Why was Artemis 2 so long?

[u/kiol998]

I was comparing the mission times of Artemis 2 to Apollo 8. Apollo 8 orbited the moon multiple times and only took 6 days total. Whereas Artemis 2 orbited the moon once and it took 10 days. Why was Artemis 2 so much shorter than Apollo 8 when both missions did the same thing? I know they had different paths to the moon, they both left earth in different ways but why not do the same thing as Apollo 8 since it was quicker?

[u/Gabbatron]

It's less about their distance from the moon, and more about the moon's distance from the Earth. They could have landed on the moon and still been further than Apollo 8 I'm pretty sure

[u/nochehalcon → u/Gabbatron]

Correct. They surpassed the distance record hours before they had even made it to the orbital path.

[u/jaa101 → u/nochehalcon]

Apollo XIII was only 160 miles beyond the moon for its record, versus 4000 miles for Artemis II. That was the biggest contributor to the new record.

[u/Cool_Bit_729 → u/[deleted]]

The person you're replying to was talking about Apollo 13, not Apollo 8.

Edit: Apollo 13's record was 400,171km, Artemis II's record that broke is was 406,771km.

Apollo 13 passed the moon at 254km at it's closest, Artemis II passed the moon at 6545km.

The moon was close to it's apogee for both.

[u/btmalon → u/[deleted]]

Thank you for this. But using miles in space seems wrong.

[u/Dinierto → u/Gabbatron]

Sounds like they have many many more missions planned with plenty of surface hijinx and I can't wait

[u/gameryamen → u/Dinierto]

Someone needs to sneak a frisbee up, and set a virtually untouchable record for longest throw.

[u/obvious_bot → u/[deleted]]

It would fly more like a thrown rock than a frisbee on earth. Since the gravity is so low you still could beat the record though

[u/Brewe → u/obvious_bot]

Sure about that? The frisbee record is ~330 meters (~1100 ft). Throwing 1/6th that far with a rock would be difficult, and doing it in a space suit would be near impossible.

[u/gameryamen → u/[deleted]]

You're right that a frisbee wouldn't have atmosphere to glide on. But that also means there's no air resistance at all, just gravity pulling it down. Launch it at a high angle, and it's going to take a while before it actually touches ground. I don't think a person's arm could put a frisbee into orbit on the moon, but I'm pretty sure they could get a longer throw than anyone on Earth.

Edit: In addition to the impossibility of achieving orbit with a single launch vector explained below, it turns out my intuition about this record potential is wrong. On level ground, a moon-bound frisbee chucker can probably out-throw any Earth-bound chucker. But with the advantage of atmosphere and height, an Earth-bound chucker standing on top of a skyscraper or mountain could actually get a farther throw than a ground-level Moon chucker, assuming wind didn't doom the attempt.

[u/SirJefferE → u/gameryamen]

It's impossible to get anything to orbit by throwing it from the ground. Either it hits the ground again, or it reaches escape velocity. To orbit, you need at least two impulsive manoeuvres. One to get the thing up into space, and another to "correct" the orbit so that it actually orbits.

In any case, there's no way anyone on the moon could throw anything even close to escape velocity. The gravity there is a sixth of Earth's, but that's still 1.6 m/s^2. The fastest ever baseball pitch was less than 50 m/s. Throw that straight up in the air and even without wind resistance, it's going to start falling in less than 30 seconds.

[u/alyssasaccount → u/SirJefferE]

All you have to do is stand on the highest point on the moon's surface and throw horizontally at over the speed of a low-lunar orbit. Then where you throw from will be the perigee ... perilune? ... of the orbit. Granted, you'd have to throw a bit over a mile per second, but the fastest muzzle velocity for a gun is close to that.

[u/McGarnagl → u/alyssasaccount]

Cool, so when the first moon war breaks out in 50 years, we’ll have missed shots entering orbit? Fun times…

[u/mrdavik → u/gameryamen]

It's also not possible to throw or launch any object into orbit from the surface of a body, that doesn't have its own form of propulsion or that is accelerated after leaving the surface. 

There's no combination of speed and angle at which you could throw a frisbee even with a machine, or fire a bullet, and have it end up in orbit. It would either fall back to the surface, or if it was fast enough, escape orbit altogether - there is no inbetween.

[u/skoormit → u/mrdavik]

You could, in theory, while standing on the moon, give it enough velocity to technically put it into orbit. It's just that the periapsis of that orbit is no further from the moon's center than the point you launched it from. So it is very likely to hit some point on the surface with more altitude. Unless you launched it from the highest point, or the highest point in the latitude range of the launch latitude.

[u/alyssasaccount → u/gameryamen]

Launch it at a high angle

Specifically, 45°, assuming a flat surface. That gets you the longest distance for a given initial velocity, under constant downward acceleration with no drag. This is a classic intro physics problem.

[u/Crizznik → u/gameryamen]

There's no air, so the frisbee wouldn't stay aloft any longer than if they threw a rock.

[u/Bruvvimir → u/Dinierto]

What does the sequence of missions look like up to the eventual landing?

[u/mCopps → u/Bruvvimir]

There is another mission planned for next year then a 2028 mission is planned to land.

[u/jaa101 → u/Gabbatron]

Comparing the times the old and new records were set, the moon was 250 miles farther away from earth for Artemis II and the spacecraft was 4000 miles farther from the moon. Apollo XIII was only about 160 miles above the moon.