First positive observations of the LED beacon of the NAPA-2 6U cubesat

 

On June 30, 2021, a Falcon 9 launched several cubesats in a rideshare launch called Transporter-2. One of the payloads was a 6U cubesat called NAPA-2. 

This cubesat was built by the Dutch company ISISpace in Delft (the same company that built Brik-II) for the Royal Thai Air Force. It is an IMINT satellite, carrying two small Earth observation camera's. It is in a 97.5 degree inclined sun-synchronous 520 x 540 km orbit with passes around local midnight and noon.

This is the NAPA-2 cubesat after assembly (image courtesy of ISISpace): the 6U cubesat measures about 10 x 20 x 30 cm.

image (c) ISISpace, used with permission.

NAPA-2 has an interesting novelty: it carries a beacon of 12 bright LED's that can be switched on and off by the satellite operators. 

It is an experiment to see if such a bright artificial lightsource on the satellite can aid in optically tracking it.

The past few days saw the commissioning of this feature. ISISpace had asked me whether I could try to image the LED beacon from Leiden. Attempts to image it were made on three nights. 

The first attempt, on August 24 using a 1.4/85 mm lens, was negative.

The second attempt was on August 25. The operators had reorientated the satellite such that the LED's were pointing at the groundstation. This attempt was marginally positive: it was seen but the satellite was extremely faint and barely visible and the trail was lost in the noise background in a frame stack.

A third attempt was made last night, in the early hours of 27 August. This time I used a more powerfull lens, the Samyang 2.0/135 mm. The camera was a WATEC 902H2 Supreme operating at 25 frames/s.

The result was a positive detection: the LED beacon of the satellite, although faint, was unambiguously imaged. The range to the satellite was 598 km during the observation. It was imaged around culmination at 61 degrees altitude in the east.

 

click to enlarge

 

Below is the video: the object, coming into the FOV from the right, is very faint, but visible. It disappears near the center of the image because the LED was switched off: the operators operated it is a "3-seconds-on, 1-second-off" mode last night.

Below is a framestack of 60 frames from the video (2.4 seconds of footage). A faint but unmistakable trail can be seen entering the FOV from the right: the LED beacon of NAPA-2! The bright star near the bottom of the image is 13 Persei.

Below is a negative image version of the same stack: and a positive version where I pushed the image such that the trail comes out better.

 

 

It should be noted that the cubesat was imaged in a part of it's trejactory where it was in Earth shadow: so all the light solely comes from the 12 LED's!

This is the LED array on the satellite (image courtesy of ISISPace):

image (c) ISISpace, used with permission.

Amazing that 12 LED's are visible from a distance of almost 600 km! 

The LED beacon does not operate continuously: it is only briefly switched on when passing over a tracking station (in this case, my observing location). It reaches an Rmag of about +10.

Below are the astrometric residuals relative to CSpOC elset 21239.30175625 (angles are in degrees, delta T in seconds), showing the good match:

     STA   YYday HH:MM:SS.sss   AZ     EL     XTRK     deltaT   Perr
( 1) 4353  21239 00:52:38.401   78.0   60.9   -0.02     0.02    0.023
( 2) 4353  21239 00:52:38.441   77.9   60.9   -0.02     0.04    0.033
( 3) 4353  21239 00:52:38.600   77.7   60.9   -0.02     0.03    0.030
( 4) 4353  21239 00:52:38.920   77.2   61.0   -0.02     0.03    0.025
( 5) 4353  21239 00:52:38.960   77.2   61.0   -0.02     0.06    0.044
( 6) 4353  21239 00:52:39.241   76.7   61.0   -0.02     0.03    0.031
( 7) 4353  21239 00:52:39.561   76.2   61.0   -0.02     0.03    0.031
( 8) 4353  21239 00:52:39.600   76.2   61.0   -0.02     0.05    0.044
( 9) 4353  21239 00:52:39.761   75.9   61.0   -0.02     0.03    0.025
(10) 4353  21239 00:52:39.801   75.9   61.0   -0.03     0.04    0.041

rms     0.03367

Imaging objects from the 'Tubular Bells' launch

image: Virgin Orbit

During the first days of July, I have tried to image objects from the June 30 Virgin Orbit 'Tubular Bells' launch, that launched a number of smallsats including Brik-II, the first Dutch military satellite (see earlier posts here and here).

I so far managed to unambiguously image three objects from the launch. One of these is probably the LauncherOne upper stage, the other two must be payloads.

On July 2nd, I imaged objects A and B, A using a 2.0/135 mm and B using a 1.4/85 mm lens on the WATEC 902H2 Supreme low light level video camera. B was very faint and barely visible.

On July 4th, I unambiguously imaged objects B and H using a 2.0/135 mm lens.

Object A is relatively bright and well ahead of the other objects. It is in a somewhat lower orbit: a 418 x 504 km orbit, whereas the other objects are in a 496 x 522 km orbit. So object 2021-058A almost certainly is the LauncherOne upper stage.

Below is video of the A-object, shot on July 2nd with the 2.0/135 mm lens. The bright star top left is Polaris. I could not see the other objects (passing about 30 minutes later): for passes to the north of me, the illumination angle is less favourable than for passes to the south of me.

 

The B and H objects are fainter, and only visible during passes to the south of me. The video below shows them, faint but unmistakenly, during a pass in evening twilight on July 4th (sun at only 7 degrees below the horizon, so the sky background was still quite bright).

 

A fourth object, Object C, was possibly seen on July 2nd when I watched the pass live on screen, but I could not see it anymore when inspecting the footage afterwards. 

Objects D, E, F and G were not seen, but on all imaged passes observing conditions were not perfect (on July 2, cirrus clouds were invading the FOV around the time of the objects D, E, F and G passing; while on July 4th the sky background was still very bright).

It is not clear which object is which at the moment, although I have reasons to believe that Brik-II must be either object D, E or F. I have some suspicion that objects B and H are part of STP27-VPA. [edit: see updates below: Object H was, but B is not).

UPDATE:

I obtained even better imagery of the two STORK objects (B and C) on July 17:

 

UPDATE 14 Jul 2021:

Object B actually appears to be one of the STORK satellites, based on Dopplerfitting of  radiosignals received at 401.1 MHz (and first detected by Alicja Musial in Poland). Object C also appears to be a STORK, based on Doppler fitting of the radio signal.. 

Objects D and E are now listed by CSpOC as CNCE3 and CNCE1, which are part of STP27-VPA.

Objects F, G and H then are Brik-II, Gunsmoke-J and Halo-NET (the latter two are part of STP27-VPA), with not certain which is which.

UPDATE 16 Jul 2021

Object F is now identified as Brik-II. Object H (One of the two objects I imaged on July 4) is now identified as Gunsmoke-J 2. 

As, from radio Doppler fitting, we know objects B and C are the STORKS (not yet identified as such by CSpOC), this means object G must be Halo-NET:

Object A    LauncherOne rb

Object B    Stork

Object C    Stork

Object D    CNCE3*

Object E    CNCE1*

Object F    Brik-II

Object G   Halo-NET*

Object H    Gunsmone-J 2*

* part of STP27-VPA

Bob Christy has pointed out that there might be a swap of the A and G designation in the future, to make the A designation a payload rather than the RB.

Navigational Warnings have appeared for the launch of the first Dutch military satellite, Brik-II [UPDATED]

 

artist impression of Brik-II in space (The Netherlands Ministry of Defense)

It was originally scheduled for launch in 2019, and postponed several times. But it now seems it will finally happen, on or near June 30: the launch of the Netherlands' first own military satellite, a 6U cubesat named 'Brik-II'.

The ministry of Defense of the Netherlands is partner in several already launched military satellites, but this will be the first satellite that is truely it's own. 

Brik-II was built by the Dutch aerospace company ISISPACE in cooperation with Delft Technical University, Oslo University and NLR and will be operated by the Royal Netherlands Air Force (RNLAF).

It is a small 6U cubesat (10 x 20 x 30 cm, weighing 10 kg) that contains equipment for communications relay, for Space Weather monitoring, and for ELINT (see my earlier post on Brik-II here).

 

image: The Netherlands Ministry. of Defense

 

Brik-II will be launched by Virgin Orbit as part of their  'Tubular Bells, part 1' mission that launches a number of small payloads: apart from Brik-II for the RNLAF, it will launch three or four (sources differ on the number [edit July 1: it were four payloads]) payloads for the US Dept. of Defense, and two payloads for the SatRevolution company.

The launch is an airborne launch, using a two-stage LauncherOne rocket launched from the Virgin Orbit Boeing 737 747-400 'Cosmic Girl' in front of the California coast.

images: Virgin Orbit

The launch was postponed several times, including this month, but Navigational Warnings have now appeared indicating an aimed launch date of 30 June (with backup dates July 1-5). 

The 3-hour launch window runs from 13:00-16:00 UT [edit: launch eventually was at 14:47 UT]. According to Virgin Orbit, the orbit aimed for is a 60-degree inclined circular orbit at ~500 km altitude. [edit] An infographic by the Royal Dutch Air Force mentions an orbital inclination of 60.7 degrees.

This is the navigational warning, NAVAREA XII 292/21:

 262041Z JUN 21
 NAVAREA XII 292/21(18,21).
 EASTERN NORTH PACIFIC.
 CALIFORNIA.
 1. HAZARDOUS OPERATIONS, ROCKET LAUNCHING
    301300Z TO 301600 JUN, ALTERNATE
    1300Z TO 1600Z DAILY 01 THRU 05 JUL
    IN AREAS BOUND BY:
    A. 33-36-44N 120-23-05W, 33-24-22N 120-17-14W,
       32-55-44N 119-55-39W, 30-38-19N 118-13-14W,
       28-24-39N 116-37-52W, 28-03-32N 116-17-09W,
       28-10-00N 116-05-44W, 28-24-41N 116-11-12W,
       29-07-31N 116-36-05W, 30-50-51N 117-46-19W,
       33-08-50N 119-32-16W, 33-33-26N 119-54-35W,
       33-45-27N 120-06-00W, 33-43-27N 120-16-02W,
       33-36-44N 120-23-05W.
    B. 23-13-25N 112-20-09W, 23-51-12N 113-00-01W,
       24-04-05N 113-17-34W, 24-00-35N 113-35-42W,
       23-49-04N 113-49-26W, 23-23-22N 113-46-59W,
       22-46-17N 113-39-25W, 22-01-49N 113-03-13W,
       21-54-11N 112-57-20W, 21-46-52N 112-49-48W,
       21-41-03N 112-38-21W, 21-40-45N 112-26-55W,
       21-44-25N 112-12-12W, 21-52-03N 112-03-22W,
       22-03-39N 111-58-08W, 22-13-42N 111-57-29W,
       22-26-28N 112-02-59W.
 2. CANCEL THIS MSG 051700Z JUL 21.

I have plotted the two areas on the map below, along with the trajectory for a 60-degree inclined ~500 km orbit, with times along the trajectory valid for launch at 13:00 UT, the start of the window (it will, however, probably launch a little after that: the second map is for a 60.7 degree inclined orbit and denotes times in minutes after launch):

click map to enlarge

click map to enlarge

While Virgin Orbit mentions a 500 km target orbit for 'Tubular Bells', earlier news reports on Brik-II mentioned a 600-700 km orbital altitude.

Brik-II is named for an earlier 'Brik', the name of the very first aircraft of the RNLAF progenitor, the 'Luchtvaartafdeeling', 108 years ago, in 1913:

The first Brik, photographed in 1916. Photo: Netherlands Institute for Military History

 

"Brik" has several meanings in Dutch. Originally it was a name for a type of ship (equivalent to the English 'Brig'), and it was also used for carts. Later, it became a name for old bicycles and old, decrepit  cars. "Brik" in addition is one of several Dutch names for a brick, hence the mission patch for Brik-II:

Brik-II mission patch (collection author)

Update 1 July 2021:

CSpOC TLE's have appeared on Space-Track for 8 objects from the launch: the seven payloads and the LauncherOne upper stage. They have catalogue numbers 48871 to 48878. The first object, 48871, is in a lower orbit  of 418 x 504 km and almost certainly the LauncherOne upper stage. The seven others are close together in higher, approximately 495 x 522 km orbits, inclined between 60.66 to 60.70 degrees.

Of these objects, either object D, E, or F (catalogue nrs. 48874, 48875, 48876) appears to be Brik-II.

My pre-launch estimate for the orbit appears to have a quite reasonable agreement with the eventual orbits for these objects (the green arrow and object in the images below indicates my pre-launch estimate. the plot is for 1 July 6:35 UT,  about 16 hours after launch):

click images to enlarge

Launching cubesats from the X-37B OTV 5: lifetime modelling with GMAT

image: USAF

Last week, CSpOC issued catalogue entries for three cubesats released as part of the X-37B mission OTV 5.

It concerns USA 295 (2017-052C), USA 296 (2017-052D) and USA 297 (2017-052E). No orbital data are given, but the catalogue entry did explicitly indicate that all three are no longer on orbit.

That cubesats were released as part of this X-37B mission had been clear from a US Air Force statement made after completion of the OTV 5 mission in October last year. The wording of that statement is however ambiguous: while most analysts take it to mean the cubesats were released by OTV 5, it is also possible that they were released as ride shares by the upper stage of the Falcon 9 rocket that launched OTV 5 in 2017.

In this blog post, I will do an academic exercise aimed at guessing when, at the latest, these cubesats could have been released by OTV 5, assuming release from the latter.

OTV 5, the 5th X-37B mission, was launched from Cape Canaveral on 7 September 2017. It landed at the Kennedy Space Center Shuttle Landing Facility on 27 October 2019, after 780 days in space. Unlike previous missions that were all launched in 38-43 degree inclined orbits, this one was launched into a 54.5 degree inclined orbit. Combined with the fall launch date, this meant it took our tracking network a while to locate it on-orbit: the first positive observations were made in April 2018, half a year after launch.

From April 2018, when we started to track it, to October 2019, when it landed, OTV 5 orbitted at various orbital altitudes between 300 and 390 km altitude (see diagram below):

click diagram to enlarge

The CSpOC catalogue entry lists all three cubesats that were released as part of this mission as "no longer on orbit". Assuming they ended their orbital life by natural decay (rather than, for example, being retrieved by OTV 5 again at a later stage, which is in theory certainly possible!), the fact that they were no longer on orbit by 11 February 2020 might yield some constraints on when they could have been released.

To get some idea of the orbital lifetime of a cubesat released from OTV 5, and spurred on to do so by Jonathan McDowell, I ran several GMAT models in which I modelled a 5 kg 3U cubesat released at three altitudes: 400 km, 360 km and 325 km.

We do not know the actual orbital altitude of OTV 5 at that  moment. Nor do we know when the cubesats were released. Hence the three altitude variants. The start point of the modelling was an assumed release into the OTV 5 orbit on October 7, 2017, one month after launch of OTV 5.

For each cubesat, the models were run in two variants: one with the cubesat in minimal drag orientation (0.01 m² cross section), and one with the cubesat in maximal drag orientation (0.03 m² cross section). I used the MSISE90 atmosphere in the model, with historic Space Weather data for October 2017 to February 2020 and estimated solar and geomagnetic activity parameters from the 'early cycle' variant of the GMAT Schattenfile for dates past early 2020.

For the three assumed orbital altitudes and an assumed release one month after OTV 5 launch, the GMAT data produce the orbital decay plots below. In these plots, the red data are for minimal drag orientation, the blue data for maximal drag orientation. If the cubesats in question were similar to NRO's Colony II cubesats, then the red minimum drag orientation curves probably represent the orbital evolution best. If they were more like Colony I cubesats, then the blue maximal drag curves are more representative.

Taking the minimal drag variants, and under the assumption that the cubesats were 3U cubesats and not retrieved on-orbit by OTV 5 at a later stage, the suggestion is a release below 350 km. Released at higher altitudes, they would still be on-orbit.

Assuming reentry before 11 February 2020 after natural orbital decay, a minimal drag orientation and release no lower and no higher than 325 km, the latest possible moment of release would be late August 2018, give or take a month to account for the uncertainties.

It appears we can rule this out however, because we know that OTV 5 was orbiting at 380 km altitude, not 325 km altitude, at that time. So the best guess (although one under many assumptions) is a release some time before August 2018, i.e. within 1 year after the launch of OTV 5.

It is still possible that the cubesats were released at a later date, but next retrieved while still on-orbit by OTV 5. If the cubesats were smaller than a 3U cubesat, a later release than August 2018 is possible as well.

Finally, given the ambiguity in US Air Force Statements on the matter, it is also possible that the cubesats were released from the Falcon 9 upper stage on the day of launch.

For more about the X-37B, and especially the active myth-making that seems to be at play around this secretive space-plane, see my earlier post here.

OTV 5 rising in April 2018. Click image to enlarge

Imaging FLOCK 2E 4 near decay

In the early morning of 27 February 2018, I was imaging a rocket stage from a classified launch, the NOSS 3-4 r/b, when suddenly a very fast, flashing object entered the FOV, and I followed it as it looked interesting (it was so fast that in the first instance I thought it was a meteor). It turned out to be the cubesat FLOCK 2E 4 (1998-067 JH, #41487).

FLOCK 2E 4 is a cubesat that was released from Cygnus OA-6 in May 2016. It is currently in a 247 x 260 km, 51.6 degree inclined orbit, and from the imagery it is clearly tumbling. It is coming down fast, with several km/day, as it is close to decay. An analysis with SatAna and SatEvo predicts that it will re-enter in about a week, on or near 2018 March 6-7.

The diagram below shows how the orbital altitude changed since it was released at 400 km altitude from Cygnus OA-6 in May 2016:

click diagram to enlarge

FLOCK 2E 4 was built by Planet Labs and was one of the imagers in their FLOCK constellation. It basically is a small 9 cm telescope with a camera, and delivered imagery of the Earth's surface with a resolution of a few meters.

FLOCK cubesat (image: Planet Labs)

It is a very small object, the smallest I have managed to image in Earth Orbit so far. The body measures only 34 x 10 x 10 cm, and with solar panels deployed, the maximum dimension is 34 x 30 cm. A lucky capture!

The camera used was the WATEC 902H with a Canon FD 1.8/50mm lens.