ISRO Missions and Discoveries

PSLV-C45/ Emisat Mission


Mains Paper 3: Science & Technology | Awareness in the fields of IT, Space etc.

From UPSC perspective, the following things are important:

Prelims level: Particulars of the payload

Mains level: Unique features of the launch 


  • For the sheer number of ‘firsts’ to its credit, the scheduled PSLV-C45/Emisat mission scheduled will be a memorable one for the ISRO.


  • C-45, which is set for lift-off from the second launchpad at Sriharikota, will mark the 47th flight of the PSLV.
  • It is meant for electromagnetic spectrum measurements, according to the ISRO.
  • It will be released into an orbit at 749 km.
  • EMISAT is primarily based on on the famous Israeli spy satellite called SARAL or (Satellite with ARgos and ALtika), and inherits its SSB-2 bus protocol for conducting sharp electronic surveillance across the length and breadth of India.
  • The satellite would serve as the country’s roving device for detecting and gathering electronic intelligence from enemy radars across the borders as it circles the globe roughly pole to pole every 90 minutes or so.
  • For the third successive PSLV mission, the ISRO plans to reuse the rocket’s spent fourth stage or PS4 to host short experiments.

Unique Features of PSLV-C45/Emisat

  • For one, it will be ISRO’s first attempt at placing payloads in three different orbits.
  • The chief payload the 436 kg Emisat will be injected into a 749 km orbit.
  • After that, the fourth stage of the rocket will be maneuvered to a 504 km orbit for releasing 28 international satellites.
  • Once that job is over, the fourth stage will be restarted and guided to an altitude of 485 km.
  • For the next six months, this stage will serve as an orbital platform for space-based experiments. This is another first for the ISRO. Normally, the spent stage simply becomes space junk.
  • The orbital platform will also sport solar panels, which too is a first.
  • The launch vehicle itself is a new variant, designated PSLV-QL. For the first time, ISRO will be employing four XL strap-on motors on the first stage.
  • The other two experimental payloads aboard the orbital platform are the Automatic Identification System (AIS), an ISRO payload for maritime satellite applications, and the Automatic Packet Repeating System (APRS), meant to assist amateur radio operators.

Foreign satellites on-board

  • As many as 28 small foreign co-passenger satellites will also travel to space with it, but to a lower orbit at 504 km.
  • They include 24 small satellites from the U.S., among them 20 which are part of previous customer Planet Labs’ earth observation constellation.
  • The other four customers are from Lithuania, Spain and Switzerland.
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