The slow, changing tumble of the USA 144 (Misty 2) decoy

The USA 144 Decoy (1999-028C)
(click image to enlarge)

Yesterday evening I did some observations on the two evening KH-11 Keyholes (USA 186 and USA 245). Following that, I targeted the USA 144 decoy (1999-028C), an enigmatic object from the launch of the stealth satellite Misty 2 in 1999.

Three classified objects and one unclassified: the USA 144 Decoy, NOSS 3-4 A & C,
and an old rocket booster with CAMEO attached
(click image to enlarge)

At left in the image above is a double trail of the classified NOSS 3-4 duo (2007-027 A & C). In the middle is an old Delta 1 rocket booster (78-098B) with CAMEO on top, an earth magnetosphere experiment from 1978. At right, the shortest trail, is the enigmatic classified object we call the USA 144 Decoy.

I have written about this enigmatic object before. It is a bright object in a high 2665 x 3155 km orbit originating from the Misty 2 Stealth satellite launch in 1999.

(click image to enlarge)

From a study of its orbital behaviour, Ted Molczan found that the orbital decay of this object is notably influenced by Solar Radiation Pressure (SRP). This suggests an object that is very "light" relative to its size, i.e. an object with a large area-to-mass ratio. This does not fit a normal payload, so we suspect that this relatively bright object might have been a decoy to attract attention away from the real, stealth payload.

The USA 144 Decoy is slowly tumbling, resulting in a clear brightness variation. Ted already noted that the period of this variation changes over time, sometimes increasing, sometimes decreasing. This is in line with the tumbling behaviour of other known objects subject to SRP (like fragments of the PAGEOS balloon satellites).

click diagram to enlarge

I took a series of images between 20:19:42 UT and 20:26:12 UT (20 Sep 2015) documenting the brightness variability. The curve fits a peak-to-peak period of about 50.5 ± 0.5 seconds (see diagram above). There is clearly much variation in amplitude peak-to-peak.

The period found, is shorter than the periods found during my earlier determinations in 2009 and 2010, a summary of which is given below:

20 Sep 2015:    50.5 seconds (this post)
5 Sep 2010:     60 seconds   (see here)
20 Jul 2010:    61 seconds   (see here)
2-9 Mar 2010:   88 seconds   (unpublished)
19 Nov 2009:    62 seconds   (see here)
25-27 Aug 2009: 71 seconds   (see here)

This variation of the period over time is in line with expectations for an SRP-influenced object like this.

Again the USA 144 (Misty-2) Decoy brightness variability, with another specular glint

Since about a year, I am regularly targetting the enigmatic object (related to what was probably the Misty-2 stealth satellite launch) we call the USA 144 Decoy (99-028C) as part of a long term monitoring of the brightness variability of this object. It shows a slow sinusoid brightness variation with a periodicity of tens of seconds. This period of variation slowly evolves over the course of months.

On the night of September 5-6 I captured a series of images again (between 23:11:22.30 - 23:16:32.35 UTC, Sep 5, 2010) allowing the construction of a curve. Below is the diagram: I find it best fits a periodicity of 60 seconds:

click diagram to enlarge

Earlier period determinations were:

20 Jul 2010: 61 seconds (see here)
2-9 Mar 2010: 88 seconds (unpublished)
19 Nov 2009: 62 seconds (see here)
25-27 Aug 2009: 71 seconds (see here)

I should actually revisit the two determinations (Aug 2009, Mar 2010) that are well off from 60 seconds to see whether I didn't make mistakes there.

As can be seen, I again captured a solitary anomalous glint produced in the "valley"part of he curve. Something very similar happened earlier on July 20th. Both glints happened near a brightness minimum. Below is imagery of the latest glint from September 5 (showing one image before the glint, then the glint image, and an image after the glint), and a comparison diagram of the July 20th and September 5th glints:

click image to enlarge

click diagram to enlarge

These spikes are quite specular in character, and suggest there is a flat mirroring surface attached to the object on (if the slow brightness variation of the object is due to exposure of long versus narrow sides) one of the narrow sides.

Altering tumbling period of the USA 144/Misty-2 decoy (1999-028C)

In August I used a series of photographs to determine the tumbling period of 99-028C, the enigmatic USA 144/Misty-2 "Decoy" (see here).

As the tumbling period of this object is known to alter, I am repeating the experiment. I still need some additional nights to construct a full curve: but the partial curve obtained from the November 19 observations (6 images) already shows a clear change compared to August:

click diagram to enlarge

The sinusoid is for a period of 62 seconds, which compares well to a very similar period visually determined by Ted the same night. It is nice to see the two results coming out so similar.

Back in August the period was 71 seconds. A change of 9 seconds in 3 months time.

In the diagram above, the greyed data points are data from when the trail was very close to both edges of the FOV. Their absolute levels have suffered from lens vignetting, so I scaled them to show that the trend of these points at least is similar to the trend of the period determined from the other four images. The black data points are raw, unaltered data from the latter images.

More observations from last evening

The clouds that threatened last evenings HTV-1 observation (see previous post) moved out somewhat later, allowing me to bag several objects.

I observed both of the evening KH-12 Keyholes, USA 129 (96-072A) and USA 186 (05-042A). USA 129 was very bright (mag. -1) while ascending through Aquila low in the south, yielding some very fine pictures of which this is the first:

click image to enlarge

The other KH-12, USA 186, featured a slow bright flare to mag. -2 around 21:10:35 UTC (12 Sep), alas outside the camera view.

Some high altitude objects were captured again as well: the by now familiar USA 184 ELINT/SBIRS (06-027A), the SDS-3 USA 198 (07-060A) and the USA 144/Misty-2 Decoy (99-028C).

I recently obtained the launch patches of both USA 184 and USA 198:

click images to enlarge

The USA 198 patch (bottom) shows the satellite constellation it is part of: two Molniya orbits and a geostationary orbit. The Latin text roughly translates to "Beware of our Sting".

A keyhole flare, and an SDS-3 satellite (USA 198)

Last two evenings were clear. On September 7th I watched and imaged the KH-12 Keyhole USA 129 (96-072A), together with my neighbour who saw her first Keyhole this way.

On September 8th I imaged both USA 129 and another KH-12 keyhole, USA 186 (05-042A). USA 129 briefly flared to mag. +0.5 at 20:49:21.7 UTC. Below is the image, and the brightness profile (the image saturates near the flare peak). In the same image, slightly below and to the right, another faint trail can be seen: this is a rocket stage, 08-049B, from the launch of a Thai communication satellite in 2008, launched from Russia with a Dnepr rocket, a converted ICBM.

click images to enlarge

I also imaged two high altitude objects: again the USA 144/Misty-2 decoy (99-028C, see my post here and here) and USA 198 (07-060A), an SDS-3 communications satellite in a Molniya orbit. One of the tasks of this type of satellite, is believed to be the relay of data from the Keyholes to ground stations.

click image to enlarge

Below animated GIF shows USA 198 as a moving object (moving from left to right) just right of the frame center:

A Keyhole flaring, a Molniya ELINT and the USA 144 decoy again

The evenings of August 31 and September 1 were clear. On August 31 I targetted two higher objects with the EF 100/2.8 Macro USM: USA 184 (06-027A), an ELINT in a Molniya orbit (see a few posts back), and the USA 144 Decoy again (99-028C). On September 1st, two LEO objects were the target: the KH-12 Keyholes USA 129 (96-072A) and USA 186 (05-042A).

USA 129 brightly flared to mag. -1 at 20:34:11.1 UTC (Sep 1st). The camera was open when it did:

Click image to enlarge

The series of images of the USA 144 Decoy yielded information again about the periodicity of it's brightness (indicating the tumbling period). Like the data of August 25 and 27, it fits a sinusoid with a period of 71 second.

Click diagram to enlarge