Wednesday, 5 April 2017

VIDEO: the ISS Fabric Shield (again), and North Korea's Kwangmyongsong-4



Yesterday I posted April 3 photographic imagery of the ISS Fabric Shield (1998-067 LF), a 1.5 x 0.6 meter anti-micrometeoroid shield astronauts inadvertently let fly into space during an EVA on March 30 (see my previous post for more details).

Yesterday evening April 4, in late twilight, I managed to film the object, which was now 1m 45s ahead of the ISS. The video, shot with a WATEC 902H low-light-level camera and a Samyang 1.4/85 mm lens, is above.

Later in the evening I also targetted  North Korea's Kwangmyongsong-4 (KMS-4, 2016-009A) which I had filmed, but as a very faint object, a week before as well. This time, KMS-4 was much brighter due to a more favourable illumination angle, and is easy to see as it cruises past Alcor and Mizar:



Both the ISS Fabric Shield and KMS-4 do not show a clear periodic brightness variation in the video imagery. The only variation that is there are slow trends (altitude and illumination angle related) and fluctuations within the fluctuation expected from atmospheric scintillationand oscillations in the video signal (estimated by looking at variations in the apparent brightness of a comparison star) :


click diagram to enlarge

Monday, 3 April 2017

The ISS Fabric Shield accidentally released from the ISS imaged in orbit

On March 30, 2017, NASA astronauts Shane Kimbrough and Peggy Whitson conducted an EVA from the International Space Station to prepare a new docking port and install new equipment on the outside of the ISS.

click to enlarge

During this spacewalk, they accidentally released a 1.5 x 0.6 meter large protective Fabric Shield, a shield against micrometeoroids that was one of four to have been installed that day on one of Tranqility module's ports. Somehow it got loose  and floated away in space, before the astronauts were able to retrieve it. Oopsy!

Once floating free in space, and having become space debris, it was catalogued by JSpOC as object nr. 42434, 1998-067LF.

The image above shows the shield, imaged from Leiden last night during a zenith pass with an 1.4/85 mm lens. It is faint and was almost exactly a minute in front of the ISS. It seemed steady in brightness on the 3 images I obtained (spanning an arc of 15 seconds in time).

Here is a screencap of the moment the object floated away during the EVA, somehow having come loose of its tether:


click to enlarge

The image below shows the ISS, a minute later (bright stars are kappa and iota UMa):


The accidentally released Fabric Shield has a relatively large surface relative to its weight [added edit: it weights 8 kg and measures 1.5 x 0.6 meter], which means it will quickly decay and re-enter, probably within 5 to 6 months from now.