SpaceX F9 : KPLO : CCSFS SLC-40 : 4 August 2022 (23:08 UTC)

[Comga]

The question remains how the mission evolved to underutilize so remarkably the capacity of the launcher.
One logical possibility is that this was the limit at the time the mission was designed.
It is possible that it was originally a rideshare, limiting the orbit to which it could be carried.
With the other passenger no longer on the vehicle, KPLO could be sent to an orbit with a higher apogee and perigee velocity, which would reduce the delta-V required for the TLI.
But KPLO has the fuel to accomplish the mission as originally planned with some margin. 
Under-fueling would represent a trivial savings, and would require the optimization of the new, shorter TLI burn.

We had a saying: "Less is more.  More is more.  Keeping things the same is more if you debate forever."
We were talking about cost.

Staying wary of Feynman's quote ("You're not thinking.  You're just being logical.") a good guess is that more launcher capacity was freed up, but there would be cost involved and nothing necessary to gain by re-planning the mission, so that capacity will be ignored.

[ccdengr]

The question remains how the mission evolved to underutilize so remarkably the capacity of the launcher.

Going back to the original NASA AO for KPLO instruments, the spacecraft mass was 550 kg into TLI https://www.nasa.gov/feature/kplo-ao .  When the mission was designed, it seems KARI was still hoping to use their own rocket (KSLV-II) as the LV.  By the time F9 was selected in early 2018, it was apparently not possible to change the spacecraft design very much (there's been some tankage/fuel increase but only 100 kg-ish), and the F9 second-stage can't provide delta V for the spacecraft to slow down to get into lunar orbit because it doesn't have the operating duration to do so (I presume.)

That said, I don't know what the maximum F9 injection mass into TLI is.

[Steven Pietrobon]

That said, I don't know what the maximum F9 injection mass into TLI is.

I estimate 5992 kg to TLI, expendable.

[su27k]

F9 C3=-1 capability can be obtained from https://elvperf.ksc.nasa.gov/default.aspx, for RTLS it's about 1800kg.

[zubenelgenubi]

SFN Launch Schedule, updated July 21:
Confirms launch from SLC-40 and ASDS landing.  Launch time approximately 23:30 UTC.

[crandles57]

the F9 second-stage can't provide delta V for the spacecraft to slow down to get into lunar orbit because it doesn't have the operating duration to do so (I presume.)

An efficient Hohmann transfer injection would require a speed up rather than a slow down to get into lunar orbit? Gravity of moon complicates things so I could easily be wrong and a slow down is needed?

Do we know where the falcon second stage is going?

[ZachS09]

Can Stage 2 do a translunar injection as its second burn after coasting in LEO?

Or will Danuri raise its apogee over time similar to CAPSTONE/Photon?

[crandles57]

Can Stage 2 do a translunar injection as its second burn after coasting in LEO?

Or will Danuri raise its apogee over time similar to CAPSTONE/Photon?

Think this is already answered by this previous reply on this thread
 

Wouldn't read much into the 300 km, there is a still a TLI required from the Falcon upper stage.  https://directory.eoportal.org/web/eoportal/satellite-missions/k/kplo

A launch of KPLO is scheduled for 1 August 2022 on a SpaceX Falcon 9 Block 5 vehicle from Cape Canaveral, Florida into a 300 km Earth orbit, followed by a translunar injection burn and a one month lunar transfer phase.

KPLO uses a WSB/BLT transfer but still needs a TLI.  See Belbruno and Carrico, "Calculation of Weak Stability Boundary Ballistic Lunar Transfer Trajectories", https://astrogatorsguild.com/wp-content/papers/0800_wsb.pdf

While the quote from the link doesn't say whether the TLI burn is done by Falcon or Danuri, I think other parts of the linked page make it clear it will be Falcon doing the TLI eg

To successfully deliver KPLO to the Moon, the spacecraft is designed to have a four Orbit Maneuver Thruster (OMT), with approximately 31.8 N of thrust with 227 s of Isp (specific impulse) for large burn execution, and eight Attitude Control Thruster (ACT) with approximately 3.48 N with 218 s of Isp for small burn execution. All of these engines will be clustered for burn executions. Four OMT engines will be clustered to be used for the main thruster set for large burns during the transfer and LOA phase

[ccdengr]

An efficient Hohmann transfer injection would require a speed up rather than a slow down to get into lunar orbit?

Depends on which reference frame you're talking about, no?  In the earth frame I'm sure you're right and my language was sloppy.  In the lunar frame it's a slowdown; see https://koreascience.kr/article/JAKO201635542397762.pdf figure 2.

I don't know where the Falcon 9 second stage will end up; I expect it will remain in the initial injection orbit unless they do a burn to depletion after spacecraft separation.

[crandles57]

An efficient Hohmann transfer injection would require a speed up rather than a slow down to get into lunar orbit?

Depends on which reference frame you're talking about, no?  In the earth frame I'm sure you're right and my language was sloppy.  In the lunar frame it's a slowdown; see https://koreascience.kr/article/JAKO201635542397762.pdf figure 2.

I don't know where the Falcon 9 second stage will end up; I expect it will remain in the initial injection orbit unless they do a burn to depletion after spacecraft separation.

It might also depend on what sort of TLI you are doing. I was thinking with a hohmann transfer it would be a speed up but if you were talking about KPLO WSB/BLT then it could well be that a slow down is needed: The ideal WSB/BLT would need very little, perhaps even 0 delta_v at LOA?

For small burns, such as for TCMs less than 10 m/s, momentum dumping, and orbit maintenance during the nominal mission phase

Not sure if that 'momentum dumping' is for lunar orbit acquisition(LOA) or just for lowering orbit once in lunar orbit.

Changing the frame of reference could cause different use of language, but this probably just us talking about different TLIs rather than different frame of reference?

[Comga]

Not sure if that 'momentum dumping' is for lunar orbit acquisition(LOA) or just for lowering orbit once in lunar orbit.

“Momentum dumping” usually refers to desaturating momentum wheels.
That is, due to force imbalances, one or more momentum wheels used for pointing and attitude maintenance and adjusting, will soak up momentum, that is rotate faster and faster, until they approach their limit. At that point they are considered “saturated”. Applying a torque in the opposite direction allows the wheel to slow down or “desaturate”.
The goal is to do that without changing the trajectory. 
So it’s not associated with LOA, etc.

[russianhalo117]

[Rondaz]

Meet Danuri! Korea Pathfinder Lunar Orbiter that SpaceX will launch

[Galactic Penguin SST]

https://twitter.com/Kor_Spaceflight/status/1552495287356489728?s=20&t=B8cGv3W5JMuojNWKY67oXw

= August 4, 23:08 UTC (7:08 pm EDT)

[mlindner]

An efficient Hohmann transfer injection would require a speed up rather than a slow down to get into lunar orbit?

Depends on which reference frame you're talking about, no?  In the earth frame I'm sure you're right and my language was sloppy.  In the lunar frame it's a slowdown; see https://koreascience.kr/article/JAKO201635542397762.pdf figure 2.

I don't know where the Falcon 9 second stage will end up; I expect it will remain in the initial injection orbit unless they do a burn to depletion after spacecraft separation.

If it's being left in the initial injection orbit it could end up anywhere as WSB transfers are by definition chaotic so even post-shutdown venting could wildly change the resultant trajectory. It could end up crashing into the moon, the earth, or shooting out into solar orbit.

[zubenelgenubi]

Danuri (KPLO) launch now scheduled for August 5th 08:08 KST, according to MSIT/KARI. [July 28 UTC]

= August 4, 23:08 UTC (7:08 pm EDT)

Launches from adjacent pads SLC-40 and SLC-41 on the same day!

Also noting, the launch time receded 29 minutes for a 2 day delay.

Edit: There is also a CZ-4C launch from Taiyuan on August 4 UTC.

[Rondaz]

The launch of Korea Pathfinder Lunar Orbiter is postponed for at least 2 days as SpaceX needs to do additional checks of the Falcon 9 rocket. SpaceX is currently in the process of obtaining a grant from US military authorities to launch the probe on 08/04

https://twitter.com/CNSpaceflight/status/1552838822198747137

[FutureSpaceTourist]

https://twitter.com/raul74cz/status/1553342557932949504

Launch Hazard Areas for #KPLO mission from CCSFS SLC-40, valid for NET 04 Aug 23:08 UTC, alternatively 05-10 Aug based on issued NOTMAR. Planned booster 1052.6 landing 640km downrange. Estimated fairing recovery position approximately 730km downrange. bit.do/LHA19

[Ken the Bin]

NGA notice.

230017Z JUL 22
NAVAREA IV 743/22(11,26).
WESTERN NORTH ATLANTIC.
FLORIDA.
1. HAZARDOUS OPERATIONS, ROCKET LAUNCHING
   042303Z AUG TO 050001Z AUG, ALTERNATE
   052255Z TO 052352Z, 062248Z TO 062345Z,
   072240Z TO 072337Z, 082228Z TO 082325Z,
   092220Z TO 092317Z AND 102213Z TO 102310Z AUG
   IN AREAS BOUND BY:
   A. 28-38.85N 080-37.58W, 28-42.00N 080-01.00W,
      28-36.00N 079-59.00W, 28-30.35N 080-32.97W.
   B. 29-26.00N 075-05.00W, 29-52.00N 072-59.00W,
      29-41.00N 072-25.00W, 29-11.00N 072-20.00W,
      28-50.00N 072-57.00W, 29-00.00N 075-04.00W.
2. CANCEL THIS MSG 110010Z AUG 22.

[ccdengr]

Interesting that even though this is a very low-mass spacecraft as discussed upthread, this is not an RTLS flight.