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This evening I got my first view of #DarkSat, the @SpaceX #Starlink satellite with a special coating to make it less bright in the night sky. The combined image below shows that #DarkSat is not much fainter than some of the other #Starlink satellites... What is going on here? 1/n
This image shows the maximum pixel value of 18 individual exposures of 10 seconds each, taken at 1 minute intervals. Each individual image exposure contains a #Starlink satellite; they just happened to be separated in time by roughly a minute. Predicted positions are overlaid.
The exposures were taken between 17:28:25UTC to 17:45:25UTC from the Netherlands. #Starlink satellite 44928 was first to appear, and each next satellite was slightly higher in elevation as the orbital plane rose in the sky with time. Elevation runs vertically in this image.
The satellites at higher elevation are also closer: 1519 km for the first (object 44928) to 1276 km for the last (44925). #DarkSat, which is supposed to be object 44932 was at a distance of 1478 km. Hence, the higher satellites are brighter because they are closer.
It appears #DarkSat was about as bright, maybe slightly fainter, than the other satellites at comparable distances (44915 and 44928). Assuming that the satellite orientation is the same for all satellites, is the coating not working?
Or could it be that #DarkSat is not object 44932 [Starlink-1130], but instead object 44927 [Starlink-1114]? This #Starlink satellite is the only one of the 18 satellites that was not visible in these images?
I'm using the @spacetrackorg orbital elements, but they, as well as the elements from @TSKelso's Celestrak.com, identify Starlink-1130 as object 44932; Starlink-1130 is supposed to be #DarkSat. Has that recently changed? Pinging @SpaceX, @TSKelso. @planet4589. n/n
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Cees Bassa
@cgbassa
Tonight we're using the Dwingeloo @radiotelescoop to track the landing of the @isro #Chandrayaan2Live Vikram lander on the surface of the Moon. The lander just reappeared from behind the Moon and locked on to the Madrid telescope of the @dsn_status network.
@radiotelescoop @isro @dsn_status @PI9CAM @tammojan The #Chandrayaan2Live Doppler curve has just reached its maximum. This means it has just passed over the lunar North pole and is now moving South towards the landing site.
@radiotelescoop @isro @dsn_status @PI9CAM @tammojan The S-band carrier of #Chandrayaan2Live is showing faint whisps over the last few minutes. Could these be reflections of the signal from the Lunar surface?
Read 12 tweets
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Cees Bassa
@cgbassa
It's not often that I retweet the US president, but he tweeted this image of the Iranian Safir launch failure. The image is very interesting as evidence suggests that it was taken by a US spy satellite on August 29th, 2019. Here's my analysis.
The image shows the aftermath of an accident with an Iranian Safir rocket at the El Khomeini Spaceport. From the features of the launch pad, I find that the viewing directions of the camera match that of USA 224, a classified spy satellite.
There are 4 towers around the launch pad. Google Earth shows that the North and South towers are aligned along 192 deg azimuth. The camera azimuth is a further ~4 degrees West. From the elliptical shape of the circular launch pad, the elevation of the camera is around 46 degrees.
Read 15 tweets
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Cees Bassa
@cgbassa
This is the impact of a ~1600 satellite @SpaceX #Starlink constellation for a location at latitude 52 degrees. At any time, about 84 satellites would be above the horizon. During twilight and the entire summer, up to 15 of those visible (sunlit and above 30 degree altitude).
These plots assume 53 degree inclined orbits at 550 km altitude, with 24 evenly spaced orbital planes, each having 66 #Starlink satellites. The total constellation would have 1584 objects. This is the initial @SpaceX plan for #Starlink.
cc @planet4589 @Alex_Parker @markmccaughrean @AstroKatie
Read 8 tweets

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Jonathan O’Callaghan
@Astro_Jonny
So, I've just had it confirmed from another ESA source that #SpaceX refused to move their #Starlink satellite when they were alerted to the risk of collision with #Aeolus, which was 1 in 1,000, ten times higher than the threshold for a collision avoidance manoeuvre. (1/5)
SpaceX sent a short email to ESA saying they would not move their satellite. It's not clear why - they didn't mention if the satellite was active or not, apparently (ESA weren't even aware what the satellite was). (2/5)
ESA have been pretty frustrated with SpaceX so far. There has been very little communication regarding Starlink, despite repeated attempts by ESA to contact them (this is the first email SpaceX had sent). (3/5)
Read 7 tweets
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Dr Marco Langbroek
@Marco_Langbroek
(1/2) Saw the @SpaceX #Starlink satellite 'train' pass again, now well spread-out. Most faint (binoculars), a number however naked eye. Around 21:55 UT, some 9 mins after main front group passed, several in succession briefly flared to +2 (easy naked eye) in the same sky area.
(2/2) That successive flaring, the one after the other with a few seconds spacing, of the #Starlink satellites in the middle of the stretched train was a very fine sight. I captured some of it on photograph.
(3/3)
Two photographs showing SpaceX #Starlink satellites briefly flaring in the same sky area, around 21:55 UT (May 28). Taken from Leiden, the Netherlands, with a Canon EOS 60D + SamYang 1.4/85 mm, 1 second exposures at 1600 ISO.
Stars are from Corona Borealis.
Read 7 tweets
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Dr. Phil Metzger
@DrPhiltill
Some perspective on @SpaceX #Starlink’s planned 12,000 satellite constellation. I agree for the long term we need to address visible sky pollution. This is just a tiny fraction of what will be put into space this century. But TBH, I don’t think it is a big deal yet.../1
2/ I am willing to be proven wrong, but some quick calculations show that bats already block about 200,000 times more of the sky than these satellites will. Also birds, clouds, etc, & there are already 4000 sats in orbit + 20k-400k pcs of spacejunk. So it’s not a VAST increase.
3/ There are 100,000 aircraft flights per day, many of these at night. In my typical evening outside, I see far more aircraft lights in the sky than spacecraft. I don’t believe the modest increase in spacecraft that Starlink provides will overturn this...though the day will come.
Read 5 tweets
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Michael Sheetz
@thesheetztweetz
SpaceX is hosting a media conference call now with CEO @elonmusk about the company’s Starlink internet satellites.

SpaceX is launching its first 60 Starlink satellites tonight (02:30 UTC) on a Falcon 9 rocket from Cape Canaveral, Florida.
Call beginning now.
Call will be about 30 minutes long.
Read 33 tweets
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Almington Capital
@AlmingtonCap
1/ Thread on Starlink, @SpaceX's proposed satellite constellation. This is the program that's eventually supposed to pay all the bills and fund its Mars mission. Yet, according to Gwynne Shotwell, it might not happen at all. $TSLA $TSLAQ

Our full article:
seekingalpha.com/article/425491…
2/ While it costs nothing to dream about a future manned Mars mission, actually undertaking one will. According to the National Research Council, a manned Mars mission would carry a hefty $220 billion price-tag. $TSLA $TSLAQ #SpaceX
nap.edu/resource/18801…
3/ SpaceX remains unprofitable & it knows that launching satellites for government & commercial customers can neither provide the cash necessary to fund its ambition of space exploration, nor justify its eye-watering $30 billion valuation. $TSLA $TSLAQ
seekingalpha.com/article/422188…
Read 9 tweets

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