SpaceX Falcon 9 : Hispasat 30W-6 (1F) : March 6, 2018 - DISCUSSION

[CJ]

Pretty sure the rotation is intentional, if you check past SSL 1300 separation video, you can see similar maneuver by the 2nd stage prior to release, so I think this is probably a requirement by the satellite.

JCSAT-16: https://www.youtube.com/watch?v=OERDIFnFvHs?t=2883

Echostar XXIII: https://www.youtube.com/watch?v=dM2Dp1Adlag?t=2739

Jim's (rather short) explanation: https://forum.nasaspaceflight.com/index.php?topic=40374.msg1654851#msg1654851

I think you nailed it. Great catch!

The vids do show what looks to be the same deploy pattern. I wonder why a sat would require that?

[deruch]

Pretty sure the rotation is intentional, if you check past SSL 1300 separation video, you can see similar maneuver by the 2nd stage prior to release, so I think this is probably a requirement by the satellite.

JCSAT-16: https://www.youtube.com/watch?v=OERDIFnFvHs?t=2883

Echostar XXIII: https://www.youtube.com/watch?v=dM2Dp1Adlag?t=2739

Jim's (rather short) explanation: https://forum.nasaspaceflight.com/index.php?topic=40374.msg1654851#msg1654851

I think you nailed it. Great catch!

The vids do show what looks to be the same deploy pattern. I wonder why a sat would require that?

Here's Jim's actual answer to George's question: 

If so, why did they do that rather than stay parallel?

Spacecraft requirements

[OneSpeed]

Parking orbit is low, just 165 km.  From this orbit, need to increase speed to 10276 m/s for GEO apogee.   But since Earth spin provided 402 m/s, we need 9874 m/s, or 35550 km/hr by SpaceX speedometer.   If it gets this it's GTO or greater.

I suspect 165kms is actually the near the perigee of a somewhat elliptical parking orbit, about 160 x 300km.
A rough analysis suggests the GTO burn will have gotten to around 9700m/s at best, and the initial orbit will be sub-synchronous. The satellite's kick motor may yet have some work to do.

[LouScheffer]

Keeping score at home:  Assuming that HispaSat is 6100 kg, and they recover (or close to recover) the booster, then something must have changed.   Previous max mass (5300 kg) recoverable missions staged at  about 8450 kmhr.  Here are 4 theories that have been proposed here and how we can tell them apart, in real time while watching the webcast.

(a) Staging less than 9000 km/hr, and transfer orbit short of GTO.: Regular block 4.  Customer accepted less than full GTO, possibly in return for recoverable discount.
(b) Staging less than 9000 km/hr, and transfer orbit GTO or greater:   Second stage must have been upgraded.
(c) Staging >= 9000 km/r, entry burn is about 20 seconds:  Must be a block 4.5 booster.  4.0 could not get to this speed with 20 seconds of entry burn fuel left.
(d) Staging >= 9000 km/hr, entry burn is about 10 seconds:  Block 4, titanium fins allow more slowing by drag and less by engine.
[...]
To tell if GTO has a GEO or greater apogee, look for a second stage cutoff speed of 35,280 km/hr (9800 m/s) or more, in the SpaceX telemetry coordinate system.

OK, (c) and (d) are ruled out.   First stage performance was normal for a Block 4, and the entry burn was about 22 seconds from the call-outs.   So we are left with (a) or (b), which we cannot yet distinguish since they did not show telemetry of second stage burn.  But the burn was short, less than a minute.   So I'm leaning towards (a), but we'll know once the TLEs come out.

[robert_d]

So, since the rotation is not along the radial axis, then would it be fair to assume that deployment of the antennae and/or solar arrays imparts an opposite force that cancels what we see? Impressive analysis of freefall dynamics if true.

[cscott]

I was just listening to the launch again, but this time I was listening to the technical audio only. Considering that we never heard the landing burn call out and since a few people were like "aww "  right after the re-entry burn shut down call out, I'm guessing they lost the signal and B1044 may not have survived re-entry. Or, they lost the signal but since they did not have a boat in the area to relay telemetry, they had to confirm visually whether or not the first stage managed a soft splashdown. That's probably what Elon's private jet was for.

(Sorry if this was obvious to some of you).

There was a cry of disappointment from the crowd but obviously it's hard to know exactly what that was about. More significantly, perhaps, one of the usual callouts is "stage 1 is transonic", which didn't happen, along with subsequent calls for landing burn and leg deploy.

I think Occam's razor is that they lost the downlink at that point, and that if Elon's plane was grabbing that portion of the telemetry (likely IMO) it doesn't have real-time relay capability so Hawthorne HQ wasn't getting a feed.

That means we just don't know anything about success or failure after the disappointed aw, unless Elon decides to tweet about it.

History seems to indicate that failures tend to happen during the final landing burn, especially with the low erosion of the new Ti fins, so I wouldn't expect anything other than loss of telemetry would cause an "aw" at the time we heard it.

[speedevil]

So, since the rotation is not along the radial axis, then would it be fair to assume that deployment of the antennae and/or solar arrays imparts an opposite force that cancels what we see? Impressive analysis of freefall dynamics if true.

It would be very unusual indeed for the satellite to deploy anything before unmating from the stage.
And indeed, we can see most of the satellite has not deployed anything (of course we can't see the bit away from the camera) when it does deploy.
As a side-note, the rotation is slow enough that this is certainly not what is driving the deployment from S2.
Perhaps to have an antenna pointed at the right ground-station during deploy?

[mn]

I was just listening to the launch again, but this time I was listening to the technical audio only. Considering that we never heard the landing burn call out and since a few people were like "aww "  right after the re-entry burn shut down call out, I'm guessing they lost the signal and B1044 may not have survived re-entry. Or, they lost the signal but since they did not have a boat in the area to relay telemetry, they had to confirm visually whether or not the first stage managed a soft splashdown. That's probably what Elon's private jet was for.

(Sorry if this was obvious to some of you).

I'm pretty sure I heard a call out for 'Stage 1 LOS (as) expected' (more or less, can't listen again right now). The call out was soon after SECO1.

[mn]

Pretty sure the rotation is intentional, if you check past SSL 1300 separation video, you can see similar maneuver by the 2nd stage prior to release, so I think this is probably a requirement by the satellite.

JCSAT-16: https://www.youtube.com/watch?v=OERDIFnFvHs?t=2883

Echostar XXIII: https://www.youtube.com/watch?v=dM2Dp1Adlag?t=2739

Jim's (rather short) explanation: https://forum.nasaspaceflight.com/index.php?topic=40374.msg1654851#msg1654851

I think you nailed it. Great catch!

The vids do show what looks to be the same deploy pattern. I wonder why a sat would require that?

Here's Jim's actual answer to George's question: 

If so, why did they do that rather than stay parallel?

Spacecraft requirements

Seems similar to the special requirements in VA241

https://forum.nasaspaceflight.com/index.php?topic=44833.msg1792515#msg1792515

Edit:
If this is indeed the same special requirement, it would be odd to be unprecedented for Ariane but has already been done several times by SpaceX

[kdhilliard]

I was just listening to the launch again, but this time I was listening to the technical audio only. Considering that we never heard the landing burn call out and since a few people were like "aww "  right after the re-entry burn shut down call out, I'm guessing they lost the signal and B1044 may not have survived re-entry. Or, they lost the signal but since they did not have a boat in the area to relay telemetry, they had to confirm visually whether or not the first stage managed a soft splashdown. That's probably what Elon's private jet was for.

(Sorry if this was obvious to some of you).

I'm pretty sure I heard a call out for 'Stage 1 LOS (as) expected' (more or less, can't listen again right now). The call out was soon after SECO1.

There was a "cape loss of signal expected" call out which can be heard clearly on the Countdown Net Audio @29:02, or in the background of the Hosted Webcast @29:04 / T+09:08.  It doesn't clarify stage 1 or stage 2.   Comparing with the GovSat-1 launch, their LOS Cape Canaveral was at T+07:51 for Stage 1 and T+08:57 for Stage 2.

[Lars-J]

Pretty sure the rotation is intentional, if you check past SSL 1300 separation video, you can see similar maneuver by the 2nd stage prior to release, so I think this is probably a requirement by the satellite.

JCSAT-16: https://www.youtube.com/watch?v=OERDIFnFvHs?t=2883

Echostar XXIII: https://www.youtube.com/watch?v=dM2Dp1Adlag?t=2739

Jim's (rather short) explanation: https://forum.nasaspaceflight.com/index.php?topic=40374.msg1654851#msg1654851

I think you nailed it. Great catch!

The vids do show what looks to be the same deploy pattern. I wonder why a sat would require that?

A slight rotation of the entire stack will help with separation if the release mechanism doesn't give its normal push, perhaps?

[speedevil]

A slight rotation of the entire stack will help with separation if the release mechanism doesn't give its normal push, perhaps?

If you look carefully at the separation, you can see that though the stage and satellite are rotating, the spin axis seems to be aligned with the centre of the satellite.
So, no aid to separation.
Plus, the separation looks to be around 1m/s, which would have taken quite a rapid spin to equal.

[LouScheffer]

Two objects related to today's #Falcon9 launch tracked in a sub-GTO orbit
2018-023A: 184 x 22,261 km, 26.97°
2018-023C: 186 x 22,215 km, 26.92°

https://twitter.com/Spaceflight101/status/971074423108358144

From this I find about 320 m/s to raise apogee to GEO, then 1800 m/s to circularize.   Total about 2120 m/s to go.

So performance was typical for a block 4, and customer accepted less than GEO apogee.

[BeamRider]

Question for discussion: what lessons, if any, should Spacex take away from the inability to recover the booster due to high seas preventing deployment of ASDS? Not sure if they wanted to recover or not but I assume they did from the way they described the situation. Do they need bigger landing ships (note the size of ship in BO landing video)? Do they need to focus on more robust RTLS capability? Sooner or later they are gonna really really want the booster back but really really need to go ahead and launch even if they can’t use ASDS, right? What then?

[gongora]

Two objects related to today's #Falcon9 launch tracked in a sub-GTO orbit
2018-023A: 184 x 22,261 km, 26.97°
2018-023C: 186 x 22,215 km, 26.92°

https://twitter.com/Spaceflight101/status/971074423108358144

From this I find about 320 m/s to raise apogee to GEO, then 1800 m/s to circularize.   Total about 2120 m/s to go.

So performance was typical for a block 4, and customer accepted less than GEO apogee.

If the numbers on the old paperwork are still close this bird had about 2700kg of fuel earmarked for reaching GEO, the dry mass was only 43% of the total launch mass.

[gongora]

Question for discussion: what lessons, if any, should Spacex take away from the inability to recover the booster due to high seas preventing deployment of ASDS? Not sure if they wanted to recover or not but I assume they did from the way they described the situation. Do they need bigger landing ships (note the size of ship in BO landing video)? Do they need to focus on more robust RTLS capability? Sooner or later they are gonna really really want the booster back but really really need to go ahead and launch even if they can’t use ASDS, right? What then?

Catching up on the manifest would be a good start.  It might be more acceptable to wait a week or two for good weather if the customer hasn't already been waiting a few months for the launch.  There are going to occasionally be sea states that don't allow recovery at sea, and RTLS often won't be an option for performance reasons with F9.

[Formica]

Two objects related to today's #Falcon9 launch tracked in a sub-GTO orbit
2018-023A: 184 x 22,261 km, 26.97°
2018-023C: 186 x 22,215 km, 26.92°

https://twitter.com/Spaceflight101/status/971074423108358144

From this I find about 320 m/s to raise apogee to GEO, then 1800 m/s to circularize.   Total about 2120 m/s to go.

So performance was typical for a block 4, and customer accepted less than GEO apogee.

Thanks for sharing all this math with us, Lou. It has been very educational and I really appreciate it. Quite revealing on the business side too.

Edit: thank you Demidrol too for finding the orbit info

[cscott]

Those not on the East Coast might not realize the severity of the storm system in play. Even commercial air shut down for this one.  A bigger boat isn't an answer here.  Some days flying things just have to stand down.

[e of pi]

Two objects related to today's #Falcon9 launch tracked in a sub-GTO orbit
2018-023A: 184 x 22,261 km, 26.97°
2018-023C: 186 x 22,215 km, 26.92°

https://twitter.com/Spaceflight101/status/971074423108358144

From this I find about 320 m/s to raise apogee to GEO, then 1800 m/s to circularize.   Total about 2120 m/s to go.

So performance was typical for a block 4, and customer accepted less than GEO apogee.

I just had checked myself and came up with similar values when I saw you'd posted already. Your conclusions from them also seem sound.

[Lar]

Question for discussion: what lessons, if any, should Spacex take away from the inability to recover the booster due to high seas preventing deployment of ASDS? Not sure if they wanted to recover or not but I assume they did from the way they described the situation. Do they need bigger landing ships (note the size of ship in BO landing video)? Do they need to focus on more robust RTLS capability? Sooner or later they are gonna really really want the booster back but really really need to go ahead and launch even if they can’t use ASDS, right? What then?

Catching up on the manifest would be a good start.  It might be more acceptable to wait a week or two for good weather if the customer hasn't already been waiting a few months for the launch.  There are going to occasionally be sea states that don't allow recovery at sea, and RTLS often won't be an option for performance reasons with F9.

Might be a better suited discussion for "customer views of reuse" or similar but I predict,[1] , that over time contracts will be written that say weather scrubs are part of the deal, they might happen, and weather at recovery site is as valid a reason for a scrub as weather at the launch site. And, if you want a guarantee of no recovery site scrubs, it costs X million extra.

Agree that being caught up on the manifest makes this more palatable...

1 -  based on nothing other than fannishness and perhaps a dose of wishful thinking