Why in News ?
Union Minister of State (Independent Charge) Atomic Energy and Space reply in Rajya Sabha that there are 32 Earth Observation Sensors with advanced capabilities, currently in orbit, providing space based information.
- Five earth observation satellites and five communication payloads were realized since January, 2018.
- Information support was provided for all the major disaster events viz. floods, cyclones and forest fires occurred since January 2020.
- Value added products comprise of geophysical & remote sensing data products derived using the data from meteorological, oceanographic and land remote sensing satellites.
- Total number of satellites launched by ISRO currently in orbit are 47
- 26 satellites are in LEO/Low-Earth-Orbit
- 21 are in GEO/Geosynchronous-Equatorial-Orbit
What are Earth Observation Sensors?
- Process of acquiring observations of the Earth’s surface and atmosphere via remote sensing instruments.
- Satellites allow for reliable, true global coverage even above the most remote locations enabling regular repeat observations.
- Types of Earth Observation
- Passive Imagery : Designed to detect electromagnetic emissions from constituents of the Earth’s surface and atmosphere.
- Active Imagery : instruments are composed of a transmitter that sends out a specific electromagnetic signal and of a sensor receiving the interaction of the signal with the Earth’s surface.
- Indian Earth Observation Satellites
- India has one of the largest constellations of remote sensing satellites in operation.
- Currently, there are thirteen operational satellites are in Sun-synchronous orbit like RESOURCESAT-1, 2, 2A CARTOSAT-1, 2, 2A, 2B, RISAT-1 and 2, OCEANSAT-2, Megha-Tropiques, SARAL and SCATSAT-1, and four in Geostationary orbit– INSAT-3D, Kalpana & INSAT 3A, INSAT -3DR.
What is Sun-Synchronous Orbit ?
- It is a kind of Polar orbit satellite usually travel past Earth from north to south rather than from west to east, passing roughly over Earth’s poles.
- Sun-synchronous orbit (SSO) is a particular kind travelling over the polar regions, are synchronous with the Sun.
- Always be in the same ‘fixed’ position relative to the Sun for instance passing a particular city every day at exact time say evening.
- A satellite in a Sun-synchronous orbit would usually be at an altitude of between 600 to 800 km.
- How can it be useful ?
- They can used for observing a particular place for many days or weeks or even more.
- This helps in analysing the changes in the area.
What is Geostationary orbit ?
- Geostationary orbit is a circular orbit 36,000 km above Earth’s Equator in which a satellite’s orbital period is equal to Earth’s rotation period of 23 hours and 56 minutes.
- They are seen as stationary in the sky and used for Telecommunication and meteorological purpose.
- What is the difference between Geostationary and Geo Synchronous Satellite ?
- Geosynchronous satellites can have any inclination with equal rotation period of Earth.
- At the same time Geostationary are placed at the equator only with same rotation speed of Earth.
- Thus all the Geostationary satellites are Geo Synchronous Satellite but all Geo Synchronous satellites are not the same as Geostationary.
Source : PIB
Topic
GS III : Awareness in the fields of IT, Space, Computers, robotics, nano-technology, bio-technology and issues relating to intellectual property rights
Current Affairs Compilation : 18 September 2020