Friday 27 March 2020

One year after India's ASAT test

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Today it is one year ago that India performed an ASAT test codenamed 'Mission Shakti'. The test consisted of the on-orbit destruction of the Microsat-R satellite (2019-006A), launched specifically to function as target for this test. The intercept occurred at 285 km altitude, but created debris pieces with apogee altitudes much higher than that. I have earlier published an extensive OSINT analysis of the test in The Diplomat of 30 April 2019.

The test generated large amounts of debris. A total of 125 larger debris pieces have been tracked and catalogued by the US tracking network. Note that these only concern larger pieces: most of the generated debris probably was too small to be tracked.

Over the past year I have periodically posted an update on the status of these larger debris pieces on this blog. Whereas the Indian DRDO claimed at the time that all debris would have been gone 45 days after the test, the reality has been quite different: 45 days after the test, 29% (less than a third) of the larger debris pieces had reentered. It took 121 days for half of the pieces to reenter, and some 200 days before 75% of the tracked debris pieces had reentered.

One year after the test, some 114 of the tracked debris pieces have reentered according to CSpOC tracking data. And two more objects for which no decay message was published by CSpOC, 2019-006AR and EA, have reentered according to my own analysis with SatEvo, bringing the total tally of reentered larger tracked pieces to 116.

Nine, or some 7%, of the original 125 larger tracked debris pieces are still on orbit.

It concerns objects 2019-006V, AJ, AX, BD, DC, DD, DE, DM and DU (red orbits in the image below: the white orbit is that of the ISS, as a comparison).  They have apogee altitudes varying from 600 to 1500 km, and perigees generally near 260 to 280 km. Six of these are expected to reenter over the next half year 9 months. And the last debris pieces may not reenter before 2022-2023.

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Wednesday 25 March 2020

SpaceX's Starlink Darksat is, indeed, darker

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The image above is a composit of stacked frames from four video sequences shot in the evening of March 22. Apart from a stray Chinese rocket booster that happened to cross the field, it shows four Starlink satellites from the 2020-001 launch: Starlink-1114 (2020-001P), Starlink-1030 (2020-001N), Starlink-1084 (2020-001B) and Starlink-1098 (2020-001D). These satellites are currently at their intended operational altitude.

Starlink 1030 is also known as DARKSAT
- it is the Starlink satellite that has been given an experimental coating to reduce its brightness.

As can be seen in the video stack, the coating indeed seems to reduce the brightness. The effect is also very apparent in the photographic imagery below, comparing Darksat to two other operational altitude Starlink satellites in the same orbital plane, Starlink-1114 and Starlink-1084 that both passed within 5 minutes of Darksat. The two regular Starlink satellites are well visible, but Starlink-1030 Darksat is very faint in the image:

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The video images were taken with a WATEC 902H and Canon FD 1.8/50 mm lens at 25 fps. The photographic images were taken with a Canon EOS 80D + EF 2.5/50 mm lens at 1000 ISO, 10 seconds exposure.

It is difficult to attach reliable magnitudes to the video and photographic imagery, but I'd say the magnitude difference between Darksat and the others is probably in the order of 1 to 2 magnitudes. Given their shape, the brightness which Darksat and other Starlink satellites can attain will probably be  highly depending on the viewing angle (as well as of course the phase angle at time of observation), i.e. which part of the satellite you are looking at.

Saturday 7 March 2020

Dragon CRS-20, 23 minutes after launch, with thruster firings

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SpaceX launched the Dragon CRS-20 cargoship to the ISS this morning at 4:50:31 UT. Some 23 minutes after launch from SLC-40 at Cape Canaveral in Florida, it was visible from the Netherlands around 6:13 local time (5:13 UT) in morning twilight. There were some fields of clouds in the sky, but I nevertheless got a clear view of the four objects associated to the launch, all still closely together.

The image above is a 2-second exposure at 800 ISO which I took during the pass, using a Canon EOS 80D DSLR and a SamYang 1.4/85 mm lens. The image shows the trails of  four objects, two of which are tumbling. In the annotated image below, I identify what is what:

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The Dragon cargoship, the Falcon 9 upper stage and the two solar panel covers were easy naked eye objects. The Dragon and Falcon 9 upper stage were very bright and steady, while the two solar panel covers slowly flashed alongside them. These solar panel covers varied in brightness between invisible (with the naked eye) and magnitude +1.5. The Falcon 9 upper stage and Dragon were about +1.5 to +2: with the naked eye, being very close together they seemed one object, while on the photographs they are clearly two.

The image below, taken a few seconds after the previous image, shows one of the tumbling, slowly flaring solar panel covers at its brightest, rivalling the Dragon and Falcon 9 upper stage in brightness:

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The slow regular flashing behaviour was nice to see: the two tumbling solar panel covers were alternating, when one of the two was bright, the other was faint (clearly visible in the image above and the video below). Due to the alternatingly flashing panel covers above and below the Dragon, it looked a bit like an aircaft.

I also captured a small part of the pass on video, using the WATEC 902H with a 1.8/50 mm lens on a fixed tripod in autonomous mode (I was outside myself witha sceond tripod and the photo camera). In this video segment (below), a thruster firing is visible as a cloudy upwards moving "puff"starting at 5:13:00 UT:

Dragon CRS-20 will berth to the ISS on Monday 9 March near 11:00 UT.

This was the last flight of a Dragon 1, and the concluding flight of a contract awarded in 2008. All future Dragon supply flights will be done by an updated model, the Dragon 2 as well as the crew-rated Crew Dragon variant of the latter.