SATELLITE Communication Viva Questions :-
1 What are the Types of Satellite?
Types of Satellite are as under:
- Anti-Satellite weapons/”Killer Satellites”
- Astronomical satellites
- Communications satellites
- Miniaturized satellites
- Navigational satellites
- Reconnaissance satellites
- Earth observation satellites
- Space stations
- Tether satellites
- Weather satellites
2 How do I interpret visible satellite pictures?
The pictures sent back to us from Weather Satellites are simply photographs taken from outer space. We get visible images during the daylight when the earth reflects sunlight back to outer space. Visible pictures show the amount of light reflected back to outer space. Thick water rich clouds, such as stratus (common along the North Coast during Summer months), show up as bright white on visible pictures. Snow pack over the Sierra Nevada during the Winter is another good reflector of sunlight. During the night, visible pictures are completely black as there is very little or no visible light to reflect!
3 How do I interpret infrared satellite pictures?
Clouds and atmospheric gases such as water vapor radiate infrared energy to space. The amount of energy radiated by clouds and gasses relates directly with its temperature. This relationship, know as the Stephan-Boltzmann Law, allows us to “see” clouds at night. The atmosphere generally cools with height. A cloud that radiates low energy is higher in the troposphere than a cloud that radiates higher energy. On a standard linear enhancement curve, bright white represent cold ice-crystal clouds, while clouds colored with light shades of gray are warm water filled clouds in the mid and lower troposphere. There are a number of enhancement curves that color pictures of clouds based on temperature. These curves accentuate temperature ranges that allow us to discern high clouds from mid and low clouds. At the bottom of every infrared image there is a key telling you the temperature range for that color. For example, on the infrared pictures provided on this web site, red represents cloud tops with a temperature of -40C which in a standard atmosphere is about 40,000 ft.
4 How do I interpret water vapor imagery?
Water vapor in the mid and upper troposphere absorbs infrared energy at discrete wavelengths. Using this information, water vapor can act like a tracer of atmospheric circulation in the mid and upper troposphere. Dark regions on water vapor pictures are generally areas where the air is sinking and drying. Light colored regions are areas of rising motion and moisture. Water vapor images are useful in locating jet streams and short-wave troughs and ridges in the mid and upper troposphere, but are lousy when trying to see clouds near the ground such as stratus.
5 Where can I find the time on satellite pictures? What time zone is this?
The date and time stamps are located at the top or bottom of every image, along with other information. For example, G-10 IMG 01 3 Jun 00 TIME=00:30UTC RES=4km NWS/WR=SSD, is a typical date-time stamp which appears on satellite images. The date and time, colored blue in the above example, is in Universal Coordinated Time (UTC). UTC is also known as Greenwich Mean Time (GMT) or Zulu Time (Z). Along the West Coast, we are about 8 hours behind the UTC during Pacific Standard Time (PST). During Daylight Saving Time (PDT), from mid April through mid October, we are about7 hours behind the UTC. In the example above, it’s June 3rd 2000, 30 minutes past midnight in Greenwich England. In order to get local time, you subtract7 hours to get June 2nd 2000, 5:30PM PDT. The next calendar day has already started in Greenwich England!
6 What is Anti-satellite weapon?
Anti-satellite weapons (ASAT) are space weapons designed to incapacitate or destroy satellites for strategic military purposes. Currently, only the United States, the former USSR (now Russia) and the People’s Republic of China are known to have developed these weapons. On September 13, 1985, the United States destroyed US satellite P78-1 using an ASM-135 ASAT anti-satellite missile and malfunctioning US spy satellite USA-193 using a RIM-161 Standard Missile 3 on February 21, 2008. On January 11, 2007, China destroyed an old Chinese orbiting weather satellite.
7. What is Space observatory?
A space observatory is any instrument in outer space which is used for observation of distant planets, galaxies, and other outer space objects. This category is distinct from other observatories located in space that are pointed toward the earth for the purpose of reconnaissance and other types of information gathering.
8. What is Bio satellite?
A bio satellite is a satellite designed to carry life in space.
NASA launched three satellites specifically named Bio satellite (1, 2 & 3) between 1966 and 1969.
- Bion series of satellites
- the Mars Gravity Biosatellite.
- Orbiting Frog Otolith
9. What is Communications satellite?
A communications satellite (sometimes abbreviated to COMSAT) is an artificial satellite stationed in space for the purpose of telecommunications. Modern communications satellites use a variety of orbits including geostationary orbits, Molniya orbits, other elliptical orbits and low (polar and non-polar) Earth orbits.
10. What is Miniaturized satellite?
Miniaturized satellites or small satellites are artificial satellites of unusually low weights and small sizes, usually under 500 kg (1100 lb). While all such satellites can be referred to as small satellites, different classifications are used to categorize them based on mass.
11. What is Global navigation satellite system?
Global Navigation Satellite Systems (GNSS) is the standard generic term for satellite navigation systems (“sat nav”) that provide autonomous geo-spatial positioning with global coverage. GNSS allows small electronic receivers to determine their location (longitude, latitude, and altitude) to within a few metres using time signals transmitted along a line-of-sight by radio from satellites. Receivers calculate the precise time as well as position, which can be used as a reference for scientific experiments.
12. What is Spy satellite?
A spy satellite officially referred to as a reconnaissance satellite is an Earth observation satellite or communications satellite deployed for military or intelligence applications.
These are essentially space telescopes that are pointed toward the Earth instead of toward the stars. The first generation type took photographs, then ejected canisters of photographic film, which would descend to earth.
13. What is Earth observation satellite?
Earth observation satellites are satellites specifically designed to observe Earth from orbit, similar to reconnaissance satellites but intended for non-military uses such as environmental monitoring, meteorology, map making etc. Geostationary satellites hover over the same spot, providing continuous monitoring to a portion of the Earth’s surface. Polar orbiting satellites provide global coverage, but only twice per day at any given spot.
14. What is Space station?
A space station is an artificial structure designed for humans to live and work in outer space for a period of time.
To date, only low earth orbital (LEO) stations have been implemented, otherwise known as orbital stations. A space station is distinguished from other manned spacecraft by its lack of major propulsion or landing facilities—instead, other vehicles are used as transport to and from the station. Current and recent-history space stations are designed for medium-term living in orbit, for periods of weeks, months, or even years. The only space station currently in use is the International Space Station. Previous stations include the Almaz and Salyut series, Skylab and Mir.
15. What is Tether satellite?
Tether satellite is a satellite connected to another by a thin cable called a tether. The space tether idea had its origin in the late 1800s. The idea became more popular in the 1960s, and subsequently NASA examined the feasibility of the idea and gave direction to the study of tethered systems, especially tethered satellites.
16. Explain Weather satellite?
Weather Satellite is a type of satellite that is primarily used to monitor the weather and climate of the Earth. Satellites can be either polar orbiting, seeing the same swath of the Earth every 12 hours, or geostationary, hovering over the same spot on Earth by orbiting over the equator while moving at the speed of the Earths rotation. These meteorological satellites, however, see more than clouds and cloud systems. City lights, fires, effects of pollution, auroras, sand and dust storms, snow cover, ice mapping, boundaries of ocean currents, energy flows, etc., are other types of environmental information collected using weather satellites.