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The Rocket fan

17:02

plus.nasa.gov/scheduled-video/…

Intuitive Machines-1 is soon going to land on the moon!

Let's hope it works because it is the first time that the US landed on the soon since 1972

Seggan

17:28

So I've been doing some orbital physics calculations recently in code and I was wondering if y'all could confirm my suspicions

I have 2 coplanar intersecting orbits, and all 3 anomalies of the intersection point for both orbits. To calculate the delta v needed to switch between the orbits at that point I just use the vis-viva equation on both and subtract the velocities, right?

(I also have the parameters of said orbits)

The Rocket fan

@Seggan not quite, but close. The issue is if the velocity is in a different direction or at a different angle. Then to get the difference (or the delta v needed to change the velocity), you have to use Pythagorean Theorem

Seggan

Ok, so I know I can get the angle from the anomalies, how would I convert that into delta v?

The explanations I've seen online assume circular orbits, which I can't assume

I don't see how the Pythagorean theorem would help here

The Rocket fan

17:43

Seggan

Ah ok I get it now

I think the vis-viva is a special case of that?

ty either way, I literally spent days on this

The Rocket fan

Here is a simple calculator which you can use to calculate any length or angle of the triangle calculator.net/triangle-calculator.html

@Seggan The vis-visa can be used to calculate the velocity of an orbit

Seggan

Oops I meant my original solution

The Rocket fan

You can calculate velocity 1 minus velocity 2 if both are in the same direction

Seggan

Mhm I get it now

The Rocket fan

17:47

Your welcome

3 hours later…

Erin Anne

20:45

it's not the Pythagorean Theorem if it doesn't involve right triangles

it's sparkling vector maths

cosine law, I think it'd be generically referred to as

anyway. Fingers crossed that the Intuitive Machines stream isn't bad

it being on nasa.gov doesn't give me confidence

The Rocket fan

21:03

@ErinAnne Your right, it is not the Pythagorean theorem since it does not include right angles.

Hopefully the Intuitive Machine stream isn't bad. I never watched anything on that webpage before so I really have no idea if it is good or not.

Also for some reason I cannot edit the comment I made about Pythagorean theorem, so it looks like that it will have to stay.

NASASpaceflight is also streaming the landing of Nova C. I am not sure where should watch it.

Erin Anne

I guess it depends on how much excited shouting you want

The Rocket fan

21:59

The live stream is now starting

Erin Anne

22:15

I know too many of these guys. Each time I see one of them on the podcast it's weird

Shaun Stewart dramatically putting on his headphones

I bet they had to do that like five times because he wouldn't stop laughing

podcast? livestream, I mean. bad brain

at one point he was late for work because the wheels got stolen off of his truck overnight, which is obviously horrible. terrible way to start your day

before he got in, we took the wheels off his office chair and rested it on a bunch of textbooks

that's the kind of friend group that was

Erin Anne

22:43

livestream guy doesn't know Descartes was French

Erin Anne

23:26

I wonder why there's a comm switchover at / near landing

they had telemetry almost the whole way down

The Rocket fan

I am nervous. It might have crashed

We have no signal right now

They did say that it can land automatic, so maybe it is just a communication issue

Fingers crossed

Erin Anne

automatic is nominal

this wasn't a piloted landing

The Rocket fan

I know. That is why I still have a bit of hope that it could be okay.

Erin Anne

this is why high-gain antennas suck

always, always have a low-gain beacon so you can find out of the spacecraft is still alive if the high-gain won't point correctly

The Rocket fan

They said it was off by 8 degrees at one point in the live stream

OMG THERE IS A RETURN SIGNAL!!

Erin Anne

23:33

and it seems like it gets deleted in all the missions I've worked on because oh it duplicates what the high gain antenna does, gotta get rid of mass

huh you must be like 30 seconds ahead of me

The Rocket fan

Where are you watching?

I am on NASA Spaceflight

Erin Anne

the nasa.gov one

The Rocket fan

Okay

It seems like the signal is weak, but is there. It might take up to 15 min or longer to fully establish communications. That is the last I heard

Erin Anne

sounds like they've landed intact and need to refine comms to get the full picture on if they're 100%

still probably better off than SLIM

The Rocket fan

I hope it didn't flip over

fyrepenguin

23:40

@ErinAnne that was honestly impressive that it restored functionality

Erin Anne

there's basically no way they'd be getting signal from a high-gain antenna if it was that far out of attitude

it's almost certainly upright, maybe not pointed exactly the way they thought, but still

gotta admit I'm a little surprised--even if you land off-nominal, surely you've got some kind of attitude determination on board. A star tracker would get you your landed attitude

presumably your HGA can re-point, so why isn't it pointed right? or is it fixed?

maybe it's not a pointing error I guess

The Rocket fan

Maybe it landed on a slope and is now facing in a slightly angled way

Erin Anne

yet more reason you'd think that, post-landing, you'd assess your attitude and re-orient your high gain antenna

it's common to be able to point those because high-gain is necessarily narrow-beam

fyrepenguin

@ErinAnne they already had some star tracking issues at the beginning that they pushed up a patch for - I wonder if they have more?

Erin Anne

well that would be embarrassing

huh. I'll be curious to hear what's going on