The craft has aerodynamics and speed. It might be figuratively true "unrecoverable" but if it takes e.g. 2 weeks to complete a return, their oxygen and food and batteries ran out. Alternatively if it enters too fast they return ... in pieces.
I think you're being a pedant, if your point is a grazing entry causing rebound skip ultimately returns to some orbital path downward.
You seem to intentionally be ignoring the original quote that any error may have caused them to be flung into space. This is patently false unless the one math error is pumping in hundreds of pounds more propellant and burning far longer than the scheduled burns. NASA would need to make a significant series of mistakes beyond orbital math for the "flung out into space" statement to be true.
They certainly could've gotten the return wrong but with a perigee of 119 miles they arent even in a stable orbit and likely could deorbit themselves using only rcs thrusters at apogee, or by just waiting a few orbits.
This is underselling the risks. On top of the many trajectories which push them into unrecoverable situations, leaving them stranded in orbit, there can be trajectories where the moon gives a gravity assist strong enough to fling the spacecraft into escape velocity, fulfilling the OP.
In fact, the trajectory they chose for this mission exploited the opposite effect to yield a free return without propellant expense.
In the modern day, the chance of a math error being the root cause behind this failure mode are vanishingly small, but minor burn execution mistakes that do not require hundreds of extra pounds of propellant are definitely plausible. They were extremely common in the early days of spaceflight and plagued most of the very first moon exploration attempts. Again, with modern RCS this is unlikely. But reentry is still incredibly tight and dangerous. Apollo famously had a +-1° safe entry corridor, and Orion is way heavier and coming in even faster. If their perigee was off they could’ve easily burned up or doubled their mission time, which they may not have been able to survive.
I’ll agree, it seems crazy that it left earth, made it to the moon, and never really left earth orbit at all. That the furthest we’ve been away is still destined to return on its own.
Hmm. Maximum speed attained by Artemis II when they left their initial orbit was about 11.1 km/s IIRC. While this is somewhat less than true escape velocity from Earth (11.2 km/s) and you are technically correct, it is also enough of a speed that if you fly away in any random direction (and not a carefully calculated one), perturbances from the Sun and other massive objects will probably prevent you from reaching any sort of stable orbit around the Earth, and you will start bouncing around the inner Solar System in an erratic way.
I certainly wouldn't like to model that trajectory for months or years.
The sun’s pull on the ship at the outside limit at the moon, is obviously negligible compared to the pull of the Earth. This should be obvious, because otherwise the moon would have left long ago.
Why is this so difficult to understand? Honestly I think that misleading NASA graphic did a lot of damage.
You throw in acceleration, which I never mentioned and doesn’t matter. The Artemis II never left Earth’s gravitional pull, the original issue was effectively what if it missed - and the answer is no big deal.
The craft has aerodynamics and speed. It might be figuratively true "unrecoverable" but if it takes e.g. 2 weeks to complete a return, their oxygen and food and batteries ran out. Alternatively if it enters too fast they return ... in pieces.
I think you're being a pedant, if your point is a grazing entry causing rebound skip ultimately returns to some orbital path downward.
You seem to intentionally be ignoring the original quote that any error may have caused them to be flung into space. This is patently false unless the one math error is pumping in hundreds of pounds more propellant and burning far longer than the scheduled burns. NASA would need to make a significant series of mistakes beyond orbital math for the "flung out into space" statement to be true.
They certainly could've gotten the return wrong but with a perigee of 119 miles they arent even in a stable orbit and likely could deorbit themselves using only rcs thrusters at apogee, or by just waiting a few orbits.
This is underselling the risks. On top of the many trajectories which push them into unrecoverable situations, leaving them stranded in orbit, there can be trajectories where the moon gives a gravity assist strong enough to fling the spacecraft into escape velocity, fulfilling the OP.
In fact, the trajectory they chose for this mission exploited the opposite effect to yield a free return without propellant expense.
In the modern day, the chance of a math error being the root cause behind this failure mode are vanishingly small, but minor burn execution mistakes that do not require hundreds of extra pounds of propellant are definitely plausible. They were extremely common in the early days of spaceflight and plagued most of the very first moon exploration attempts. Again, with modern RCS this is unlikely. But reentry is still incredibly tight and dangerous. Apollo famously had a +-1° safe entry corridor, and Orion is way heavier and coming in even faster. If their perigee was off they could’ve easily burned up or doubled their mission time, which they may not have been able to survive.
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Anyone who has had hit period key once too many during Munar free-return in KSP knows it's exactly how orbits work...
Hilarious the the intellectual forum downvoted you for being absolutely right.
Artemis II never escaped Earth’s pull.
That video that NASA put out where the craft did a sling shop around the moon is extremely deceptive. The pull of the moon had very little effect.
If they had missed, they would have eventually crashed back to earth in the worst case, and best case just re-adjusted and returned a little bummed.
> The pull of the moon had very little effect.
No, it had a very significant effect: it's what made possible the free return trajectory while observing the far side of the moon.
Ok, but no not really. This is incorrect, the “free return” would have happened if they launched entirely in the wrong direction.
Like I said, the gif you saw makes it look that way.
Here is a link that explains it very well. https://youtu.be/MF8IbYbVIA0?t=269
I’ll agree, it seems crazy that it left earth, made it to the moon, and never really left earth orbit at all. That the furthest we’ve been away is still destined to return on its own.
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"Artemis II never escaped Earth’s pull."
Hmm. Maximum speed attained by Artemis II when they left their initial orbit was about 11.1 km/s IIRC. While this is somewhat less than true escape velocity from Earth (11.2 km/s) and you are technically correct, it is also enough of a speed that if you fly away in any random direction (and not a carefully calculated one), perturbances from the Sun and other massive objects will probably prevent you from reaching any sort of stable orbit around the Earth, and you will start bouncing around the inner Solar System in an erratic way.
I certainly wouldn't like to model that trajectory for months or years.
The sun’s pull on the ship at the outside limit at the moon, is obviously negligible compared to the pull of the Earth. This should be obvious, because otherwise the moon would have left long ago.
Why is this so difficult to understand? Honestly I think that misleading NASA graphic did a lot of damage.
You throw in acceleration, which I never mentioned and doesn’t matter. The Artemis II never left Earth’s gravitional pull, the original issue was effectively what if it missed - and the answer is no big deal.
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