The Zhurong rover, part of Tianwen-1 mission, has found evidence of water at low latitudes on modern Mars

#geology #Mars #Tianwen1 #Zhurong #science #news

https://phys.org/news/2023-04-tianwen-zhurong-rover-evidence-latitudes.html

Finally something to show for a nights worth of tracking #TIANWEN1...

Oddly #TIANWEN1 hasn't emitted this entire pass thus far this night. It's been increasingly invisible over the last week with this night's pass showing no detected emissions. Sometimes a blank waterfall says more than a busy one... I'll share data on the weekend.

After a very prolonged absence (or wideband) signal #TIANWEN1 is back sending the bizarre signal last seen on Jan 13th.

𝗭𝗼𝗿𝗴𝗲𝗻 𝗼𝘃𝗲𝗿 𝗭𝗵𝘂𝗿𝗼𝗻𝗴: 𝗖𝗵𝗶𝗻𝗲𝘀𝗲 𝗠𝗮𝗿𝘀𝗿𝗼𝘃𝗲𝗿 𝗸𝗼𝗺𝘁 𝗻𝗶𝗲𝘁 𝘂𝗶𝘁 𝘄𝗶𝗻𝘁𝗲𝗿𝘀𝗹𝗮𝗮𝗽

Wat is er gebeurd met de Chinese Marsrover Zhurong? Het apparaat had al weken geleden uit zijn winterslaap moeten komen, maar tot nu toe geeft de rover nog geen teken van leven. Het Chinese ruimtevaartagentschap houdt zich stil over de status van het Marswagentje.

https://nos.nl/l/2460636 #nieuws #nos #zhurong #tianwen1 #insightlander #mars

If you're studying my #TIANWEN1 Doppler data I have updated the archive:
https://github.com/ScottTilley/tianwen1/tree/main/anomaly

If you noticed that for the first time in 11 days #TIANWEN1's signal vanished before periareion and reappeared immediately afterwards and was in lock. Notice how the spacecraft unlocks just prior the signal disappearing. ⬇️

#TIANWEN1 is up to something else interesting this night. Have a look at this running plot a spot the divergence in the behaviour. 🧵⬇️

Why is the 'tick' odd? Coherent lock has the ground station take over the function of providing the spacecraft with a frequency/phase reference, so either the g/s has a tick or there's something up with #TIANWEN1's ability to properly lock...

The period of the #TIANWEN1 'tick' is about 3.6s.

#TIANWEN1 is presently in lock with what I believe is JAIMUSI 64m ground station in NE China. Here you can see it has developed a 'tick', I saw this before in November during one pass. The signal didn't display this until lock occurred.

The data collected so far in 2023 from #TIANWEN1 is located here in the STRF format:
https://github.com/ScottTilley/tianwen1/tree/main/anomaly

Over the past 9 days I've recorded #TIANWEN1 data during every visible moment the spacecraft is viewable to my station (tree horizon). During this observation campaign I have noted anomalies in the signal that are not explained by the usual Doppler analyse methods. 🧵⬇️

#TIANWEN1 is going through another bout of odd downlink behaviour with an unknown uplink station. This time well between periareions.

I think it's time to do a more detailed analysis, as I have a hunch that whatever is creating the 'unknown' curve may be on Mars...

If #TIANWEN1 begins an aerobrake test what could be see?
- Weak/no signals around periareion,
- Slow initial change in orbital period particularly at first as they dip their toes,
- Odd signal behaviour as the spacecraft attitude is constantly changed.🛑

What orbit would #TIANWEN1 be targeting? I would expect something that a MAV could reach if they are doing a full up test and want to something that really tests their mission capabilities so something in the 300-400km near circular range similar to what #ESA is proposing.⬇️

One of the reasons #TIANWEN1 needed such a large rocket is that it propulsively lowered it's orbit. This can use almost as much delta-V as the insertion burn. MRO used 1015m/s for MOI burn, and aerobraking to science orbit saved 1080m/s, double the mass would have been needed!⬇️

To quantify what it takes in time to change an orbit lets consider a few past missions at Mars that used aerobraking. For comparison #TIANWEN1 is in a ~7hr period orbit presently. So any test will take time and continued focus to demonstrate an operational capability.⬇️

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.
https://spacenews.com/china-aims-to-bring-mars-samples-to-earth-2-years-before-nasa-esa-mission/#:~:text=Sun%20added%20that%20the%20Tianwen%2D1%20orbiter%20will%20conduct%20an%20aerobraking%20test%20in%20Mars%20orbit%20later%20this%20year%20as%20part%20of%20the%20sample%20return%20mission%20preparation

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. 🧵⬇️