Starlink Galore! [UPDATED]

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Last week was dominated by impressive - if worrying - displays of SpaceX Starlink satellites. Over several nights, objects from the 18 March 2020 launch (Starlink 5) made impressive passes in the sky. And on April 22, there was a new launch, Starlink 6, that could be well observed in the evening of the 22nd and 23rd, causing an impressive satellite 'train' on April 23.

In this blogpost I provide photographs, video, and descriptions.

The new launch on April 22 (Starlink 6)

On 22 April 2020 at 19:30 UT, SpaceX launched the 7th Starlink batch of 60 satellites, Starlink 6, from SLC 39A on Cape Canaveral. Some 23 minutes later, the newly launched objects made a pass over the Netherlands, in a blue twilight sky, and were well visible.

Just some seven minutes prior to this pass, and 15 minutes after launch, the payloads had been deployed from the Falcon 9 Upper Stage while the latter was over the Northern Atlantic.

With the naked eye, the Falcon 9, the just released satellites and the associated debris objects all looked like one bright object (mag 0 to -1) crossing the sky. In binoculars, they could be separated into multiple objects.

The photograph below is a stack of 12 photographs, 2.5 seconds exposed each with a Canon EOS 80D and EF 2.0/35 mm lens at F2.2, 400 ISO, showing it pass over my house in Leiden.

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In 10 x 50 binoculars, the view was spectacular. It consisted of a bright object (the Falcon 9 upper stage), slightly separated from another, elongated bright object (the clump of released satellites), and four fainter flashing objects surrounding them in a paralellogram shape. These were the four tumbling retaining rods that had held the satellite stack together before deployment.

Some of this is visible in this video I shot with the WATEC 902H and FD 1.8/50 mm lens. Falcon 9 and payloads still appear merged as one object here, but the retention rods are visible as separate objects:




The provisional orbit that I had calculated prior to the launch turned out to be quite good: the objects were only 28 seconds early on predictions and less than 0.5 degrees off-track at culmination.

The next night, April 23, saw a twilight pass of the satellites again, that by now had developed into a clear 'train' of objects. They were not as bright as in May 2019 with Starlink 0.1, but in 10 x 50 binoculars the moving string of 60 lights, some 10-15 degrees long, was impressive. While low in the west, in Orion, they briefly became bright and clearly visible to the naked eye for a few seconds, then they grew fainter and I turned to my binoculars to observe them.

My WATEC 902H video camera, this time equipped with a Canon EF 2.0/35 mm lens, captured the train passing in Hydra. The video gives a good impression of the view as it was visible in binoculars:




The next day, April 24, I also filmed the 'train'. This was a low pass (21 degrees maximum elevation) in twilight, at rooftop level, shot from the loft window of my home. Video withe the WATEC 902H and a 1.8/50 mm lens:

Starlink 5 passes, April 19-21

Earlier that week, we were treated on some spectacular, if eerie and worrying, displays of Starlink satellites from the previous launch, the Starlink 5 launch on 18 March.

(worrying, because of the implied impact on the night sky)

A month after launch, the objects from this launch are dispersing as they one-by-one are lifted to a higher orbit, but mid-April there was still a recognizable main group that took about 20 minutes to pass. When passing south of the zenith they are bright (but faint when passing north of the zenith, due to satellite orientation and sun-satellite-observer angles), on the first few passes even very bright (up to magnitude +0.5 for almost a full pass).

At any given moment during the pass of this group, there were 5-8 bright satellites moving in the sky at the same time, following each other in file, typically some 20 degrees apart. It was a very eerie sight reminiscent of a Science Fiction Movie: almost like the Mothership had unloaded the invasion fleet into earth orbit! The long duration, 20 minutes that satelite after satellite after satellite appeared in file, made it very impressive.

Here is a single photographic image from 19 April, showing 4 Starlink satellites traversing the sky (the fainter one that is somewhat off-set is already rasing its orbit). It is a 5 second exposure with an EF 2.0/35 mm lens on a Canon EOS 80D:

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Below is a stack of 202 images from 21 April, showing 39 Starlink satellites that appeared over a 20-minute period. Note how the trails become fainter when located more north (image is looking west, so north is at the righthand side of the image). Also note the two flaring satellites:

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Here are single images showing the two flaring satellites, Starlink- 1274 and Starlink-1309, flaring close to Pollux:

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I used the 202 photographs, shot over a 19-minute period,  to create this time-lapse movie showing the steady stream of satellites:




This is another time-lapse video, from images from the deep-twilight pass of the previous night, 20 April:



Below are three more stacks of photographic images from April 19 and April 20 (the gaps in the trails are the brief moments between two consecutive photographs, hence the dashed appearance of the trails):

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Starlink "train" photographed from the International Space Station

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The image above (image ISS062-E-148365, original at high resolution here) was shot from the International Space Station (ISS) on 13 April 2020, 21:25:02 UT. It shows the Aurora Australis (southern lights) and a train of SpaceX Starlink satellites.

The presence of the Starlink train in this image was first noted by Twitter user Riccardo Rossi (@RikyUnreal) and brought to my attention by Huub Eggen (@phi48). It is present in two earlier images as well, taken the preceeding minute (images ISS062-E-148363 and ISS062-E-148364).

ISS was at 48.25 S, 81.03 E and 440 km altitude at the time the photo above was taken. With this information, I came to the following probable satellite ID's (annotations in image below) for the objects in the imaged "train": these are all objects from the 17 February 2020 launch ("Starlink 4").

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Numbers: the SpaceX Starlink constellation in perspective with what is currently orbiting earth

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The image above was taken by me in the evening of May 28 with a Canon EOS 60D and Samyang 1.4/85 mm lens. It shows a part of the now already dispersing "train" of SpaceX Starlink objects. They briefly flared, one by one, while passing north of Corona Borealis.

In this post, I want to put in perspective what adding 12000 Starlink objects to the current population of satellites orbiting Earth means.

Quite some numbers are floating about in articles and on internet, concerning current numbers of objects orbiting Earth. I made a tally this morning, including both classified and unclassified objects. Datasources were the database of classified objects maintained by Mike McCants; CSpOC's satellite catalogue for all unclassified objects; and the UCS Satellite database for the number of operational satellites. Numbers given in the diagrams in this post are rounded numbers.

A number of  "44000" is floating around the internet regarding the number of objects orbiting earth currently. This figure is wrong: CSpOC is tracking some 23000 objects of which some 18000 are well-tracked and can be indentified as to origin. This excludes, of course, objects that are not well-tracked, or are not tracked at all (e.g. because they are very small), the exact number of which is unknown. In the remainder of this post, we will restrict us to the ones that are known. These are generally objects larger than 10 cm.

In addition, our amateur network tracks some 300 additional "classified" objects.

The "44000" figure comes from the fact that the catalogue numbers (the unique identifiers given to each object) have now added up to 44306 entries: however, this concerns all objects catalogued since 1957, including many objects that have since re-entered into the atmosphere.

So the correct number to go with for objects currently in orbit around Earth and well-tracked, is slightly over 18300 objects.

Of these 18300, about 5500 are payloads, both operational and defunct. The UCS database currently lists some 2000 operational payloads, leaving 3500 defunct payloads.

In addition to operational and defunct payloads, there are some 2000 spent rocket boosters orbiting our planet. The remainder, almost 11000 objects, concerns other space debris (including sometimes very small objects, only detectable by radar).

Here I have visualized these basic data in the form of a pie-diagram:

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So, in perspective to these numbers for the current population of Earth-orbiting objects, what will be the result of the addition of  the 12000 planned objects in the Starlink constellation? How does their number compare to the other objects?

In the pie diagram below, you can see that adding 12000 Starlink objects would mean they would represent about one third of all objects orbiting Earth:

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In the diagram, I have lumped payloads and rocket stages as these generally represent larger objects, and put the rest into "other debris". The latter category includes very small objects, fragments from exploded rocket stages and disintegrated satellites. The diagram includes objects in geostationary orbit.

Starlink will operate in Low Earth Orbit. Musk's plan is to launch 1600 satellites to an operational altitude of 550 km; another 2800 to an operational altitude of 1150 km; and a whopping 7500 to an operational altitude of 340 km.

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When we only count objects with a perigee below 1150 km, the topmost orbital altitude shell of the proposed Starlink constellation, there are currently some 13800 objects orbiting up to these altitudes. Adding 12000 Starlink objects would almost double the population total.

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When we only count objects with a perigee below 550 km, which includes the lower and middle of the three orbital altitude shells of the proposed constellation, some 2900 objects are currently orbiting up to these altitudes. Adding almost 9100 Starlink objects (the sum of the lower and middle shell objects), would mean that about three quarter of the resulting population would be Starlink satellites (!).

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In other words: the amount of objects added by Starlink, compared to the current population of objects, is certainly significant, especially where it concerns the lower parts of Low Earth Orbit.

Below 550 km, the population would increase to four times as much as currently - and this includes all very small debris pieces that can only be observed by radar in the tally. If we restrict the comparison to the larger objects, it means an at least five times increase in object number. That is truely significant.

With these massive additions by just one company, the question arises whether some kind of regulation is in order, e.g. through the UN. If not, we allow one company to, basically, take over and massively dominate Low Earth Orbit. There are all kinds of ramifications: like, will current Space Tracking Networks be able to deal with the increased detection load on their networks? (if not, space will become less safe).  What will this do to our night sky? Etcetera.

(with regard as to what might be the effect to our night sky, I refer to this twitter tread by Cees Bassa, who has cracked some numbers as to visibility)

It seems to me that the World, the international community as a whole instead of one US corporation,  should have some say into this. I am otherwise a fan of Elon Musk, who undoubtedly has given space exploration and space technology a new impetus and good shake-up: but concerning Starlink, this all seems not well thought out to me.

The Starlink "train" on 28 May 2019. Click to enlarge

WOWOWOW!!!! A SPECTACULAR view of the SpaceX Starlink satellite train!

On 24 May 2019 at 2:30 UT, SpaceX launched STARLINK, a series of 60 satellites that is the first launch of many that will create a large constellation of satellites meant to provide global internet access.

Just short of a day after the launch, near 22:55 UT on May 24, this resulted in a spectacular view over NW Europe, when a "train" of bright satellites, all moving close together in a line, moved across the sky. It rained UFO reports as a result, and the press picked it up as well.

There were no orbital elements for the objects available yet on Space-Track, but based on the orbital information (53 degree inclination, initially 440 km orbital altitude) I had calculated a search orbit and stood ready with my camera.

My search orbit turned out to be not too bad: very close in sky track, and with the objects passing some 3 minutes early on the predictions. And what a SPECTACULAR view it was!

It started with two faint, flashing objects moving into the field of view. Then, a few tens of seconds later, my jaw dropped as the "train" entered the field of view. I could not help shouting "OAAAAAH!!!!" (followed by a few expletives...).

Here is the video I shot, be prepared to be mind-blown!



The video was shot, in a partly clouded sky, with a WATEC 902H low-light-level surveillance camera, equipped with a Canon FD 1.8/50 mm lens. I could count at least 56 objects in the original video.

Over the coming days the "train" of objects will be making 2-3 passes each night. As they are actively manoeuvering with their ion thrusters, they will be more spread out with each pass, so the "train" will probably quickly dissipate.

The objects were launched into a ~440 km altitude, 53 degree inclined orbit. Using their ion thrusters, they will raise their orbits to ~550 km the coming days/weeks.

STARMAN (Falcon Heavy/Tesla Roadster) 2018-017A imaged in Space

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The image series above shows the Falcon Heavy upper stage 2018-017A, with the Tesla Roadster of Elon Musk and STARMAN attached to it, coasting through interplanetary space towards the orbit of Mars.

At the time these images were taken, 16:39-16:50 UT on 8 February 2018, it was well beyond the moon, at a distance of 550 000 km or about 1.4 Lunar distances c.q. 0.0037 AU. The images are 30-second exposures taken by Peter Starr and me with the 0.43-m F6.8 remote robottic telescope of Dubbo Observatory in Australia

I also created an animated GIF of these images:

The @SpaceX #FalconHeavy / #Starman /#Tesla Roadster imaged yesterday 8 Feb 2018, 16:29-16:50 GMT, by Peter Starr and me using the 0.43-m telescope of Dubbo Obs., Australia. From four 30s exposure CCD images.
Dsitance at that moment 550 000 km or 1.4 Lunar Distances@elonmusk pic.twitter.com/FHKe3mjgJc

— Dr Marco Langbroek (@Marco_Langbroek) 9 februari 2018

These 4 images are part of a lerger seies of images taken from Dubbo and from Q65 Warrumbungle, and they show a clear, slow brightness variation of +- 2 magnitudes between ~+14.6 and +16.6, with a period of perhaps approximately 4m 42s (the dataseries is not very detailed, so the real periodicty might be off from this estimate).

While I did image objects in trans-Lunar orbit before, this is the first time I imaged something on an outbound true interplanetary trajectory.

The trajectory and ephemerids are available on JPL HORIZONS. An early orbit integration I made yesterday before orbit updates from telescopic observations became available, suggests 2018-017A will be close to earth again in 2073. I did not have time yet to redo the integration now telescopic observations are improving the orbit, but will do so later. So stay tuned.

[UPDATE: based on the (thanks to observations like these!) improved orbit, the 2073 close encounter that the initial orbit suggested, is no longer on the table.]

Safe travels, Starman! 

 UPDATE 2: I am quoted in this CNN article, which also features some of my imagery.

image: SpaceX

There's a Starman Waiting in the Sky

image: SpaceX

This is the freakiest, most surrealistic image related to Space I have ever seen.

On February 6/7, as part of the Maiden Flight of the SpaceX Falcon Heavy, a Tesla Roadster with a dummy called Starman behind the wheel (and various other references to pop-culture tucked in the car) has been orbiting Earth in a 180 x 6950 km orbit for 6 hours, after which it was boosted into a heliocentric Apollo orbit with aphelion near the orbit of Mars.

Yep, that's right: a car in space! That is something beyond my wildest dreams.

Image: M. Langbroek

Above is the  ground track of the slightly under 6 hours earth orbit. Launch was at 20:45 UT (6 February) from pad 39A at Cape Canaveral; SECO 2 was over Africa 28m 52s later, boosting it into a 180x 6950 km, 29 degree inclined elliptical coasting orbit. After just under two orbital revolutions, a third and final boost sent it into heliocentric orbit. The boost was widely observed from the US West Coast (see for example this hefty 256 Mb movie shot by Derek Breit in Morgan Hill, California).

The heliocentric orbit is below. It has perihelion at 0.98 AU, aphelion at 1.67 AU and an orbital inclination of 1.05 degrees. The orbital period is 1.53 year. If this was an asteroid instead of a rocket stage and a car, we would call it an Apollo orbit.

image: M. Langbroek

The aphelion distance of the orbit is similar to the aphelion of Mars, but located near the perihelion of Mars.

The rocket stage and car will periodically come back to Earth's orbit. Near 27 January 2073, the rocket stage and car might make an actual close approach to Earth. My current orbit integration with MERCURY 6 has it passing at a nominal distance of ~0.004 AU or ~1.6 Lunar distances, and likely will be in reach of telescopes on Earth then. [EDIT 15 Feb 2018: after new orbit updates based on optical observations, the 2073 close approach is off the table]. The real distance might be more (or less) as the current orbit probably isn't very accurate (SpaceX earlier presented an orbit that was dead wrong) and the object(s), being of low area-to-mass ratio and shiny, moreover will be strongly influenced by Solar Radiation Pressure, which will perturb the orbit and is difficult to model over a 55 year timespan.

A  less close approach (nominal values in the order of 9 Lunar distances) will happen in March 2137. Close approaches to Mars will not happen over the next three centuries.

image: SpaceX

image: SpaceX

image: SpaceX

To me, this was the most exciting launch since I watched the first Shuttle launch on tv when I was a teenager. That big Falcon Heavy roaring into the sky was very impressive. Even more impressive was the synchonous return of both side boosters, landing smoothly and brotherly next to each other. The core booster alas did not fare that well, and smashed to bits in sea.

And then there were those surreal images of the Tesla orbiting earth, with "Starman" at the steering wheel. I reckon these will be iconic images for a very long time.

The whole idea of launching a car into orbit is crazy of course, and it has drawn critique from some people. I do not share that critique. This is one of the daring, crazy, whimsical things that is so characteristic of humanity, and it fits iconic moments in exploration. The World needs people who are a bit crazy, in a good way. Otherwise it would remain dull and boring, with very little progress.

Say what you want of Elon Musk, and of course this is primarily a publicity stunt (and brilliant marketing), but it appears Elon Musk is giving the human space program a real boost of the kind we haven't seen in a long time. After this stunt, I for the first time in my life get the feeling that I might really see humans walk on Mars in my lifetime. After all, if we can send a Tesla Roadster towards the orbit of Mars, we can send more. To my mind, this was absolutely awesome!

UPDATE: see more in my follow-up post here with my telescopic imagery of the Falcon Heavy/Tesla Roadster in Space!

And I am quotes (and some of my imagery features) in this article on the CNN website.