Read the four-flight record

The four-flight sequence began on August 10, 1979 with the Rohini Technology Payload. ISRO’s launch list marks that orbital-launch attempt unsuccessful. The July 18, 1980 flight then delivered Rohini RS-1 to orbit. A broad statement that the program eventually succeeded should not erase the earlier unsuccessful attempt.

Development records can preserve useful subsystem observations from an unsuccessful mission. However, useful observations do not turn a missed orbital objective into a successful launch. Keep the measured behavior, the mission outcome and any later explanation of the cause as separate parts of the account.

On May 31, 1981, SLV-3 launched Rohini RS-D-1. ISRO’s spacecraft record calls that launch a partial success: the satellite reached a lower orbit than intended and remained in orbit for nine days. Saying only “it reached space” or “it reached orbit” would hide the shortfall that mattered to the mission.

The next developmental flight, on April 17, 1983, successfully launched Rohini RS-D-2. These hyphenated archive-card names refer to the spacecraft also written RS-D1 and RS-D2 in ISRO’s records. They are separate satellites and flights; the later success does not change the earlier orbit or its lifetime.

Read four flights without losing their differences

Imagine three original test reports. A never delivers its payload to orbit. B reaches orbit but outside a required lifetime-supporting envelope. C meets the stated delivery conditions. A useful comparison records these distinctions instead of assigning all three the same label because the rockets left their pads.

Four development flights are also a small, changing sample. They do not establish a permanent numerical reliability for every later vehicle derived from the program. The more useful learning question is what was tested, what was measured and what evidence justified carrying an engineering practice into the next design.