GALILEO SPACECRAFT PASTS EARTH FOR THE FIRST TIME

Today, The Grandma has received the wonderful visit of Joseph de Ca'th Lon, one of her closest friends. They have been talking about Galileo, the American robotic space probe that flew past Earth for the first time on a day like today in 1992.

Galileo was an American robotic space probe that studied the planet Jupiter and its moons, as well as the asteroids Gaspra and Ida. Named after the Italian astronomer Galileo Galilei, it consisted of an orbiter and an entry probe. It was delivered into Earth orbit on October 18, 1989, by Space Shuttle Atlantis, during STS-34.

Galileo arrived at Jupiter on December 7, 1995, after gravitational assist flybys of Venus and Earth, and became the first spacecraft to orbit an outer planet.

The Jet Propulsion Laboratory built the Galileo spacecraft and managed the Galileo program for NASA. West Germany's Messerschmitt-Bölkow-Blohm supplied the propulsion module.

NASA's Ames Research Center managed the atmospheric probe, which was built by Hughes Aircraft Company. At launch, the orbiter and probe together had a mass of 2,562 kg and stood 6.15 m tall.

Spacecraft are normally stabilized either by spinning around a fixed axis or by maintaining a fixed orientation with reference to the Sun and a star. Galileo did both. One section of the spacecraft rotated at 3 revolutions per minute, keeping Galileo stable and holding six instruments that gathered data from many different directions, including the fields and particles instruments.

More information: NASA

Galileo was intentionally destroyed in Jupiter's atmosphere on September 21, 2003. The next orbiter to be sent to Jupiter was Juno, which arrived on July 5, 2016.

Jupiter is the largest planet in the Solar System, with more than twice the mass of all the other planets combined. Consideration of sending a probe to Jupiter began as early as 1959.

NASA's Scientific Advisory Group (SAG) for Outer Solar System Missions considered the requirements for Jupiter orbiters and atmospheric probes. It noted that the technology to build a heat shield for an atmospheric probe did not yet exist, and facilities to test one under the conditions found on Jupiter would not be available until 1980.

NASA management designated the Jet Propulsion Laboratory (JPL) as the lead center for the Jupiter Orbiter Probe (JOP) project. The JOP would be the fifth spacecraft to visit Jupiter, but the first to orbit it, and the probe would be the first to enter its atmosphere.

On December 19, 1985, it departed the JPL in Pasadena, California, on the first leg of its journey, a road trip to the Kennedy Space Center in Florida. Due to the Space Shuttle Challenger disaster, the May launch date could not be met.

The mission was re-scheduled October 12, 1989. The Galileo spacecraft would be launched by the STS-34 mission in the Space Shuttle Atlantis. As the launch date of Galileo neared, anti-nuclear groups, concerned over what they perceived as an unacceptable risk to the public's safety from the plutonium in the Galileo's radioisotope thermoelectric generators (RTGs) and General Purpose Heat Source (GPHS) modules, sought a court injunction prohibiting Galileo's launch. RTGs were necessary for deep space probes because they had to fly distances from the Sun that made the use of solar energy impractical.

More information: NASA

 The moon is a friend for the lonesome to talk to.

Carl Sandburg

AMALTHEA, A NEW MOON OF JUPITER IS DISCOVERED

Today, The Grandma has received the wonderful visit of one of her closest friends, Joseph de Ca'th Lon.

Joseph loves astronomy, and they have been talking about Amalthea, the third closest and fifth found moon of Jupiter, that was discovered by Edward Emerson Barnard on a day like today in 1892.

Amalthea is a moon of Jupiter. It has the third-closest orbit around Jupiter among known moons and was the fifth moon of Jupiter to be discovered, so it is also known as Jupiter V.

It is also the fifth-largest moon of Jupiter, after the four Galilean Moons. 

Edward Emerson Barnard discovered the moon on 9 September 1892 and named it after Amalthea of Greek mythology. It was the last natural satellite to be discovered by direct visual observation; all later moons were discovered by photographic or digital imaging.

Amalthea is in a close orbit around Jupiter and is within the outer edge of the Amalthea Gossamer Ring, which is formed from dust ejected from its surface.

Jupiter would appear 46.5 degrees in diameter from its surface. Amalthea is the largest of the inner satellites of Jupiter and is irregularly shaped and reddish. It is thought to consist of porous water ice with unknown amounts of other materials. Its surface features include large craters and ridges.

Close range images of Amalthea were taken in 1979 by the Voyager 1 and Voyager 2 spacecraft, and in more detail by the Galileo orbiter in the 1990s.

More information: NASA

Amalthea was discovered on 9 September 1892 by Edward Emerson Barnard using the 91 cm refractor telescope at Lick Observatory.

It was the last planetary satellite to be discovered by direct visual observation, as opposed to photographically, and was the first new satellite of Jupiter since Galileo Galilei's discovery of the Galilean satellites in 1610.

Amalthea is named after the nymph Amalthea from Greek mythology, who nursed the infant Zeus, the Greek equivalent of Jupiter, with goat's milk. Its Roman numeral designation is Jupiter V.

The name Amalthea was not formally adopted by the IAU until 1976, although it had been in informal use for many decades. The name was initially suggested by Camille Flammarion. Before 1976, Amalthea was most commonly known simply as Jupiter V.

The surface of Amalthea is very red. This colour may be due to sulphur originating from Io or some other non-ice material. Bright patches of less red tint appear on the major slopes of Amalthea, but the nature of this colour is currently unknown.

The surface of Amalthea is slightly brighter than surfaces of other inner satellites of Jupiter. There is also a substantial asymmetry between leading and trailing hemispheres: the leading hemisphere is 1.3 times brighter than the trailing one.

More information: NASA

The asymmetry is probably caused by the higher velocity and frequency of impacts on the leading hemisphere, which excavate a bright material -presumably ice- from the interior of the moon.

There are four named geological features on Amalthea: two craters and two faculae (bright spots). The faculae are located on the edge of a ridge on the anti-Jupiter side of Amalthea.

Craters are named after characters in Greek mythology associated with Zeus and Amalthea, faculae after locations in associated with Zeus.

During 1979, the unmanned Voyager 1 and Voyager 2 space probes obtained the first images of Amalthea to resolve its surface features, they also measured the visible and infrared spectra and surface temperature.

Later, the Galileo orbiter completed the imaging of Amalthea's surface. Galileo made its final satellite fly-by at a distance of approximately 244 km from Amalthea's centre at a height of about 160–170 km on 5 November 2002, permitting the moon's mass to be accurately determined, while changing Galileo's trajectory so that it would plunge into Jupiter in September 2003 at the end of its mission.

In 2006, Amalthea's orbit was refined with measurements from New Horizons.

More information: Solar Views

 Jupiter is so big and its gravitational pull so strong
that man would find it difficult to move about on the surface.
The answer is to whittle it down to proper size
with terrajets and nuclear power,
using the debris to increase the size of Jupiter's moons so they,
too, can be colonized.

Fritz Zwicky