,000km) on its long axis. NASA Voyager 1 and Voyager 2 flybys of Jupiter in 1979 measured it to be 14,500 miles (23,300km) across. In 1995, a Hubble photo showed the long axis of the spot at an estimated 13,020 miles (21,000km) across. And in a 2009 photo, it was measured at 11,130 miles (17,900km) across.
 Beginning in 2012, amateur observations revealed a noticeable increase in the rate at which the spot is shrinking — by 580 miles (930km) per year — changing the shape of the Great Red Spot from an oval to a circle.

“In our new observations, it is apparent very small eddies are feeding into the storm,” said Simon. “We hypothesized these may be responsible for the accelerated change by altering the internal dynamics and energy of the Great Red Spot.”

Simon’s team plans to study the motions of the small eddies and the internal dynamics of the storm to determine whether these eddies can feed or sap momentum entering the upwelling vortex, resulting in this yet unexplained shrinkage.