#CrewDragon tracking continues as the mystery of the status of the 'trunk' intrigues me. More to come...
No sign of the #CrewDragon "trunk" on a decent pass with the dish aimed along the expected track waiting for it to drift through the beam.
Another pass of the plane of #CrewDragon "trunk", this time over my zenith. No signals noted on 2216MHz.
When I say pass, I'm meaning that I'm monitoring for the signal along the plane of the last known orbit and bracketing considerably in time. This is called a planar search. Satellites don't change their orbital planes much as it takes huge amounts of energy.
Let's try 2203.2MHz next go around.
@SpaceTrackOrg released final TLE before reentry burn. Based on this the 'trunk' has re-entered already. #CrewDragon mission is complete.
In a chat with @planet4589 I retract the above until we get some more orbital data. The track of the last orbit published by @SpaceTrackOrg does not go over the landing site. Let's continue to monitor and see...
I've used the @SpaceTrackOrg TLE 46024 (thanks @planet4589) and previously planar searches and have not noted any signals from the #CrewDragon DM-2 trunk since separation from the capsule on any of the FCC co-ordinated frequencies for the mission.
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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. ⬇️
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. ⬇️
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. 🧵⬇️
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... ⬇️
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? 🧵⬇️
#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. ⬇️
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...⬇️
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. ⬇️
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⬇️
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. 🧵⬇️
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. ⬇️