Artemis 2

[Pinball1970]

Certainly worth a thread as this mission will (hopefully) last ten days.
Here is the live feed from NASA. Launch 6.24 pm EDT.
If you live in Florida or South Georgia you are some of the lucky ones.
This is a big deal, first manned mission since 1972.

 

[exchemist]

Certainly worth a thread as this mission will (hopefully) last ten days.
Here is the live feed from NASA. Launch 6.24 pm EDT.
If you live in Florida or South Georgia you are some of the lucky ones.
This is a big deal, first manned mission since 1972.

Must admit I haven’t been following this. What are they doing, going round the moon and coming back, like Apollo 8?

If so, re-entry will be hairy bit, presumably.

 

[foghorn]

If I've understood what I have been reading here and there over the past few weeks...
Apparently that swing round the far side of the moon will take them farther out than any Apollo craft before.
Resulting in a much smaller moon image in their window, and so giving them a whole moon far side picture instead of patchwork pictures made up of many shots.
Saying that, I think I have seen a probe's picture of the whole of the far side in one shot, so it must be 'a' first for a human to see a whole view of the far side and not just a part.

 

[exchemist]

If I've understood what I have been reading here and there over the past few weeks...
Apparently that swing round the far side of the moon will take them farther out than any Apollo craft before.
Resulting in a much smaller moon image in their window, and so giving them a whole moon far side picture instead of patch work pictures made up of many shots.

Does the engine have to fire 3 times, once to set them on their way, once to slow down enough to be captured by the moon and a third time to escape the moon and return to Earth? I seem to remember this was one of the points causing anxiety in the Apollo missions.

https://img.xooimage.com/files112/4/8/6/tibaxter-2018-597bed4.gif

 

[foghorn]

Does the engine have to fire 3 times, once to set them on their way, once to slow down enough to be captured by the moon and a third time to escape the moon and return to Earth? I seem to remember this was one of the points causing anxiety in the Apollo missions.

I don't know. But, again if I remember correctly, their shot in the moon's direction will put them in a natural swing around when they get there.
I will have to see if they have to do any slowing down out of the natural swing and any positioning towards earth.
Ps. I'm not Patrick Moore here, so I could be wrong.
I'm back... looks like they do a correction burn to put them on course to moon and a burn after swinging round moon to head home.
That is points 10 and 12 in picture below:

 

[Pinball1970]

Must admit I haven’t been following this. What are they doing, going round the moon and coming back, like Apollo 8?

If so, re-entry will be hairy bit, presumably.

There is significance to this because this is the next stage of the space race for the human race.
I am not interested in politics, when China, Russia, Japan and India make their progression that is just as important.
This is important for NASA too, the Shuttle programme was dampened by Columbia and the Apollo missions ended by public opinion, when that drops, votes can drop and funding follows.
The moon was a goal in the 1960s now it is a stepping stone.
This is new tech but with the cautious NASA approach, a completely different animal to SpaceX who have made unbelievable progress.
SpaceX have not lost anyone yet, NASA lost 3 people before Musk was born and another 14 by the time Falcon 1 launched.

 

[exchemist]

I don't know. But, again if I remember correctly, their shot in the moon's direction will put them in a natural swing around when they get there.
I will have to see if they have to do any slowing down out of the natural swing and any positioning towards earth.
Ps. I'm not Patrick Moore here, so I could be wrong.
I'm back... looks like they do a correction burn to put them on course to moon and a burn after swinging round moon to head home.
That is points 10 and 12 in picture below:
View attachment 7419

Does that suggest 9 gives them enough velocity to escape from Earth, yet by the time they reach the moon Earth’s gravity has slowed them enough that the moon can capture them? So no powered deceleration when they get there? But if so they will need to give it a kick to get out of lunar gravity for the return.

However I see they seem to plan on various correction burns en route, both out and back. Evidently they are content that the engine can be restarted at will, then. That’s different from my recollection of the CSM engine in Apollo.

 

[Roosters for ever]

There is significance to this because this is the next stage of the space race for the human race.
I am not interested in politics, when China, Russia, Japan and India make their progression that is just as important.
This is important for NASA too, the Shuttle programme was dampened by Columbia and the Apollo missions ended by public opinion, when that drops, votes can drop and funding follows.
The moon was a goal in the 1960s now it is a stepping stone.
This is new tech but with the cautious NASA approach, a completely different animal to SpaceX who have made unbelievable progress.
SpaceX have not lost anyone yet, NASA lost 3 people before Musk was born and another 14 by the time Falcon 1 launched.

I followed the Mercury, Gemini and Apollo programs religiously during that era. The near catastrophe of Gemini 8 with its "out of control" spin, when the cool, calm actions of Neil Armstrong saved them from certain death and failure, and was paramount in NASA's decision to select him for Apollo 11. While that mission was aborted early, many lessons were learnt from that near catastrophe, including of course the most essential part of any trip to the Moon and/or beyond, the docking of two space craft together.
In my opinion, the greatest decision made by NASA, was the step by step process they undertook with the mercury, Gemini and Apollo programs to finally put men on the Moon. The best example of that "step by step" process was of course Apollo 10, "dress rehearsal" which may have brought the first Moon landing forward to May '69.

 

[Roosters for ever]

There is significance to this because this is the next stage of the space race for the human race.

I hope that turns out to be fact. I would dearly love to see "boots on Mars" before I kick the bucket!

I am not interested in politics, when China, Russia, Japan and India make their progression that is just as important.

I couldn't be any happier for the progress made by those or any other nation in furthering the space program, particularly the incredible progress of China and its space station. An incredible achievement!!

This is important for NASA too, the Shuttle programme was dampened by Columbia and the Apollo missions ended by public opinion, when that drops, votes can drop and funding follows.

Yet much was learnt with the Apollo 1, Challenger and Columbia space shuttles tragedies. How and why public opinion waned, is still a mystery to me. I mean even going back to Apollo 13, public opinion had waned, and it took a near tragedy to bring it back to life...at least for a little while.

This is new tech but with the cautious NASA approach, a completely different animal to SpaceX who have made unbelievable progress.
SpaceX have not lost anyone yet, NASA lost 3 people before Musk was born and another 14 by the time Falcon 1 launched.

Let's hope that Space X can continue in that vein, as well as the astronauts and programs of all other countries.

 

[James R]

Impressive launch this morning (Australian time). Artemis 2 is particular significant because it is the first mission in 50 years where astronauts have gone further away from Earth than near-Earth orbit. The astronauts will be in space for the next 10 days.

 

[James R]

Does the engine have to fire 3 times, once to set them on their way, once to slow down enough to be captured by the moon and a third time to escape the moon and return to Earth?

In the diagram that foghorn posted (also quoted below), you can see that, after the initial launch (steps 1-3), Artemis was put into a large elliptical orbit, but still an orbit around the Earth (steps 4-8). There will be some "proximity operations" during that large orbit (which lasts for about a day), in which the astronauts will be practicing some parts of a docking manoeuvre (mentioned in item 6 on the diagram).

There is another burn at 8 to increase the radius of the elliptical orbit at perigee (the closest point to the Earth on the orbit, which is at point 9).

At step 9, there is a long "trans-lunar injection" burn, which takes the spacecraft out of the elliptical orbit and puts it on track to the moon. That will happen tomorrow, at around the same time as today's launch. After that burn, the astronauts are going around the Moon, no matter what. There's no turning back.

From there, there are no more engine burns, except possibly for slight course alterations. Gravity does all the work between points 9 and 14.

I will have to see if they have to do any slowing down out of the natural swing and any positioning towards earth.

They won't be slowing down. Basically, the moon's gravity will slingshot them around the moon and put them onto the return path to Earth. Point 12 allows for slight course corrections, if necessary.

Ps. I'm not Patrick Moore here, so I could be wrong.
I'm back... looks like they do a correction burn to put them on course to moon and a burn after swinging round moon to head home.
That is points 10 and 12 in picture below:
View attachment 7419

Does that suggest 9 gives them enough velocity to escape from Earth...

Yes, but the Moon's gravity will put the spacecraft back onto a return trajectory.

... yet by the time they reach the moon Earth’s gravity has slowed them enough that the moon can capture them?

No. The moon won't capture the spacecraft. It is not going into lunar orbit on this mission. In future missions, where NASA does want to orbit and/or land on the moon, some slowing down will be needed (and then speeding up again to start back towards the Earth).

So no powered deceleration when they get there?

No. This is a "free return trajectory". No power from the spacecraft needed.

But if so they will need to give it a kick to get out of lunar gravity for the return.

Not on this trip. At the moon, the spacecraft will have sufficient velocity to escape the Moon's gravity, once it goes around.

However I see they seem to plan on various correction burns en route, both out and back.

Those are mostly to make sure that the spacecraft is headed in the right direction. Small corrections far away can make enormous differences later on. It's a very long way from the Earth to the Moon (380,000 km).

Evidently they are content that the engine can be restarted at will, then.

As well as the main engine, the spacecraft also has smaller manoeuvring thrusters. For example, at times it is put into a slow rotation to allow for more even heating by the Sun.

That’s different from my recollection of the CSM engine in Apollo.

Apollo also had manoeuvring thrusters.

 

[Pinball1970]

For those who missed it. Launch at 17.40

 

[Sarkus]

I find it all a tad underwhelming at the moment, tbh. NASA are very much hamming it up for the cameras, trying to wax lyrical about the importance, and how they're doing this "for all humanity" (no, you're doing it for your job, and to keep NASA relevant in this area compared to SpaceX), but let's be clear: we went to the moon over 50 years ago. We're basically now showing that a modern car can do something impressive that a car from the 60s did. That said, it's great that we're back doing such manned missions, and maybe a more permanent presence on the moon will have some benefit (?) as and when we set foot back there. And if that's not the plan... why are we going back at all?? What do a few extra footprints on the moon's surface get us?

 

[exchemist]

I find it all a tad underwhelming at the moment, tbh. NASA are very much hamming it up for the cameras, trying to wax lyrical about the importance, and how they're doing this "for all humanity" (no, you're doing it for your job, and to keep NASA relevant in this area compared to SpaceX), but let's be clear: we went to the moon over 50 years ago. We're basically now showing that a modern car can do something impressive that a car from the 60s did. That said, it's great that we're back doing such manned missions, and maybe a more permanent presence on the moon will have some benefit (?) as and when we set foot back there. And if that's not the plan... why are we going back at all?? What do a few extra footprints on the moon's surface get us?

My sentiments exactly, Doctor.

I find NASA a bit preoccupied with public relations exercises these days. This Trump appointee director Jared Isaacman is yet another tech bro billionaire, close to Musk, without any significant background in space technology (Yes, he was in one Space X crew but that does not qualify.) His expertise is in setting a sort of alternative Paypal called Shit4 or something, nothing to do with engineering technology at all. His job seems to be to kick ass and speed everything up, which is often the way to shortcuts and accidents, cf. Boeing. We'll see, I suppose.

I'm unclear what benefit establishing a lunar base is intended to have, other than beating the Chinese - a very Trumpy objective.( Mind you, if we get what my 9yr old little brother used to call the "pinch-botty secretaries" * in UFO up there it would be something I suppose.)

* very 70s and un-PC: they included the incomparable Gabrielle Drake and Michael Caine's future wife.

 

[exchemist]

In the diagram that foghorn posted (also quoted below), you can see that, after the initial launch (steps 1-3), Artemis was put into a large elliptical orbit, but still an orbit around the Earth (steps 4-8). There will be some "proximity operations" during that large orbit (which lasts for about a day), in which the astronauts will be practicing some parts of a docking manoeuvre (mentioned in item 6 on the diagram).

There is another burn at 8 to increase the radius of the elliptical orbit at perigee (the closest point to the Earth on the orbit, which is at point 9).

At step 9, there is a long "trans-lunar injection" burn, which takes the spacecraft out of the elliptical orbit and puts it on track to the moon. That will happen tomorrow, at around the same time as today's launch. After that burn, the astronauts are going around the Moon, no matter what. There's no turning back.

From there, there are no more engine burns, except possibly for slight course alterations. Gravity does all the work between points 9 and 14.

They won't be slowing down. Basically, the moon's gravity will slingshot them around the moon and put them onto the return path to Earth. Point 12 allows for slight course corrections, if necessary.


Yes, but the Moon's gravity will put the spacecraft back onto a return trajectory.

No. The moon won't capture the spacecraft. It is not going into lunar orbit on this mission. In future missions, where NASA does want to orbit and/or land on the moon, some slowing down will be needed (and then speeding up again to start back towards the Earth).

No. This is a "free return trajectory". No power from the spacecraft needed.

Not on this trip. At the moon, the spacecraft will have sufficient velocity to escape the Moon's gravity, once it goes around.

Those are mostly to make sure that the spacecraft is headed in the right direction. Small corrections far away can make enormous differences later on. It's a very long way from the Earth to the Moon (380,000 km).

As well as the main engine, the spacecraft also has smaller manoeuvring thrusters. For example, at times it is put into a slow rotation to allow for more even heating by the Sun.

Apollo also had manoeuvring thrusters.

OK thanks. So the speed they will have is low enough for the combined pull of the moon and Earth to pull them back, once they have passed it.

What confused me a bit was the diagram. I imagine the actual trajectory will be much more elongated than shown, passing the moon but then going out some distance before being pulled back past it again. I have now read they will pass the moon at a distance of 6500km, so not very close.

 

[Sarkus]

OK thanks. So the speed they will have is low enough for the combined pull of the moon and Earth to pull them back, once they have passed it.

Bear in mind that Artermis II is being sent on an elliptic trajectory that would automatically return the craft to Earth. And actually in roughly the same time-frame. It's not a straight line path to the moon and then using the moon to reverse course. The craft will, always be on a return trajectory, as it doesn't get close to escape velocity, so when it makes its insertion burn it will burn into an elliptic orbit, with the perigee at LEO and apogee somewhere beyond but near moon's distance.

So why the need to do this "free-return" trajectory? It adds a layer of safety, as well as saves some fuel. The safety comes from being able to use the slingshot to help optimise the re-entry angle into Earth's atmosphere. So if engines somehow fail after the insertion burn, they should still be safe. If they just went on their initial elliptic orbit (i.e. if moon wasn't there) then there would need to be mid-course correction burns to ensure the right re-entry angle. And if engine failure...

As for what happens around the moon, Artemis will enter the moon's sphere of influence with speed X, and will likely leave the sphere of influence with speed X as well. It's the joy of a hyperbolic trajectory. (In more exciting manoeuvers around a planet with an atmosphere you could aero-brake to dramatically alter the speed of departure relative to speed of approach.) The key, though, is the angle that the trajectory will change, which, relative to the moon, will be about 60-70-degrees (although from the Earth's perspective it will look more like 140-150). So it will still be on an elliptic orbit relative to Earth, but now such that the re-entry angle is safer for all concerned.

(It would be safer still if rather than return straight into re-entry, they insert back into LEO and then re-enter from there, but that requires as much fuel again as to insert - and more for the insertion burn because you'd have to carry that fuel all the way to the moon and back. Hence the return straight into re-entry and why the slingshot is useful).

What confused me a bit was the diagram. I imagine the actual trajectory will be much more elongated than shown, passing the moon but then going out some distance before being pulled back past it again. I have now read they will pass the moon at a distance of 6500km, so not very close.

It's all relative. The moon and earth are some 380k km apart, so not quite as loopy as the diagram might suggest.

Relative to the moon, Artemis will swoop in from c.60k km when it enters the moon's sphere of influence, fo the fly-by at 6-7k, and then fly out again. Trajectory will have changed, safety achieved, and all will be good with the world.

 

[Sarkus]

I'm unclear what benefit establishing a lunar base is intended to have, other than beating the Chinese - a very Trumpy objective.( Mind you, if we get what my 9yr old little brother used to call the "pinch-botty secretaries" * in UFO up there it would be something I suppose.)

* very 70s and un-PC: they included the incomparable Gabrielle Drake and Michael Caine's future wife.

I have UFO on Bluray. Excellent series. Just a shame they only made the 1 series before giving way to the much-poorer "Space: 1999"!

 

[Pinball1970]

You dash beastly spoil sports, this is epic and an important land mark!
We can find out a huge amount from the moon in terms of the formation of the earth, the moon and our solar system, that's for starters.
Much more sophisticated kit to isolate and identify abiogenesis seeds on pristine samples on the moon too.
A science lab on the moon (I would have that job) access to space with no atmosphere getting in the way.
Stepping stone, at some point our descendants will have to leave this planet and develop technology to deal with deep space, this is the first step.

Why did Apollo stop? Public opinion? Cancer? Starving Africans? Vietnam?
Public opinion probably would have said the LHC was a waste, 7 billion dollars?
CERN gave us the internet, particle accelerators (also a waste) gave us PET, CAT and MRI, actually we call it NMR but the public get squeamish about "nuclear."
Fuck em!

 

[Pinball1970]

I have UFO on Bluray. Excellent series

I'm still too cross to upvote the party poppers on this thread but UFO was totally awesome. The concept, the tech, the beautiful 1960s ladies and of course.....the music.

 

[Seattle]

You dash beastly spoil sports, this is epic and a huge land mark!
We can find out a huge amount from the moon in terms of the formation of the earth, the moon and our solar system, that's for starters.
Much more sophisticated kit to isolate and identify abiogenesis seeds on pristine samples on the moon too.
A science lab on the moon (I would have that job) access to space with no atmosphere getting in the way.
Stepping stone, at some point our descendants will have to leave this planet and develop technology to deal with deep space, this is the first step.

Why did Apollo stop? Public opinion? Cancer? Starving Africans? Vietnam?
Public opinion probably would have said the LHC was a waste, 7 billion dollars?
CERN gave us the internet, particle accelerators (also a waste) gave us PET, CAT and MRI, actually we call it NMR but the public get squeamish about "nuclear."
Fuck em!

We should be more understanding. They would much prefer watching a series on the BBC about the NHS.

I was a teenager when they first landed on the Moon and when they last landed there. By the end, when the average person heard that there was a crew up there now, the reaction was "meh, what's new?":

It was a big let down when they stopped going and instead of building a permanent Moon Colony, they decided to build Skylab in LEO.

The general consensus for why we stopped the Apollo program was money and diminishing returns. "Why don't we pay teachers more, what about the poor...?"