190
3 A Brief History of Space Flight
(17) On December 11, 2014, the Voyager-2 reached 106.65 AU away from the
Sun.
(18) On November 5, 2018, the Plasma Science Experiment onboard of the
Voyager-2 observed a steep decline in the speed of the solar wind particles.
Since then, the plasma instrument has not observed the solar wind in the environment around the Voyager-2, which shows that the Voyager-2 has left the
heliosphere.
(19) On April 9, 2020, the Voyager-2 is predicted to be 123.55 AU (1.848 ×
10
10 km) away from the Earth.
The Voyager-2 is not headed towards any particular star, although about
40,000 years later it should pass within 1.7 light years of star Ross 248, which is 10.3
light years away from the Earth and is located in the constellation of Andromeda. If
undisturbed for 296,000 years, the Voyager-2 should pass by star Sirius at a distance
of 4.3 light years. The Sirius, also known as Alpha Canis Majoris, is the brightest
star in the night sky, with the apparent visual magnitude of −1.46, and a binary star
in the constellation of Canis Major, located in about 8.6 light years away from the
Earth. The Voyager-2 is expected to keep transmitting weak radio message until least
2025, over 48 years after it was launched.
It is noted that there are different flight directions for the Pioneers and the
Voyagers. The Pioneer-10 is flying away from the center of the Galaxy, almost 180
degrees from the Pioneer-11, Voyager-1 and Voyager-2. The Voyager-2 is flying
below the Galactic plane, while the other spacecrafts are flying above the Galactic
plane.
3.6.4.3 Voyager Golden Record
The gold-anodized aluminum plaque carried on the Pioneer-10 and Pioneer-11 is
similar to a greeting card or a telegram, which transmits the time and location of
launching the probes and the information of human beings on the planet Earth to the
extraterrestrial intelligence life. Based on the design idea of the Pioneer plaque, the
NASA had specially set up a committee chaired by Carl Sagan to design a gold-plated
copper record, known as “Sounds of Earth”, which was mounted on one side of the
decagonal base of the Voyager probes [13]. The golden record contains abundant
information of human civilization on the Earth, with the mission of communication
between human beings and extraterrestrial civilization. The record’s cover was made
of the material aluminum, and an ultra-pure sample of the isotope uranium-238
was electroplated upon it. It is well known that uranium-238 is the most abundant
radioisotope found in nature, with a half-life of 4.468 billion years. Therefore, it is
possible that the extraterrestrials that intercept the golden record will be able to use
the ratio of remaining uranium to daughter elements to determine its age.
The patterns drawn on the back of the golden record are mainly divided into
four parts. Firstly, the circular pattern drawn in the upper left corner represents the
phonograph record and the stylus carried with it. Secondly, the line pattern drawn
3 A Brief History of Space Flight
(17) On December 11, 2014, the Voyager-2 reached 106.65 AU away from the
Sun.
(18) On November 5, 2018, the Plasma Science Experiment onboard of the
Voyager-2 observed a steep decline in the speed of the solar wind particles.
Since then, the plasma instrument has not observed the solar wind in the environment around the Voyager-2, which shows that the Voyager-2 has left the
heliosphere.
(19) On April 9, 2020, the Voyager-2 is predicted to be 123.55 AU (1.848 ×
10
10 km) away from the Earth.
The Voyager-2 is not headed towards any particular star, although about
40,000 years later it should pass within 1.7 light years of star Ross 248, which is 10.3
light years away from the Earth and is located in the constellation of Andromeda. If
undisturbed for 296,000 years, the Voyager-2 should pass by star Sirius at a distance
of 4.3 light years. The Sirius, also known as Alpha Canis Majoris, is the brightest
star in the night sky, with the apparent visual magnitude of −1.46, and a binary star
in the constellation of Canis Major, located in about 8.6 light years away from the
Earth. The Voyager-2 is expected to keep transmitting weak radio message until least
2025, over 48 years after it was launched.
It is noted that there are different flight directions for the Pioneers and the
Voyagers. The Pioneer-10 is flying away from the center of the Galaxy, almost 180
degrees from the Pioneer-11, Voyager-1 and Voyager-2. The Voyager-2 is flying
below the Galactic plane, while the other spacecrafts are flying above the Galactic
plane.
3.6.4.3 Voyager Golden Record
The gold-anodized aluminum plaque carried on the Pioneer-10 and Pioneer-11 is
similar to a greeting card or a telegram, which transmits the time and location of
launching the probes and the information of human beings on the planet Earth to the
extraterrestrial intelligence life. Based on the design idea of the Pioneer plaque, the
NASA had specially set up a committee chaired by Carl Sagan to design a gold-plated
copper record, known as “Sounds of Earth”, which was mounted on one side of the
decagonal base of the Voyager probes [13]. The golden record contains abundant
information of human civilization on the Earth, with the mission of communication
between human beings and extraterrestrial civilization. The record’s cover was made
of the material aluminum, and an ultra-pure sample of the isotope uranium-238
was electroplated upon it. It is well known that uranium-238 is the most abundant
radioisotope found in nature, with a half-life of 4.468 billion years. Therefore, it is
possible that the extraterrestrials that intercept the golden record will be able to use
the ratio of remaining uranium to daughter elements to determine its age.
The patterns drawn on the back of the golden record are mainly divided into
four parts. Firstly, the circular pattern drawn in the upper left corner represents the
phonograph record and the stylus carried with it. Secondly, the line pattern drawn