Indian space history: INSAT-IB replacing INSAT-IA The communication satellite INSAT-IB had to take over the role of INSAT-IA because INSAT-IA failed within how many months of its launch?

Introduction / Context:
India’s early INSAT programme faced teething problems. Understanding the timeline of INSAT-IA's failure and the subsequent operational takeover by INSAT-IB is a common general-awareness topic in satellite communications and Indian space history.

Given Data / Assumptions:

• INSAT-IA was India’s first operational multipurpose communication satellite of the INSAT-1 series.
• INSAT-IB was the immediate successor in the same series and assumed services after INSAT-IA failed.
• The question asks the number of months after launch when INSAT-IA effectively collapsed in service.

Concept / Approach:

We recall the chronological facts from standard references on the INSAT programme. INSAT-IA was launched in 1982 and suffered power bus and attitude control problems, leading to loss of service a few months later. INSAT-IB was launched in 1983 to restore and expand services—telecommunications, TV broadcasting, and meteorology.

Step-by-Step Solution:

Verification / Alternative check:

Multiple historical summaries note that INSAT-IA became inoperative within about five months, prompting urgent deployment and utilization of INSAT-IB to maintain national services.

Why Other Options Are Wrong:

12 months (a) and 20 months (b) are too long; 36 months (d) is far beyond the known early failure; 9 months (e) also exceeds the documented time frame.

Common Pitfalls:

Learners may confuse INSAT-IA's short life with later satellites that performed nominally for several years, or they may mix up dates from different INSAT-1 satellites.

Final Answer:

5