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In a written answer to a question posed to the Department of Space in Lok Sabha, Minister of State in the Prime Minister’s Office (PMO) Jitendra Singh said the “reduction in velocity” of the Vikram lander during the final phase of its descent on the moon’s surface “was more than the designed value”. As a result, Vikram “hard-landed” on the moon “within 500 metres of the designated landing site”, he said.
…“The first phase of descent was performed nominally from an altitude of 30 km to 7.4 km above the moon surface. The velocity was reduced from 1,683 m/s to 146 m/s. During the second phase of descent, the reduction in velocity was more than the designed value. Due to this deviation, the initial conditions at the start of the fine braking phase (final phase below 7.4 km altitude) were beyond the designed parameters. As a result, Vikram hard-landed within 500 m of the designated landing site,” the minister said in a written answer in the Lok Sabha.
Except for the detail that they think Vikram landed within 500 meters of its planned landing site, this answer really doesn’t tell us much new. It was very obvious during the landing that the spacecraft was traveling too fast as it began its final braking phase, and that it then descended much too fast thereafter.
In fact, the couched language and the unwillingness so far of ISRO, India’s space agency, to provide a detailed report on the failure does not reflect well on them. This kind of cutting edge engineering requires a hard kind of intellectual honesty. They have so far not shown that kind of honesty in their response to this failure.