NROL-108: another mystery launch perhaps similar to NROL-76 (USA 276)? [UPDATED]

UPDATE 17 December 2020 16:15 UT:

today's launch was scrubbed due to a pressure anomaly in the upper stage. A new launch attempt will be on December 18th 19th.

UPDATE 20 December 2020 12:20 UT:
NROL-108 launched succesfully on 19 december at 14:00 UT. A fuel dump was observed from New Zealand.

On 17 18 19 December 2020, SpaceX will launch a classified payload for the National Reconnaissance Office (NRO). The launch, from Cape Canaveral platform 39A in Florida, is designated NROL-108. The Navigational Warnings window opens at 13:55 UT and closes at 17:52 UT, pointing to launch somewhere between ~14:00-17:45 UT [edit: the scrub on December 17 suggests a window starting at 14:45 UT and ending at 17:00 UT] . The first stage will attempt to do a RTLS (return-to-launch-site).

NROL-108 is very odd as it was a surprise addition to the launch schedule in early October 2020, seemingly coming out of nowhere. It was originally slated for launch on October 25, but was postponed to December. The character of the mission is a mystery: this looks to be something new again.

The following Navigational Warnings have appeared for the launch hazard areas and the Falcon 9 upper stage deorbit area:

 NAVAREA IV 1201/20
 WESTERN NORTH ATLANTIC.
 FLORIDA.
 1. HAZARDOUS OPERATIONS, ROCKET LAUNCHING
    171355Z TO 171752Z DEC, ALTERNATE
    181355Z TO 181752Z DEC
 IN AREAS BOUND BY:
 A. 28-39-43N 080-38-12W, 29-02-00N 080-15-00W,
    28-57-00N 080-08-00W, 28-40-00N 080-11-00W,
    28-27-00N 080-24-00W, 28-26-52N 080-32-07W.
 B. 30-12-00N 079-06-00W, 30-28-00N 078-56-00W,
    30-54-00N 078-52-00W, 31-14-00N 078-13-00W,
    31-06-00N 077-36-00W, 30-47-00N 077-22-00W,
    30-27-00N 077-26-00W, 30-08-00N 078-20-00W,
    30-03-00N 078-58-00W.
 2. CANCEL THIS MSG 181852Z DEC 20.//

 HYDROPAC 3673/20
 EASTERN PACIFIC.
 DNC 06, DNC 13.
 1. HAZARDOUS OPERATIONS, SPACE DEBRIS
    171508Z TO 171841Z DEC, ALTERNATE
    181508Z TO 181841Z DEC
 IN AREA BOUND BY
    12-27S 135-24W, 11-03S 135-01W,
    04-31N 125-02W, 12-23N 118-23W,
    11-34N 117-22W, 01-11N 123-20W,
    11-32S 132-38W, 13-10S 134-27W.
 2. CANCEL THIS MSG 181941Z DEC 20.//

These hazard areas plotted on a map:

click map to enlarge

 

The time window for the upper stage deorbit and the fact that the first stage will attempt an RTLS point to a launch into Low Earth Orbit. The launch direction and the location of the Falcon 9 upper stage deorbit area point to a launch into an orbit with an orbital inclination near 52 degrees.

The location of the launch hazard areas is somewhat similar to the launch hazard area for the May 2017 mystery launch of USA 276 (NROL-76). In the map below, the two hazard areas for NROL-108 are in red, while the launch hazard area for NROL-76 (USA 276) from May 2017 is in blue:

click map to enlarge

USA 276/NROL-76 was a mystery NRO launch, like NROL-108 launched by SpaceX, in May 2017, that raised eyebrows because the payload made a series of very close flyby's of the International Space Station a month after launch (see my July 2017 article in The Space Review).

USA 276 went, as subsequent orbital observations of the payload by our amateur network showed, into a ~400 km altitude, 50-degree inclined orbit, so a 50-degree inclined orbit is perhaps also an option for NROL-108.

Such a 50-degrees inclined orbit does not match well with the position of the deorbit zone for the Falcon 9 upper stage. The latter will be deorbitted over the eastern Pacific near the end of the first revolution, the Navigational Warnings show. So for now, the 52-degree inclination (give or take a degree) looks a bit more likely. Still, I do not want to rule out a 50-degree inclined orbit altogether, as the Falcon 9 upper stage might end up in a somewhat different orbit than the payload

In May 2017, USA 276 was launched into an orbital plane very close to that of the ISS, which resulted in the close encounters a month later. 

The launch window for NROL-108 (~14:00-17:50 UT) rules out that NROL-108 will do something similar: the ISS orbital plane does not pass over or near the launch site during this time window. 

It is possible however that NROL-108 aims for an orbital plane near that of USA 276. The orbital plane of USA 276, which due to orbital precession over the past 3 years no longer is close to that of the ISS, passes over Cape Canaveral Launch Pad 39A near 17:02 UT, inside the NROL-108 launch window. This opens up the possibility that NROL-108 is perhaps a close approach target for USA 276, or USA 276 is a close approach target for NROL-108 (but that is pure and wild speculation: Caveat Emptor). [UPDATE: see the update at end of this post. It did not target the USA 276 orbital plane]

It will be interesting to see in which orbit NROL-108 will end up. As I have remarked with some launches earlier  this year, the latest NRO launches all seem to be  'new' kinds of payloads that are likely experimental/Mission demonstrators, and which go into 'new' kinds of orbits: lately we have frequently seen orbital inclinations near 50-degrees and odd orbital altitudes (either very low or very high). NROL-108 will certainly go into a Low Earth Orbit, and it will be interesting to see what the exact launch time will be, whether it will go into a 400 km orbit similar to the orbital altitude of USA 276, and what the eventual orbital inclination will be.

UPDATE 20 December 2020:

NROL-108 launched succesfully at 14:00 UT on December 19th. Slightly over an hour after launch, near 15:15 UT, a fuel dump (following a deorbit burn) from the Falcon 9 upper stage was observed from New Zealand. The facebook-post here shows the classic spiral shape of such a fuel dump. The Youtube video below shot from Pukehina Beach by Astrofarmer shows less detail but includes time details:

 

 

Assuming the included times in the video are correct, this allows me to make a new estimate of the orbital altitude in which the satellite was inserted, which is probably ~600 km rather than the ~400 km of my initial estimate, looking at the time the rocket stage passed south of New Zealand:

NROL-108
1 70000U 20999A   20354.58333333  .00000000  00000-0  00000-0 0    04
2 70000 051.9000 194.4979 0003581 047.9699 326.1978 14.88539141    08

The orbital inclination of the satellite is still a bit uncertain but likely ~52 degrees.

The launch time (14:00 UT) excludes that the orbital plane of USA 276 was targetted (the orbital plane of the latter passed over the launch site two hours after launch).

 

UPDATE 2 (20 Dec 2020):

Radio observers have now catalogued the payload in a 519 x 539 km, 51.35 degree inclined orbit.

Close Encounters of the Classified Kind

The Space Review has just published my paper on the close ISS flyby of US spy satelllite USA 279.

[UPDATED] Close Encounters of the Classified Kind: a post-event analysis of the close approach of USA 276 to the ISS on June 3

3 July 2017: A paper which is a further evolved version of this blog post has appeared in The Space Review. I advise you to read that paper

(UPDATED 7 Jun 2017 15:50 UT with two new figures showing circular motion of USA 276 around the ISS)

Something odd happened a few days ago, high above our heads. In an earlier blogpost, I discussed in detail how the odd spy satellite USA 276 (2017-022A) was set to make a peculiarly close approach to the International Space Station ISS on 3 June 2017. The spy satellite was recently launched for the NRO as NROL-76 by SpaceX, on 1 May 2017.

With the close approach moment now in history and post-approach observations of USA 276 available (as well as an orbit for ISS based on tracking data, rather than an orbital prognosis), I present my final analysis of the situation in the current post.

With the new data included, we can establish the moment of closest approach as 3 June 2017, 14:01:52 UT. It happened over the southern Atlantic north of the Falklands, near 43^o.75 S, 45^o.45 W, with a miss distance of only 6.4 ± 2 km (the  ± 2 km stems from the fact that TLE predicted positions have a typical positional accuracy of no more than 1 km at epoch).

The latter is significantly closer than the approach distances calculated before the approach (which were in the order of 17-20 km, see my earlier post). Ted Molczan also analyzed the situation and he finds an even closer nominal distance of 4.5 km (but within uncertainty intervals our results overlap).

For the ISS, I used elset  17154.48611204. For USA 276, I used the elset below which I calculated based on amateur observations including my own:


USA 276
1 42689U 17022A   17155.88026473 0.00004763  00000-0  65979-4 0    01
2 42689  50.0047 103.5284 0014136 110.9138 249.3345 15.56256291    00

rms     0.020                             arc May 31.92 - Jun 4.90 UT

For detailed purposes like this, the orbit determination is a bit sensitive to what observer data are included. I restricted myself to observers with known high accuracy in the orbital solution above.

click image to enlarge

click image to enlarge

Below is an updated animation of the situation:




A table of all close approach moments with distances smaller than 500 km:

DATE       UT         km 
3 JUN 2017 02:28:52   478.5 
3 JUN 2017 03:13:37   464.4 
3 JUN 2017 04:01:17   413.2 
3 JUN 2017 04:46:14   398.9 
3 JUN 2017 05:33:41   347.8 
3 JUN 2017 06:18:50   333.3 
3 JUN 2017 07:06:04   282.4 
3 JUN 2017 07:51:26   267.7 
3 JUN 2017 08:38:28   217.1 
3 JUN 2017 09:24:03   202.2 
3 JUN 2017 10:10:52   151.9 
3 JUN 2017 10:56:39   136.6 
3 JUN 2017 11:43:15    87.1 
3 JUN 2017 12:29:16    71.0
3 JUN 2017 13:15:38    26.3 
3 JUN 2017 14:01:52     6.4  **
3 JUN 2017 14:48:01    48.8 
3 JUN 2017 15:34:28    60.5 
3 JUN 2017 16:20:24   112.5 
3 JUN 2017 17:07:05   126.1 
3 JUN 2017 17:52:46   177.5 
3 JUN 2017 18:39:41   191.7 
3 JUN 2017 19:25:09   242.9 
3 JUN 2017 20:12:18   257.4 
3 JUN 2017 20:57:31   308.3 
3 JUN 2017 21:44:54   323.1 
3 JUN 2017 22:29:53   373.7 
3 JUN 2017 23:17:30   388.8 
4 JUN 2017 00:02:15   439.2 
4 JUN 2017 00:50:07   454.5

Note: as positions from TLE's have an intrinsic uncertainty (about 1 km at epoch time), the values in the table above have an uncertainty of about 2 kilometer.

The distance variation around close approach in diagram form:

click diagram to enlarge

click diagram to enlarge

The variation in orbital altitude of both objects around the time of close approach (actual geoid heights):

click diagram to enlarge

As can be seen, USA 276 was a few km (nominally 3.65 km) above the ISS at closest approach. It was nominally also a little bit over 5 km behind the ISS.

In the following diagram, nominal distances in km in X, Y and Z of USA 276 are measured with respect to the ISS. The X is in the direction of movement of the ISS, Y is perpendicular (lateral) to it, Z is the zenith-nadir direction:

click diagram to enlarge

[UPDATE 7 Jun 2017, 15:45 UT, revised 21:14 UT] The variation in position of USA 276 with respect to the ISS was such that it effectively circled the ISS at close approaches, both laterally (cross-track) as wel as along-track, as can be seen in these diagrams below. Please note that, to get a more clear diagram, the axes of the first diagram (crosstrack circling) are not to scale. The second diagram is the same figure, but with axes to scale. The third diagram (along track circling) is also to scale:

click diagram to enlarge

click diagram to enlarge

click diagram to enlarge

A collision avoidance manoeuvre is usually evaluated if an object comes within a box of 4 x 4 x 10 km of the ISS.

If upon further evaluation the chance of collision is larger than 1:10000, an avoidance manoeuvre is done, if circumstances allow this.

USA 276 remained just outside the 4 x 4 x 10 km box at closest approach, as can be seen in the illustration below (red box, the situation shown is for the moment of closest approach). The box represents a collision risk in the order of 1 in 100 000.

USA 276 relative to the ISS proximity safety box . Click image to enlarge  (image made with STK)

I remain agnostic on the question whether this close approach was intentional or not (see discussion in my previous post regarding some possible goals would the approach  have been intentional).

Ted Molczan published a discussion of pro and contra arguments on the question whether the approach was on purpose or not on the Seesat-L list on June 3. While Ted argues that the April 16 and April 30 postponements of the launch indicate a non-planar preference of the orbit (which argues against intention), this also means that this close approach could have been avoided by picking another launch moment.

While USA 276 remained just outside the safety concern box, it is weird to have your just launched classified payload pass so close (6.4 ± 2 km) to a high profile, crewed object like the ISS.

I can and do not believe for a moment that the NRO was not aware that the launch on May 1 would lead to the close ISS approach a month later. It would be extremely sloppy of them, from a Space Situational Awareness viewpoint, if they were not aware, especially given how close the orbital parameters are to that of the ISS.

So I am struggling to understand why the NRO allowed this close approach to happen, if it was not intentional. This event was bound to attract attention and that harms the classified character of the mission. USA 276 is relatively brigh and the approach was bound to be noted by independent observers. Indeed, some space enthusiasts in Europe unaware of the issue who were out to spot DRAGON CRS-11 and Cygnus OA-7 close to the ISS on June 4, did accidentally spot USA 276 passing some 3 minutes in front of it.

It is also an extremely sloppy thing to do because this close an approach to a high profile object like ISS is politically risky. As the ISS is an international cooperation which includes two parties (the United States and the Russian Federation) that are currently geopolitically on an uneasy footing, sending your military payload so close to the ISS as one party is eyebrow raising.

This, and the timing (the close coincidence with the Dragon CRS-11 arrival at the ISS [edit: this refers to the originally planned date of arrival at June 4, later postponed by one day]) was bound to generate questions and suspicions (as it did). What the NRO did with USA 276 in the last few days was therefore really weird.

But then, the current administration of the USA is doing very weird things, and perhaps someone in the new administration signed off on this without fully understanding the depths of it. The Trump administration after all is not quite the posterchild for competence.

(the video below shows a USA 276 pass I filmed in evening twilight of June 4, at low elevation)

The Plot Thickens (Ball Aerospace, USA 276, RAVEN and the ISS)

(I acknowledge that what I write below is, again, matter of a highly speculative nature, and should be treated as such)

In a previous post, which is currently gaining media traction (e.g. here for a serious article on CNet, and here for a raunchy UK tabloid version, which is also NSFW by the way), I wrote in detail about the curious situation with the recently launched US spy satellite USA 276 (launched as NROL-76 on May 1). It appears to be moving towards a series of surreptitious very close approaches with the International Space Station (ISS). For more details see my post here.

While browsing the website of Ball Aerospace, the company that built USA 276, I found that they also have built RAVEN, an instrument delivered to and installed on the outside of the ISS in February this year.

RAVEN. Image: NASA’s Goddard Space Flight Center/Chris Gunn

As Ball Aerospace writes about RAVEN on their website:

"RAVEN is a technology demonstration mission that aims to advance the state-of-the art in rendezvous, proximity operations and docking. Raven includes visible cameras, an infrared camera and a flash LIDAR, called the Vision Navigation Sensor (VNS). In building and designing the VNS, Ball has provided Raven with its “eyes,” which will watch vehicles approach and depart the ISS."

So, let that sink in: Ball Aerospace, the company that built USA 276, a spacecraft that appears to be secretly moving towards a  series of clandestine very close approaches to the ISS, also built RAVEN, an experiment installed on the ISS to monitor close approaching spacecraft. 

NROL-76 is said to have been part of a "delivery to orbit" contract: e.g. the spacecraft and its launch is the responsibility of the builder (Ball Aerospace, who hired SpaceX for the launch), who hands over the spacecraft to the customer (the NRO) once in operational orbit. The question now is, is USA 276 at this stage still operated by Ball Aerospace, or has it been handed over to the NRO already?

(even if it isn't, I cannot believe that the NRO would have been kept in the dark about these ISS approaches. It would, however, create 'plausible deniability').

RAVEN was built by Ball Aerospace for NASA’s Goddard Space Flight Center. It is a possibility that it was jointly funded by NASA and the NRO (but that is pure speculation). Still, to use the ISS in this way is quite brazen, to say the least.

Note that while NASA participates in the ISS, the ISS is not owned by NASA: it is an international partnership that besides NASA includes ESA (Europe), JAXA (Japan), Roscosmos (Russia) and Canada, who would probably reject the idea of the ISS being made part of a classified US military experiment (certainly the Russians would).

Of course, this is all, and I emphasize this, pure speculation. But it is curious, to say the least, how Ball Aerospace and close approach monitoring come together here, from multiple angles (pun not intended). The plot thickens....

UPDATE, 3 June 13:15 UT:

A good summary of the pro's and con's on whether the ISS-USA 276 conjunction is coincidence or not, and whether there is a connection to RAVEN , by Ted Molczan is on the SeeSat-L list.

[UPDATED] USA 276 (the NROL-76 payload) and the ISS near DRAGON CRS-11 berthing.

click image to enlarge

>> UPDATES to this story with new observational data, updated calculations and new visualizations ARE AT THE END OF THE POST, below the main story <<

(NOTE: this post contains matter of a *very* speculative nature. I am the first to admitt this...and you are forwarned) 

Five days ago I wrote about the odd NROL-76 payload, USA 276, which was launched as NROL-76 for the NRO by SpaceX on 1 May 2017. In that post  I pointed out that its orbit was peculiarly close to that of the International Space Station ISS.

I have prepared two animations to show the extend of this, and what will happen in the first week of June if USA 276 does not change its orbit before that date (this is an important caveat!).

This is what will happen on June 3, when USA 276 would make a couple of very close approaches to the ISS, perhaps to distances as close as 20 km (!) near 14:48 UT (3 June 2017):




Note how the satellite is effectively circling around the ISS, at close range.

If the DRAGON CRS-10 history is to go by, and CRS-11 is launched on-time, the latter will be close to the ISS as well (although perhaps not as close as in the animation). [UPDATE June 2: the launch of CRS-11 was postponed to June 3 due to the weather]

The next day, June 4 near 15:30 UT, the DRAGON CRS-11 supply ship will berth to the ISS if launch goes as planned. This is the situation around the time of berthing [UPDATE June 2: the launch of CRS-11 was postponed to June 3 due to the weather] :



Again, and I can't say this enough: this will be the approximate situation if USA 276 stays in the orbit we currently have for this satellite, and does not manoeuvre.

In terms of the closest approaches, these happen the day before the CRS-11 berthing.

I calculate these close approach moments, from a USA 276 orbit that is a week old by the time these events happen (the ISS orbit used is the planned orbit for that date available here). The table provides the times for approaches closer than 500 km to the ISS [edit June 2: SEE UPDATES of table in the updates at the bottom of  this post):


DATE       TIME (UT)  DISTANCE (km)
3 JUN 2017 03:13:34   476.5 
3 JUN 2017 04:01:30   443.3 
3 JUN 2017 04:46:11   411.8 
3 JUN 2017 05:33:53   378.8 
3 JUN 2017 06:18:48   347.1 
3 JUN 2017 07:06:16   314.3 
3 JUN 2017 07:51:25   282.5 
3 JUN 2017 08:38:39   249.9 
3 JUN 2017 09:24:02   217.8 
3 JUN 2017 10:11:02   185.6 
3 JUN 2017 10:56:39   153.1 
3 JUN 2017 11:43:25   121.5 
3 JUN 2017 12:29:16   88.5 
3 JUN 2017 13:15:47   58.5 
3 JUN 2017 14:01:53   24.1 
3 JUN 2017 14:48:10   20.3 
3 JUN 2017 15:34:31   41.3 
3 JUN 2017 16:20:32   75.7 
3 JUN 2017 17:07:08   105.8 
3 JUN 2017 17:52:55   139.2 
3 JUN 2017 18:39:45   170.4 
3 JUN 2017 19:25:17   203.4 
3 JUN 2017 20:12:22   235.1 
3 JUN 2017 20:57:39   267.7 
3 JUN 2017 21:44:59   299.7 
3 JUN 2017 22:30:01   332.0
3 JUN 2017 23:17:36   364.3 
4 JUN 2017 00:02:23   396.4 
4 JUN 2017 00:50:14   428.9 
4 JUN 2017 01:34:45   460.8 
4 JUN 2017 02:22:51   493.5


Note that the calculated distances in the table have quite some uncertainty, perhaps by a factor of 2 or more. Likewise, the times listed have uncertainties of at least several seconds. And then there is the possibility that USA 276 manoeuvres into another orbit between now and June 3....

The planned moment of CRS-11 berthing to the ISS, around 4 June 15:30 UT, coincides with another close approach of USA 276, although not as close as the previous day: about 1040 km:


DATE       TIME (UT)  DISTANCE (km)
4 JUN 2017 15:25:53   1039.5


I am still not sure what to think of this all. Is this coincidence? You would almost start to think that USA 276 is a demonstrator for technology to closely monitor third party space berthings....

While I admittedly go out on a limb here, this idea does not come out of the blue. China and Russia have been busy practising such berthings and (very) close approaches in space with dedicated satellites disguised as space debris the past 10 years, which has the US military worried. Is the technology demonstrated by USA 276 perhaps meant to test whether such events can be observed (either optically, with radar, lidar, or whatever technology) from close by, to determine in detail what is going on?

It would be incredible (and politically sensitive) to use the International Space Station as a test subject in this way, which is why I and others are hesitant to accept this idea.

On the other hand, the ISS is there and you get frequent dockings and berthings of DRAGON's, PROGRESS, SOYUZ and HTV to watch for free, objects you don't have to launch yourself (saving development and launch costs and time. Launching a bunch of satellites for this purpose also atttracts attention, as the story with the Russian satellites shows).

I still don't know what to think of this all. Are these figments of my imagination or is there really something going on here? I am at a loss. Opinions are welcome.

Postscript, 30 May 2017, 21:15 UT :
I used the following TLE for USA 276, based on amateur tracking of the satellite between May 24 and May 27:

USA 276
1 42689U 17022A   17147.01934012 0.00004742  00000-0  65889-4 0    01
2 42689  50.0000 149.4666 0015489  97.4973 262.7756 15.56150729    04

The positions of DRAGON CRS-11 in the animations are based on elsets of DRAGON CRS-10 relative to those of ISS at the time, and (for the 3 June animation) are less certain than the ISS and USA 276 orbital positions.


UPDATES  (newest at the bottom):

UPDATE 1:  31 May 2017, 8:55 UT

The issue of launch windows and orbital plane shifts was rightfully raised on e.g. the NASA Spaceflight forum. It is true that the launch time needed to target the ISS orbital plane shifts by ~20 minutes each day. The crubbed launch on April 30 targetted 11:15 UT, the same time as the eventual launch a day later. Curiously enough, the Area Warning given out before the launch does open 20 minutes earlier, at 10:55 UT. Very confusing (and I initially goofed with that in a comment on the NASA Spaceflight forum).

It should be noted that USA 276 of course isn't in the exact plane of ISS (there is a 1.6 degree inclination difference anyway). A small difference in RAAN does not matter that much in this situation, it transpires.

I have looked into the effect would NROL-76 have actually been launched at 11:15 UT on April 30, when the launch was scrubbed.

The effects of a fixed launch time at 11:15 UT rather than a daily launch time shift to match the plane crossing time are actually not that large, it turns out. To investigate the effect, I adjusted the RAAN of the current orbit accordingly to match launch on 30 April, 11:15 UT..

USA 276 actually then would have made even somewhat closer passes to the ISS (to minimum distances less than 15 km on June 3 near 18:44 UT), but with the approach times  some 4 hours shifted compared to those for the actual launch date.

 During CRS-11 berthing on June 4, it would actually have been somewhat closer too, although with all other parameters of the orbit kept equal the time of approach would not match so neatly with berthing. These are not things that cannot be solved by a small manoeuvre however.


UPDATE 2: 1 June 2017, 10:30 UT

After updating the orbit of USA 276 with observations from last night, the time of closest approach has shifted a bit to an earlier approach instance (14:01:53 UT, June 3) and to a slightly smaller nominal distance (~18 km). The overall scenario remains the same, its details that change.

USA 276
1 82689U 17022A   17151.89933357 0.00004751  00000-0  65887-4 0    01
2 82689  50.0016 124.1750 0015094 116.7818 243.4697 15.56210183    01

Distance of USA 276 with regard to ISS in diagram form, from June 2.0 to June 5.0 (x-axis is in decimal days, e.g. 3.50 = 3 June 12:00):

click diagram to enlarge

click diagram to enlarge

This is the new updated list of close approach times:

DATE       TIME (UT)  DISTANCE (km)
3 JUN 2017 01:40:58   503.4 
3 JUN 2017 02:28:57   468.5 
3 JUN 2017 03:13:35   438.3 
3 JUN 2017 04:01:20   403.6 
3 JUN 2017 04:46:12   373.3 
3 JUN 2017 05:33:43   338.7 
3 JUN 2017 06:18:49   308.2 
3 JUN 2017 07:06:06   273.9 
3 JUN 2017 07:51:25   243.1 
3 JUN 2017 08:38:29   209.1 
3 JUN 2017 09:24:02   178.1 
3 JUN 2017 10:10:52   144.6 
3 JUN 2017 10:56:39   113.1 
3 JUN 2017 11:43:15   80.6 
3 JUN 2017 12:29:16   48.2 
3 JUN 2017 13:15:38   22.6 
3 JUN 2017 14:01:53   17.7   * closest
3 JUN 2017 14:48:00   54.4 
3 JUN 2017 15:34:30   82.3 
3 JUN 2017 16:20:23   117.6 
3 JUN 2017 17:07:07   147.3 
3 JUN 2017 17:52:45   182.0
3 JUN 2017 18:39:44   212.3 
3 JUN 2017 19:25:07   246.6 
3 JUN 2017 20:12:21   277.3 
3 JUN 2017 20:57:29   311.3 
3 JUN 2017 21:44:58   342.2 
3 JUN 2017 22:29:51   376.1 
3 JUN 2017 23:17:35   407.2 
4 JUN 2017 00:02:13   440.8 
4 JUN 2017 00:50:12   472.2 
4 JUN 2017 01:34:34   505.6 
4 JUN 2017 02:22:49   537.1 
4 JUN 2017 03:06:56   570.3 
4 JUN 2017 03:55:26   602.1 
4 JUN 2017 04:39:17   635.0
4 JUN 2017 05:28:04   667.0
4 JUN 2017 06:11:38   699.7 
4 JUN 2017 07:00:41   731.9 
4 JUN 2017 07:43:59   764.4 
4 JUN 2017 08:33:18   796.7 
4 JUN 2017 09:16:20   829.1 
4 JUN 2017 10:05:55   861.6 
4 JUN 2017 10:48:41   893.7 
4 JUN 2017 11:38:32   926.4 
4 JUN 2017 12:21:01   958.3 
4 JUN 2017 13:11:09   991.2 
4 JUN 2017 13:53:21   1022.9 
4 JUN 2017 14:43:46   1055.9 
4 JUN 2017 15:25:41   1087.4  * CRS-11 berthing
4 JUN 2017 16:16:23   1120.6


Here is a photograph of last night's pass of USA 276 over my house:

click image to enlarge

I also captured part of the pass on video:





UPDATE 3:  2 June 2017, 12:45 UT

Updated orbital elements based on observations from June 1:

USA 276                                                  389 x 408 km
1 42689U 17022A   17152.86247082 0.00004757  00000-0  65966-4 0    06
2 42689  50.0043 119.1561 0014209 109.6377 250.6127 15.56228316    08

USA 276 appears to have been making small manoeuvers over the past days. The current schedule for close approaches to the ISS, based on the elements above, is:

DATE           UT    DISTANCE (KM) 
3 JUNE 2017 01:41:01   503.2 
3 JUNE 2017 02:28:55   460.1 
3 JUNE 2017 03:13:38   437.9 
3 JUNE 2017 04:01:19   395.0
3 JUNE 2017 04:46:14   372.6 
3 JUNE 2017 05:33:42   329.9 
3 JUNE 2017 06:18:51   307.3 
3 JUNE 2017 07:06:05   264.8
3 JUNE 2017 07:51:28   242.1 
3 JUNE 2017 08:38:29   199.8 
3 JUNE 2017 09:24:05   176.8 
3 JUNE 2017 10:10:52   135.1 
3 JUNE 2017 10:56:41   111.5 
3 JUNE 2017 11:43:15   71.0
3 JUNE 2017 12:29:18   46.3 
3 JUNE 2017 13:15:37   18.1 **
3 JUNE 2017 14:01:55   19.6 **
3 JUNE 2017 14:48:00   64.1 
3 JUNE 2017 15:34:32   84.6 
3 JUNE 2017 16:20:22   128.0
3 JUNE 2017 17:07:08   149.8 
3 JUNE 2017 17:52:45   192.7 
3 JUNE 2017 18:39:45   215.0
3 JUNE 2017 19:25:07   257.6 
3 JUNE 2017 20:12:22   280.3 
3 JUNE 2017 20:57:28   322.6 
3 JUNE 2017 21:44:59   345.5 
3 JUNE 2017 22:29:50   387.6 
3 JUNE 2017 23:17:35   410.7 
4 JUNE 2017 00:02:12   452.6 
4 JUNE 2017 00:50:12   475.9 
4 JUNE 2017 01:34:33   517.5 
4 JUNE 2017 02:22:49   541.1 
4 JUNE 2017 03:06:54   582.5 
4 JUNE 2017 03:55:26   606.3 
4 JUNE 2017 04:39:15   647.5 
4 JUNE 2017 05:28:03   671.5 
4 JUNE 2017 06:11:36   712.4 
4 JUNE 2017 07:00:39   736.6 
4 JUNE 2017 07:43:56   777.3 
4 JUNE 2017 08:33:16   801.7 
4 JUNE 2017 09:16:17   842.2 
4 JUNE 2017 10:05:53   866.8 
4 JUNE 2017 10:48:37   907.1 
4 JUNE 2017 11:38:30   931.8 
4 JUNE 2017 12:20:57   971.9 
4 JUNE 2017 13:11:07   996.8 
4 JUNE 2017 13:53:16   1036.7 
4 JUNE 2017 14:43:43   1061.8 
4 JUNE 2017 15:25:35   1101.5 
4 JUNE 2017 16:16:20   1126.8 
4 JUNE 2017 16:57:54   1166.2 
4 JUNE 2017 17:48:57   1191.7 
4 JUNE 2017 18:30:13   1230.9 
4 JUNE 2017 19:21:34   1256.6 
4 JUNE 2017 20:02:32   1295.6 
4 JUNE 2017 20:54:10   1321.5 
4 JUNE 2017 21:34:50   1360.2 
4 JUNE 2017 22:26:47   1386.3 
4 JUNE 2017 23:07:07   1424.8 
4 JUNE 2017 23:59:24   1451.1

Distance variation over time in diagram form:

click diagram to enlarge

click diagram to enlarge

It will be interesting to see whether the schedule will change with new orbit updates, now the launch of DRAGON CRS-11 has been postponed to June 3.

Update 4, 3 June 13:15 UT:

In a post on SeeSat-L, Ted Molczan has summed up the pro's and con's of the  conjunction between ISS and USA 276 being coincidental or not. Like me, he does not really know what to think of it.

Update 5, 3 June  14:00 UT:

Updated elements based on adding observations from June 2:


USA 276                                                  388 x 408 km
1 42689U 17022A   17153.82560337 0.00004761  00000-0  65966-4 0    09
2 42689  50.0075 114.1658 0015063 110.3625 249.8963 15.56237668    07

Updated list with times and distances of close approaches to the ISS:

DATE          UT       DISTANCE (km)
3 JUN 2017 01:40:57   505.7 
3 JUN 2017 02:28:57   460.2 
3 JUN 2017 03:13:35   440.4 
3 JUN 2017 04:01:20   395.1 
3 JUN 2017 04:46:12   375.1 
3 JUN 2017 05:33:43   330.0
3 JUN 2017 06:18:49   309.8 
3 JUN 2017 07:06:06   265.0
3 JUN 2017 07:51:26   244.5 
3 JUN 2017 08:38:29   200.0
3 JUN 2017 09:24:03   179.3 
3 JUN 2017 10:10:52   135.3 
3 JUN 2017 10:56:40   114.0
3 JUN 2017 11:43:14    71.2 
3 JUN 2017 12:29:17    48.8 
3 JUN 2017 13:15:37    18.7 **
3 JUN 2017 14:01:54    17.4 **
3 JUN 2017 14:47:59    64.1 
3 JUN 2017 15:34:31    82.1 
3 JUN 2017 16:20:21   127.9 
3 JUN 2017 17:07:08   147.3 
3 JUN 2017 17:52:43   192.5 
3 JUN 2017 18:39:46   212.5 
3 JUN 2017 19:25:04   257.4 
3 JUN 2017 20:12:23   277.8 
3 JUN 2017 20:57:26   322.3 
3 JUN 2017 21:45:00   343.0
3 JUN 2017 22:29:47   387.3 
3 JUN 2017 23:17:37   408.2 
4 JUN 2017 00:02:08   452.3 
4 JUN 2017 00:50:14   473.4 
4 JUN 2017 01:34:29   517.3

Distance to the ISS with time in diagram form:

click diagram to enlarge

UPDATE 6, 6 June 15:25 UT:

A new blog post with a detailed post-event analysis of the close approach can be read here

Brightness variation of USA 276 (NROL-76)

click image to enlarge

Last night was very clear again. I observed two passes of the new USA 276 (2017-022A) satellite, also known under its NRO launch number NROL-76. It was launched early this month by SpaceX, and I wrote in detail about this mystery payload in my post from yesterday.

The image above, taken with a Canon EOS 60D and EF 2.0/35 mm lens, shows the satellite passing over the roof of my house during the first pass (00:36 local time, 22:36 UT). It was bright and an easy naked eye object at mag +2.5 near culmination.

During the second pass, 02:06 local time (00:06 UT) it was somewhat fainter, mag +3 to +3.5, but still visible naked eye. Below are two images from this pass:

click image to enlarge

click image to enlarge

During this second pass, I visually seemed to note some brightness variation, notably after culmination.

Analysis of the pixel brightness of the trails in my imagery seems to confirm this. They show an irregular brightness variation, notably in the third image (the last of the images above), that looks like it is a combination of several periods.

The diagrams below show the curve obtained from 4 images, and a detail curve of the third image where brightness variation seems most pronounced. Pixel values of the trails were measured with IRIS.

click diagram to enlarge

click diagram to enlarge

This variation could hint at some form of spin stabilization, or alternatively the presence of some rotating element perhaps.

I did not note this variation during earlier passes, so  it could perhaps strongly depend on the viewing angle.

Observing USA 276, the odd NROL-76 payload

click image to enlarge

The image above shows USA 276 passing over the roof of my house last night. USA 276 is the mystery payload of the May 1 SpaceX NROL-76 launch from Cape Canaveral.

Also visible in the image are three rocket boosters: the r/b of the classified Milstar 3 launch, and two Russian objects. Skies surely are crowded these days...

The photograph above was shot near 3:07 local time (1:07 UT) during the second of two consecutive passes. During the first pass, near 1:30 local time (23:30 UT), I obtained this video record:


USA 276 was quite faint during the first pass (I could not see it by naked eye from Leiden town center). During the second pass it was brighter, attaining mag. +3 near culmination, visible to the naked eye without problem. Due to its low orbital altitude it was very fast: the object is in a 389 x 409 km, 50.0 degree inclined orbit.

After its May 1 launch, there was a lot of discussion among our observers. The launch azimuth seemed to suggest a 50 degree orbital inclination. That would be odd (see below), so not everybody was willing to believe this. Some suggested a dog-leg manoeuvre towards a 63.4 HEO orbit. Because of the lack of precedent, orbital altitudes could only be guessed, making a quick recovery by observers more troublesome.

It took a while (23 days) before the payload was finally observed and the orbit could be confirmed. On May 23-24, the night before I obtained the imagery above, Leo Barhorst in the Netherlands finally found the payload. And it was in a 50 degree inclination, 389 x 409 km Low Earth Orbit.

The purpose of this payload in this odd orbit is a bit of a mystery. The orbital inclination of 50.0 degrees does not match common orbital inclinations attached to specific functions: US military radar satellites (ONYX, TOPAZ) tend to be in 57 degree LEO orbits or their 123 degree retrograde equivalents; SIGINT sats in 63.4 degree orbits (either LEO or HEO); optical reconnaissance satellites in 98 degree sun-synchronous LEO orbits; the X-37B space plane was in a 39-degree inclined very Low Earth Orbit. An orbital inclination of 50.0 degrees, as shown by USA 276, is odd and unusual.

The common opinion is that USA 276 is some technology demonstrator, somewhat similar to the ill-fated USA 193 from 2006, blown from the sky with a SM-3 in 2008. But what technology does it demonstrate?

click map to enlarge

Orbital inclination and orbital altitude are in fact very (some would say oddly) similar to the ISS (see diagrams above and below, showing how close the orbits currently are): the two objects in theory (and based on the current USA 276 orbit) can potentially even make quite close approaches, to within a few km (!), as Ted Molczan showed in a private communication.

click image to enlarge

I have found that on June 4, USA 276 will in fact be very close by when (if all goes according to plan)  the SpaceX DRAGON CRS-11 should arive at the ISS at this date. That is, if USA 276 doesn't change its current orbit before then.

Observers in Europe might see the three objects close together in their evening twilight of June 3, with USA 276 some 15-30 degrees distant from the ISS.

The diagram below shows the position of USA 276 relative to the ISS on the European evening of June 3, if USA 276 has not manoeuvered by then:

click image to enlarge

Due to slightly different rates of precession of their orbital nodes, the orbits will slowly diverge from their current close coincidence over time, unless USA 276 makes a corrective manoeuvre.

I have pondered the question whether this all is coincidental or not. While I can in fact think of a potential goal where this all would be on purpose, that would be a very wild thing to do, so perhaps it is not so likely. For the moment, let's better chalk it up to coincidence until new developments seem to point otherwise.

What is NROL-76 and what orbit wil it be launched into?

Tomorrow, 30 April 2017, with (from the area warnings) a three-hour launch window starting at 10:55 UT, SpaceX will launch a classified satellite for the NRO. The launch is designated NROL-76 and will happen from launchpad 39A at Cape Canaveral, Florida. The press-kit is here.

There has been some speculation on what this launch might be and what orbit it will go into.

Considering the latter, Ted Molczan discussed three options in two separate SeeSat-L posts (here and here): a launch into HEO (Molniya) orbit of a new SDS satellite; a launch into GEO of a new NEMESIS; or a launch into LEO, perhaps a new version of the ill-fated USA 193 launch from 2006.

The launch azimuth deduced from the Area Warnings that appeared after Ted posted his initial speculation on the payload, narrowed the options down to two: HEO or LEO. To me, the Area Warnings strongly suggest the second option: a launch into LEO, perhaps a USA 193 follow-up.

The Maritime Area Warnings published for the launch show two hazard zones: one near Cape Canaveral, and one, with a window opening four-and-a-half hours later than the launch window, in the Indian Ocean stretching from south of Madagascar to north of Kerguelen:

NAVAREA IV 342/17 [1 of 1][[WWNWSFOLDER]]

WESTERN NORTH ATLANTIC.
FLORIDA.
1. HAZARDOUS OPERATIONS 301055Z TO 301354Z APR,
ALTERNATE 011055Z TO 011354Z MAY
IN AREA BOUND BY
28-39N 080-39W, 30-34N 078-45W,
31-32N 077-34W, 31-26N 077-13W,
31-06N 077-11W, 30-47N 077-32W,
30-08N 078-26W, 28-29N 080-21W,
28-26N 080-27W, 28-25N 080-35W,
28-25N 080-38W.
2. CANCEL THIS MSG 011454Z MAY 17.//

Authority: EASTERN RANGE 211830Z APR 17.

Date: 271553Z APR 17
Cancel: 01145400 May 17


HYDROPAC 1447/17 [1 of 1][[WWNWSFOLDER]]

SOUTHWESTERN INDIAN OCEAN.
DNC 02, DNC 03.
1. HAZARDOUS OPERATIONS 301438Z TO 301715Z APR,
ALTERNATE 011438Z TO 011715Z MAY
IN AREA BOUND BY
30-31S 038-04E, 30-40S 040-19E,
40-11S 060-06E, 47-31S 080-01E,
48-56S 079-46E, 49-00S 075-21E,
47-12S 063-50E, 41-51S 049-33E,
35-39S 040-15E, 32-07S 037-37E.
2. CANCEL THIS MSG 011815Z MAY 17.//

Authority: EASTERN RANGE 211827Z APR 17.

Date: 250231Z APR 17
Cancel: 01181500 May 17

I have put them in maps for your convenience:

click map to enlarge

The first area points to a launch azimuth of 43-45 degrees, indicating (if no dog-leg is involved) launch into an orbital inclination of 50-51 degrees as can be seen in the first map I prepared, above. This would at first sight exclude launch into HEO/Molniya orbit at inclination 63.4 degrees, unless of course a dog-leg manoeuvre is involved, which is possible.

click map to enlarge

The second area, in the Indian Ocean, points to the de-orbit of the upper stage about 4.5 hours after launch and actually matches a launch into an ~51 degree inclined LEO orbit as well.

In the map below, I have printed an estimated Low Earth orbit for the upper stage of the launch, based on the 2006 USA 193 orbit in terms of apogee and perigee, but with the orbital inclination changed to 51 degrees. About 2.4 orbits after launch, near 14:38 UT when the hazard warning window opens, the stage would be over Africa on its way to the hazard area, which has a position and curvature matching the trajectory (given the uncertainties in my orbit estimate) close enough, in my opinion, to accept this potential scenario of launch into an approximately 51 degree inclined, about 355 x 375 km orbit, or something similar to that:

click map to enlarge

One has to wonder though why the de-orbit is 2.5 revolutions after launch, and not simply during the second part of the first revolution. Perhaps some experiments will be done with the stage? Or does it deliver additional (small) payloads perhaps? Your guess is as good as mine.

In terms of the payload itself, Ted Molczan has posted some interesting info to SeeSat-L suggesting the payload is based on  Boeing's commercial, completely electrical thrust BSS-702SP bus.

The purpose of the payload(s?) is completely unclear at the moment. Radar satellites such as Lacrosse/ONYX were previously launched into 57-58 degree inclined orbits or their retrograde 123 degree equivalent (FIA/TOPAZ). Optical reconnaissance satellites such as KH-11 are launched in 97 degree inclined sun-synchronous orbits. NOSS (INTRUDER) SIGINT duo's are launched into 63.4 degree inclined stable perigee orbits. If this payload ends up in a 51 degree orbit, this is new.

There is a possibility that, while initially launched and inserted into a 51 degree orbit (a launch trajectory with which SpaceX is familiar from their CRS launches to the ISS), the payload next manoeuvres into a 58 degree or even 63.4 degree orbit on its own, using its electrical thrusters.

It will be interesting to see what orbit the object or objects eventually will be found in. It is likely it will be designated "USA 276".

If the 51-degree orbital inclination scenario is correct, observers in the Northern hemisphere will, unfortunately for me, not have visual sighting opportunities after launch: optical detection will rest on the shoulders of Southern hemisphere observers.

[added note 29 apr 15:15 UT] On April 30, be aware for possible re-entry sightings from Madagascar, especially the southern part of the island, near 14:40 UT, in early twilight (assuming launch at ~11:00 UT).