Sunday 20 April 2014

[UPDATED & CORRECTED] Observing the SpaceX Dragon CRS-3, the ISS and two pieces of Dragon launch debris

CORRECTION (21/04/2014 12:55 UT): in the initial post, the two debris pieces were misidentified. "2014-022C" turned out to be 2014-022H, and "2014-022H" turned out to be 2014-022G.

click image to enlarge

Last Friday at 19:25 UT, SpaceX launched the Dragon CRS-3 commercial supply ship to the International Space Station ISS. It passed over Europe 20 minutes later but unfortunately I was clouded out in Leiden. In the middle and eastern parts of the Netherlands as well as elsewhere in Europe, observers were treated to a spectacular view of the Dragon, the Falcon upper stage, and two faint pieces of debris passing by as a thight group of objects.

SpaceX Dragon CRS-3
click image to enlarge

I was more lucky yesterday when the sky was clear and the Dragon and ISS made a late twilight pass culminating at approximately 26 degrees altitude in the SW near 20:06 UT (22:06 local time, sun at -12 deg.). The image above shows the Dragon CRS-3 due south already somewhat past culmination. It was easy to see with the naked eye, attaining magn. +1.5. Its brightness is more similar to a Progress or ATV then to the much fainter commercial Orbital Sciences Cygnus.

The Dragon was about 1m 12s behind the ISS, a visual distance of somewhat over 40 degrees. Pre-observation predictions based on elements a few hours old had put it in front of the ISS, so at first I was wondering whether I missed it. Then, as the ISS was descending towards the SE, I saw it approaching in the SW, chasing the ISS. A very fine sight!

The ISS passing the same sky area as the
earlier image, 1 min earlier
(click image to enlarge)

While I was photographing at the nearby city moat, I had also set up the video in my girlfriend's appartment, and this capture both objects as well: first the ISS, then a minute later the Dragon:

(the display says "GPS BAD" because my GPS time inserter failed to lock on a GPS satellite. I hope it is not broken...)

Apart from the Dragon and the ISS, I observed and photographically imaged a third debris object related to the launch. It is the object catalogued by JSpOC as 2014-022C/#39682. 2014-022H, #39687. It is either the jettisoned Dragon nose cone cover, or one of the solar panel covers   or possibly one of the Nanosat dispensers: I think it is too bright to be one of the several released nanosats itself. It was faint and slowly tumbling, alternating between invisibility and a max magnitude of about +3.5:

tumbling Dragon debris 2014-022H
(click image to enlarge)

[UPDATE:] Later I discovered a second piece of Dragon CRS-3 launch debris on my imagery. It is faint, irregular in brightness and present on two images, the best of which is this one from 20:04:07 UTC:

tumbling Dragon debris 2014-022G
(click image to enlarge)

This turns out to be the object designated 2014-022H, #39687  2014-022G, #39686. This is the other solar panel cover.

Saturday 12 April 2014

Progress M-22M in twilight

Yesterday evening in late twilight (sun 11 degrees under the horizon, waxing gibbous moon low in the sky) I observed Progress M-22M (2014-005A), the Russian cargoship that undocked from the ISS on April 7.

 click image to enlarge

The undocked Progress will be flying solo for several days, during which ionospheric tests are conducted. It will be de-orbitted on April 18 near 15:43 UT.

As usual, the Progress spacecraft was easily visible to the naked eye, reaching about mag. +2. It passed between Gemini and Canis minor (and roughly halway between Procyon and Jupiter, see image above), then over the head and body of Leo and through the Coma Berenices cluster (see imagebelow) before disappearing behind the roof. It was about 25 minutes ahead of the ISS.

click image to enlarge

25 minutes later I did a first attempt to image the ISS in high resolution through my C6. I managed to get two images of it, but they are not of good quality. I guess I have to practise a bit more :-)

Thursday 10 April 2014

Eagle Eyes

Recently I posted a topic on USA 184, one of the SBIRS-HEO satellites. That post was illustrated with amongst others this patch:

click image to enlarge

A sharp eyed reader, graphic designer and illustrator Olivier Rossel (PXP), noted something odd in the patch. More exactly, in the bothom "beard" of feathers of the Eagle's head.

I had not noted it until Olivier pointed it out (and it is so obvious now!), but letters are spelled out there:

(image courtesy of Olivier Rossel)

You can read the words "GEO", "DSP" and "HEO". These are all relevant to the US Infrared Early Warning system. SBIRS has satellites in two kind of orbits: GEO (geosynchronous) and HEO (Highly Elliptical Orbit - see my earlier post). DSP is the Defense Support Program, the predecessor of the newer SBIRS, consisting of a number of satellites in GEO.

Some Russian guy, Ivan Karavay, identified the words earlier in a post in this forum (in Russian) but I had never seen it until Olivier pointed it out to me.This while I knew words are sometimes hidden in NRO-related patches. Take these patches for example, from the NRO launches NROL-25, NROL-34, NROL-41 and NROL-49:

click images to enlarge

In the "vermicelli" that fills in the Earth in these patches, letters can be discerned that sometimes solve into acronyms: "4 SLS" (4th Space Launch Squadron),  NRO or NROL, and other letter combinations that are less easy to interpret.

Speaking of logo's and patches: I recently re-designed the logo of SatTrackCam. The new design is based on the older design but less cluttered:

click image to enlarge

Like in NRO patches, there is some coded information in this design: the Coat of Arms for example has a double meaning. The (pig-) Latin actually refers to a notorious NRO patch, as well as a famous internet meme.

Tuesday 1 April 2014

[updated] The bright fireball over Germany of 31 March 2014, 22:34 CEST: an earthgrazing meteor, not a satellite re-entry

[updated 20:55 UT (1/4/2014) to reflect revised fireball duration]

Yesterday evening German astronomical internet fora and my Twitter timeline erupted in a frenzy about a very bright, magnitude -10, west to east moving, very long duration fireball seen over southern Germany near 20:34 UT (22:34 CEST, March 31).

The fireball was widely seen by eye witnesses and captured by a video all-sky station near Ulm. The very spectacular image, by Thomas Tuchan, can be seen here (scroll down in the message list) on the AKM message forum.

As usual, it was science writer Daniel Fischer who was the first to knock on my digital door for an opinion. The question that had popped up, as it does with every long duration slow fireball, was whether this was a meteoric fireball or perhaps a satellite re-entry? In most cases, it is not, although there are exceptions.

My first check in such cases always is with JSpOC to see whether there was a suitable re-entry candidate in the TIP-messages. There was not. This while a re-entering artificial object of this brightness must be a very big object, for which you expect a TIP message.

Next more information came available on the fireball length and duration, notably through Thomas Tuchan's all-sky video image. It shows an almost horizon to horizon event, with a duration of 16 33 seconds. It starts at approximately 15 degrees elevation in Perseus, culminates at 60 degrees North, and ends low on the opposite horizon, at an elevation of about 12 degrees. A span of some 150 degrees!

[Update 20:55 UT: the duration was later revised to 33 seconds]

The very long 150 degree trajectory with a duration of 16 seconds rules out the re-entry of an artificial object. It shows that this was a meteoric fireball, and one that entered the atmosphere at a very shallow angle: a so called Earthgrazing meteor. There are even some examples (most famous one the Grand Tetons fireball of 1972) where such Earthgrazing fireballs left the Earth's atmosphere again!

Satellite re-entries take place between 150 and 50 km altitude. At such altitudes, an earth-orbiting object has a speed of 7.5-7.8 km/s and the resulting apparent angular velocity is about 3 degrees/second for 100 km, and about 5 degrees/seconds for 50 km altitude: but only in the zenith. Lower above the horizon, the angular speed is much less.

I constructed an artificial set of orbital elements for an orbital altitude of 90 km (re-entry in progress) as a test: it takes such an object 1 minute 15 seconds to move from 15 degrees elevation above the western horizon to 15 degrees elevation on the opposite horizon. By contrast, it took the German fireball only 16 33 seconds: i.e. almost a factor two-and-a-half faster.

[Update: the duration was first reported as 16 seconds, later revised to 33 seconds]

All this makes very clear that the German fireball of March 31 was not the re-entry of an artificial object, but a meteoric fireball, most likely an Earth-grazing object of asteroidal origin..