National Space Organization (NSPO) of Taiwan in the past ten years has successfully launched three different types of satellites. The latest one is FORMOSAT-3/COSMIC, a joint Taiwan-US project, which was successfully launched on April 15, 2006. The FORMOSAT-3 is a constellation of 6 satellites and each satellite is equipped with GPS Occupation Receiver (GOX), Tri-Band Beacon (TBB), and Tiny Ionospheric Photometer (TIP). The constellation is on the way to its final orbit configuration. All satellites remain healthy except spacecraft flight model no. 2 (FM2) with a problem of power shortage and FM3 currently staying at an orbit of 711 km due to a mechanism issue to be solved. The current sounding profiles retrieved from the GPS occultation measurements are over an average of 1800 daily. The sounding profiles have been used to study atmospheric and ionospheric structures and total electron content, and assimilated into numerical atmospheric and space weather predictions models to improve the accuracy of prediction. Taiwan has taken an active role and grown remarkably well in remote sensing researches during the last decade. Taiwan will continue to share her resources with the international community for scientific research and applications. In this paper, we will present an overview of significant contributions of the FORMOSAT-3/COSMIC satellite mission to the global community. We will also describe the constellation challenges and novel operations solutions and the future follow-on mission planning.