ISRO workhorse PSLV-C40 puts 31 satellites in space

The News

• The 42nd Polar Satellite Launch Vehicle (PSLV), PSLV-C40, was launched successfully by the ISRO, which placed 31 satellites across two orbits.
• The space agency has also placed the 100th satellite it has built in its laboratory.

About Satellites

• Cartosat-2:
• The PSLV had launched the country's fourth satellite in the remote sensing Cartosat-2 series, weighing 710 kg, into a polar sun synchronous orbit at an altitude of about 510km.
• It is the seventh satellite in the series of Cartosat and has design life of five years.
• Cartosat-2 Series satellite will provide regular remote sensing services using its panchromatic and multispectral cameras. 
• The images sent by the satellite will be useful for land and geographical information system applications, urban and rural applications, coastal land use and regulation, utility management like road network monitoring, water distribution, creation of land use maps, change detection to bring out geographical and man-made features and various other land information system (LIS) as well as geographical information system (GIS) applications.
• 30 other satellites:
• The 30 other co-passenger smaller satellites, together weigh 613 kg. Of them, 28 are from other countries and 2 are from India (1 microsatellite and 1 nanosatellite).
• Of the 28 foreign satellites, launched as part of deals made by ISRO's commercial arm Antrix Corporation Limited, three were microsatellites and 25 nanosatellites. 
• There were 19 satellites from the United States and five from South Korea. The United Kingdom, France, Canada and Finland had a satellite each.

Multiple-burn technology demonstration:

• The launch was significant for another reason - ISRO demonstrated multiple-burn technology that it tested in three previous launches.

1st burn and placement: 

• Around 17 minutes after the lift-off from the launch pad at Satish Dhawan Space Centre in Sriharikota at 9.28am, the rocket injected its main payload- the 710kg weighing Cartosat-2 series, into a polar sun synchronous orbit at an altitude of about 510km.
• Within a span of around seven minutes, the rocket ejected 29 satellites as it maneuvered its way up the altitude to 519km.

2nd burn and placement: 

• After the ejection of the 30th satellite, the fourth stage earth storable liquid engine was restarted for the first time 30 minutes later and was shut off within five seconds. 
• For the next nearly 45 minutes of coasting period, the rocket moved from 505km to 359km altitude before the engine was restarted again for the second time for another five seconds.
• Roughly around one and 45 minutes later, the rocket ejected its 31st satellite - Isro's Microsat -- in the second orbit at an altitude of 359km. 
• Fifteen minutes later, the engine was again ignited for the last time and shut off in 13 seconds.

Two technology demonstrators

• It is the two other Indian satellites in the payload that have generated much excitement. Both are called technology demonstrators, indicating significant strides in miniaturisation.
• Micro-satellite: Of the two, one is a microsatellite of the 100 kg class. "This is a technology demonstrator and the forerunner for future satellites of this series," the ISRO said.
• Nano-satellite: The other one, a nanosatellite, named Indian Nano Satellite (INS) - 1C, is the third in its series; its predecessors were part of the PSLV-C37 launch of February 2017. 
• The INS-1C, whose mission life is six months, carries the Miniature Multispectral Technology Demonstration payload from the Space Applications Centre.