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INSAT 3DR : India will believe in IMD a little more

INSAT – 3DR Update
September 21, 2016

A couple of days ago, on September 19, ISRO released the first colour photo captured by the satellite. Like its predecessor INSAT-3D, INSAT-3DR carries a Data Relay Transponder as well as a Search and Rescue Transponder. Thus, INSAT-3DR will provide service continuity to earlier meteorological missions of ISRO and further augment the capability to provide various meteorological as well as search and rescue services.

Earlier, on September 15, the INSAT – 3DR satellite transmitted its first image and was subsequently released by ISRO on the same day. Though the image was in black and white, it was highly praised by science and space enthusiasts and retweeted several times.

The satellite multi-spectral imager can capture images of the Earth disk from an altitude of 36,000km once in every 26 minutes. It can provide information on various parameters like radiation, precipitation, sea surface temperature, snow cover, cloud motion winds. Images can be captured in six wavelength bands.


“INSAT-3DR is basically a weather satellite, with same sensors as in INSAT-3D. It has imagers and atmospheric sounders in different bands and all this data is directly used by Atmospheric Numerical Model. Today all weather forecast is by numerical models and these models have now proved to be very reliable. However, the data that goes in to models is very sparse and that limits the accuracy of the model. If more spatial and temporal data is fed in to the model, more the accuracy of the weather forecast can be achieved. More accurate weather forecast improves life of general public in many ways, particularly in extreme weather events.

Satellite weather data, particularly from GEO like INSAT-3DR is high resolution and faster updates. It will improve the frequency of the data. So it is expected to improve the IMD weather forecast even further and hence, the common man will be hugely benefited.”

-Dr P. S. Goel, Distinguished Professor, India Space Research Organisation (ISRO), HQ, Bangalore.

September 8, 2016

The Indian Space Research Organisation’s GSLV-F05 rocket was successfully placed INSAT-3DR advanced weather satellite in the intended orbit on the eve of September 8, 2016. The satellite is expected to provide a variety of meteorological services to the country. As Dr. Ajit Tyagi, Fmr director general, India Meteorological Department (IMD), Government of India says, ‘The INSAT-3DR satellite is designed to benefit meteorological services of the country. The prior version – INSAT-3D, launched in 2013, used to give observations every half an hour while INSAT-3DR will provide observations every 15 minutes. Apart from this, the satellite will provide a better monitoring system of weather events by giving data more frequently.’

Dr P. S. Goel, fmr secretary, Ministry of Earth Sciences and a space scientist, outlined how this data will enhance the numerical modeling capacity of IMD and other research bodies working on meteorology. He went on to add that the accuracy achieved now through the INSAT-3DR will accentuate weather forecasting and ended succinctly by pointing out that, “India will believe in IMD a little more”.

Satellite FAQs – a peek into space stuff.

Let’s take you through some of the common questions which come into one’s mind when it comes to satellites.

The first question – how does a satellite go to space?

Putting a satellite into orbit is fairly straightforward. The launch vehicle gets the satellite above the atmosphere and sets it moving tangentially (i.e. at right angles to the line connecting the satellite and the Earth’s center). The speed required depends on the altitude: anywhere from about 7.8 km/s in low Earth orbit to  3.1 km/s in geosynchronous orbit, or even about 1 km/s for the Moon.

How long will INSAT-3D and INSAT-3DR last?

The INSAT-3D satellite has a planned life span of seven years and will go on till 2020, while the INSAT-3DR is envisaged to last for ten years, till 2026.

If you wondered what Geosynchronous orbit is, look no further.

A geosynchronous orbit (sometimes abbreviated GSO) is an orbit around the Earth with an orbital period of one sidereal day, intentionally matching the Earth’s sidereal rotation period (approximately 23 hours 56 minutes and 4 seconds). The synchronisation of rotation and orbital period means that, for an observer on the surface of the Earth, an object in geosynchronous orbit returns to exactly the same position in the sky after a period of one sidereal day. Over the course of a day, the object’s position in the sky traces out a path, typically in a figure-8 form, whose precise characteristics depend on the orbit’s inclination and eccentricity.

Geostationary satellite? What is that?

Satellites that surround our Earth orbit at different height, speed and path. A geostationary satellite moves from West to East at the same speed that of the Earth in a manner that it appears standing still at the same point all the time.

Ever wondered what happens to the old satellites after they die?

There are two choices, depending on how high the satellite is. For the closer satellites, engineers will use its last bit of fuel to slow it down. That way, it will fall out of orbit and burn up in the atmosphere. When a satellite falls out of orbit, between 10 and 40 per cent of its mass survives re-entry. Hundreds of objects from orbit hit the surface of the Earth at random locations every year, but so far no one has been reported injured or killed by falling space debris.

The second choice is to send the satellite even farther away from Earth. It can take a lot of fuel for a satellite to slow down enough to fall back into the atmosphere. That is especially true if a satellite is in a very high orbit. For many of these high satellites, it takes less fuel to blast it farther into space than to send it back to Earth.

Like on earth we have graveyards in outer space too. We call them graveyard orbit. It is also called a junk orbit or disposal orbit. This orbit lies significantly away from common operational orbits, where spacecraft can be placed at the end of their operational life. Most commonly, it refers to a super-synchronous orbit that lies significantly above synchronous orbit. Satellites are moved into such orbits to reduce the probability of colliding with operational spacecraft or generating space debris. A spacecraft moved to a graveyard orbit will typically be passivated.

So what is passivate?

Defunct satellite can pose a threat because of any unused energy source material on it which causes explosion spraying debris down on an operational satellite and even a little debris can cause significant damage. Thus, each defunct satellite needs to be ‘passivated’ by discharging batteries, releasing compressed gases or dumping propellant.

How is a satellite powered?

Many satellites are powered by rechargeable batteries, taking advantage of the ultimate battery charger, the sun. Silvery solar panels are prominent features on many satellites. Other satellites have fuel cells that convert chemical energy to electrical energy, while a few rely on nuclear energy.

Did you know that INSAT-3DR has a indigenous cryogenic engine – what is it?

A cryogenic rocket engine is an engine that uses a cryogenic fuel or oxidizer, that is, its fuel or oxidizer (or both) are gases liquefied and stored at very low temperatures. India has for the first time been able to formulate this engine, which makes way for its advent into superior technologies in other spheres as well.

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