PSLV-C61/EOS-09 Mission

• 19 May 2025

Source: TH 

ISRO’s Polar Satellite Launch Vehicle (PSLV-C61) mission failed to place the Earth Observation Satellite-09 (EOS-09)  into its intended sun-synchronous polar orbit due to a glitch in the rocket’s third stage.  

• This was ISRO’s 101st mission and the 63rd using the PSLV. The EOS-09 satellite carried a Synthetic Aperture Radar (SAR) payload designed to capture all-weather Earth images. 

Note 

• A sun-synchronous polar orbit (SSO) is a polar orbit where a satellite passes over the same Earth location at the same local solar time each day, maintaining a consistent position relative to the Sun. 

What is PSLV? 

• About: The Polar Satellite Launch Vehicle (PSLV) is a highly reliable and cost-effective launch vehicle developed by ISRO.  
  • It is used to transport satellites into various orbits, including sun-synchronous, geostationary, and navigation orbits. 
• Function: It carries satellites (payloads) into space, overcoming Earth's gravity through powerful propulsion systems. Once the desired orbit is reached, satellites are deployed from the vehicle. 
• Structure: PSLV has 4 stages: 
  • PS1: Solid rocket motor with 6 strap-on boosters. 
  • PS2: Liquid engine (Vikas engine). 
  • PS3: Solid rocket motor for high thrust post-atmospheric phase. 
  • PS4: Two liquid-fuel engines for final orbital insertion. 
• Variants: PSLV-XL (with extended strap-ons), PSLV-DL, PSLV-QL, etc., are selected based on payload weight and target orbit. 
• Significance: Known as ISRO’s “workhorse” due to its versatility and high success rate. 
  • Used in major missions like Chandrayaan-1 (2008) and Mars Orbiter Mission (2013). 
  • Achieved global recognition by launching 104 satellites in a single mission (PSLV-C37, 2017). 
• Earlier Failure: The PSLV has failed twice in its history. The first failure was in 1993 (PSLV-D1) due to software issues, causing the IRS-1E satellite to crash into the ocean.  
  • The second was in 2017 (PSLV-C39), when a heat shield separation failure trapped the IRNSS-1H satellite, preventing its deployment into orbit. 

What is Earth Observation Satellite-09 (EOS-09)? 

• About: EOS-09, also called RISAT-1B, is an advanced Indian remote sensing satellite equipped with a C-band Synthetic Aperture Radar (SAR) for all-weather, day-and-night Earth imaging.  
  • It is designed for diverse applications including land-use mapping, hydrology, disaster management, agriculture, forestry, and coastal security. 
• Key Features: 
  • All-weather capability: SAR penetrates clouds, rain, fog, and darkness, ensuring continuous surveillance. 
  • High resolution: Offers up to 1-meter resolution and wide swath coverage (10 to 225 km). 
  • Multiple Imaging modes: Supports five modes like High-Resolution Spotlight and Medium Resolution ScanSAR for varied uses. 
  • Dual-use: Supports both civilian applications and defence surveillance, including monitoring military activity and maritime security. 
  • Orbit: Intended for a sun-synchronous polar orbit for consistent daily coverage. 

UPSC Civil Services Examination, Previous Year Question (PYQ) 

Q. With reference to India’s satellite launch vehicles, consider the following statements: (2018)

1. PSLVs launch the satellites useful for Earth resources monitoring whereas GSLVs are designed mainly to launch communication satellites. 
2. Satellites launched by PSLV appear to remain permanently fixed in the same position in the sky, as viewed from a particular location on Earth. 
3. GSLV Mk III is a four-staged launch vehicle with the first and third stages using solid rocket motors, and the second and fourth stages using liquid rocket engines. 

Which of the statements given above is/are correct? 

(a) 1 only 
(b) 2 and 3 
(c) 1 and 2 
(d) 3 only 

Ans: (a)