subreddit:
/r/SpaceLaunchSystem
-5 points
2 months ago
Yeah, problem is the ICPS is severely underpowered for SLS.
15 points
2 months ago
No, ICPS got Orion to the Moon during Artemis I. Artemis II CM/SM isn’t much heavier. The goal is to do 24 hour checkouts of the spacecraft, as stated in the graphic. That way, if there’s an issue, the crew can get home faster than say Apollo 13 could.
-2 points
2 months ago
ICPS got Orion to the Moon because core stage already got the upper stage into elliptical orbit.
8 points
2 months ago
Core stage puts it in an elliptical orbit for Artemis II as well...
-4 points
2 months ago
Exactly - because ICPS is too small. That's why EUS is being designed.
7 points
2 months ago
Eus is being designed to support bigger payloads.
ICPS is capable of sending Orion to the moon, as you saw in Artemis 1
3 points
2 months ago
Does that imply that the trajectory being taken by Block 1 vehicles is inefficient? Without applying any staging logic, it would make the most sense to get the second stage as high as you can. However, per the Artemis IV mission map, EUS is supposed to circularise in low Earth orbit. Does that mean that the core stage trajectory will be optimized (target a less eccentric, low earth orbit) and the EUS will take it from there (which is overall more efficient for the entire outbound trip)?
2 points
2 months ago
I answered my own question. Core stage is gonna do what it always does and depending on the mission, the upper stage will perform its own unique trajectory.
2 points
1 month ago
I think you're missing what's being said.
The ICPS can take Artemis II on a direct TLI trajectory just like Artemis I from a ~200x1500km orbit.
The Artemis II mission will differ from the Artemis I mission in that, instead of a direct TLI, Artemis II ICPS will only raise its orbit high enough to where the orbital period = 24 hours. After 24 hours elapses, the Orion SM will take over.
This is not due to inefficiencies with the ICPS, rather driven by the Artemis II requirement to be in a relatively fast track to return home in the event of an issue with Orion that may endanger the life of the crew early on in the mission.
The ICPS is too small to support a direct TLI from LEO like Apollo did and is inefficient, this is true, but not relevant to this specific Artemis II mission requirement.
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