Scott Tilley 🇺🇦 Profile picture
Sep 14, 2019 26 tweets 13 min read Read on X
No status change in #Chandrayaan2 mission in last 24 hours. No signals reported from the #VikramLander, orbit of #Chandrayaan2 remains stable. No new official reports from #ISRO, speculation in the Indian media as to the cause of the landing anomaly continues.
#NASA's #DSN appears to have stopped active transmission of commands to #VikramLander to stimulate a response. DSN NOW website appears to show stations tasked to #VikramLander but emissions have not been observed.
#Chandrayaan2 orbiter continues to emit strong S-band radio signals. I found an error in my earlier period timings for the orbiter and now my data nicely matches that of @df2mz. It’s safe to say rumours of the orbiter lowering its orbit are not true. ImageImage
Tonight, I hope to bring my 3m dish into action and listen for #VikramLander as the declination of the #moon has risen to the point that it has a clear view above my tall trees. Thanks to all that shared good will!
Many questions on @LRO_NASA image timing. The moon needs to rotate for a few more days until LRO's orbital plane is over the landing site. Here's an image showing the landing site and where LRO is now. The moon rotates ~13 degree/day. So 3-4 days needed to get there... Image
You can keep up on @LRO_NASA's position at this website. It updates in real time.…
#DSN24 is reporting emitting 10KW of RF in testing position. It appears tasked with signalling #VikramLander. Image
To Moon is about 20 degrees above the horizon at Goldstone, CA. Image
The testing behaviour is consistent with earlier nights where strong emissions where made toward the Moon.
DSN24 appears to be tracking the Moon now.
DSN NOW reports emissions from DSN24!
I'm not hearing the reflected signal yet but the Moon is still in my trees so signal level will be heavily attenuated (reduced).
Here we go, weak detection of the DSN24 reflection! So #NASA is trying again.
#NASA gives it a go again! This is an image of the reflected search signal from California DSN24, not #VikramLander. Image
Here's a recording of DSN24's call to #VikramLander.
#Chandrayan2 orbiter and China's #Queqiao putting in great signals tonight! Image
Here's a video of #Chandrayaan2 orbiter signal. The signal to the left is the Chinese #Queqieo relay satellite at the Earth-Moon L2 point.
This was obtained with the 3m dish antenna.
Here I've connected the dish antenna to the radio I can hear and record videos from. This is #VikramLander's radio frequency. You can see NO radio signals in the passband. If lander was active we would see similar signal levels to those I've shared earlier.
Interestingly I've caught #Chandrayaan2's orbit entirely visible from Earth tonight! The entire plane of the orbit is only visible from Earth twice a month for a few hours. Lucky me! That allows me to hear the radio signal for entire orbit as not blocked by moon. Image
Orbital period remains around 7136seconds. About 112Km nominal altitude.
#NASA DSN operator @nascom1 sent an update about #NASA using one of their largest antenna to contact #VikramLander, unfortunately no signals.
Another demonstration of #Chandrayaan2 being alive and well is it just locked to DSN 26 at Goldstone. Hence the frequency jump. Image
Here's the @LRO_NASA just emerging from the other side of the moon. Near the end of the clip you can hear the rapid change in frequency as it locks to the ground station in New Mexico.
I misspoke LRO was heading behind the moon.
Well folks, its 2am here almost, no signals from #VikramLander. I'll leave the system running and recording. Meanwhile DSN24 continues to transmit to Vikram.... Thanks to all for sharing a night of satellite tracking with me. It's usually a solo gig :-) Image

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More from @coastal8049

Dec 22, 2023
Update on the Chinese 'spaceplane' monitoring effort. @plugger_lockett observed possible emissions from objects from the 2023-195 launch. Despite using the same modulations it turns out these emissions are from other secret Chinese military sats, raising more questions. 🧵⬇️
Upon fixing a minor timing issue with his ground station @plugger_lockett sent me data from a pass yesterday & I was able to determine that the object being tracked yesterday was in fact YAOGAN-30 X the track of which passed over one of 2023-195. ⬇️ Image
I went back and looked at the erroneously timestamped data from the passes we thought detected OBJECT D and E finding that if I adjusted the timing YAOGAN-30 AA and YAOGAN-30 R passed closely to the track of these objects. ⬇️
Read 8 tweets
Aug 19, 2023
Moon rise here at the station. As the Moon clears the trees, an "Emergency" was declared by @roscosmos for #Luna25 as it failed to perform an orbital adjustment burn. Lets discuss how this could affect the mission. 🧵⬇️ Image
A telegram post by @roscosmos provides limited information of the status of #Luna25. Apparently, the spacecraft failed to adjust its orbit as planned.⬇️
Russian controllers now need to troubleshoot and fix the issue. This is complicated by their lack of a global deep space communications network. So recovery efforts will be limited to when the Moon is visible over Russia due to their geopolitical misadventures... ⬇️ Image
Read 8 tweets
Aug 13, 2023
I have been asked repeatedly about #Luna25.

Thus far I have no independent observations of the mission to share. That is not without extensive trying to observe it.

So why am I not detecting anything? 🧵⬇️ Image
#Luna25 was launched into a trajectory that is largely only visible on Earth in daylight. Secondly, that trajectory is not exactly known. I have calculated one based on the launch timing and the scant public info shared and used GMAT to find a good direct trajectory. ⬇️ Image
The trajectory isn't arbitrary. You need to carefully line things up to the extreme to get anywhere close to the Moon. So it constrains where to look. As we're looking into the glare of the Sun, we need radio. ITU records report two bands, X and Ku-band. But wait...⬇️ Image
Read 10 tweets
Aug 13, 2023
A follower asked if #Chandrayaan3 could land on the Moon before #Luna25. The short answer is maybe.

As we'll see in this thread changing a plan as complex as landing on the Moon is not a great idea.🧵⬇️
#Chandrayaan3 is presently largely locked into an orbital plane above the Moon. What that means is that it needs to wait for the Moon to rotate under-neigh it to reach the primary landing site that @isro has painstakingly planned to land at. ⬇️
Therefore, if you want to rush to get to the landing site it's too late. Therefore, you need to pick a new landing site under up coming terrain that may be suitable and also change the mission plan. Recalculate, adjust and then execute. ⬇️
Read 6 tweets
Aug 3, 2023
#Chandrayaan3 trajectory update 2023-08-02 #2.

Despite my better judgement, I did a TLE update on the Doppler data. The problem with TLEs in these types of orbits is they degenerate fast as the model is not designed to deal with long periods et. al. 🧵⬇️
Small changes in the data or the fit has profound effects on the TLE and the orbital model. But they are convenient. So I offer a couple of TLEs to aid anyone wishing to hunt for #Chandrayaan3. NO WARRANTY offered 😉, look with WIDE field... ⬇️
Data fit to released orbital parameters:
1 57320U 23213.95526600 .00000000 00000-0 00000-0 0 04
2 57320 21.4000 180.4625 9648325 12.6358 39.3505 0.10345282 04
# 20230801.30-20230802.61, 53466 measurements, 0.005 kHz rms⬇️
Read 4 tweets
Jan 12, 2023
I've recently renewed an observing campaign on #TIANWEN1. The orbit hasn't changed so an aerobrake test claimed for late 2022 has not occurred yet. In preparation for observing an aerobraking manoeuvre I thought it would be interesting to study past missions that did one. 🧵⬇️ By NASA/JPL/Corby Waste -
First a bit a reference of why we believe #TIANWEN1 will conduct an aerobraking test. This all relates to the #TIANWEN3 Mars sample return mission.…
Aerobraking is used to allow a spacecraft to lower its apopasis by using a planet's atmosphere to decelerate the spacecraft as it passes through the tenuous upper atmosphere of the planet at periapsis at just the right altitude as not to cook the spacecraft and max. drag. ⬇️
Read 13 tweets

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