Hoisting of PSLV-C45 liquid second stage during vehicle integration. (Image: isro.gov.in)

India on April 1 will launch an electronic intelligence satellite 'Emisat' for the Defence Research Development Organisation (DRDO) along with 28 third party satellites. ISRO, for the first time, will also demonstrate its new technologies like three different orbits with a new variant of the Polar Satellite Launch Vehicle (PSLV) rocket.

Emisat is a satellite based on ISRO's Indian Mini Satellite -2 (IMS-2) bus platform. The satellite is intended for electromagnetic spectrum measurement.

About the flight sequence

The whole flight sequence will take about 180 minutes from the rocket's liftoff slated at 9:30 am on April 1, 2019.

The new variant of the PSLV rocket will first put the 436 kg Emisat into a 749 km orbit. After that, the rocket will be brought down to put the 28 satellites into orbit, at an altitude of 504 km.

#ISROMissions #PSLVC45 set to launch #EMISAT and 28 foreign satellites from Satish Dhawan Space Centre in Sriharikota on April 1, 2019, subject to weather conditions. Updates will continue. pic.twitter.com/xs5ZLT5Jt3 ISRO (@isro) March 25, 2019

This will be followed by bringing the rocket down further to 485 km when the fourth stage/engine will turn into a payload platform carrying three experimental payloads:

1. Automatic Identification System (AIS) from ISRO - for maritime satellite applications capturing messages transmitted from ships.

2. Automatic Packet Repeating System (APRS) from AMSAT (Radio Amateur Satellite Corporation), India - to assist amateur radio operators in tracking and monitoring position data.

3. Advanced Retarding Potential Analyser for Ionospheric Studies (ARIS) from Indian Institute of Space Science and Technology (IIST) - for the structural and compositional studies of the ionosphere.

About the international customer satellites

The 28 international customer satellites (24 from US, 2 from Lithuania and one each from Spain and Switzerland) include 25 3U type, two 6U type, and one 2U type nano satellites and will weigh about 220 kg.

"It is a special mission for us. We will be using a PSLV rocket with four strap-on motors. Further, for the first time we will be trying to orbit the rocket at three different altitudes," said ISRO Chairman K Sivan.

About PSLV

1. The PSLV is a four-stage engine expendable rocket with alternating solid and liquid fuel.

2. In its normal configuration, the rocket will have six strap-on motors hugging the rocket's first stage.

3. On January 24, ISRO flew a PSLV with two strap-on motors while in March, it had four strap-on motors.

4. The Indian space agency also has two more PSLV variants, viz Core Alone (without any strap-on motors) and the larger PSLV-XL.

5. ISRO selects the kind of rocket to be used based on the weight of the satellite it carries.

6. It will also be launching two more defence satellites in July or August with its new rocket Small Satellite Launch Vehicle (SSLV).

7. In January, the space agency launched a defence imaging satellite Microsat R for the DRDO.

Read | PSLV-C44 carrying India's military satellite Microsat-R, students' payload Kalamsat, launched