SpaceX F9 - KLPO - SLC-40

[Grendal]

Launch Date: August 4
Launch Window: 7:08pm EDT (4:08pm PDT, 23:08 UTC)
Launch site: SLC-40, Cape Canaveral Space Force Station, Florida
Core Booster Recovery: ASDS
Booster: B1052.6
Fairings: Reused - 4th time each.
Mass: 678 kg (1,495 lb)
Orbit: TLI
Yearly Launch Number: 34th

A SpaceX Falcon 9 rocket will launch the Korea Pathfinder Lunar Orbiter, or KPLO. This is South Korea’s first space exploration mission. The KPLO spacecraft carries science instruments to image permanently shadowed craters to search for signs of water ice, measure the composition of lunar regolith, and capture high-resolution images to map future landing sites.

B1052 is the ex-FH side booster that completed two successful FH launches. It sat around for 2 1/2 years and finally got converted into a traditional booster. It has subsequently completed three F9 launches. It was going to be converted back to a FH side booster for the ViaSat 3 launch in September but apparently, due to FH delays, it will do at least one more F9 launch first.

Danuri - Wikipedia

en.wikipedia.org

 

[ecarfan]

Interesting that South Korea has decided to contribute towards learning more about Moon and possible water deposits.

From Wikipedia:

As KPLO uses Ballistic Lunar Transfer (BLT) to transfer to a moon orbit, it will take the spacecraft about one month to reach the Moon. The orbiter will perform at least three highly elliptical orbits of Earth, each time increasing its velocity and altitude until it reaches escape velocity, initiating a trans-lunar injection.

I read more about BLT but do not understand the diagram from the Korea Aerospace Research Institute. I don’t see the “three highly elliptical orbits of Earth” in their diagram.

 

[Grendal]

First post updated with current launch data.

 

[bxr140]

I read more about BLT but do not understand the diagram from the Korea Aerospace Research Institute. I don’t see the “three highly elliptical orbits of Earth” in their diagram.

The earth escape elliptical orbits are not represented in the diagram. Those orbits are around earth (not the earth-moon system) and are generally small enough that representing them would be both a little confusing and also not to scale. (For reference, the moon is about ~30 earth diameters away from the earth, so the represented earth-moon system is already not to scale). Why they weren't shown in an blown up view like the moon capture orbits, I don't know.

What you see in the red/blue gradients are many of the three-dimensional ballistic trajectories KPLO can take from earth-escape to moon-capture. Its not really well described, but KPLO will only actually fly on one of those gradient lines (the red and blue parts of the gradients just represent when the orbit is below or above the moon's orbital plane). There are many potential trajectories shown as an attempt to represent that the BLT has pretty forgiving timing--you don't have to lock down specific launch or earth escape windows, as over time the resultant (and dynamic) earth-moon gravitational pull kinda funnels all the trajectories back into lunar capture. The upside to that is easier scheduling--no instantaneous launch windows, plenty of ability for the satellite production to over-run, etc.

As one is visualizing the diagram, its worth noting that the BLT duration is ~about a month and the moon's orbit around the earth is also ~about a month, so when the satellite escapes earth, the moon is ~at 12 o'clock, and then as the satellite moves through the orbit the moon rotates counter clockwise. The flow is something like this
--After the satellite escapes earth "away" from the earth-moon system (again, that's after the three elliptical earth orbits) the moon's contribution to the earth-moon resultant gravity vector starts to pull the satellite "up" , which is why the red gradients all kinda curve up.
--As the moon comes around the left side of the earth the earth-moon resultant gravity gets stronger (gravity is inversely proportional to distance squared) and maxes out the pull on the satellite back toward the E-M system.
--As the moon swings toward the lower half of its orbit the E-M resultant gravity pulls the satellite "down" and the blue gradients come over the top (top = out of the page) of the red gradients. At the same time the moon is moving farther away from the satellite, so the total gravitational pull is feathering off.
--Concurrent with above, and probably hardest to visualize, the blue gradients all funnel back toward each other because the E-M resultant gravity of the "outer" gradients provides a stronger side pull than the "inner" gradients, so they all kind of pull the satellite's energy back toward the inner gradients with increasing force. One can kind of think of it in sailing terms: If a vessel is on a reach, the wind generally wants to push it toward a run--and the further the reach, the more the wind wants to turn the heading into a run.
--Finally, back to orbits, the satellite catches up with the moon as it swings to the right side and back to ~12 o'clock. At that point it performs a capture maneuver to exit the earth-moon system orbit and enter the moon system. (Again, represented by the blown up view)

 

[Grendal]

 

[Grendal]

Weather maintained. Looking good.

 

[bmah]

Qapla' KPLO!

Bruce.

 

[808?]

 

[EVCollies]

Qapla' KPLO!

Bruce.

Never thought I'd learn Klingon.

 

[Grendal]

So far successful and likely 100% successful. The booster landing seemed like it may have missed but it was announced that it landed successfully. We're just waiting on SES-2 and deployment soon after.


...And full success.

 

[ecarfan]

Booster landed successfully though I have not see one that far off center in awhile! Just before the booster video feed cut off with a few seconds to go before touchdown I thought it looked a bit off.

 

[ecarfan]

Now I understand the BLT orbit better after seeing this diagram.

 

[Cosmacelf]

Now I understand the BLT orbit better after seeing this diagram.

View attachment 836885

Me too but I still don’t understand why it is more fuel efficient. They said it does a gravity assist maneuver around the L1 point which I guess makes sense.

 

[Grendal]

Booster landed successfully though I have not see one that far off center in awhile! Just before the booster video feed cut off with a few seconds to go before touchdown I thought it looked a bit off.

View attachment 836884

Me too. I thought it may not have made from the angle it was coming in. It looked like it was going to hit the edge of JRTI. JRTI is the size of a football field. So this landing was off by 50 or 60 feet. Hopefully, the octograbber can attach to stabilize it for the return.

 

[petit_bateau]

Me too but I still don’t understand why it is more fuel efficient. They said it does a gravity assist maneuver around the L1 point which I guess makes sense.

Is the easiest way to conceptualise the fuel efficiency by thinking of it as climbing the gravity well at the least angle, almost just traversing. And by aiming to traverse out of the eath's well by aiming for the col in the gravity landscape that gives access to the moon's well in such a way that the least amount of energy is expended both on the climb out of earth, and the descent in to moon.

?

 

[Grendal]

South Korean spacecraft enters lunar orbit with deceleration maneuver - SpaceNews

South Korea’s first robotic lunar orbiter, Danuri, entered the lunar orbit after conducting its first lunar orbit insertion maneuver Dec. 16.

spacenews.com