Author Topic: SpaceX Falcon 9 - NROL-76 - May 1, 2017 - DISCUSSION  (Read 219284 times)

Offline Star One

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Re: SpaceX Falcon 9 - NROL-76 - May 1, 2017 - DISCUSSION
« Reply #640 on: 05/28/2017 07:40 PM »
An object, a few meters across doesnt look much from 25km distance. I doubt that any astronaut would be able to tell any details without magnification gear like a very good binocular or small telescope.

I am pretty sure they have those aboard.

Online Lars-J

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Re: SpaceX Falcon 9 - NROL-76 - May 1, 2017 - DISCUSSION
« Reply #641 on: 05/28/2017 10:44 PM »
So is the theory that NROL-76 is an experimental observer of space assets, and that it was placed near ISS to use it as a calibration target?

Online toren

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Re: SpaceX Falcon 9 - NROL-76 - May 1, 2017 - DISCUSSION
« Reply #642 on: 05/29/2017 01:20 AM »
How about a small, on-orbit version of this, using ISS / cube sat releases - among other potential encounters - to test feasibility of a network of hostile sat detectors in the future?

Offline cscott

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Re: SpaceX Falcon 9 - NROL-76 - May 1, 2017 - DISCUSSION
« Reply #643 on: 05/30/2017 02:20 PM »
Disadvantage would be that Russians on ISS could also observe the satellite at the 25km approach.  So unless proximity to ISS was key to its mission I can't see why they'd let their supersecret experiment wander so close to ISS.

Offline Comga

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Re: SpaceX Falcon 9 - NROL-76 - May 1, 2017 - DISCUSSION
« Reply #644 on: 05/30/2017 02:35 PM »
Disadvantage would be that Russians on ISS could also observe the satellite at the 25km approach.  So unless proximity to ISS was key to its mission I can't see why they'd let their supersecret experiment wander so close to ISS.

None of this conjecturing about the NROL-76 payload seems convincing to me, but this point has technical issues.
From where would the cosmonauts observe nadir?
I am sure someone here knows exactly where windows are located in Zvezda etc.  Are there any Earth facing windows on the Russian side?
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline 4353

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Re: SpaceX Falcon 9 - NROL-76 - May 1, 2017 - DISCUSSION
« Reply #645 on: 05/30/2017 03:18 PM »
So, I made some animations.

If the *current* orbit for USA 276 does not change (an important caveat!!!), this is what will happen on June 3 when USA 276 makes a couple of (very) close approaches to the ISS. If the DRAGON CRS-10 history is taken as a guideline, DRAGON CRS-11 should also be close (although perhaps not as close as in this animation):



Note how it is effectively circling the ISS.

And this is what the situation would be a day later, when CRS-11 berths to the ISS.



Odd, isn't it? Still do not know what to think about it.


« Last Edit: 05/30/2017 03:21 PM by 4353 »

Offline Star One

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Re: SpaceX Falcon 9 - NROL-76 - May 1, 2017 - DISCUSSION
« Reply #646 on: 05/30/2017 04:26 PM »
Disadvantage would be that Russians on ISS could also observe the satellite at the 25km approach.  So unless proximity to ISS was key to its mission I can't see why they'd let their supersecret experiment wander so close to ISS.

None of this conjecturing about the NROL-76 payload seems convincing to me, but this point has technical issues.
From where would the cosmonauts observe nadir?
I am sure someone here knows exactly where windows are located in Zvezda etc.  Are there any Earth facing windows on the Russian side?

Why?

It seems a pretty logical capability to put in place especially as not far down the line time wise ISS will not be the only space station in LEO.

Online Lars-J

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Re: SpaceX Falcon 9 - NROL-76 - May 1, 2017 - DISCUSSION
« Reply #647 on: 05/30/2017 05:26 PM »
Disadvantage would be that Russians on ISS could also observe the satellite at the 25km approach.  So unless proximity to ISS was key to its mission I can't see why they'd let their supersecret experiment wander so close to ISS.

None of this conjecturing about the NROL-76 payload seems convincing to me, but this point has technical issues.
From where would the cosmonauts observe nadir?
I am sure someone here knows exactly where windows are located in Zvezda etc.  Are there any Earth facing windows on the Russian side?

Yes. The best window in Zvezda is Earth facing.

Offline John Santos

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Re: SpaceX Falcon 9 - NROL-76 - May 1, 2017 - DISCUSSION
« Reply #648 on: 05/30/2017 05:37 PM »
From the animations, it appears the closest approaches are at orbital sunrise and sunset.  Is this significant?

Online Semmel

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Re: SpaceX Falcon 9 - NROL-76 - May 1, 2017 - DISCUSSION
« Reply #649 on: 05/30/2017 08:12 PM »
Here is an argument against the ISS spying:

Launch date NET is April 16 with the window opening at 7am local, for around two hours.

If it was planned to chase the ISS, it seems odd to have a 2 hour launch window. Unless you have two ~ 1-min discrete launch windows within 2 hours exactly 92 minutes and 39 seconds apart..

There was also this odd 15 minute delay of the launch, rescheduling it to 7:15 instead of 7:00 local. Might have been done to target the station, might be coincidence.

Online Lars-J

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Re: SpaceX Falcon 9 - NROL-76 - May 1, 2017 - DISCUSSION
« Reply #650 on: 05/30/2017 11:02 PM »
Here is an argument against the ISS spying:

Launch date NET is April 16 with the window opening at 7am local, for around two hours.

If it was planned to chase the ISS, it seems odd to have a 2 hour launch window. Unless you have two ~ 1-min discrete launch windows within 2 hours exactly 92 minutes and 39 seconds apart..

There was also this odd 15 minute delay of the launch, rescheduling it to 7:15 instead of 7:00 local. Might have been done to target the station, might be coincidence.

The ISS position at launch is irrelevant. A tiny orbital maneuver will allow any spacecraft launch in phase to match it. All that is needed is a slight lowering or raising of the orbit, and eventually you'll drift closer to ISS.

Offline envy887

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Re: SpaceX Falcon 9 - NROL-76 - May 1, 2017 - DISCUSSION
« Reply #651 on: 05/30/2017 11:20 PM »
Here is an argument against the ISS spying:

Launch date NET is April 16 with the window opening at 7am local, for around two hours.

If it was planned to chase the ISS, it seems odd to have a 2 hour launch window. Unless you have two ~ 1-min discrete launch windows within 2 hours exactly 92 minutes and 39 seconds apart..

There was also this odd 15 minute delay of the launch, rescheduling it to 7:15 instead of 7:00 local. Might have been done to target the station, might be coincidence.

The ISS position at launch is irrelevant. A tiny orbital maneuver will allow any spacecraft launch in phase to match it. All that is needed is a slight lowering or raising of the orbit, and eventually you'll drift closer to ISS.

You mean any launch in plane, not any launch in phase. Which brings up another point... Falcon 9 doesn't do yaw steering, so launches to a specific plane are instantaneous windows.

Of course, this could have been a de facto instantaneous window even though they announced it as a 2 hour window. Or they could have been targeting a specified range of planes around ISS, which would have allowed a small window instead on an instantaneous one. But not 2 hours.

Online Lars-J

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Re: SpaceX Falcon 9 - NROL-76 - May 1, 2017 - DISCUSSION
« Reply #652 on: 05/30/2017 11:48 PM »
Here is an argument against the ISS spying:

Launch date NET is April 16 with the window opening at 7am local, for around two hours.

If it was planned to chase the ISS, it seems odd to have a 2 hour launch window. Unless you have two ~ 1-min discrete launch windows within 2 hours exactly 92 minutes and 39 seconds apart..

There was also this odd 15 minute delay of the launch, rescheduling it to 7:15 instead of 7:00 local. Might have been done to target the station, might be coincidence.

The ISS position at launch is irrelevant. A tiny orbital maneuver will allow any spacecraft launch in phase to match it. All that is needed is a slight lowering or raising of the orbit, and eventually you'll drift closer to ISS.

You mean any launch in plane, not any launch in phase. Which brings up another point... Falcon 9 doesn't do yaw steering, so launches to a specific plane are instantaneous windows.

Of course, this could have been a de facto instantaneous window even though they announced it as a 2 hour window. Or they could have been targeting a specified range of planes around ISS, which would have allowed a small window instead on an instantaneous one. But not 2 hours.

Yes, I meant plane. And you are correct, the fact that they had a 2hr launch window indicates that the near plane to ISS was a coincidence, not the plan. (unless the secret launch window really was instantaneous) ;)

Offline manoweb

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Re: SpaceX Falcon 9 - NROL-76 - May 1, 2017 - DISCUSSION
« Reply #653 on: 05/31/2017 12:15 AM »
Falcon 9 doesn't do yaw steering, so launches to a specific plane are instantaneous windows.

We know this simply because they never announced it can do it, or it has been confirmed it cannot? I am not an expert at all, is specific hardware needed that is obviously not present on the Falcon 9?

Offline intrepidpursuit

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Re: SpaceX Falcon 9 - NROL-76 - May 1, 2017 - DISCUSSION
« Reply #654 on: 05/31/2017 12:20 AM »
Falcon 9 doesn't do yaw steering, so launches to a specific plane are instantaneous windows.

We know this simply because they never announced it can do it, or it has been confirmed it cannot? I am not an expert at all, is specific hardware needed that is obviously not present on the Falcon 9?

I second this question. It seems really odd to me that a rocket that can land on a boat in the ocean can't do yaw steering. It has the control authority, so this would have to be a flight computer issue, which also seems like a strange limitation.

Offline cscott

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Re: SpaceX Falcon 9 - NROL-76 - May 1, 2017 - DISCUSSION
« Reply #655 on: 05/31/2017 12:35 AM »
The yaw steering question has come up in the past and Jim has stated definitively that SpaceX does not do yaw steering during ascent, and that it is an avionics issue.  Take that as you will, I suspect various posters have different theological positions on Jim's infallibility.

Offline kevin-rf

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Re: SpaceX Falcon 9 - NROL-76 - May 1, 2017 - DISCUSSION
« Reply #656 on: 05/31/2017 01:24 AM »
The yaw steering question has come up in the past and Jim has stated definitively that SpaceX does not do yaw steering during ascent, and that it is an avionics issue.  Take that as you will, I suspect various posters have different theological positions on Jim's infallibility.
I read that not as they can not, but do not do it. Which says nothing for the capability, they may or may not be able to, just they do not feel at present that having and using the capability is worth the cost.
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Offline Star One

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Re: SpaceX Falcon 9 - NROL-76 - May 1, 2017 - DISCUSSION
« Reply #657 on: 05/31/2017 07:18 AM »
Here is an argument against the ISS spying:

Launch date NET is April 16 with the window opening at 7am local, for around two hours.

If it was planned to chase the ISS, it seems odd to have a 2 hour launch window. Unless you have two ~ 1-min discrete launch windows within 2 hours exactly 92 minutes and 39 seconds apart..

There was also this odd 15 minute delay of the launch, rescheduling it to 7:15 instead of 7:00 local. Might have been done to target the station, might be coincidence.

The ISS position at launch is irrelevant. A tiny orbital maneuver will allow any spacecraft launch in phase to match it. All that is needed is a slight lowering or raising of the orbit, and eventually you'll drift closer to ISS.

You mean any launch in plane, not any launch in phase. Which brings up another point... Falcon 9 doesn't do yaw steering, so launches to a specific plane are instantaneous windows.

Of course, this could have been a de facto instantaneous window even though they announced it as a 2 hour window. Or they could have been targeting a specified range of planes around ISS, which would have allowed a small window instead on an instantaneous one. But not 2 hours.

Yes, I meant plane. And you are correct, the fact that they had a 2hr launch window indicates that the near plane to ISS was a coincidence, not the plan. (unless the secret launch window really was instantaneous) ;)
The fact that it had a supposed 2 hour launch window does not necessarily mean that was the actual launch window when it comes to an NRO launch. I'd think they would deliberately be vague about such stuff.
« Last Edit: 05/31/2017 09:45 AM by Star One »

Offline 4353

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Re: SpaceX Falcon 9 - NROL-76 - May 1, 2017 - DISCUSSION
« Reply #658 on: 05/31/2017 08:48 AM »
Regarding the orbital plane target, there is every reason to believe the ISS orbital plane was deliberately targetted.

The launch time needed for launching directly into the ISS orbit plane shifts by 20 minute per day.

Launch of NROL-76 was originally set for 30 April but as we all know, a booster issue at the last minute caused a hold and a 1-day delay.

The Area Warning given before the launch actually has a window opening at 10:55 UT:

NAVAREA IV 342/17

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

Launch on May 1, after the 1-day delay was 11:15 UT, which is 20 minutes later than the opening time of the area warning. Which happens to equal the ISS orbital plane shift for a 1-day delay.


EDIT: I take that back. I overlooked that on April 30 they also targetted 11:15. Confusing, confusing...
« Last Edit: 05/31/2017 08:51 AM by 4353 »

Offline 4353

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Re: SpaceX Falcon 9 - NROL-76 - May 1, 2017 - DISCUSSION
« Reply #659 on: 05/31/2017 09:47 AM »
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. Note that USA 276 is not exactly in the orbital plane of the ISS (there is a 1.6 degree inclination difference anyway).

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.

« Last Edit: 05/31/2017 09:48 AM by 4353 »

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