Author Topic: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION  (Read 173929 times)

Online kdhilliard

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #460 on: 10/16/2017 01:06 PM »
Do you need to be logged in or something? Reply 637 in that thread no longer has the picture. At least on a mobile device.

Yes sorry. Because I am always logged in I forgot.

Apparently another poster said the same model featured in a 60 minutes documentary two years back so it obviously isn’t as intriguing as thought.



The X-37B discussion starts at 22:20.  The model, seen from several different angles, is shown from 22:34 to 23:16.  This 60 Minutes episode, "The Battle Above", aired on 26 April 2015.

~Kirk

Offline Star One

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #461 on: 10/16/2017 10:41 PM »
Some others online have picked up about that model X-37B now.

https://mobile.twitter.com/FG_STrim/status/919941483851079680

Offline SpaceCadet1983

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #462 on: 10/27/2017 08:30 PM »
The Boeing X-37B mock-up is in HQ Air Force Space Command not Global Strike Command.

Offline astropl

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #463 on: 11/03/2017 01:10 PM »
Quote
On the evening of 2017 Nov 02 UTC, Russell Eberst made new observations of the bright UNID he spotted on the morning of 2017 Oct 03 UTC, that we suspect is OTV 5.

The following circular orbit fits Russell's timed positions, one each on Oct 03 and Nov 02:

OTV 5 suspect                                            403 X 404 km
1 77203U 77203A   17306.77911249  .00000000  00000-0  00000-0 0    08
2 77203  63.5883 190.6553 0001000   0.0010   0.1122 15.54162386    02

It should be recovered easily in the above orbit. The eccentricity could be somewhat greater, in which case there will be small time and cross-track errors.

I would like to perform a bit more analysis to assure myself this is OTV 5, before I assign the ID: OTV 5 (USA 277), 2017-052A / 42932.

OTV 5 most likely was inserted into an approximately 43 deg parking orbit. My guess is that the second stage of its Falcon 9 booster performed the manoeuvre to change the inclination, which I intend to attempt to verify.

Russell's relevant observation reports:

http://satobs.org/seesat/Oct-2017/0007.html

http://satobs.org/seesat/Nov-2017/0007.html

Russell, what was its approximate magnitude on Nov 02, prior to entry into the penumbra?

Ted Molczan

Link.
« Last Edit: 11/03/2017 01:28 PM by gongora »
Waldemar Zwierzchlejski (astropl)
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Online Comga

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #464 on: 11/04/2017 02:23 AM »
63.588 deg inclination if this one is correct.  Unexpected, but an interesting inclination - not far from Molniya orbit inclinations (63.4 deg), though obviously those satellites are in 12 hour orbits versus OTV-5's likely 1.5 hour orbit.

 - Ed Kyle

But doesn’t any orbit at 63.4 degrees inclination have a fixed argument of perigee, where the apogee and perigee do not roll around the orbit, as it is not a function of semi-major axis (orbit altitude)? Even if the orbit is only slightly elliptical the apogee could remain over a fixed latitude.  You could get a somewhat longer “hang time” or a somewhat lower perigee over a specific target once a day with that inclination.

Do we need a better determined orbit to see what the apogee and perigee are over?
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline OneSpeed

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #465 on: 11/04/2017 05:30 AM »
63.588 deg inclination if this one is correct.  Unexpected, but an interesting inclination - not far from Molniya orbit inclinations (63.4 deg), though obviously those satellites are in 12 hour orbits versus OTV-5's likely 1.5 hour orbit.

 - Ed Kyle

If it is correct, it's over the Himalayas right now.

Online meberbs

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #466 on: 11/04/2017 05:52 AM »
63.588 deg inclination if this one is correct.  Unexpected, but an interesting inclination - not far from Molniya orbit inclinations (63.4 deg), though obviously those satellites are in 12 hour orbits versus OTV-5's likely 1.5 hour orbit.

 - Ed Kyle

But doesn’t any orbit at 63.4 degrees inclination have a fixed argument of perigee, where the apogee and perigee do not roll around the orbit, as it is not a function of semi-major axis (orbit altitude)? Even if the orbit is only slightly elliptical the apogee could remain over a fixed latitude.  You could get a somewhat longer “hang time” or a somewhat lower perigee over a specific target once a day with that inclination.

Do we need a better determined orbit to see what the apogee and perigee are over?
You need the orbit period to be an integer fraction of a sidereal day for that to matter (usually 12 hours) Otherwise the earth rotating underneath it means that when it reaches apogee the longitude directly underneath it will be (effectively) random. The special inclination for Molinya eliminates J2 perturbation on the argument of perigee, but this is not important if your orbit period isn't correlated to the Earth's rotation to begin with.

Offline Star One

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #467 on: 11/04/2017 09:31 AM »
Further to the above.

Quote
I did an attempt this evening. Unfortunately, the sky deteriorated rapidly after
sunset. Quite hazy conditions, but stars visible on the photographs and video.

Video (WATEC + 1.8/50 mm) and photo camera registered nothing around the 18:20
UT pass. I had shadow ingress predicted for 50 degrees elevation in the N-NW
near 18:21:00 UT.

If weather cooperates, new attempts tomorrow and the day after tomorrow (when I
should have a good near-zenith pass).

- Marco

http://www.satobs.org/seesat/Nov-2017/0011.html

Offline zubenelgenubi

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #468 on: 11/04/2017 01:53 PM »
HYDROPAC 3033/2017 (GEN) 

WESTERN SOUTH PACIFIC.
SOUTHERN INDIAN OCEAN.
1. HAZARDOUS OPERATIONS SPACE DEBRIS
   071754Z TO 072226Z SEP, ALTERNATE
   081754Z TO 082226Z AUG IN AREA BOUND BY
   51-00S 077-10E, 44-44S 160-09E,
   58-59S 161-33E, 65-20S 078-27E.
2. CANCEL THIS MSG 082326Z SEP 17.

( 051942Z SEP 2017 )

(Map attached to quoted post)

If the orbital inclination were increased from the parking orbit inclination by the 2nd stage in a second burn, followed by release of the OTV payload, and then followed by the 3rd disposal burn of the 2nd stage into this warning area, then this could explain why the disposal area over the deep southern "Southern Ocean" did not match the expected orbital inclination derived from the Northern Atlantic Notices to Airmen/Mariners.  (I believe this was noted at the time of the warning postings.)

The disposal area warning appears to match an 63.6 deg. orbital inclination.  What do our satellite observing experts think?

How many orbits after launch would the 2nd stage re-entry have been?

How much delta-v would the 2nd stage have to expend to change orbital inclination from 43 deg. to 63.6 deg.?
« Last Edit: 11/04/2017 03:46 PM by zubenelgenubi »
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Online kevin-rf

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #469 on: 11/05/2017 12:37 AM »
Yaogan and NOSS, etc., the multisatellite SIGINT formations that orbit around 1,000 km or so circular, are around the same inclination (63.4 deg).  This orbit is used to avoid a "gradual increase in orbital eccentricity" caused by perturbations in Earth's gravity, according to Wiki.  Perhaps a strong hint at whatever test payload(s) is/are on board.

 - Ed Kyle
Instead of some prototype...

Maybe, the low orbit will give what ever is in that payload bay a good view of all these fancy satellites and space (debris) around 63 degrees.. Kinda like ORS-5, or some covert SIGNIT. Maybe the 63 degrees doesn't require the near constant surveillance that is being done with the GEO.

Just a wild guess. 
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Offline zubenelgenubi

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #470 on: 11/06/2017 02:30 AM »
How much delta-v would the 2nd stage have to expend to change orbital inclination from 43 deg. to 63.6 deg.?

According to Ted Molczan, a lot!  See: RE: OTV 5 search elements
Quote
The search orbit I posted for the 63.6 deg inclined OTV 5 suspect is too far in plane from the estimated 43 deg parking orbit of OTV 5, to have been manoeuvred there by the Falcon 9 second stage. The burn angle would have been nearly 45 deg, requiring an orbital manoeuvre with delta-V in excess of 5800 m/s.

More details follow in his post about searches using the search elements supplied on November 3.
Quote
Russell Eberst and David Hopkins report that the OTV 5 suspect was a no-show in the search TLE that I posted, which casts serious doubt on the reliability of that orbit.

And, Russell Eberst's November 2 observation was likely of another "lost" satellite:
Quote
Russell has suggested that his Nov 02 UTC sighting may have been of an old NOSS object. NOSS 1-7 (E) (86014E / 16624) appears to correlate.

However, I do note that Mr. Eberst does not call his observation of October 3 into question.

And, we still apparently have a 2nd stage that de-orbited along a final trajectory with an orbital (suborbital?) inclination substantially greater than 43 deg.

The amateur search continues, I presume!
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Offline aero

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #471 on: 11/06/2017 03:55 AM »
Quote
How much delta-v would the 2nd stage have to expend to change orbital inclination from 43 deg. to 63.6 deg.?

delta-v = v * sin (alpha) , alpha is the angular change in inclination.
delta-v = v * sin(20.6 deg)
delta-v = v * 0.36, approximately.

so it depends on the slowest velocity that the second stage reached which happens at apogee.
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Offline deruch

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #472 on: 11/06/2017 04:15 AM »
It would be really funny if the Air Force has tasked someone to follow posts by amateur observers and then every time someone catches a glimpse of the vehicle, they perform a maneuver to change the orbit.
Shouldn't reality posts be in "Advanced concepts"?  --Nomadd

Offline Ted Molczan

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #473 on: 11/06/2017 12:29 PM »
Quote
How much delta-v would the 2nd stage have to expend to change orbital inclination from 43 deg. to 63.6 deg.?

delta-v = v * sin (alpha) , alpha is the angular change in inclination.
delta-v = v * sin(20.6 deg)
delta-v = v * 0.36, approximately.

so it depends on the slowest velocity that the second stage reached which happens at apogee.

I agree with your numeric result, for a manoeuvre at the equator in a circular orbit. The precise formula is delta-v = 2 * v * sin (alpha/2), but for small alpha, your version is close enough. However, alpha would only be the change of inclination for a manoeuvre at the equator, where RAAN (right-ascension of the ascending node) would not change. The case in question would have required a manoeuvre at a latitude other than the equator; therefore, both inclination and RAAN would have changed.

The search orbit (now probably defunct) that I derived from Russell Eberst's observations was:

1 77203U 77203A   17306.77911249  .00000000  00000-0  00000-0 0    08
2 77203  63.5883 190.6553 0001000   0.0010   0.1122 15.54162386    02

Based on NOTAMs, OTV 5 was targeted for a 43 deg inclination orbit. Assuming same altitude as the above 77203 orbit, the parking orbit at the time of launch on Sep 07 would have been as follows:

1 77202U 77202A   17250.58750000  .00000000  00000-0  00000-0 0    09
2 77202  43.0000  82.2000 0001000   0.0000  44.3000 15.54162000    05

Propagating the 77203 elements to the epoch of the 77202 elements yields RAAN near 31.3 deg. Therefore, a manoeuvre from the 77202 parking orbit to the 77203 final orbit would have required increasing the inclination from 43 deg to 63.6 deg, but also decreasing the RAAN from 82.2 deg to 31.3 deg.

The following formula is applicable to a change of both inclination and RAAN:

cos(alpha) = cos(INC1) cos(INC2) + sin(INC1) sin(INC2) cos(RAAN1 - RAAN2)

For the above case, alpha would have been about 44.7 deg, requiring delta-V of about 76% of initial velocity, or more than 5800 m/s.

The manoeuvre could only have occurred at a point of intersection between the orbits, which for the above case would have been near 42.5 deg N descending (true anomaly ~99 deg) or 42.5 S ascending (true anomaly ~279 deg). Alpha would have been the same for both.

Ted Molczan



Online LouScheffer

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #474 on: 11/06/2017 01:01 PM »
Quote
How much delta-v would the 2nd stage have to expend to change orbital inclination from 43 deg. to 63.6 deg.?

delta-v = v * sin (alpha) , alpha is the angular change in inclination.
delta-v = v * sin(20.6 deg)
delta-v = v * 0.36, approximately.

so it depends on the slowest velocity that the second stage reached which happens at apogee.

I agree with your numeric result, for a manoeuvre at the equator in a circular orbit. [But...]

For the above case, alpha would have been about 44.7 deg, requiring delta-V of about 76% of initial velocity, or more than 5800 m/s.
There are lots of practical problems here, but suppose the stage made a left turn right after staging.  Then the orbit change would be MUCH cheaper, particularly since Falcon stages at a low velocity.

The first stage provides something like 2600 m/s.  If it's aimed 20 degrees from where you want it, the component in the desired direction is 2600*cos(20) or about 2443 m/s.  So the second stage has only to make up 157 m/s or so, easily within its capabilities.

I think there are at least two problems with this.  First Falcon has never demonstrated such steering.  Second I think (without calculation) this would take the stage over the northeast USA and Canada, where (a) people could see it, and (b) it might be a hazard.   

But in theory they could change at any time in the ascent, not just right after staging.  The longer they wait, the more expensive it is.  But the second stage has a lot more delta-V than needed (something like 2800 m/s for GTO flights) so some compromise might be possible - wait long enough to miss the land masses, but short enough to keep the delta-V plausible.

Offline zubenelgenubi

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #475 on: 01/18/2018 09:01 PM »
Re: amateur satellite observer's observations (or not) of the OTV-5 flight of an X-37B: A thought.

Has anyone thought of asking as many amateur astronomers as possible to participate in a "maximum effort" to find it?

(I'm sure the Air Force knows where it is, and I'm almost 100% sure that one or more of our "frenemies" is tracking OTV-5/USA-277, but if they shared their observations, "that would be telling."  But it's rare for a satellite in (assumed) LEO to go so long without confirmed observations and an orbit derived by the amateur satellite observing community.)

(See 02:18 in the YouTube clip.)


« Last Edit: 01/18/2018 09:15 PM by zubenelgenubi »
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Offline Star One

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #476 on: 08/30/2018 08:07 PM »
The X-37B OTV 5 is manoeuvering to a higher orbit

https://sattrackcam.blogspot.com/2018/08/the-x-37b-otv-5-is-manoeuvering-to.html?m=1

Let the speculation begin!

Offline Draggendrop

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #477 on: 09/02/2018 04:55 AM »
Dr Marco Langbroek has some nice images ( 8 hrs ago from this post) on his twitter account...

https://twitter.com/Marco_Langbroek

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