PSLV-C18 to put four satellites in orbit

Preparations are on for the lift-off of the Polar Satellite Launch Vehicle (PSLV-C18) from the spaceport at Sriharikota at 11 a.m. on October 12.

Global tropical weather

The rocket will put four satellites in the orbit: Megha-Tropiques, built by India and France to understand global tropical weather and climate; SRM Sat, built by the students of SRM University, near Chennai; Jugnu, a satellite integrated by students of the Indian Institute of Technology (IIT), Kanpur; and VesselSat from Luxembourg.

The information sent by the instruments on board the Megha-Tropiques will help understand the behaviour of Indian monsoons and occurrence of cyclones, floods and droughts.

Heat shield

The PSLV has been fully integrated, said K. Radhakrishnan, Chairman, Indian Space Research Organisation (ISRO), on Tuesday from Bangalore. “The Megha-Tropiques and the three co-passenger satellites have been fully integrated with the vehicle. The heat-shield was closed last morning.” The heat-shield around the satellites protects them from the intense heat during the launch and the vehicle's ascent into the atmosphere. After the rocket reaches a certain altitude, the heat-shield falls off.

Dr. Radhakrishnan said the final checks were under way. “On October 8, we will have a launch rehearsal. The vehicle readiness review will take place on October 9 followed by the Launch Authorisation Board meeting the same day itself. As of now, the launch is scheduled on October 12 at 11 a.m.”

The PSLV-C18 — which will be the 20th PSLV to be launched — is the core-alone version of the four-stage PSLV, without the strap-on booster motors that will put the four satellites in orbit.

Megha-Tropiques (Megha in Sanskrit means cloud and Tropiques in French is tropics) is one of the most advanced and complex satellites built to monitor the weather in the short-term and climate in the long-term in the tropical regions of the world. It is a joint project of ISRO and the French space agency, Centre National d'Etudes Spatiales (CNES).

Thermal engine

ISRO officials said the 1,000-kg satellite had been built to investigate the tropical regions which received the maximum energy from the sun than they radiated back into space.

The excess energy received in the tropical region is used as a thermal engine and provides circulation in the atmosphere and the oceans.

‘Life cycle'

“The complex processes between solar radiation, water vapour, clouds, humidity, precipitation and atmospheric motion determine the life-cycle of convective systems and influence the Indian monsoon in the tropical region,” the ISRO officials explained.

From its perch in the sky at an altitude of 867 km, the Megha-Tropiques would help study, on a sustained basis, the rapidly developing weather systems in the entire tropical world. Thus, the information beamed by the Megha-Tropiques will be useful not only to India but to all the countries in the Indian Ocean region and other parts of the world.

Scientific payloads

The satellite has four scientific payloads. The Microwave Analysis and Detection of Rain and Atmospheric Structures (MADRAS), built by ISRO and the CNES, will provide an estimation of rainfall, water vapour, liquid water, ice and surface wind. Scanner for Radiative Budget (SCARAB) will study the radiation received by the earth and reflected by it. The third instrument, Sondeur Atmospherique du Profil d'humidite Intertropicale par Radiometrie (SAPHIR) will investigate the humidity present in the tropical atmosphere.

The CNES has built the SCARAB and the SAPHIR. The GPS-ROS (Global Positioning System- Radio Occultation System) from Italy will study the temperature and humidity at different altitudes.

The ISRO Satellite Centre, Bangalore, integrated the entire satellite.

The 10-kg SRM Satwill help in understanding global warming and pollution by studying carbon-dioxide and carbon-monoxide present in the atmosphere. The three-kg Jugnu has a camera to take pictures of the earth to monitor, vegetation, reservoirs, lakes, and ponds. VesselSat will help in locating the ships in the sea-lanes of the world.