(Nehru Centre Newsletter October 2018)
Sixty one years ago, on 4 October 1957, the Soviet Union successfully launched the world’s first artificial satellite, Sputnik 1, into orbit. That date marked the beginning of the Space Age for all mankind.
‘Sputnik’ in Russian means ‘fellow traveller’. But this word has now become synonymous with the artificial satellite. Externally, the satellite was a metal sphere with a diameter of 58.5 cm, which is just about twice the length of this page. The sphere had two pairs of antennae for transmitting radio
signals. Weighing 83.6 kg on Earth, it was covered with a highly polished heat shield of 1 mm thickness.
Sputnik 1 travelled around the Earth in an elliptical orbit, inclined to the equator by 65.1°, and completed one orbit in 96.2 minutes. At the farthest point (apogee) it was 939 km from the Earth; and at the closest (perigee), 215 km. Its orbital speed was about 29,000 km per hour.
Sputnik 1 did not carry any scientific instruments; it only transmitted simple radio signals on 20.005 and 40.002 MHz frequencies. The signals were nothing but simple beeps transmitted continuously. The radio signals were received by a large number of monitoring stations including amateur wireless operators. They provided data about the ionosphere, which is at a height of 60–1,000 km above mean sea level and affects the propagation of radio signals. Ground stations tracking the satellite were able to obtain valuable information about the density of the Earth’s upper atmosphere.
Sputnik 1 remained operational for three weeks before its batteries ran out on 26 October. It continued to orbit the Earth and then re-entered the atmosphere on 4 January 1958 after burning up due to the heat created by friction with the upper atmosphere. It had completed 1,440 orbits around the Earth by then.
The successful launch of Sputnik 1 triggered the Space Race which went on to become a significant part of the Cold War. Ten years later, on 10 October 1967, the Outer Space Treaty, which forms the basic legal framework of international space law, came into force. The Treaty bars states that are signatory to it from placing weapons of mass destruction into the earth’s orbit, on the Moon or any other celestial body, or stationing them in outer space.
The United Nations General Assembly declared in 1999 that World Space Week will be observed each year from October 4-10 to commemorate these two important events in space history. They are the launch of Sputnik 1, the first human-made Earth satellite on October 4, 1957 and the signing of the Treaty on Principles Governing the Activities of States in the Exploration and Peaceful Uses of Outer Space, including the Moon and Other Celestial Bodies on October 10, 1967. The theme for World Space Week 2018 is ‘Space Unites the World.’
Celestial events for viewing pleasure 