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Old 09-06-2019, 08:27 PM   #16
Urwumpe
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Quote:
Originally Posted by Notebook View Post
 Loss of telemetry never a good sign.
Was that area well surveyed?

I am sure it was... I saw the lander in the visualization rotate heads down before the dive really accelerated and the signal was lost.



Maybe a software glitch when switching to fine landing mode.
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Old 09-06-2019, 08:35 PM   #17
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Originally Posted by Urwumpe View Post
 I am sure it was... I saw the lander in the visualization rotate heads down before the dive really accelerated and the signal was lost.

Maybe a software glitch when switching to fine landing mode.

I missed that. I hope it wasn't a sign error.


Tough luck.
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Old 09-06-2019, 08:43 PM   #18
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Originally Posted by Thunder Chicken View Post
 I missed that. I hope it wasn't a sign error.

Looked more like an attitude control failure, tumbling out of control. But it descended very fast, much faster than I would have expected from lunar gravity.
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Old 09-06-2019, 09:16 PM   #19
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I'm no expert in interpreting Doppler

From https://forum.nasaspaceflight.com/in...23#msg1989823:



My guess it that anything is possible. Perhaps it was really firing upside down
Anyway, the signal seems to be lost a bit high (around 300m per ISRO last data-point).

Last edited by 4throck; 09-06-2019 at 09:25 PM.
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Old 09-06-2019, 09:19 PM   #20
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 Didn't look like tumbling, it really seemed to be upside down and firing.
It completely nulled horizontal speed and seemed to increase vertical - consistent with such a firing.

So perhaps a navigation software fault ? Those seem quite common recently...

At 2.5 km, it was heads down, while at 1.5 km, it was heads up again, which is why I wonder if it was tumbling.

The Doppler shift also suggests it was rotating rapidly.
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Old 09-06-2019, 11:24 PM   #21
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Sure.
I deleted those comments because I realized that
Probably tumbling but with 1 second telemetry sampling we only see it on random positions.
(strobe effect)

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Old 09-07-2019, 02:27 PM   #22
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Does the Orbiter have capability to view the landing area?
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Old 09-07-2019, 02:38 PM   #23
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 Does the Orbiter have capability to view the landing area?

I am sure it has.
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Old 09-08-2019, 11:51 AM   #25
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Post Re: Chandrayaan-2 mission news

Hello everyone,

On 7 September, when I heard that the Vikram lander was failed to land, I was so overwhelmed that I could not eat much.

However, after some thinking, I found that despite the failure of the Vikram lander, it reached the lunar south pole regime! Yes, India becomes the first country to send anything on the surface of the lunar south pole regime!

After using Wikipedia, I found that the US would deliver some uncrewed landers and rovers to there.

Last edited by soumya-8974; 09-08-2019 at 11:59 AM. Reason: Fixed typo
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Old 09-08-2019, 05:10 PM   #26
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ISRO has announced they have located Vikram on the surface of the Moon. No word on the status of the lander, but given the fact that they're going to continue to attempt to establish communication with it for the next 14 days, I'd say there's a decent chance it's intact and upright!
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Old 09-08-2019, 05:14 PM   #27
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ISRO will never communicate with the Vikram lander until 14 September, a full moon. 🌝

Full moon is the moment when the sun shines on the lunar south pole regime, and the solar panels of the lander may work.

Sent from my Lenovo YT3-850M using Tapatalk
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Old 09-08-2019, 09:58 PM   #28
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Sounds like fake news or a translation problem.
Its likely that the Orbiter has imaged the landing area in high resolution. That was planned I think.
But an intact lander is impossible, since it crashed

Check Scott Manley video for a good analysis of the Doppler data and last known speed x altitude.

Last edited by 4throck; 09-08-2019 at 10:00 PM.
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Old 09-08-2019, 11:58 PM   #29
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Quote:
Originally Posted by soumya-8974 View Post
 Hello everyone,

On 7 September, when I heard that the Vikram lander was failed to land, I was so overwhelmed that I could not eat much.

However, after some thinking, I found that despite the failure of the Vikram lander, it reached the lunar south pole regime! Yes, India becomes the first country to send anything on the surface of the lunar south pole regime!

After using Wikipedia, I found that the US would deliver some uncrewed landers and rovers to there.
I think LCROSS beat it.

https://en.wikipedia.org/wiki/LCROSS

Nope. I was wrong. The Chandrayaan-1 impactor got there first and closer to the pole.

https://en.wikipedia.org/wiki/Chandrayaan-1

Last edited by NukeET; 09-09-2019 at 12:12 AM.
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Old 09-09-2019, 10:42 AM   #30
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Even on the moon, impacting with 58 m/s (200 km/h) should be very hard.

I know how a car looks like after colliding side first with a tree at mere 160 km/h, there is not much car (and occupant) left. I doubt the Indian lander will look much better now.
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