Tianlian I 

The China National Space Administration (CNSA) Tianlian I, also known as the "Sky Link" or "Heavenly Link" satellite, is a geostationary data relay satellite system that provides communications and data transmission services for China's space missions.

When: 

The Tianlian I project was first proposed in the late 1990s, with development and testing taking place over several years. The first satellite was launched on April 25, 2008.

Launching Date: 

The first Tianlian I satellite was launched on April 25, 2008, and several additional satellites have been launched since then to expand and improve the system.

Why: 

The Tianlian I satellite system was developed to address the communication and data transmission challenges faced by China's space program. Prior to the development of the system, China relied on ground-based communication facilities, which had limited coverage and were subject to weather conditions and other disruptions. With the Tianlian I system, China has been able to establish a reliable and robust communication network that supports its space missions, including manned missions and deep space exploration.

How: 

The Tianlian I satellite system operates in geostationary orbit, which means that the satellites remain in a fixed position relative to the Earth's surface. The system includes a series of ground stations that communicate with the satellites and relay data and communications signals to and from China's space missions. The satellites use advanced technologies to ensure high-quality and reliable communication and data transmission, even in challenging environments.

Cost: 

The exact cost of the Tianlian I project is not publicly available, but it is believed to be a significant investment for the Chinese government. However, the benefits of the system, including improved communication capabilities and enhanced space exploration capabilities, are considered to be well worth the cost.

Achievements:

The Tianlian I satellite system has played a critical role in supporting China's space program and has enabled a number of significant achievements. Some of the notable achievements include:

Supporting China's manned space missions: The Tianlian I system has played a critical role in supporting China's manned space missions, including the Shenzhou spacecraft and the Tiangong space station. The system has provided reliable and continuous communication and data transmission capabilities, allowing mission control to monitor and communicate with astronauts in real-time.

Enabling deep space exploration: In 2013, China launched its Chang'e 3 lunar lander and Yutu rover, which marked the country's first soft landing on the Moon. The Tianlian I system played a critical role in enabling this mission by providing reliable communication and data transmission capabilities.

Supporting international cooperation: The Tianlian I system has also been used to support international space cooperation, including China's collaboration with the European Space Agency's Mars Express mission.

Demonstrating technological advancements: The development of the Tianlian I system has demonstrated China's capabilities in advanced space technologies, including high-precision orbit control and advanced communication and data transmission technologies.

Overall, the Tianlian I satellite system is a significant achievement for China's space program and has enabled the country to establish a robust and reliable communication and data transmission network that supports its ambitious space exploration goals.