Showing posts with label PSLV. Show all posts
Showing posts with label PSLV. Show all posts

Indian Remote Sensing Satellites


Indian Remote Sensing Satellites

Remote Sensing effort in India started in late sixties with the aerial survey using multi-data instrument and aircraft carrying variety of sensors like infra-red scanner and multi-specialty scanner, radio meter etc. for monitoring different crops, soil degradation, water pollution, land usage etc. Considering the need to have a global picture on a larger scale, development efforts for remote sensing satellite were pursued. Based on the successful launch of Aryabhata and Bhaskara, new series of remote sensing satellite called IRS were developed. 
 Aryabhata
ISRO has designed and developed high performance remote sensing satellite system for India and the first one, IRS-1A was launched on March 17, 1988 on board a Soviet Vostok Rocket.
The second satellite IRS-1B identical to IRS-1A was launched August 29, 1991. This carried complex payloads like linear imaging Self Scanner – LISS-1 with the resolution of 72.5 m and LISS -2A, LISS -2B with a resolution of 36.25 m. The satellite was placed in 904 km polar sun synchronous orbit with an orbital period of 103 minutes. The satellite return to their original orbital trace every 22 days enabling repeated collection of data over the same place and at the same local time. This was followed by IRS-1C class satellites.

With the PSLV getting operational, IRS-P2 satellites were placed in sun-synchronous orbit on October 15, 1994.
 The satellite control center located at Bangalore and other ground stations at different locations regularly track and monitor IRS satellite. National Remote Sensing Agency (NRSA) at Hyderabad receives the data from the IRS satellites. After processing & distribute it to the user agencies.

IRS data has been extensively used to evaluate agricultural crops yield estimate, drought monitoring and assessment, flood mapping, land use and land cover mapping, waste land management, water resource land management, ocean/marine resource survey, urban planning, mineral prospecting, various resource survey etc. The IRS system has become one of the main service sectors of ISRO for the nation.
 The TES-Satellite has provided a resolution of better than 1 m in which one could clearly identify the vehicles moving on the road. 

Comparison of Solid Rocket Motors around the world



Comparison of Solid Rocket Motors around the world







Parameter
RSRM
  (Space     Shuttle)
P230
(Araine 5)
PS1 (S139)(PSLV/
GSLV)
S200
(LVM3)
Diameter (m)
3.7
3.05
2.8
3.2
Length (m)
38.2
27.0
20.2
24.9
Motor case material
D6AC
D6AC
M250
M250
Propellant mass (t)
504
237
138
207
Nozzle expansion ratio
7.7
11
9
12
Vacuum specific impulse (s)
268
275
270
274.5





Comparison of Solid Rocket Motors of Space Shuttle, Araine 5, PSLV, GSLV, and LVM3, 
 Comparison of  RSRM, P230, S139 and S200 Solid Rocket Motors 





Polar Satellite Launch Vehicle (PSLV)




Polar Satellite Launch Vehicle (PSLV)

Polar Satellite Launch Vehicle (PSLV) can carry 1 ton class spacecraft in 900 Km sun synchronous orbit.   The PSLV is a four stage vehicle adopting solid and liquid propulsion systems.


First stage
The first stage motor has 2.8 m diameter. The first stage propellant casing is made of maraging steel.  139 tons of HTPB solid propellant is used in first stage of PSLV vehicle. This stage also has six numbers of strapon motors derived from SLV programme. The control of first stage is done by adopting multi-port SITVC system.

Second stage
The second stage is a liquid stage. It uses N2O4 as the oxidiser and UDMH as the propellant. The fuel and propellant are stored in 2.8 m dia tankages. It has a Vikas engine generating a thrust of 75 tons.


 Third stage
The third stage of PSLV is also a solid motor. It is carrying 7 tons of propellant. The third stage motor case is made out of Kevlar composite materials and it uses a flex nozzle control system. 


Fourth  stage
The fourth stage is a liquid stage using N2O4 as oxidizer and MMH as propellant . It have two engines of 7 kN thrust. The tankages are made of titanium alloy. 




The vehicle equipment Bay is housed around the 4th stage which consists of vehicle onboard navigation, guidance and control system, Power system etc. 
The spacecraft is interfaced with the payload adaptor with merman band separation system. 

The first successful launch of PSLV took place on October 15, 1994 carrying Indian Remote Sensing Satellite of 900 kg mass. This was followed by number of successful launches of PSLV for IRS missions including that of carrying multiple spacecraft in the same launch. PSLV is an operational system which can carry LEO/ SSPO/ GTO missions in a cost effective manner.

The overall lift-off mass of the vehicle - 297 tons

Payload capacity of PSLV : 

Low Earth Orbit (LEO)                         - 3.5 tons
Sun Synchronous Polar Orbit (SSPO) - 1.6 tons
Geo Transfer orbit (GTO)                    - 1 ton. 




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