SpaceX FH: STP-2 : LC-39A : June 25, 2019 - DISCUSSION

[duh]

Somehow I messed up the following in trying to quote from an earlier post. Sorry
===================================================
STP-2 Max-Q is at T+00:42, a full 27 seconds earlier than for Arabsat-6A at T+01:09. This is going to be interesting.
[/quote]
====================================================

My comment(s):

Am I missing something on the other side of T-0 or have the times changed for the fuel and oxidizer loading?

SpaceX Launch Director verifies go for propellant load
 It is llsted as -53 minutes. My memory tells me it used to be 38 minutes.


1st stage RP-1 (rocket grade kerosene) loading begins
 This also, according to my memory and calculation, suggests this is also move forward by 15 minutes

1st stage LOX (liquid oxygen) loading begins
  Another 15 minute change

Also the final  satellite deployment is at:
   03:34:09

Prior indications were that this is a 6 hour mission. Is some interesting stuff being left out of the press kit
or is my imagination  running wild or ?

[gongora]

Somehow I messed up the following in trying to quote from an earlier post. Sorry
===================================================
STP-2 Max-Q is at T+00:42, a full 27 seconds earlier than for Arabsat-6A at T+01:09. This is going to be interesting.
====================================================

My comment(s):

Am I missing something on the other side of T-0 or have the times changed for the fuel and oxidizer loading?

SpaceX Launch Director verifies go for propellant load
 It is llsted as -53 minutes. My memory tells me it used to be 38 minutes.


1st stage RP-1 (rocket grade kerosene) loading begins
 This also, according to my memory and calculation, suggests this is also move forward by 15 minutes

1st stage LOX (liquid oxygen) loading begins
  Another 15 minute change

Also the final  satellite deployment is at:
   03:34:09

Prior indications were that this is a 6 hour mission. Is some interesting stuff being left out of the press kit
or is my imagination  running wild or ?

FH seems to have longer load times than F9 (they have to pump a lot more propellant into the rocket).  These are the same timings given for the Arabsat launch.

Everything I saw before today said around a 6 hour mission, maybe that was wrong.  All of the engine burns are listed in the press kit.

[gongora]

Everything I saw before today said around a 6 hour mission, maybe that was wrong.  All of the engine burns are listed in the press kit.

Maybe there is still a coast phase between releasing the last payload and passivating the second stage?  That would explain the difference in times.

[TrueBlueWitt]

Somehow I messed up the following in trying to quote from an earlier post. Sorry
===================================================
STP-2 Max-Q is at T+00:42, a full 27 seconds earlier than for Arabsat-6A at T+01:09. This is going to be interesting.
====================================================

My comment(s):

Am I missing something on the other side of T-0 or have the times changed for the fuel and oxidizer loading?

SpaceX Launch Director verifies go for propellant load
 It is llsted as -53 minutes. My memory tells me it used to be 38 minutes.


1st stage RP-1 (rocket grade kerosene) loading begins
 This also, according to my memory and calculation, suggests this is also move forward by 15 minutes

1st stage LOX (liquid oxygen) loading begins
  Another 15 minute change

Also the final  satellite deployment is at:
   03:34:09

Prior indications were that this is a 6 hour mission. Is some interesting stuff being left out of the press kit
or is my imagination  running wild or ?

Have to wonder if there was some added parameter to the mission.. Air Force wants to demonstrate mission requirements met while having flexibility for a 15 minute launch window(after fueling commences)?

Being forced to launch with less dense LOX and RP1 than normal would explain the ASDS move far downrange.. Correct?

Feels like the Air Force is making SpaceX demonstrate they're still capable even with both hands tied behind their backs..

The 6 hours goes out to the final burn to lower orbit and deplete all propellants if I remember correctly?

[llanitedave]

Somehow I messed up the following in trying to quote from an earlier post. Sorry
===================================================
STP-2 Max-Q is at T+00:42, a full 27 seconds earlier than for Arabsat-6A at T+01:09. This is going to be interesting.
====================================================

My comment(s):

Am I missing something on the other side of T-0 or have the times changed for the fuel and oxidizer loading?

SpaceX Launch Director verifies go for propellant load
 It is llsted as -53 minutes. My memory tells me it used to be 38 minutes.


1st stage RP-1 (rocket grade kerosene) loading begins
 This also, according to my memory and calculation, suggests this is also move forward by 15 minutes

1st stage LOX (liquid oxygen) loading begins
  Another 15 minute change

Also the final  satellite deployment is at:
   03:34:09

Prior indications were that this is a 6 hour mission. Is some interesting stuff being left out of the press kit
or is my imagination  running wild or ?

Have to wonder if there was some added parameter to the mission.. Air Force wants to demonstrate mission requirements met while having flexibility for a 15 minute launch window(after fueling commences)?

Being forced to launch with less dense LOX and RP1 than normal would explain the ASDS move far downrange.. Correct?

Feels like the Air Force is making SpaceX demonstrate they're still capable even with both hands tied behind their backs..

The 6 hours goes out to the final burn to lower orbit and deplete all propellants if I remember correctly?

Lower orbit, or higher orbit?  Seems like it would take a lot of fuel to lower from a 6000 km x 12000 km orbit to a point where it would decay in a reasonable amount of time.  I'd think a higher orbit than that, in an area little used by satellites, would keep it out of the way.


Just guessing here, though.

[gongora]

Have to wonder if there was some added parameter to the mission.. Air Force wants to demonstrate mission requirements met while having flexibility for a 15 minute launch window(after fueling commences)?

Being forced to launch with less dense LOX and RP1 than normal would explain the ASDS move far downrange.. Correct?

Feels like the Air Force is making SpaceX demonstrate they're still capable even with both hands tied behind their backs.. ?

This is the same timing as the previous FH flight.  It doesn't using the F9 timings.

[Draggendrop]

For a quick comparison...

https://www.spacex.com/sites/spacex/files/stp-2_press_kit.pdf

https://www.spacex.com/sites/spacex/files/arabsat-6a_press_kit.pdf

[TrueBlueWitt]

Have to wonder if there was some added parameter to the mission.. Air Force wants to demonstrate mission requirements met while having flexibility for a 15 minute launch window(after fueling commences)?

Being forced to launch with less dense LOX and RP1 than normal would explain the ASDS move far downrange.. Correct?

Feels like the Air Force is making SpaceX demonstrate they're still capable even with both hands tied behind their backs.. ?

This is the same timing as the previous FH flight.  It doesn't using the F9 timings.

Extrapolating from Faulty data.. Mea Culpa

[ZachS09]

Will they use the F9 prop loading procedure for Falcon Heavy in the near future?

My reasoning is so that it can get more performance when launching heavier payloads or when going to extreme orbits (geostationary, hyperbolic, or several orbits like in STP-2).

[gongora]

Will they use the F9 prop loading procedure for Falcon Heavy in the near future?

My reasoning is so that it can get more performance when launching heavier payloads or when going to extreme orbits (geostationary, hyperbolic, or several orbits like in STP-2).

F9 and FH use slightly different amounts of propellants.  Is the infrastructure even capable of filling those two vehicles in the same amount of time?

[whitelancer64]

Is SpaceX still putting tail numbers on each booster? Is soot obscuring them or am I looking in the wrong place?

[gongora]

Is SpaceX still putting tail numbers on each booster? Is soot obscuring them or am I looking in the wrong place?

They're little numbers below the grid fins.  I haven't seen a picture from today that is clear enough to read them.

[ulm_atms]

https://twitter.com/elonmusk/status/1143287719075950593

Odds of center core surviving are about 50% imo, as it’s coming in about 4 times faster than a rifle bullet

OK, since this mission has been on the books for quite a while even before B3 and B4 if I remember right....they had to be planning a multi-droneship capture at that time.  Since they only have one drone ship currently, the boosters have to RTLS and they figured why not try to catch the center core.  This one does seem to be on the edge of "survivable"

So questions:

How many times has this mission changed over the years?  When it was announced...and if it had the same mission as now....I don't see how it could not be 100% expendable.  Could the 2nd stage even do it at that point in time?

Other question....Has there ever been a mission with this many orbital requirements/changes and a disposal burn?

[gongora]

OK, since this mission has been on the books for quite a while even before B3 and B4 if I remember right....they had to be planning a multi-droneship capture at that time.  Since they only have one drone ship currently, the boosters have to RTLS and they figured why not try to catch the center core.  This one does seem to be on the edge of "survivable"

So questions:

How many times has this mission changed over the years?  When it was announced...and if it had the same mission as now....I don't see how it could not be 100% expendable.  Could the 2nd stage even do it at that point in time?

Other question....Has there ever been a mission with this many orbital requirements/changes and a disposal burn?

This contract was signed when SpaceX was flying F9 v1.0.  The original plan must have been expendable.  They added the first orbit where most of the cubesats are getting released (720-circular was a bit high to be dumping a bunch of cubesats that may not have propulsion.  Prox-1/Lightsail is only being released at 720 because they can't use the sail at lower altitudes).

[LouScheffer]

[...]
From: 720 km x 720 km x 24 deg
To:     6000 km x 12000 km x 43 deg

I calculate [...] 2829.9 m/s from the second to third orbit.

Enter initial perigee height (km): 720
Enter initial apogee height (km): 720
Enter required inclination change (deg): 19
Enter required perigee height (km): 6000
Enter required apogee height (km): 12000

Burn at   720.0 km: theta1 =  0.00 deg, dv1 = 1507.4 m/s
Burn at 12000.0 km: theta2 = 19.00 deg, dv2 = 1440.6 m/s
dv = 2947.9 m/s

Burn at   720.0 km: theta1 =  4.25 deg, dv1 = 1625.8 m/s
Burn at 12000.0 km: theta2 = 14.75 deg, dv2 = 1204.1 m/s
dv = 2829.9 m/s

This is good burn sequence for minimum delta-V, but it's not the way SpaceX seems to be doing it.  As specified above, there would be a coast of 1/2 of a 720 x 12000 km orbit.  That's 1.98 hours, or about 118 minutes.

Instead, SpaceX appears to be going to a 720 x 6000 orbit, then firing at apogee to create the 6000 x 12000 orbit.  The coast in this case should be 1.33 hours, or 80 minutes, almost exactly what is specified in the press kit (2:08:04 to 3:27:29).  It's going to be slightly less efficient, since the plane change is done at a lower altitude, but I guess SpaceX prefers the shorter coast to the smaller delta-V.

[cscott]

Any chance the 2am delay isn't official yet because they are discussing a scrub instead?  I've got to decide whether to get on the bus at KSC...

[RocketLover0119]

Any chance the 2am delay isn't official yet because they are discussing a scrub instead?  I've got to decide whether to get on the bus at KSC...

Could be wrong, but honestly if it was an official delay/scrub spacex would have tweeted by now, and that’s not the case, wondering if someone on clock team goofed?

[cscott]

Any chance the 2am delay isn't official yet because they are discussing a scrub instead?  I've got to decide whether to get on the bus at KSC...

Could be wrong, but honestly if it was an official delay/scrub spacex would have tweeted by now, and that’s not the case, wondering if someone on clock team goofed?

I like how you think. Fingers crossed...

Edit: delay not scrub. That's still okay... (My kids are just going to be very sleepy, and my 8am flight home is going to be... fun.)

[Yellowstone10]

New T-0 of 2:30 am EDT / local.

https://twitter.com/SpaceX/status/1143321392785477633

[OxCartMark]

From Gizmodo - https://gizmodo.com/all-the-cool-things-going-to-space-tonight-aboard-a-spa-1835816425

"The Falcon Heavy will also release a dozen Oculus-ASR nanosatellites, each weighing 154 pounds (70 kg). Built by a student group from Michigan Technological University, these satellites will be used as targets for calibrating ground-based telescopes tasked with monitoring spacecraft in orbit."

I don't know where the classification breaks are (or if there are any official break points) but 154 pounds seems to me to be more than "nano".  What I do know for sure though is that those folks up at Michigan Technological University are super awesome