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India Loses Contact with Probe Just as It Prepares to Land on Moon

wsj.com

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Re: India Loses Contact with Probe Just as It Prepares to Land on Moon

#211

Post by sandworm101 »

adt2bt wrote: post #205
kappi wrote: post #152

Latest update.. DSN did a carrier lock on lander https://twitter.com/dsn_status/status/1170391223040954368 DSS 54 carrier lock on Chandrayaan-2 Lander Frequency: 2.2846GHz Signal strength: -143dBm IDLE OFF 1 TURBO

Can you explain in layman’s terms what this might mean?

It means they are trying to contact it using the most powerful antennas available. It hasn't phoned home yet.

Re: India Loses Contact with Probe Just as It Prepares to Land on Moon

#212

Post by sandworm101 »

jcims wrote: post #167
abhiminator wrote: post #2

Here's [1] a data graph of the Doppler curve from Dwingeloo Radio Telescope (based in Netherlands) showing the exact moment the probe crashed into the surface of the moon. https://twitter.com/cgbassa/status/1170072672266592256

Any RF experts in here kniw what that cirrus cloud effect on the center transmission could be? Good view here: https://twitter.com/cgbassa/status/1170069055140765700?s=21

The blur is because the vehicle was vibrating. It means the thrusters were on. Note how they smooth out shortly after deceleration stops. Some of the larger movements could be maneuvering. If it is orientating itself then the antenna would intermittently move back and forth relative to the receiver.

Re: India Loses Contact with Probe Just as It Prepares to Land on Moon

#213

Post by Trias11 »

kappi wrote: post #152

Latest update.. DSN did a carrier lock on lander https://twitter.com/dsn_status/status/1170391223040954368 DSS 54 carrier lock on Chandrayaan-2 Lander Frequency: 2.2846GHz Signal strength: -143dBm IDLE OFF 1 TURBO

That singal strength is like barely above photonic noise

Re: India Loses Contact with Probe Just as It Prepares to Land on Moon

#214

Post by dang »

burgerzzz wrote: post #208
dang wrote: post #160

Earlier quoted context omitted.

Please don't take HN threads into nationalistic flamewar. This one is a classic flamewar tangent that has happened countless times, leads nowhere good, and is quite off topic. https://news.ycombinator.com/item?id=20900411 https://news.ycombinator.com/item?id=20900396

How is this "nationalistic"? How does this lead nowhere good? How is it off topic?

Internet arguments where people say angry things for/against the nations they like/dislike are nationalistic flamewars. They lead nowhere good because the statements are invariably repetitions of previous flamewars, which means they contain no new information but do get people very angry and very nasty. That also makes them off topic here. Please see the site guidelines: https://news.ycombinator.com/newsguidelines.html.

Re: India Loses Contact with Probe Just as It Prepares to Land on Moon

#215

Post by SamReidHughes »

ever1 wrote: post #194
SamReidHughes wrote: post #163

Earlier quoted context omitted.

The USA just had a lot of land and a low population. America already had a better quality of life than Europe in the 1700's.

source ?

Well you might ask why people kept going on ships across the ocean if the quality of life was worse.

A randomly googled source is https://www.encyclopedia.com/history/news-wires-white-papers... , which casually mentions a bunch of relevant numbers.

Re: India Loses Contact with Probe Just as It Prepares to Land on Moon

#216

Post by CMCDragonkai »

coldtea wrote: post #96
Razengan wrote: post #92

Earlier quoted context omitted.

> aside from the Chinese and India Do you know how many different empires, rulers, internal wars and government systems China and India have gone through in 2000 years, and how many "races" and "cultures" they have?

> Do you know how many different empires, rulers, internal wars and government systems China and India have gone through in 2000 years, and how many "races" and "cultures" they have? Yes. Still more homogeneous and stable than most other empires...

I don't think you know much about China nor India.

Re: India Loses Contact with Probe Just as It Prepares to Land on Moon

#219

Post by sandworm101 »

brij0102 wrote: post #135

What do we think went wrong? I expect maths to be right but there was a comment somewhere about the regolith with fine particles whose specific composition could have caused unexpected dust clouds as the lander sped to the ground ... how was this tech different from the other 3 successes?

Those dust clouds, depending on particle size/composition, could start reflecting radar. Lander then gets confused about its altitude and crashes. This sort of thing makes some areas, the dusty flat ones, potentially more dangerous than others. But they are also flatter and so you don't worry about landing on a rock and tipping over. It's a judgement call.

Re: India Loses Contact with Probe Just as It Prepares to Land on Moon

#220

Post by jcims »

sandworm101 wrote: post #212
jcims wrote: post #167

Earlier quoted context omitted.

Any RF experts in here kniw what that cirrus cloud effect on the center transmission could be? Good view here: https://twitter.com/cgbassa/status/1170069055140765700?s=21

The blur is because the vehicle was vibrating. It means the thrusters were on. Note how they smooth out shortly after deceleration stops. Some of the larger movements could be maneuvering. If it is orientating itself then the antenna would intermittently move back and forth relative to the receiver.

I was thinking vibration but wouldn't we see a change when the retro-thrusters hit halfway through? I'm assuming the first part with downward slope is the craft accelerating due to gravity?

Given it's a polar landing I don't know how to translate this to the velocity vector of the lander.

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