Author Topic: LIVE: Soyuz-2-1A - Progress MS-07 Events - October 14 onwards, 2017  (Read 24782 times)

Offline Nick

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Apologies if I've missed this somewhere but does anyone know how long the launch window actually was today? I can't find that nugget either in the thread or referenced articles (I have looked...).

Thanks
Nick

Offline Sam Ho

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I'm guessing that this will require reprogramming of the Progress's navigation computer for the new post-seperation flight profile? Will they need to roll back to do that?

34-orbit profile is always available as a backup to the fast rendezvous profile. The decision to use the fast rendezvous is made after launch when they have tracking data.

Apologies if I've missed this somewhere but does anyone know how long the launch window actually was today? I can't find that nugget either in the thread or referenced articles (I have looked...).

I think it's usually ten seconds.

Offline Nick

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Apologies if I've missed this somewhere but does anyone know how long the launch window actually was today? I can't find that nugget either in the thread or referenced articles (I have looked...).

I think it's usually ten seconds.
Crikey, I didn't realise it was as short as that - and that's the normal window, not the two-orbit window presumably? Which I assume is likely to be shorter still, if anything.

Nick

Online centaurinasa

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Did the scrub ruin the two-orbit planned manuever?
Yes, but only for today. They may try again next Saturday.
Nope. The 2 orbit rendezvous profile require certain orbital conditions to be present, mainly phase angle. On Saturday the phase angle is too large so they have default back to the standard rendezvous profile that takes two days.
For a 4 orbit RDV profile, the phase angle can be no more than 35 ...
« Last Edit: 10/12/2017 11:01 AM by centaurinasa »

Online Salo

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Online eeergo

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Abort/cut off occurred after the separation of the first umbilical tower but prior to the separation of the second/final umbilical tower. This could have something to to do with the cut off. Maybe it's a case of command sent but not executed so a automatic cut off was initiated.

I have rewatched the Tsenki webcast (see below, starting at 7:07) and the abort is called *before* the separation of the first umbilical tower (which happens a full 13 seconds later, at 7:20). Therefore the cause of the abort wouldn't be the engine start-up sequence.

Incidentally, considering the first umbilical mast is retracted at T-40s, there are two main events happening right before that (20s): transfer to internal power and autosequence start (T-1m).

-DaviD-

Offline Mark McCombs

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Thank you to Steven, Chris and all others for coverage of the aborted launch attempt.

 8)
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Offline Sam Ho

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Crikey, I didn't realise it was as short as that - and that's the normal window, not the two-orbit window presumably? Which I assume is likely to be shorter still, if anything.
Launch window is set by the need to launch when Baikonur is in the plane of the ISS orbit, so that Progress and ISS have the same RAAN.  You can adjust the RAAN a bit by flying a yaw profile if performance and the guidance program support it, but of current vehicles that fly to the ISS, only Atlas does that.  (Shuttle could do it as well.)

The ability to use the fast rendezvous is limited by the phase angle, how far the ISS is around its orbit at the moment of the Progress launch.  The launch window set by the limit on the phase angle for fast rendezvous would be about ten minutes.

Online Phillip Clark

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Never seen this before! They turned off the main screens at MCC-M!
Next launch opportunity is Saturday. 9:46 UTC - if they can correct the issue.

My photo of the control room just as  our BBC TV team were leaving on March 24, 1988.   While we were filming the Russians were showing a re-run of the Soyuz-TM 4 redocking.
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Online Alter Sachse

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a small amateur radio satellite is to be launched with Progress MS-07
https://amsat-uk.org/tag/iskra-5/
Iskra 1,2 and 3 were launched 1981 and 1982
Iskra MAI 85 14.07.2017 (with Canopus V-IK)

Offline Nick

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Launch window is set by the need to launch when Baikonur is in the plane of the ISS orbit, so that Progress and ISS have the same RAAN.  You can adjust the RAAN a bit by flying a yaw profile if performance and the guidance program support it, but of current vehicles that fly to the ISS, only Atlas does that.  (Shuttle could do it as well.)

The ability to use the fast rendezvous is limited by the phase angle, how far the ISS is around its orbit at the moment of the Progress launch.  The launch window set by the limit on the phase angle for fast rendezvous would be about ten minutes.
Sorry, I'm a bit confused now. How does the ten minutes relate to the ten seconds you mentioned earlier?

Do you mean that the phase angle constraint (10mins) is irrelevant because the RAAN constraint is tighter?

Nick

Online Mike_1179

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Sorry, I'm a bit confused now. How does the ten minutes relate to the ten seconds you mentioned earlier?

Do you mean that the phase angle constraint (10mins) is irrelevant because the RAAN constraint is tighter?


Probably due to launching in-plane as opposed to because of phase angle.

Rough calculation: launch site and ISS have to have a phase angle of no more than 35 degrees of each other at launch. One orbit would be 360 degrees, so the phase angle constraint is about 10% of the orbital period of the ISS (360/35 = 10%). ISS orbital period is about 90 minutes, 10% of 90 minutes is about 10 minutes. Hence the reason he said you have about a 10 minute window where the ISS would be at the right phase angle to launch.

However, if the Soyuz can't do yaw steering, then you have to liftoff when the launch site rotates into the plane of the ISS orbit which would happen twice a day (well, once a day if you only go on an ascending or descending node). That's what drives the short launch window - having to lift off when you're in plane with the ISS. The Earth rotates really fast so once you're more than a few seconds off you'd launch to the correct inclination but the longitude of your ascending node will be wrong. You'd have to wait for the nodal precession to move your orbit into the same one as the ISS. Nodal precession is slow, the ISS's nodal precession period is about every 2 months (360 / 60 days = 3-ish degrees per day).

Getting the right longitude for the ascending node is more time-critical than the phase-angle requirement.
« Last Edit: 10/12/2017 06:01 PM by Mike_1179 »

Offline BabaORileyUSA

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Getting the right longitude for the ascending node is more time-critical than the phase-angle requirement.

Isn't the longitude of ascending node dependent only on launch azimuth?  Same booster, same payload, same launch site, same launch azimuth, same ground trace, and same longitude of ascending node.  I don't see a time dependence here....
« Last Edit: 10/12/2017 06:29 PM by BabaORileyUSA »

Offline Sam Ho

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Getting the right longitude for the ascending node is more time-critical than the phase-angle requirement.
Isn't the longitude of ascending node dependent only on launch azimuth?  Same booster, same payload, same launch site, same launch azimuth, same ground trace, and same longitude of ascending node.  I don't see a time dependence here....
Yes, the longitude of the ascending node is dependent only on the launch azimuth, but the right ascension of a given longitude rotates with the Earth.  The ISS orbit is in inertial space so (disregarding precession) it has a fixed right ascension of ascending node.  Thus, you have to time the launch to match right ascensions of the respective ascending nodes.

And yes, my earlier comment meant that if you don't do yaw steering, and want to match RAANs, you only have a few seconds of launch window before fixing the RAAN error in orbit becomes prohibitively costly, whereas if you were just trying to get a phase angle within a 35 range and didn't care about the RAAN, you have about 10% of the orbital period, which gives you around 10 minutes.  If you were trying to fly a hypothetical 4-orbit rendezvous for a Cygnus on Atlas, which has yaw steering profiles to correct RAAN across a 30-minute window, the phase angle limits would only let you use about 10 of those 30 minutes.  The rest of the window, the Atlas could get you to the right RAAN, but you would need a longer rendezvous to match phases.

We're drifting a bit from the topic of this thread, but oddly enough, the threads in the Q&A section that seem like they would be relevant only touch on launch windows tangentially.  In any case, the fast rendezvous we are talking about here is presently used only on Progress and Soyuz.

Offline Sam Ho

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Coming back to Progress MS-07, Roscosmos has confirmed that the next launch attempt is on Saturday:
Quote
ROSCOSMOS. THE LAUNCH OF SPACE ROCKET SOYUZ-2.1A IS MOVED TO THE RESERVE DATE
October 12, 2017, 14:27 GMT
By decision of the State Commission, the launch of the space mission vehicle as part of the carrier rocket Soyuz-2.1A and transport cargo vehicle Progress MS-07 has been moved to reserve date of October 14, 2017.
http://en.roscosmos.ru/20699/

Online Galactic Penguin SST

Regarding yesterday's scrub, it seems that on NK forums the reason was stated as due to some electrical connector failing to disconnect just before lower mast retraction, which prevented switching to internal power.

Source
Chinese spaceflight is a cosmic riddle wrapped in a galactic mystery inside an orbital enigma... - (not) Winston Churchill

Online centaurinasa

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Re: LIVE: Soyuz-2-1A - Progress MS-07 - October 14, 2017 onwards
« Reply #116 on: 10/14/2017 07:15 AM »
Another Sunny day for this second attempt !

Online centaurinasa

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Re: LIVE: Soyuz-2-1A - Progress MS-07 - October 14, 2017 onwards
« Reply #117 on: 10/14/2017 07:17 AM »

Online centaurinasa

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Re: LIVE: Soyuz-2-1A - Progress MS-07 - October 14, 2017 onwards
« Reply #118 on: 10/14/2017 07:20 AM »

Online centaurinasa

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Re: LIVE: Soyuz-2-1A - Progress MS-07 - October 14, 2017 onwards
« Reply #119 on: 10/14/2017 07:28 AM »
The "famous" unidentified experiment...

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