SpaceX Falcon 9 : SES-12 : June 4, 2018 : Discussion

[harry2680]

Spaceflightnow has the launch date set to NET 24th of May as of the 24th of April.

[Ben the Space Brit]

So, as matters stand, the count-down stands at about 8 days. Any news? Is the launcher at the Cape yet? Payload processing?

[mn]

[Spaceflight Now] New target dates set for next two Falcon 9 launches

On that mission, which an SES official said is currently scheduled for no earlier than May 31, SpaceX will haul the Airbus-built SES 12 communications satellite toward a perch in geostationary orbit more than 22,000 miles (nearly 36,000 kilometers) over the equator.

Let's see what happens here because the Range is supposed to be closed from 29 May - 8 June for scheduled down period maintenance. 

---
https://www.nasaspaceflight.com/2018/04/spacexs-may-manifest-takes-shape-block-5-debut/

"The Eastern Range in Florida will close on 29 May for a scheduled 11 day period of maintenance and upkeep.  These planned Range down periods are communicated well in advanced to all Range customers and are vital to ensuring reliable Range functionality.

The Range will reopen on 9 June for normal launch operations."

So it seems at least as of now the launch is going ahead on the 31st.

Perhaps thanks to AFTS the range can support a launch even partially into the maintenance window? (depending on what equipment is being 'maintained').

Or did the range postpone the maintenance to accommodate SpaceX (wouldn't be the first time)?

[Yeknom-Ecaps]

Is there an image of the mission logo? I haven't been able to find it. Thanks.

[The Roadie]

Is there an image of the mission logo? I haven't been able to find it. Thanks.

SpaceX has been releasing the press kits with the logo recently only one day before launch.

[Roy_H]

So this comm license was applied for about a month ago and only granted today?

[gongora]

So this comm license was applied for about a month ago and only granted today?

What are you talking about?

[ChrisGebhardt]

[Spaceflight Now] New target dates set for next two Falcon 9 launches

On that mission, which an SES official said is currently scheduled for no earlier than May 31, SpaceX will haul the Airbus-built SES 12 communications satellite toward a perch in geostationary orbit more than 22,000 miles (nearly 36,000 kilometers) over the equator.

Let's see what happens here because the Range is supposed to be closed from 29 May - 8 June for scheduled down period maintenance. 

---
https://www.nasaspaceflight.com/2018/04/spacexs-may-manifest-takes-shape-block-5-debut/

"The Eastern Range in Florida will close on 29 May for a scheduled 11 day period of maintenance and upkeep.  These planned Range down periods are communicated well in advanced to all Range customers and are vital to ensuring reliable Range functionality.

The Range will reopen on 9 June for normal launch operations."

So it seems at least as of now the launch is going ahead on the 31st.

Perhaps thanks to AFTS the range can support a launch even partially into the maintenance window? (depending on what equipment is being 'maintained').

Or did the range postpone the maintenance to accommodate SpaceX (wouldn't be the first time)?

From what I've got, the Range was able to move a few things around to allow for the new date for SpaceX.  It appears, based on today's forecast that does not list a backup date for 1 June, that this is going to be a 1 shot only launch before having to stand down until the Range reopens.  I've reached out to SpaceX for confirmation on this last part.

[Bubbinski]

I see now the launch is delayed to at least June 4th to look at a possible 2nd stage issue. Will the range want to push it back to June 9th? Also how’s the weather looking for the 4th?

[gongora]

I see now the launch is delayed to at least June 4th to look at a possible 2nd stage issue. Will the range want to push it back to June 9th? Also how’s the weather looking for the 4th?

They wouldn't be saying the 4th if they hadn't already checked with the range.

[hkultala]

One subsequent tweet:

SES CTO Halliwell: "Monster engine" in #Falcon9 upper stage will fire 3 to 5 seconds longer to get #SES12 even higher. "Completely changes the dynamics of the project," he says. Those few seconds of burn time could get the satellite up to 7 more years of operational life.

https://twitter.com/emrekelly/status/1002234168015761408

Block 5 Mvac I wonder? (follow up to discussion thread)

Where does the fuel for those extra seconds come? Shouldn't more powerful engine consume the fuel faster?

Or did they leave some fuel unused for margin or deorbit burn, and now leaving less?

[DatUser14]

[/size]

One subsequent tweet:

SES CTO Halliwell: "Monster engine" in #Falcon9 upper stage will fire 3 to 5 seconds longer to get #SES12 even higher. "Completely changes the dynamics of the project," he says. Those few seconds of burn time could get the satellite up to 7 more years of operational life.

https://twitter.com/emrekelly/status/1002234168015761408Block 5 Mvac I wonder? (follow up to discussion thread)

Where does the fuel for those extra seconds come? Shouldn't more powerful engine consume the fuel faster?Or did they leave some fuel unused for margin or deorbit burn, and now leaving less?

Per Tom Cross, no  legs or fins on this booster. That might be enough fuel for 3-5 seconds more burn time on the second stage.
https://twitter.com/_TomCross_/status/1002218931703177216

[Doesitfloat]

Maybe it has a big party balloon so it doesn't need a orbit burn.

Maybe now that the legs and fins are removed from the booster, it stages faster leaving the upper stage with a few more seconds of fuel.

[Steven Pietrobon]

Some information from SES conference. SES 12 mass is 5,383.85 kg. Target orbit is 294x58,000 km. Extra performance from Falcon 9 increases satellite lifetime from 15 to 22 years. Geosynchronous orbit achieved 20 days faster in early January 2019.

[envy887]

Maybe it has a big party balloon so it doesn't need a orbit burn.

Maybe now that the legs and fins are removed from the booster, it stages faster leaving the upper stage with a few more seconds of fuel.

The only ways for the engine to burn longer are to either reduce mass flow through the engine or make more mass available for the engine to use. Changing the staging time does neither, and since Block 5 MVac has a 5% thrust increase, the mass flow through the engine is likely increased.

However, the faster LOX load in the Block 5 upper stage means that more LOX mass can be loaded since it stays colder and denser.

[edkyle99]

Maybe it has a big party balloon so it doesn't need a orbit burn.

Maybe now that the legs and fins are removed from the booster, it stages faster leaving the upper stage with a few more seconds of fuel.

The only ways for the engine to burn longer are to either reduce mass flow through the engine or make more mass available for the engine to use. Changing the staging time does neither, and since Block 5 MVac has a 5% thrust increase, the mass flow through the engine is likely increased.

However, the faster LOX load in the Block 5 upper stage means that more LOX mass can be loaded since it stays colder and denser.

Could be that the first stage is burning longer, using propellant that would have been used for landing.  That would reduce the second stage first burn length to reach its parking orbit, which would allow for a longer second burn.

Falcon 9 has already lifted at least one heavier payload to a higher orbit. 

 - Ed Kyle

[mark_m]

Maybe it has a big party balloon so it doesn't need a orbit burn.

Maybe now that the legs and fins are removed from the booster, it stages faster leaving the upper stage with a few more seconds of fuel.

The only ways for the engine to burn longer are to either reduce mass flow through the engine or make more mass available for the engine to use. Changing the staging time does neither, and since Block 5 MVac has a 5% thrust increase, the mass flow through the engine is likely increased.

However, the faster LOX load in the Block 5 upper stage means that more LOX mass can be loaded since it stays colder and denser.

Could be that the first stage is burning longer, using propellant that would have been used for landing.  That would reduce the second stage first burn length to reach its parking orbit, which would allow for a longer second burn.

Falcon 9 has already lifted at least one heavier payload to a higher orbit. 

 - Ed Kyle

Similarly, it seems that any extra performance by the first stage (compared with the most recent SES mission I assume?) would leave less work for the second stage first burn to reach the parking orbit, allowing for a longer second burn.

[LouScheffer]

Falcon 9 has already lifted at least one heavier payload to a higher orbit. 

That would be Inmarsat-5, mass 6086 kg, orbit 385 x 70134 x 24.5^o.   That was a burn-to-depletion.

Since this one has lower mass, and a lower apogee, the performance must be going towards inclination reduction.  This choice appears driven by the satellite - at the press conference, SES said the apogee is near the spacecraft limit.  However,  the performance is very similar.  Starting from a 300 km, 27^o parking orbit, by applying 2775 m/s (Inmarsat above) you can get:
    300 x 70,000 x 24.5^o with 1577 m/s to go, or
    300 x 58,000 x 22.3^o with 1588 m/s to go.

Compared to Inmarsat, dropping the payload to 5384 from 6086 should give 220 m/s more.  But it looks like a targeted shutdown, not a burn to depletion.  If we assume this leaves 1% of the fuel, and the second stage burns for 500 seconds, that's 5 seconds of operation, or something like 250 m/s at the final acceleration of 5G.  So the two effects should roughly cancel.  But we also have the Block 5 second stage.  Extra thrust would seem to have little effect since the second stage gravity losses are small, but better ISP or lower stage mass could help.  But by how much is not clear.

Considering all these factors and making a lottery-quality guess, I predict the final orbit will be:
  300 x 58,000 x 21.7^o with 1582 m/s to go.

[gongora]

I wonder how much that "little bit of chemical" propulsion is for initial perigee raising.  Will be interesting to see what this does after separation.

[RDMM2081]

Does this latest shift of the launch day to the 4th mean that the range maintenance has also shifted to start after the launch, or are they able to have squeezed the maintenance period in before the launch is scheduled to occur?