4 comments

• wayne

  September 9, 2019 at 5:13 pm

  “Hovering above the surface…” that’s a good one–just goes to show how stupid the Fake News is, worldwide.

  Video from Scott Manley is very interesting–

  What We Know About India’s Failed Lunar Landing
  Scott Manley 9-7-19
  https://youtu.be/5xKJG00-S_c
  10:39
• Edward

  September 9, 2019 at 6:46 pm

  wayne,
  Thanks for that link.

  I agree with Manley on most points. I, too, was concerned about the orientation that was shown on the screen in the late part of the landing. That is a terrible time to be upside down.

  I am thinking, however, that the kink seen in the chart at about 4 km altitude may be the lander beginning to use its landing radar rather than its inertial motion unit to determine the distance to the Moon’s surface. That seems to be about the time that the lander turned its engine toward the surface rather than parallel to it for the rough braking phase.

  As with Manley, I was disappointed that the telecast chose to show reactions more that the actual data and position information. Judging from the deviation from the predicted path, the unexpected orientation of the lander, and the rapid fall toward the Moon at the last part of the downlink, I thought that the lander had hit catastrophically hard. Judging from the looks on the controllers’ faces, I think they thought so, too.

  I still have plenty of questions, because some of what I just wrote and what Manley said do not quite line up with what we saw. For instance, the craft seemed to follow the predicted course, the red line, even while upside down. There was a phase that they labelled “cam coasting phase,” between the rough braking and fine braking phases, but I don’t understand what that phase meant. It looked like the spacecraft may have turned upside down during that time. At some point, they showed a chart displaying the expected events, labeled “Vikram Events Display,” but the cam coasting phase was not on the list.

  The fact that the green line deviated from the red prediction line suggests to me that the green line was based upon the data downlink or other tracking data, otherwise the two lines would not have deviated from each other.

  Finally, it looked like they never reached the event of the central engine turning on. The events display suggested that this would occur after the fine braking phase ended, but there was never an announcement of the end of this phase or of the center engine firing. Toward the end of the landing, the green line fell toward the Moon far too fast for it to seem likely that the center engine would have time to slow the lander enough to have eased itself safely onto the Moon.

  Robert wrote: “you can’t succeed in this kind of challenging endeavor without an uncompromising intellectual honesty, which means you admit failure as quickly as possible, look hard at the failure to figure out why it happened, and then fix the problem.”

  Hopefully, their scientists and engineers are doing just that. I am hopeful, because the country’s leadership has been supportive of its space program, in recent years. They should know that space is difficult and dangerous, and that they need to keep trying, just as other countries have learned before they became successful landing on the Moon.
• mpthompson

  September 9, 2019 at 8:09 pm

  “…you can’t succeed in this kind of challenging endeavor without an uncompromising intellectual honesty, which means you admit failure as quickly as possible, look hard at the failure to figure out why it happened, and then fix the problem.”

  One of the best ways to deal with failure is to assume failure will occur and pre-plan on what exactly will be done when it rears its ugly head. It’s never pleasant to go through, but if you already have a plan in place on what will happen when a failure occurs, it’s much easier to pick up the pieces, figure out what went wrong and begin to move forward. I think a LOT of this occurred in the 50’s and 60’s in the US and Soviet space programs — particularly with the early planetary missions where failure was more the rule than the exception. I sincerely hope that the Indian space program has the maturity to take this in stride and move forward confidently and try again with the new knowledge gained.
• wayne

  September 10, 2019 at 5:35 am

  Edward/mpthompson–
  Good stuff.

  Ref–prime minister Modi— he should have had the “we failed this time, but everyone including me, has absolute faith in our rocket-scientists going forward…” speech, already written.