DF2MZ – Edgar J. Kaiser – Kiel – Germany
Welcome to df2mz.de!
This is my new web presence. It will be a little basic for some time, but I hope it will evolve into an attractive blog about my activities in physics, deep space monitoring, the cats and more. Times are UTC.
0069, 01.08.2023, 17:46, #Chandrayaan-3
Last night Chandrayaan-3 appeared at my southeastern horizon at around 21:00 after the translunar insertion burn. The signal on 2241.6 MHz was loud and deviations from the planning trajectory (from JPL Horizons) seemed to be small. Everything looked good and I could assume a successful burn.
The other plot shows the relative positions of Chandrayaan-3 (the ‘extra’ object) and the Moon. The spacecraft will slowly approach the Moon over the next few days. According to JPL Horizons data the periselene will occurr around 14:00 UTC on August 5th. If this is correct I won’t be able to observe the event, because the Moon will be below horizon here. Observers in the Americas may have a chance.
0068, 24. July 2023, 19:13, #Miscellaneous
This morning I decided to leave Twitter and delete my account when indeed the Twitter bird was replaced by an X. It is not just a new logo, it stands for a completely new adjustment of Twitter in future. This is being discussed intensively and I won’t contribute to that. I decided that I don’t want to be part of this transformation, even though I only posted announcements without content and removed my complete timeline after Elon Musk bought twitter. Twitter is no longer the environment I want to be present in, in which form ever.
For those who want to follow my work in future I am assembling an email list to announce news in the blog and other activities such as live youtube streams of deep space signals. Or you just set a bookmark and browse along in between. I am currently not planning to join any other social platform. Instead I will invest my time to cast the current clumpsy blog format into something more structured. May still take a while though.
If you want to be included in the list, please drop me an email to firstname.lastname@example.org . The members of the list will of course not be disclosed in the messages. Thank you for your interest and hope to hear from you.
0067, 21. July 2023, 17:38, #Chandrayaan-3
It turned out that it was possible for me to observe the perigee burn yesterday on July 20th. The spectrogram below shows the complete pass. Around 23:00 the signal begins to emerge from the noise after it became visible from behind the forest. Around 04:45 a small frequency shift indicates coherent lock to a groundstation. Around 07:45 the spacecraft unlocks from the groundstation, again indicated by a small frequency shift.
So far my station didn’t compensate Doppler and the trace shows the orbital Doppler profile. At 08:10 I activated orbital Doppler compensation which is indicated by a large frequency shift in the plot. The spacecraft frequency didn’t shift in this moment. I was using Space-Track TLE, and this way only nominal orbital Doppler is compensated but not Doppler contributions form the orbit planning. This is different to the preceding post where I was using JPL Horizons data to compensate. Horizons data already comprised the manoeuvre while the TLE do not.
This time we see the absolute efffect of the burn while in the preceding post only deviations from the orbit planning are visible.
Some horizontal traces in the plot are local interference while some very steep traces are interference from LEO satellites.
The second plot shows the manoeuvre in a detail display. I cannot rule out that a fraction of the observed Doppler profile is due to inaccuracies in the TLE and not to the burn.
0066, 18. July 2023, 17:01, #Chandrayaan-3
This morning I was observing Chandrayaan-3 on 2241.6 MHz before its perigee manoeuvre. The signal trace on the spectrogram is compensated for my downlink Doppler using NASA JPL Horizons ephemeride. Compensation was excellent and there obviously was no coherent lock to a groundstation. ISRO announced the burn for a time interval from 14:00 to 15:00 IST. This might correspond to Doppler deviations starting at 8:30 UTC and lasting until 9:10 UTC when I lost the signal because the spacecraft set for my location. I believe the planned burn was already included in the Horizons ephemeris and range rate data.
What we see in the spectrogram may be small deviations from the planning data. The engine may have been controlled in a certain way in real time to achieve the best result for this apogee raising manoeuvre. This control action was likely not included in the Horizons data and resulted in the oberved frequency fluctuations.
It looks all very smooth and ISRO reported a new orbit of 51400 km x 228 km orbit as planned. The next manoeuvre is announced for July 20th and unfortunately the spacecraft won’t be in view of my station then.
I want to mention that ISRO’s public outreach has improved in this mission. They announce milestones and allow publication of orbit data by JPL Horizons. Thanks for sharing this exciting mission with the global public.
Addendum 25. July 2023: More observations of perigee passes suggest that the frequency fluctuations in this plot are not a result of the burn, but rather inconsistencies between JPL Horizons ephemeris data and the real trajectory. Orbit prediction around perigee is notoriously difficult because spacecraft velocity is very high.
0065, 15. July 2023, 06:53, #Chandrayaan-3
Chandrayaan-3 made me get up at an unfriendly time, 03:00 CEST, this morning to catch the first option to see a signal from the spacecraft. Strong signals were visible at 2217.12 MHz and 2284.56 MHz. Both frequencies were used by Chandrayaan-2, the latter one for the lander. I learned about the new frequencies 2203.00 MHz and 2241.60 from Roland @DF3LZ. Roland cites his source, which I don’t have access to.
I am not showing spectrograms because they are a little messy due to the many frequency changes. I hope to record something cleaner in the days ahead.
I didn’t see a signal on the known Chandrayaan-2 frequencies on x-band.
Meanwhile TLE for the geotransfer orbit are available. That makes it convenient to plot the orbit in a satellite-tracking program. The NORAD ID is 57320.
It won’t be possible for me to observe orbital manoeuvres because they will be taking place in perigee which is not visible for me. One planned apogee burn to raise the perigee might be observable but I don’t know the timing.
0064: 14. July 2023, 09:49, #Chandrayaan-2
The Indian Chandrayaan-3 moon lander was successfully launched today. My congratulations to the ISRO team. I was testing my s-band system and was using the moon orbiter Chandrayaan-2 on 2217.12 MHz for this. The spectrogram shows a full orbit with groundstation lock quickly after AOS. The signal is relatively weak and only clearly visible around the Doppler extrema. So, the s-band system works and is ready to acquire the Chandrayaan-3 signal once it becomes visible here.
The Chandrayaan-3 trajectory is on JPL Horizons, although it is a little bit hidden. It is not on the spacecraft list, but can be found by a search. The ID is -158. According to this it should become visible here above the forest around 00:30 UTC. The most likely frequency is 2230.80 MHz.
0063: 25. May 2023, 09:32, #Exomars
Yesterday evening Exomars 16 – TGO emitted a transmission intended to simulate an alien message from the stars. Details of this activity can be found there: https://asignin.space/decode-the-message/
While it is debatable whether something like this is in any way realistic it can create some attention to the work of SETI.
It was indeed a nice opportunity to receive a signal from the spacecraft in Mars orbit with my small x-band antenna. Most times Exomars-TGO is transmitting in a mode without residual carrier. This is efficient because all the transmission power can be used to transport content. However, it makes the signal invisible for small amateur deep space stations like mine. I need a residual carrier to detect the signal and make it visible.
The spectrogram below shows the event. The signal showed up at 18:48 when the spacecraft appeared at the eastern rim of Mars after a far side pass. Along the subsequent near side pass it exhibits some frequency pattern. I believe this is due to some kind of uplink modulation. Estrack Cebreros was supporting the activity. At 20:05the signal disappears because the spacecraft goes behind Mars again and the signal path is blocked by the planet. At 20:45 the signal comes back when the spacecraft shows up from behind Mars again.
A few minutes later the spacecraft changes to a carrierless mode and the signal gets invisible for me.
Of course I cannot decode the digital message that was transmitted. I can only see the carrier. However, in case we saw a carrier signal with such a frequency profile from the stars and we could rule out a terrestial origin or a transmission from a space probe, it would be a proof of an intelligent origin on its own. Such a narrowband signal cannot originate from a natural source we know about. It can only be generated by a technical transmitter. Of course it doesn’t contain any detail information. It only tells ‘we are here and we are smart enough to generate and transmit a radio wave’.
The signal is Doppler compensated using JPL Horizons data. Without compensation the signal trace would mainly show a Doppler profile resulting from its orbital motion and earth rotation. It would probably be invisible too, because the fast Doppler rate makes the FFT less sensitive. I would only see Doppler extrema and nothing in between.
I saw the TGO signal only one time before in this mode and that was some 2 years ago.
The other picture shows TGO’s orbit around Mars as calculated from JPL Horizons ephemerides for the spacecraft and for Mars.
0062: 23. April 2023, 09:38, #Hakuto-R
I continue receiving x-band signals from Hakuto-R while it is still orbiting the moon in an approximately 100 km high orbit. The residual carrier is very weak and it won’t be easy to observe the landing on Tuesday, 16:40 UTC due to the high orbital Doppler rate. Once landed I am pretty confident that I will see the signal, because the Doppler rate will be low on the surface. Hakuto-R’s orbit will probably be similar to the picture below. It is an estimate derived from my earlier observations. This website https://www.unistellar.com/de/blog/observe-hakuto-r-landing/ says Hakuto_R’s landing site will be Atlas crater, marked by the red circle in the picture. It is quite a good match with my orbit estimate.
With my current knowledge of Hakuto’s orbit I think the spacecraft will be approaching from the north. However, there may still be orbital manoeuvres and I will try to refine the estimate on Monday and/or Tuesday.
Moon image from: https://svs.gsfc.nasa.gov/Gallery/moonphase.html
0061: 21. April 2023, 08:40, #Hakuto-R
This morning Hakuto-R’s x-band signal remains visible along the complete orbit. This means that the spacecraft is whizzing around the lunar limb. The picture below shows the currently very slim fresh crescent moon and an illustration of Hakuto’s orbit. It also means that the spacecraft is in a polar orbit. Such visibilty is not possible in an orbit with lower inclination. LRO and Chandrayaan-2 are in similar orbits with different phasing and different altitude. The spacecraft is orbiting over the terminator on the moon. This will probably stay like this and the landing will take place somewhere just a little to the right of the terminator. The terminator will have moved into the lunar disc by then. This way the lander can take advantage of almost the complete 14 earth-days long lunar day. I hope to see signals from the surface for almost 14 days. The lander and its payload are probably not fit to survive the freezing lunar night. Of course, I would love to be proven wrong and to see signals again in the next lunar morning.
During the extrema of the Doppler trace in the spectrogram, the spacecraft is close to the poles. I can’t say which extremum coincides with which pole. The x-band signal became visible for me at 06:00, it locked to a groundstation at 06:30. It unlocked at 09:12 and disappeared a few minutes later. It may come back later today.
Good luck for the landing on Tuesday, April 25, 16:40 UTC.
Moon image from: https://svs.gsfc.nasa.gov/Gallery/moonphase.html
0060: 18. April 2023, 08:34, #Hakuto-R
This morning I detected two subsequent Doppler minima in Hakuto-R’s x-band signal. This allows to determine an orbital period of 7066 seconds, that is 1 hour, 57 minutes, 46 seconds. The corresponding mean altitude is 99.9 km. In both minima the signal was locked to a groundstation.
The spacecraft is scheduled for landing on April 25, 16:40 UTC. The map below shows the visibility of the moon at that time. It will be perfectly visible over Europe and for my station, but not over Japan. It will probably be handled by Estrack Cebreros in Spain. The signal has recently been pretty weak, but there may be a chance to see the signal during the landing sequence.
0059: 15. April 2023, 07:22, #JUICE
I like long term observations. I recorded a spectrogram of JUICE’s first pass after launch over my location in northern Germany. We see two groundstation handovers. The first one may be a handover from New Norcia to Cebreros. The second one then to Malargue. But I didn’t verify that. The frequency profiles are due to uplink Doppler from the groundstations, which was not compensated for. My downlink Doppler is compensated. Without uplink from a groundstation we would see a horizontal signal trace. The short gaps at the beginning (left side) are due to local tests.
Please ignore the legend of the picture, it was not updated for this very new spacecraft yet.
0058: 14. April 2023, 17:39, #JUICE
After the successful launch I detected JUICE’s x-band signal on 8436.05 MHz (at spacecraft) after it rose here over the southeastern horizon. It is a very strong signal with over 40 dBHz SNR in my small 1 m dish antenna. The spectrogram shows rising Doppler due to the groundstation uplink. I am compensating my downlink Doppler.
Congratulations to the ESA team and everyone involved into this exciting project. Thanks to the fabulous JPL Horizons team for providing the pre-launch trajectory to the public.
0057: 10. April 2023, 06:37, #Tianwen-1
I did some long term monitoring of Tianwen-1 in the last days. The two spectrograms show complete Mars passes, which are long theses days, more than 17 hours. We note LOS events on the rising part of the Doppler curves. I am now pretty sure that those are not a result of some groundstation interaction. They are due to occultations by Mars. The spacecraft is going behind the planet and the radio signal is cut. The occultation lasts some 70 minutes. The signal is not always coming back after the occultation. This depends on the spacecraft’s agenda. Those LOS events are in phase with the orbital period of 7h 4min 44s. The occultations will change over time and sooner or later we will see the full orbit again. This was the case for a long time. I was expecting to see occultations sooner or later and now they are there.
It would be interesting to have this confirmed by people with a more quantitative understanding of the Tianwen-1 orbit.
0056:06. April 2023, 06:41, #Hakuto-R
Last night Hakuto-R showed quite some activity and I observed two subsequent Doppler minima. The first one around 20:25 and the following one around 00:25. Still not very precise timings because the station was running in unattended mode. However, I can state with some reasonable certainty that the spacecraft is now in a 4 hours orbit plus/minus a few minutes. This corresponds to a semi major axis of approximately 2953 km. I cannot say since when it is in this orbit.
The second spectrogram shows some groundstation interaction too.
0055: 05. April 2023, 05:49, #Hakuto-R
I observed Hakuto-R last night and saw a few activity intervals. The first started at 21:42 and the last ended at 23:35. Look at the slowly falling signal traces in the spectrograms. They are interrupted a few times. The horizontal traces are local interference. The signal is very weak. When the probe was heading outward it was at least ten times stronger at a comparable distance. Even at SEL2 distance it was stronger than it is now. My observations are not sufficient to determine a precise orbital period. I think it is still in an approximately 8 hours orbit and not much has changed since lunar orbit insertion. The owners ispace aren’t sharing any information about orbital parameters. I hope they will be sharing the timing of the landing, which is announced for later this month.
0054: 03. April 2023, 08:21, #Chang’e-3
Last night the Chang’e-3 lander on the lunar surface in Mare Imbrium was active on x-band again. It followed the usual pattern. It switched on, drifted for 10 minutes and then locked to a groundstation. The slowly falling Doppler profile results from groundstation uplink Doppler.
The moon was not visible over China when Chang’e-3 started up. This activity must have been supported by the groundstation in Zapala, Argentina.
Quite amazing to see that the lander is not only emitting radio signals after more than 9 years on the moon’s surface, but is even actively being supported from Earth.
0053: 25. March 2023, #Hakuto-R
I observed Hakuto-R all day and it showed two downlink sessions. First with Estrack Cebreros and then with Estrack Malargue. Four days after lunar orbital insertion it is quite difficult to evaluate orbital landmarks in the Doppler profiles. I think the spacecraft is in an essentially polar orbit and these days we are looking from a perpendicular direction on the orbital plane. This means that the orbital Doppler profile is shallow and the resulting uplink Doppler profile superimposes. What I read from the curves is that the orbital period is 8 hours or a little less. I think that no orbital manoeuvre or only small manoeuvres were carried out after the lunar orbital insertion four days ago.
In the days ahead, we will increasingly be looking at the edge of the orbital plane and it will become easier to extract orbital parameters from the observations. We will probably observe occultations by the moon as well.
0052: 24. March 2023, 17:57, #Hakuto-R
I let the station on after the periselene pass until moonset around 16:50, which is indicated by LOS on the plot. The spacecraft showed a grounstation handover at 15:00.
Unfortunately, I couldn’t evaluate the second Doppler maximum because it occurred after LOS, but based on the Doppler profile I can estimate an orbital period between 8 hours and 8 h 30 min. This corresponds to a semi major axis between 4687 km and 4880 km. I have no idea whether this is a polar or an equatorial orbit or something in between.
This result is now more than 3 days old, so things may have changed by one or the other manoeuvre.
The Japanese owners ispace are not sharing any significant data. Those are the joys of private spacefare. There is no commitment to public outreach except some marketing propaganda facilitating their commercial interests. Nevertheless, I am pretty sure that most of the budget of such a project comes from the taxpayer in unknown indirect ways. I don’t like the concept, to be honest.
I will carry on observing the thing in order to provide at least a minimum of information to the public.
0051: 21. March 2023, 10:45, #Hakuto-R
Now we have the beautiful Doppler curve of a periselene pass of Hakuto-R. This makes me quite confident that the spacecraft is now in a highly elliptical orbit around the moon. If the prognosis of the first periselene pass at 01:34 UTC this morning by Bill Gray’s ephemerides is correct, it the orbital period may be around 8 hours. This can be determined more precisely after a next Doppler maximum or minimum. Also the semi major axis can be determined then. I won’t be able to observe that today because the moon will set before. Click on the image to see the extrema timing in the legend.
Ispace are still remaining silent.
0050: 21. March 2023, 09:00, #Hakuto-R
Hakuto-R locked to an unknown groundstation at 07:57. None of the Estrack stations showed respective activity. At 08:53:16 I observed a Doppler maximum. This can be an indication of a lunar orbit but is not yet a proof. I will be more convinced when I see a Doppler minimum.
I am now pointing at the moon and I am compensating for my earth rotation Doppler. Bill Gray’s Hakuto ephemerides are no longer available after the prognosed periselene last night. Thanks Bill for giving directions until then.
Ispace are remaining silent so far.
0049: 19. March 2023, 16:57, #Hakuto-R
I think I saw two short activities of Hakuto-R today. It switched on, drifted for a few minutes and switched off. There was no indication of a groundstation lock. First occurrence was around 08:40, second was around 11:35. I cannot rule out that it was local interference but the frequency profile is similar to earlier observations.
None of the Estrack groundstations showed an assignment to Hakuto-R today.The spacecraft was not visible over Japan when those emissions occurred.
0048: 18. March 2023, 11:43, #Hakuto-R
Hakuto-R switched on this morning at 08:55, remained unlocked for a few minutes and locked to Estrack Malargue groundstation indicated by a frequency shift of almost 60 kHz. It remained locked until it set at my location. The Moon is climbing up in elevation these days and my observation window will get longer.
The spacecraft is now about 3° separated from the moon and is about 60.000 km behind the moon. The lunar orbit insertion manoeuvre is announced until end of March but not much (nothing?) is known about intended orbital parameters.
0047: 15. March 2023, 08:24, #Akatsuki
By chance I noticed that the Madrid NASA deep space complex had assigned not less than four antennas to the Japanese Venus orbiter Akatsuki on March 9th. Akatsuki is at a distance of almost 200 million km these days and it is a weak signal for my small 1 m antenna. I decided to monitor the frequency in a slow running plot with 1 minute integration intervals. Akatsuki has a very stable signal frequency and ephemeride data from JPL Horizons is very accurate. This way such long signal integration is feasible with precise Doppler compensation in my receiver.
The patience was rewarded and I saw an almost two hours long downlink signal as shown in the spectrogram below. At the time of the observation the Venus orbiter was in the apoapsis orbital phase. Akatsuki’s orbit is visualized here: https://akatsuki.isas.jaxa.jp/en/gallery/orbit/
Currently the fabulous DSN Now website is not operational. The DSN schedule can nevertheless be found here for Madrid: https://www.mdscc.nasa.gov/index.php/en/mdscc-antennas-weekly-schedule/ and here for Canberra: https://www.cdscc.nasa.gov/Pages/trackingtoday.html
To my knowledge, DSN Goldstone are not publishing their schedules.
0046: 27. January 2023, 08:58, #Hakuto-R
The ongoing observations of Hakuto-R showed the signal with some frequency drift, which is not related to uplink Doppler. I decided to record a long-term spectrogram to get a better view on the situation. The long-term plot reveals a periodic frequency modulation with a period of some 2 h 30 min. This is most likely the result of a spinning spacecraft. Spacecraft often spin for thermal equilibration and axis stabilization. This gives rise to periodic temperature changes that affect the master clock oscillator of the communication system. A frequency amplitude of 100 – 150 Hz can easily be explained this way. The frequency profile is not exactly repeating with the period. This may be due to other thermally relevant activities like activity of the onboard computers, battery charging and others. The signal is not exactly strong these days but will be some 10 dB stronger when the spacecraft arrives at the moon. It will then be an easy target for 1 m class antennas like mine.
0045: 25. January 2023, 16:35, #Hakuto-R
I saw this morning that Estrack New Norcia was tracking Hakuto-R. When the spacecraft rose at my location, the Estrack session was already finished but I decided to have a look nevertheless. Unfortunately, the Hakuto-R trajectory is not public, JPL Horizons is not listing it and the Japanese owners are not publishing it to my knowledge. We know that the spacecraft was launched together with Lunar Flashlight, which is listed on JPL Horizons and is also manoeuvering to the moon on a low energy trajectory.
So, my attempt was to point at LFL and do a spiral search around this direction. However, Hakuto-R’s signal was there when pointing to LFL. Just a minor optimization by pointing 1° above LFL in elevation optimized the signal. It is weak but it is there. I asked other deep space observers to confirm but don’t have a response so far, neither negative nor positive. So, at the moment I cannot rule out a local artifact.
I will keep on observing the spacecraft and I am looking forward to its arrival at the moon and the landing. If you are a deep space observer with x-band capability I would be happy about a notice whether you can confirm or not. If you are from ispace, please consider to publish more detail information about your exceptional project, particularly the trajectory. I am sure JPL Horizons would be more than happy to process your data and publish the ephemeris we amateurs rely on so much.
0044: 21. January 2023, 21:35, #Cat
Our sweet tigers are having a rest.
0043: 17. Jamuary 2023, 09:55, #Tianwen-1
I observed unlocked Tianwen-1 Doppler maxima on 10. January and on 16. January with 21 orbits in between (see image legends). This results in an orbital period of 7h 4min 44.4s. Not a significant change to the earlier value of 7h 4min 31.8s that I determined end of May last year.
0042: 6. January 2023, 08:07, #Chang’e-3
She is alive and fidgeting. The Chang’e-3 moon lander emitted an x-band signal on 8470 MHz for more than an hour last night. It locked to a groundstation after a short drift phase. This device has now been active under the very harsh conditions on the lunar surface for more than nine years since she landed in December 2013. And obviously she is still being operated actively. I hope to see the 10 years anniversary in December this year. Congratulations to the Chinese scientists and engineers who made this remarkably sustainable system.
0041: 12. December 2022, 19:36, #Hakuto-R
The Japanese moon lander Hakuto-R shows a strong x-band signal on 8492.54 MHz after it launched yesterday morning. The plot shows the signal while the spacecraft is in coherent lock with Estrack’s Cebreros groundstation in Spain. I am using the trajectory data from JPL Horizons for Lunar Flashlight, which is on a similar orbit. Specific orbital data for Hakuto-R are not available so far.
My station can also detect Lunar Flashlight but the signal is much weaker.
0040: 3. December 2022, 09:05, #Capstone
I hadn’t heard much about Capstone in its Near Rectilinear Halo Orbit (NRHO). It is not showing up on DSNnow very often and the website of Advanced Space isn’t very informative. So I decided to have a look myself. The thing is active on x-band. I saw two activity phases last night. Each time the same pattern. Roughly 5 minutes showing frequency drift, followed by 42 minutes with a frequency stable signal. Neither DSNnow nor NENnow showed either of those activities, so a different groundstation must have handled it.
Horizons has recently published ephemerides again. I was using those for the detection above.
0039: 1. December 2022, 11:23, #Mars Odyssey
Mars Odyssey was not detectable for me until a few days ago. Whenever I tried, even with good signals indicated at DSNnow, I never succeeded to see the signal. Until a few days ago. Mars is close to opposition and thus only 81 million km away. This results in a strong signal from all Mars orbiting spacecraft and helped to finally detect Mars Odyssey as well.
It also shows why in general it is tricky to see the signal. The x-band transmitter is not very stable. The downlink signal exhibits strong frequency drift. When in coherent lock with a groundstation, the frequency gets disciplined by the uplink signal. The uplink, however, exhibits a frequency ramp for uplink Doppler compensation that again smeares the signal and limits the efficacy of long term signal averaging. The periodicity of the unlocked signal seems to follow the orbital period of roughly 2 hours. It is unclear wht the reason for this periodic drift is. It may be of thermal nature.
Well I am happy I could close this white spot on my list of spacecraft in the Mars domain. Mars opposition will provide more opportunity to observe Mars Odyssey before it disappears into larger distance that makes it invisible for my small antenna setup.
The spectrogram below shows the almost complete pass of Mars last night.
0038: 14. November 2022, 08:56, #CAPSTONE
CAPSTONE performed its Lunar Orbit Insertion Burn into the Near Rectilinear Halo Orbit. I observed the signal along its visibility last night. The downlink was interrupted in between and was not active during the burn itself.
The spectrogram below shows the signal before and after the LOI. I cannot determine the magnitude of the burn with this data. It looks like something has happened and Advanced Space report a successful manoeuvre.
0037: 08. November 2022, 10:43, #Chang’e 3
The Chang’e 3 moon lander was active on x-band again last night. The spacecraft has been sitting on the lunar surface in Mare Imbrium for almost 9 years, and is still emitting x-band signals each lunar day. Typically her emissions on 8470 MHz lasted about an hour. It mostly follows the pattern as shown in the spectrogram below. The signal shows up, drifts for some 10 minutes, locks to a groundstation, remains on for about another 50 minutes and then switches off.
This time it was different . The signal remained active and locked much longer. After unlocking from the groundstation it remained on for more than another two hours. Signal strength went weaker and appeared to be intermittent for a long time , see the second plot for that.
Of course I cannot tell if this observation is an indication for upcoming technical issues in the x-band transmitter. I will keep on listening towards the moon along the rest of this lunar day. The lunar eclipse on 8. November had not yet started during my observation and it is not visible here in Europe. American observers are in the first row seats.
For reference check blog entry 0018 showing the last observation on 16. May 2022.
0036: 25. October 2022, 19:31, #Sun
Northern German weather doesn’t care about interesting astronomical events. So, today’s partial solar eclipse was not visible in the Kiel area due to cloudy sky and rain. Ok, it wasn’t visible optically but I was able to detect it on microwaves. I directed the x-band antenna towards the sun and recorded noise power on 8427 MHz. The plot shows an intensity dip of some -0.5 dB at the time of maximum exclipse at 10:15 UTC. The large fluctuations before the eclipse are due to bad antenna alignment. The fluctuations along the plot are most likely due to thermal noise from clouds and rain showers in between. Given the eclipse magnitude of some 20% we would expect a dip of 0.97 dB. The discrepancy shows that my antenna, just a 1 m dish is far from perfect.
0035: 17. October 2022, 12:32, #LUCY
I tracked LUCY’s x-band signal along today’s complete pass. She emerged from behind the forest in the northeast in the morning and set behind the trees in the northwest. At the beginning we note the handover from a groundstation in Australia to the Madrid groundstation. At the very end of the spectrogram she unlocks from Madrid before setting.
Zooming into the frequency axis reveals the interesting signal pattern resulting from uplink compensation. My station is compensating for downlink Doppler in a continuous way. That means the receiver is adjusted in one second intervals to keep the signal at constant baseband frequency. With a spacecraft emitting a constant frequency this should result in a flat horizontal trace.
In some spacecraft such as LUCY the groundstation compensates uplink Doppler. They aren’t doing it continuously but rather apply stepwise ramping. This results in those nice ornamental signal wobbles. Each ramp creates a new wobble. When the spacecraft culminates at the groundstation location, the Doppler curve inverts its curvature, i.e. the second derivative changes sign. This results in the wave pattern in the middle.
In the last part of the plot I changed from compensating downlink Doppler to compensating for my Earth rotation Doppler only. The rising profile indicates that the escape motion of LUCY is slowing down because she is still feeling Earth gravity. She is still within the Hill sphere.
In the last few minutes I switched back to ephemeris controlled compensation. The spacecraft unlocked from Madrid and set a few minutes later.
It is a very strong signal as LUCY is just some 0.5 million km away after yesterday’s Earth flyby.
0034: 16. October 2022, 10:47, #LUCY
LUCY’s x-band signal as far as I could see it during the low pass this morning. The observation started at a distance of some 80.000 km and ended at 28.000 km when LUCY set here in the south. Signal strength was continuously increasing.
She will come back after the flyby around 21:30 in a northeastern direction at a distance of already 230.000 km and escaping at 5.3 km/s.
Keeping fingers crossed for a flawless manoeuvre.
0033: 15. October 2022, 16:09, #LUCY
I was observing almost the complete pass of LUCY today while she is approaching for an Earth flyby that will accelerate her on her way to the Jupiter trojans. The spectrogram shows the typical signature resulting from uplink Doppler compensation. The signal faded out because I was accidentally using an outdated ephemeris file. In reality the signal should have increased because the distance was decreasing some 585.000 km to 427.000 km.
I won’t be able to observe closest approach tomorrow morning because the spacecraft will be below my horizon. I will see her in a shallow pass in the southwest afterwards and then coming back in the northeast in the afternoon.
At closest approach she will even be inside the ISS orbit. Somebody clean up there from space junk, mega constellations and the like.
0032: 9. October 2022, 09:56, #CAPSTONE
Since yesterday I observe an x-band signal on Capstone’s frequency coming from its direction. The signal shows up each 118 minutes and the trace is about 6 minutes long with rising frequency profile.
The periodicity may be explained by slow spacecraft rotation for thermal equilibration. This may also explain the rising frequency, which can be due to thermal effects in the spacecraft caused by the spin. If the spacecraft frequency was stable I should receive a flat line because my station is compensating for downlink Doppler.
I think the observed pattern is not due to the antenna pattern rotating into and out of my direction. AOS and LOS are too fast for this. I think the signal switches on and off whenever the antenna points to Earth. This can save a lot of power, which may still be somewhat critical on CAPSTONE.
It was recently reported that the uncrontolled tumbling of the spacecraft after an orbital manoeuvre could be stabilized:
0031: 4. October 2022, 17:30, #Sun
Today I pointed the x-band antenna to the sun and did a long term recording of the noise level. I intended to find out if the sun’s x-ray activity as shown by GOES (https://www.swpc.noaa.gov/products/goes-x-ray-flux) correlates with its x-band noise level. Well it certainly does, but the big question is whether my station can detect that. And indeed the M1.6 flare around 13:20 correlates nicely with increased x-band noise at the same time.
It is interesting that the x-band signal exhibts a sharp peak, while it otherwise follows the profile of the GOES x-ray signal. So, this was a moderate M-class flare. X-class flares may show much higher noise outbursts.
X-band microwave signals and x-ray signals are extremely different animals. The x-band wavelength is about 3.5 cm while x-rays measured by GOES are in the nm-range. So there is a ratio in energies of some 1:30.000.000.000. The physical processes of microwave and x-ray generation are completely different.
Today’s GOES plot from https://www.swpc.noaa.gov/products/goes-x-ray-flux
0030: 02. October 2022, 17:12, #MOM
According to news in Indian media the Indian Mars orbiter MOM (Mars Orbiter Mission or Mangalyaan) is no longer operational. The news say that the batteries were drained during a long eclipse in April this year. This means that planet Mars threw its shadow on the spacecraft and the batteries got completely drained. It was likely not possible to recharge the batteries and realign the spacecraft after the eclipse. It is not uncommon that batteries fail ofter long lasting deep discharge.
MOM was launched on 5. November 2013 and entered Martian orbit on 24. September 2014.
I was observing the mission from launch to its end this year. The last time I observed and recorded the s-band signal on 2292.96 MHz was on 29. March 2022. It is probably one of the last emissions by the spacecraft before the orbital eclipse and battery failure. The spectrogram is shown below:
For a long period of time the spacecraft was emitting daily 10 minutes long beacon signals. This was taking place almost each day in the Indian afternoon. An example of the beacon beeps is shown below:
I observed ground station interactions with MOM in rare occasions. Here is the last observation of this kind on 8. March 2022:
MOM was designed for an initial lifetime of 6 months in Martian orbit. The total lifetime of more than 8 years is a really remarkable result and success. I will be missing this deep space s-band beacon. To my knowledge there is currently no other s-band source in interplanetary space.
All my observation were perfomed with my amateur deep space station using a 1 m parabolic dish.
ISRO is still to officially confirm the decommissioning and details.
0029: 05. August 2022, 10:11, #KPLO
KPLO was successfully launched last night and is now on the way on a long trajectory to the moon. The spacecraft is currently heading in direction of SEL1 and is expected to arrive in lunbar orbit in December.
I detected its s-band signal on 2260.8 MHz at a distance of roughly 110.000 km. It is a strong signal in my RHCP antenna, although there are rumours its signal might be LHCP. The plot shows the spectrogram with Doppler compensation based on published Horizons ephemerides at the left part. At 09:00 I switched to earth rotation compensation for my station to show the geocentric Doppler. There we see rising Doppler as is expected for a spacecaft climbing up in earth’s gravitational field and thus slowing down its upward movement.
It is not clear why the Horizon’s compensation shows a falling frequency. It is expected to be a horizontal line. NASA DSN 54 in Madrid is not showing a coherent lock so far, only downlink is indicated.
The signal exhibits some short term frequency jitter.
0028: 10. July 2022, 15:32, #CAPSTONE
CAPSTONE continues its cruise out in direction of SEL1. This recording is Doppler compensated for Earth rotation. The rising signal trace indicates that at the distance of roughly 681.000 km the pull of earth’s gravity still slows down the outbound movement. The little kinks on the left side rersults from swiching off the station related Doppler compensation and changing to earth rotation. The very small wobbles in the trace are a result of the piecewise uplink ramping for uplink Doppler compensation.
0027: 9. July 2022, 20:10, #CAPSTONE
I need to correct my statements on the CAPSTONE manoeuvre below: Obviously, the Doppler shift was to some degree a result of the JPL Horizons ephemeris data I was using for Doppler compensation. The ephemeris data contained the planned trajectory correction manoeuvre. What the plot shows is the inverse of the manoeuvre that didn’t occurr this way.
However, things remain a little mysterious. The initial, about 1 minute long rapid Doppler shift can not be explained by the JPL Horizons based Doppler compensation. I am using 10 minute steps in the ephemeris file. This means such a rapid shift is not resolved by the correction method. So far, I don’t have an explanation for this.
The initial 1 min long steep shift seems to be a real signal, while the rest is probably an artifact.
What I learn from this? I will only compensate for earth rotation in future. This is anyway the major component in such signals and it is based on a purely local calculation without unknowns.
0026: 9. July 2022, 16:22, #CAPSTONE
A very nice recording of CAPSTONE’s second trajectory correction manoeuvre (TCM2). This time the downlink signal remained active and it shows the dynamics of the manoeuvre very nicely. Indeed the best manoeuvre recording I achieved so far.
The burn starts exactly 15:30 as announced by Advance Space. It starts at high thrust and gets throttled to much lower thrust after 1 minute. The total frequency shift is +126 Hz at the end, which corresponds to decrease in range rate of 4.5 m/s for my station.
So, this time it was a braking manoeuvre. I think, this is the reason why the signal remained visible this time. It was not needed to turn the spacecraft around for braking, while this was required for speeding up two days ago.
0025: 7. July 2022, 16:33, #CAPSTONE
CAPSTONE performed its first trajectory manoeuvre this afternoon. The signal disappeared 15:15 and came back with a frequency shift of -559 Hz at 15:58. This corresponds to an increase in range rate from my station of 19.8 m/s. The absolute magnitude ∆v is larger but cannot be determined by a simple Doppler measurement.
Congratulations to the successful manoeuvre!
0024: 7. July 2022, 12:13, #CAPSTONE
Capstone shows a 10 dB weaker residual carrier for some 11 minutes. Whatever this may mean …?
0023: 7. July 2022, 08:51, #CAPSTONE
I observed the handover from a Canberra groundstation (left part) to Madrid’s DSS 53 (right part) this morning. In between roughly 15 minutes of unlocked operation, as indicated by the frequncy shift. JPL Horizons ephemerides are on spot and also provide excellent Doppler match. Advanced Space are planning a trajectory correction burn at 15:30 today. If I still see the signal I will provide a Youtube stream that could show the Doppler pattern during the burn.
The unlocked part of the signal trace with high frequency resolution. It is perfectly flat.
Downlink signal when locked first to Canberra and then to Madrid. We recognize small frequency wobbles with a period of roughly 10 minutes. Those result from the stepwise frequency ramping on the uplink of the groundstation. This is done in order to compensate for uplink Doppler and keep the uplink frequency constant for the spacecraft receiver and speak to the spacecraft at the sweet frequency spot of the coherent transponder. Downside of this procedure is, that it is no longer possible to determine the location of the groundstation in case it is unknown.
Only NASA DSN is applying this uplink compensation. Neither ESA’s Estrack nor China’s groundstations are doing that.
Also note that the wobbles reverse their second derivative after the handover. This results from the fact that the Doppler profile reverses the second derivative before and after culmination during a pass for a certain location.
0022: 6. July 2022, 20:15, #CAPSTONE
The station was tracking CAPSTONE in unattended mode using the freshly updated ephemerides on JPL Horizons. The spectrogram shows the signal coming up around 15:30. It may have been present earlier as well. It shows some intensity fluctuations and gets much weaker after 16:10. We see a flat line, which indicates a very good Doppler match. So the signal is very likely being emitted by Capstone.
Later I optimzed the antenna pointing and we see a strong and stable signal until the spacecraft sets behind the local forest.
0021: 4. July 2022, #CAPSTONE
CAPSTONE was separated from the stack with Photon and I detected the signal on 8465 MHz. It showed pronounced intensity fluctuations in the beginning but stabilized later. It was in contact with DSN Madrid to the DSS 54 and DSS 55 antennas.
Available TLE and the JPL Horizons ephemerides were completely off, so I used the directions the Madrid antennas were pointing to, to calculate my antenna pointing. It is now possible to track for a while using celestial coordinates. This will get even better as the spacecraft is going further out and the movement relative to the celestial background will slow down.
Nevertheless, the celestial coordinates will need to be updated each day at least to find the thing with even a small antenna. DSS antenna pointing can be used for that. The trajectory may also be available on JPL Horizons sooner or later.
Update: I have to add that the Doppler profile is not correct, because Doppler compensation was on with wrong TLE by accident. It definitly is the CAPSTONE signal though.
0020: 19. June 2022, #BepiColombo
We are getting closer to BepiColombo’s second Mercury flyby on Thursday, June 23rd, 09:44 UTC (https://twitter.com/ESA_Bepi/status/1537370692336898048).
The signal is coming from a distance of some 130 million km these days. It is weak but can be detected in my station. The flyby will be perfectly visible from Europe. The plot shows the signal unlocked for 20 minutes. The spacecraft then locked to Estrack Malargue groundstation thus showing falling uplink Doppler. ESA groundstations don’t compensate for uplink Doppler. The spacecraft will become very fast during the flyby and the then very fast Doppler may make the signal undetectable. I hope BepiColombo’s emission will be cranked up a little. We know from DDOR sessions that it can be at least 10 dB stronger than now. That would be very helpful.
Anyway good luck to the team for the flyby. The thing will be whizzing across the surface at an altitude of only 200 km. Don’t take the wrong turn at that crossing!
If I can detect the signal on Thursday morning I will launch a Youtube stream showing my receiver signal. You can check the DF2MZ channel.
0019: 22. May 2022, 15:30, #BepiColombo
Some fun with BepiColombo. I observed the DDOR session with Cebreros and Malargue. The track starts with the spacecraft in an unlocked low power mode. At 10:53 the power increases by 10 dB. The trace with Earth rotation Doppler compensation only represents the geocentric motion of the spacecraft. The DDOR mode ends at 12:00 and the spacecraft returns to the unlocked low power mode. Later I observed a coherent lock to Malargue groundstation. This is detectable because Estrack groundstations do not compensate for uplink Doppler and the signal trace shows falling Doppler in the coherent mode.
0018: 16. May 2022, 08:13, #Chang’e-3
This morning’s total lunar eclipse couldn’t be observed completely at my location in northern Germany. Here is a picture from the antenna camera shortly before moonset. There are tons of much better pictures in the web, but I have a goodie. See below:
The x-band station was monitoring the usual Chang’e-3 frequency 8470 MHz and sometimes wishes come true. I was not exactly expecting but hoping for a signal from the lunar surface along with the eclipse. And Chang’e-3 did me the favour. She switched on the transmitter at 00:11, the signal drifted for 9 minutes and then locked to a groundstation. That is the usual pattern. The moon wasn’t visible over China at that time, so it was probably the Chinese groundstation in Zapala/Argentina. The fainter, slowly rising signal trace is a local interference.
The signal remained active until 02:39, that is much longer than usual. Typically I see the Chang’e-3 lander signal for some 50 – 60 minutes in the days after lunar sunrise in Mare Imbrium. The cutoff of the signal at 02:39 obviously happened when the eclipse umbra touched the Chang’e-3 location on the moon. The moon picture above was taken 10 minutes after loss of signal. The Chang’e-3 lander location is at the upper part of the umbral terminator in the picture.
Obviously the lander was activated to observe the lunar eclipse from the lunar surface. Of course this had to come to an end when the umbra touched the landing site. After 8.5 years the lander’s batteries are certainly dead and she has a nuclear heater but not a nuclear electric power supply.
A lunar eclipse observed from the lunar surface must be a spectacular view. I hope we will see pictures of that.
It would be interesting if the signal came back after the eclipse. Observers in the Americas would have had perfect conditions to observe the complete activity.
0017: 13. May 2022, 19:25, #Geomagnetometer
I am quite happy with the progress on the new software for the SAM III geomagnetometer. Data acquisition from the controller seems to be robust now. The GUI is improving, but still in debugging mode. Automatic FTP upload to the website has been proven to work. It is not active yet. I am planning to provide a 1 hour short term display and a 24 hour long term display. I find it amazing to observe the tiny fluctuations of this planet wide huge magnetic field that is surrounding us and that is affected by solar activity.
0016: 12. May 2022, 15:29, #Geomagnetometer
I decided to take the SAM III geomagnetometer to a presumably magnetically more quiet place in the house. The picture shows the styrofoam thermal insulation box. Thermal insulation is very important because the fluxgate sensors are very temperature sensitive and the daily temperature pattern would obscure weak to medium magnetic signals.
Here is the open box with some 20 kg of sand inside. While the box alone reduces the thermal signal by a factor 4, the sand load makes it practically disappear. The sand establishes a large heat capacity. So the remaining thermal leak of the box must warm/cool the sand.
The traditional way to thermally insulate a geomagnetometer is to bury it in the garden. This way there is a huge thermal load outside the box. In my approach I put the thermal load inside the box. Now to see to what degree magnetic disturbancies from inside the house will compromise the system. In case the interference is too high I am still considering to bury the box. Particularly for system testing it very convenient to have it in house.
The sensor platform with three mutually perpendicular fluxgate sensors. There is quite a load of sand under the platform.
North alignment of the geomagnetometer. I am aligning it to magnetic north instead of true north because any magnetic aberration inside the house is unknown. Now to pack the sand in, put the lid on and connect the controller.
I am also putting together custom software for the thing. It looks a little messy in the current debugging mode. When it is finished it will be looking cleaner (are projects like this ever finished?) and it will continuously record the geomagnetic field, archive data and upload a plot in 5 minute intervals to the website. Go ahead solar cycle 25!
0015: 09. May 2022, 14:00, #Equipment
My latest toy is a FLIR E60BX thermal camera. The bright dot on top is today’s half moon. The camera measures about +20 °C on the moon, but this is an average with a few pixels of cold sky around the moon. The cold sky is -33 °C in the crosshair. Pointing to zenith the temperature is below the camera’s lower limit of -40 °C.
The main application of this camera is examining electronic circuitry for thermal issues.
The camera takes a visual image together with each thermal image. I find it quite remarkable that the moon shows a much higher contrast in the thermal picture above.
0014: 07. May 2022, 15:58, #Chang’e-5
Chang’e-5 must have been in a coherent groundstation link. Telemetry sidebands are visible +/- 8 kHz from the carrier. The signal showed slow intensity fluctuations after unlock. I hadn’t seen this in the current lunar orbit before. The other frequency is weakly detectable too.
The antenna is pointing to Chang’e-5 after she passed earth-moon Lagrange point 2 (EML2) and is moving further west.
0013: 03. May 2022, 20:27, #Chang’e-5
Chang’e-5 on her way to EML2 behind the moon.
The antenna is pointing to Chang’e-5 and a nice young crescent moon.
0012: 2. May 2022, 09:15, #Tianwen-1
A very nice plot of Tianwen-1 showing the Doppler maximum and minimum before and after the periapsis pass. The spacecraft was in a groundstation lock during the maximum. It unlocked around 08:20 and showed an unlocked minimum after periapsis.
From today’s and yesterday’s maxima, with 3 orbits in between, I calculate an orbital period of 7h 4min 49s, that is 11s longer than the period I calculated a few months ago. However, there is some uncertainty due to the coherent lock, which may add some phase shift to the Doppler curve. Orbit determination can be more accurate from unlocked signals, provided the spacecraft has a stable enough master oscillator. This seems to be the case in Tianwen-1.
0011: 1. May 2022, 15:09, #Chang’e-5
Chang’e-5 this afternoon. She is heading to the far side of the moon for an encounter with EML2. There is no groundstation activity and we note the notorious frequency jitter of this signal. Frequency was compensated for eart rotation Doppler of my station.
0010: 1. May 2022, 11:15, #Tianwen-1
I caught a Doppler maximum of Tianwen-1 while it was locked to a groundstation, probably Zapala in Argentina. Now to catch tomorrow’s maximum some 3 hours earlier in the day to calculate a new orbital period.
0009: 30. April 2022, 14:00, #Tianwen-1
Tianwen-1 shows a strong signal. First unlocked and at 08:48 it locks to a groundstation. Mars is not visible over China, so Zapala in Argentina must be at the helm.
0008: 28. April 2022, 19:45, #Cat
It was about time to introduce fabulous Space Cat to the new timeline.
0007: 28. April 2022, 14:44, #Chang’e-5
Chang’e-5 is passing the L1 libration point between Moon and Earth. The signal on 8486.28 MHz is strong, the other frequency 8471.23 MHz is no longer detectable for me. Earth rotation Doppler compensation was activated at 13:12.
0006: 28.April 2022, 12:00, #MOM
No signal from MOM received this morning.
0005: 27. April 2022, 12:40, #Osiris-Rex
I caught Osiris-Rex’ signal while it was still unlocked and showed some drift. It locked to Madrid’s DSS 54 at 11:04. Madrid is obviously emitting Doppler compensated uplink, otherwise we would see falling Doppler rate. At 12:35 the signal faded out for me. It came back for DSS 54, but some 35 dB weaker which is not detectable for me.
The NASA Eyes simulation shows the spacecraft between the solar orbits of Mars and Earth. The current range rate to Earth is some -10 km/s. The probe is expected to drop a material sample it collected from asteroid Bennu in September 2023. Still some way to the next Whiskey bar.
0004: 26. April 2022, 14:15, #BepiColombo
BepiColombo showed a strong x-band signal coherently locked to Estrack Cebreros groundstation when I started observing at 12:42. It unlocked at 13:28 and the signal faded out after 14:00. I am not sure why the signal faded away slowly. Typically spacecraft just switch off. Maybe it was realigning with the high gain antenna still transmitting.
The ESA simulation ( https://sci.esa.int/web/bepicolombo/-/48871-getting-to-mercury ) shows the spacecraft is currently quite close to Earth, only 48 million km away. It is heading for another close encounter with Mercury, I think it will be in July.
0003: 26. April 2022, 11:17, #Chang’e-5
Chang’e-5 on 8486.28 MHz. The other frequency is detectable, but much weaker. Earth rotation Doppler compensation was activated at 09:10. See Bill Gray’s https://projectpluto.com/sat_eph.htm for ephemerides. Use NORAD number 47097 for Chang’e-5.
0002: 26. April 2022, 08:50, #MOM
Again no signal from the Indian Mars orbiter MOM received this morning.
0001: 26. April 2022, 08:30
My antennas for deep space monitoring and the VHF/UHF amateur radio bands.