#ARTEMIS1 observational planning 🧡

Overall visibility of the spacecraft from my ground station location. Elevation above the horizon will be a key factor. As you can see during the early and late stages of the mission Artemis will be low in my sky.

Next lets consider the range to #ARTEMIS1 so a model of the expected signal level can be obtained using Free Space Path Loss (FSPL) assumptions. Data is only plotted when Artemis is above my horizon.
The following are estimates of the SNR of #ARTEMIS1's signal in my 1.8m dish using an Equivalent Noise Bandwidth (ENBW) of ~2Hz for my usual SDR setup during the course of the mission. Assumed spacecraft High Gain Antenna (HGA) and the known sensitivity of my system used here.
As you can see the prime time to observe the mission at northern latitudes is during the lunar orbit operations phase while it's in Distant Retrograde Orbit (DRO) of the Moon. Overall, the signal levels while conducting lunar operations will be fairly stable.
Source of Ephemeris data: JPL Horizons
ssd.jpl.nasa.gov/horizons/

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More from @coastal8049

Mar 19
MERIDIAN 9 on it's Eurasian apogee.

As you can see here there's legit Russian military traffic here.

Aircraft spotters I make a call for you to pay attention to this 🧡.
MERIDIAN 9, 990MHz transponder narrow data. This type of traffic has been observed for decades on the Molniya-T1 spacecraft too. It is thought to be part of the Russian Strategic Rocket Force's communication system.
A call for #OSINT air traffic gurus to see if any Russian aircraft with strange humps on their back are orbiting somewhere over Russia right now. Like RSD79 in this post.
Read 7 tweets
Mar 18
MERIDIAN 8 RADAR re-emissions seen this morning.

Using the AM demodulator to examine the pulse dynamics of each RADAR.
Here's another recording revealing a 4th radar with a much different higher pitched pulse pattern. It comes and goes so listen to the entire track.
A dramatic change in RADAR emissions and new low frequency pulse...
Read 4 tweets
Mar 17
My wife says this blown to bits Russian EW warfare equipment looks like our backyard. Not sure why they need 2.4GHz grid but we've seen other off the self comms equipment blown up too.
If you look carefully at the second image there are two feeds, so they had two complete WiFi antennas. Most likely for some local link they planned to establish. I wonder if they use secure or open WiFi networks?
Maybe they want to capture weather satellite images? πŸ˜‰
Read 4 tweets
Mar 12
Russian military MERIDIAN 7 C-band this evening. There's now a 100KHz non-regenerative transponder on the band. I've seen these appear rarely on X-band but until now not on C-band.
MERIDIAN 7 with the usual TTY beacon on 3610MHz.
Here's what I think is the MERIDIAN 7 regenerative transponder. ~500KHz wideband data on 3625MHz.
Read 4 tweets
Mar 6
Here's how to understand the RADAR data I'm sharing.

The Russian MERIDIAN satellites are in High Earth Orbit and have their apogees fixed above the Northern hemisphere over Russia and North America. This allows the spacecraft to see both places at once.

THREAD
1.
Being in a highly elliptical orbit the MERIDIAN satellite is actually visible to observers on the opposite side of the world at a very low elevation in their sky. Here's an example plot of simulation of MERIDIAN 8 at the North American apogee visible from Ukraine.
2.
Examining geometry you can easily see that the satellite is visible to both stations in North America and Europe/Asia. The geometry below is when MERIDIAN 8 is setting over Ukraine. Satellite footprint is the yellow circle on the Earth. Anything within that can see satellite.
3.
Read 8 tweets
Mar 5
Some details on what is known about the MERIDIAN 990MHz transponder system. This transponder seems to be a legacy of the older Soviet MOLNIYA system as evidenced by this excerpt from a report to the US congress in the 1980s.
THREAD
When the last of the MOLNIYA's were still operational amateurs noted transponder activity from them while the spacecraft were on the Russian/European apogee. But by 2011 MOLNIYA went silent and was replaced by MERIDIAN and during the gap no one looked...
Amateurs lost track of the 990MHz transponder and it wasn't until the Breakthrough Listen Candidate 1 signal was reported on 982MHz that I began searching the band in an effort to determine if there was satellite activity that we noted there actually was.
Read 15 tweets

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