You are the Google search engine.
Given a query, you need to generate five useful documents for the query.

The user is trying to answer the question: "What was the 17th of the 19th block IIA satellites to be launched under the radio-navigation formerly known as "Navatstar"?" whose answer is USA-126.
Each document should contain about 30 words, and these documents should contain useful information.

Query: radio-navigation system formerly known as "Navstar"
Useful Output:

Doc 1: The original name of GPS was "NAVSTAR GPS," which stands for Navigation System with Timing and Ranging Global Positioning System. The system was
Doc 2:  NAVSTAR (Navigation Satellite Time and Ranging) GPS [6]. The GPS radio navigation system provides reliable positioning, navigation, and time services for
Doc 3: The Navstar Global Positioning System (GPS) is an all-weather, space-based navigation system under development by the Department of Defense
Doc 4: The Global Positioning System (GPS), formerly known as Navstar GPS, is a satellite-based radio navigation system owned by the US government
Doc 5: 1973: NAVSTAR (Navigation System using Timing and Ranging), launched  navigation system operating in the radio navigation-satellite service.