Co-passenger satellites are small satellites that are launched alongside a larger satellite on the same launch vehicle. Co-passenger satellites are typically smaller and less expensive than the larger satellite, and they can be used for a variety of purposes, such as Earth observation, communication, and scientific research.

Co-passenger satellites are small satellites that are launched alongside a larger satellite on the same launch vehicle. Co-passenger satellites are typically smaller and less expensive than the larger satellite, and they can be used for a variety of purposes, such as Earth observation, communication, and scientific research.

ISRO has launched a number of co-passenger satellites over the years, including:

• PSLV-C37: Launched on February 15, 2017, this mission carried 103 co-passenger satellites, including two ISRO Nano Satellites (INS-1A and INS-1B).
• PSLV-C40: Launched on January 12, 2018, this mission carried 30 co-passenger satellites, including the Cartosat-2 Series Remote Sensing Satellite.
• PSLV-C51: Launched on February 28, 2021, this mission carried 18 co-passenger satellites, including the Amazonia-1 satellite.
• PSLV-C56: Launched on July 25, 2023, this mission carried 6 co-passenger satellites, including the DS-SAR satellite, ARCADE Atmospheric Coupling and Dynamics Explorer (ARCADE), SCOOB-II, NuLIoN, Galassia-2, and ORB-12 STRIDER.

The use of co-passenger satellites allows ISRO to launch more satellites into space at a lower cost. It also allows ISRO to share the launch vehicle with other countries and organizations, which helps to promote international cooperation in space exploration.