Space Technology

The electromagnetic waves, which are used for satellite communication, are

[amp_mcq option1=”infrared radiations” option2=”ultraviolet radiations” option3=”radio waves” option4=”visible lights” correct=”option3″]

Satellite communication relies on electromagnetic waves that can travel through the Earth’s atmosphere and the vacuum of space with minimal attenuation and interference. Radio waves, particularly in the microwave frequency range, are ideal for this purpose. These frequencies allow for high bandwidth transmission and can penetrate the ionosphere and lower atmosphere effectively.

Infrared radiation is used for shorter-range communication like remote controls or fiber optics but is not suitable for long-distance satellite communication due to atmospheric absorption. Ultraviolet radiation is largely absorbed by the atmosphere and is not used for this purpose. Visible light is also affected by atmospheric conditions (clouds, scattering) and is generally not used for long-distance space communication, although optical communication with satellites is an emerging technology. Radio waves/microwaves are the standard for current satellite communication systems.

Different frequency bands within the radio/microwave spectrum are allocated for various types of satellite communication, including C-band, Ku-band, Ka-band, etc., depending on the application (e.g., broadcasting, telecommunications, navigation).

Which one of the following statements with regard to Antrix Corporation Limited is correct?

[amp_mcq option1=”It is a commercial arm of the Department of Industrial Policy and Promotion.” option2=”It is under the administrative control of the Department of Space.” option3=”It is under the administrative control of the Ministry of Health and Family Welfare.” option4=”It is a commercial arm of the Department of Science and Technology.” correct=”option2″]

Antrix Corporation Limited is the commercial arm of the Indian Space Research Organisation (ISRO). ISRO functions under the Department of Space (DoS). Therefore, Antrix Corporation Limited is under the administrative control of the Department of Space.

Antrix Corporation is a Public Sector Undertaking (PSU) of the Government of India. Its primary role is to market the products and services of ISRO, including satellite launches, satellite data, and related services, to international customers.

The Department of Space (DoS) is directly under the charge of the Prime Minister of India. Antrix plays a crucial role in India’s space program by securing contracts and collaborations with foreign space agencies and companies.

Which of the following statements is/are correct?

• 1. In June 2016, the LIGO group of scientists announced the detection of a second set of gravitational waves.
• 2. Gravitational waves were generated due to merger of two black holes at about 1.4 billion light-years distant.
• 3. Gravitational waves were inserted due to collision of two white dwarf stars at about 1.4 billion light-years distant.

Select the correct answer using the code given below.

[amp_mcq option1=”1 only” option2=”1 and 2 only” option3=”2 and 3 only” option4=”1, 2 and 3″ correct=”option2″]

Statement 1 is correct; the LIGO (Laser Interferometer Gravitational-Wave Observatory) collaboration announced the detection of the second set of gravitational waves (GW151226, detected in December 2015) in June 2016, following the historic first detection announcement (GW150914, detected in September 2015, announced Feb 2016). Statement 2 is correct; both the first and second gravitational waves detected by LIGO were attributed to the merger of two black holes. The second detection (GW151226) involved black holes estimated to be about 1.4 billion light-years away. Statement 3 is incorrect; the gravitational waves detected by LIGO up to that point were from the merger of stellar-mass black holes, not white dwarf stars. Mergers involving neutron stars were detected later.

Gravitational waves detected by LIGO in its initial phase were primarily generated by the violent merger of massive compact objects, specifically black holes.

The detection of gravitational waves provided strong evidence for Einstein’s theory of general relativity and opened up a new window for observing the universe, leading to the Nobel Prize in Physics 2017 for the founders of the LIGO project.

Among the currently operational Indian Satellites, there is no :

[amp_mcq option1=”Communication satellite” option2=”Navigation satellite” option3=”Earth observation satellite” option4=”Jupiter orbiter satellite” correct=”option4″]

India has a comprehensive satellite programme managed by ISRO. It operates communication satellites (e.g., GSAT series), navigation satellites (NavIC/IRNSS system), and numerous Earth observation satellites (e.g., Cartosat, RISAT, Oceansat, RESOURCESAT series). India has successfully sent missions to the Moon (Chandrayaan) and Mars (Mangalyaan), but it does not currently have an operational satellite orbiting Jupiter. Jupiter orbiter missions are complex deep-space missions undertaken by a few space agencies globally (e.g., NASA’s Juno).

Awareness of the types of satellites India currently operates in space is necessary.

ISRO’s operational satellites serve various purposes including telecommunications, television broadcasting, internet services, navigation, weather forecasting, disaster management, resource monitoring, and scientific research.