Author Topic: The Artemis Program  (Read 11272 times)

bknight

• Neptune
• Posts: 3100
Re: The Artemis Program
« Reply #30 on: November 20, 2022, 05:38:25 PM »
I was tinkering with finding the point at which the Moon's gravity becomes larger the Earth's.  Solving a simple quadratic is not something that I have accomplished lately (15 years or so) but I calculated if my math was correct that point is about, from memory as the calculation sheet is gone, about ~4500 Km from the Moon.  This sounded too low and that prompted me to discard the sheet.  Anyone have a better figure?

Not OTTOMH. But the Apollo Flight Journal would have transcripts discussing it for the various missions.

Quote
ETA: I see that at 0938 CST that the velocity has decreased to 451 mph today.

ETA1: I see that at 1106 CST the velocity has decreased to 420 mph but the distance to moon is decreasing more rapidly perhaps the number is ~44060 miles currently (70908 kph)  I might have made a decimal error ~45000 Km.

I note that Artemis has gone beyond the Moon's orbit as well. And its encounter with the Moon is now about 15.5 hours away...I think I'll be tuning it to that.

The trajectory is very different than that of Apollo.  Currently 1632 CST velocity is 301 mph distance to Earth is 233315 m.  now the mean distance to the moon is 238900 m, but it may be closer in this orbital position so I'm not sure it is beyond the Moon. The burn will be about 8 hrs. currently and the burn will occur beyond the Moon.

ETA: from https://history.nasa.gov/afj/ap11fj/11day4-approach.html
Quote
PAO:This is Apollo Control at 62 hours, 29 minutes. The Flight Surgeon reports that the crew appears to have been asleep now for about the past 30 minutes. The spacecraft appears also to be holding its Passive Thermal Control attitude very well and at this time Apollo 11 is about 32,000 [nautical] miles [59,000 km] from the Moon, traveling at a speed of 3,782 feet per second [1,153 m/s]. In the past 50 minutes or so, we've seen that velocity increase about 10 feet per second [3 m/s], going from 3,772 feet per second [1,150 m/s] to the present 3,782 [1,153 m/s], as the spacecraft continues to accelerate toward the Moon. The Change-of-Shift Briefing following this shift will occur at about 11:15 pm Central Daylight Time. Flight Director Glynn Lunney and his team of flight controllers are coming on now, being debriefed by the Eugene Kranz team, and that shift change will be occurring shortly here. The new capsule communicator will be astronaut Ron Evans. At 62 hours, 30 minutes, this is Apollo Control.{/quote]

Artemis at over 100 hr. is still slowing now 287 mph that translates to 128 m/s in comparison.
« Last Edit: November 20, 2022, 06:08:12 PM by bknight »
Truth needs no defense.  Nobody can take those footsteps I made on the surface of the moon away from me.
Eugene Cernan

gillianren

• Uranus
• Posts: 2211
Re: The Artemis Program
« Reply #31 on: November 21, 2022, 11:33:07 AM »
I really don't understand looking at current events and thinking, "Yes, I trust an Elon Musk-run company to be handled well."  I'd far rather trust NASA.
"This sounds like a job for Bipolar Bear . . . but I just can't seem to get out of bed!"

"Conspiracy theories are an irresistible labour-saving device in the face of complexity."  --Henry Louis Gates

Allan F

• Jupiter
• Posts: 997
Re: The Artemis Program
« Reply #32 on: November 21, 2022, 11:57:28 AM »
I really don't understand looking at current events and thinking, "Yes, I trust an Elon Musk-run company to be handled well."  I'd far rather trust NASA.

I'm pretty sure he's not micro-managing things, just setting overall goals. He's not an engineer or scientist himself, he has people doing those things for him.
Well, it is like this: The truth doesn't need insults. Insults are the refuge of a darkened mind, a mind that refuses to open and see. Foul language can't outcompete knowledge. And knowledge is the result of education. Education is the result of the wish to know more, not less.

Peter B

• Saturn
• Posts: 1261
Re: The Artemis Program
« Reply #33 on: November 22, 2022, 03:46:52 PM »
I really don't understand looking at current events and thinking, "Yes, I trust an Elon Musk-run company to be handled well."  I'd far rather trust NASA.

I'm pretty sure he's not micro-managing things, just setting overall goals. He's not an engineer or scientist himself, he has people doing those things for him.

The micro-managing seems to be happening at Twitter ATM. Maybe that's a good thing for SpaceX? And Tesla?

bknight

• Neptune
• Posts: 3100
Re: The Artemis Program
« Reply #34 on: November 28, 2022, 12:20:40 PM »
I have a question for anyone concerning the mission.  I'm looking at a "top down" ASPECT AND AS OF 1 CST, the MET is 12:13:16 and the spacecraft is approaching the apogee of this orbit.  The is another point on the orbital track that is labelled Distant Retrograde Departure, but it is later than the apogee.  What is the benefit of this burn occurring after the apogee has past?
Truth needs no defense.  Nobody can take those footsteps I made on the surface of the moon away from me.
Eugene Cernan

Peter B

• Saturn
• Posts: 1261
Re: The Artemis Program
« Reply #35 on: November 28, 2022, 03:31:59 PM »
Out of interest, would the SLS's first stage be the largest stage ever launched?

Peter B

• Saturn
• Posts: 1261
Re: The Artemis Program
« Reply #36 on: November 30, 2022, 02:59:39 AM »
Out of interest, would the SLS's first stage be the largest stage ever launched?

Well...apparently it is. Cool!

smartcooky

• Uranus
• Posts: 1958
Re: The Artemis Program
« Reply #37 on: December 04, 2022, 03:09:05 AM »
I have a question for anyone concerning the mission.  I'm looking at a "top down" ASPECT AND AS OF 1 CST, the MET is 12:13:16 and the spacecraft is approaching the apogee of this orbit.  The is another point on the orbital track that is labelled Distant Retrograde Departure, but it is later than the apogee.  What is the benefit of this burn occurring after the apogee has past?

Ask, and Lord Scott Manley shall answer

https://www.youtube.com/watch?v=XFIvKSVRtZ0
► What you can assert without evidence, I can dismiss without evidence
► When you argue with idiots you risk being dragged down to their level and beaten with experience.
► Conspiracism is a shortcut to the illusion of erudition

Peter B

• Saturn
• Posts: 1261
Re: The Artemis Program
« Reply #38 on: December 04, 2022, 03:29:37 AM »
I have a question for anyone concerning the mission.  I'm looking at a "top down" ASPECT AND AS OF 1 CST, the MET is 12:13:16 and the spacecraft is approaching the apogee of this orbit.  The is another point on the orbital track that is labelled Distant Retrograde Departure, but it is later than the apogee.  What is the benefit of this burn occurring after the apogee has past?

Ask, and Lord Scott Manley shall answer

https://www.youtube.com/watch?v=XFIvKSVRtZ0

Square orbit? I would have laughed if that had come from most other people...

smartcooky

• Uranus
• Posts: 1958
Re: The Artemis Program
« Reply #39 on: December 04, 2022, 05:28:21 AM »
I have a question for anyone concerning the mission.  I'm looking at a "top down" ASPECT AND AS OF 1 CST, the MET is 12:13:16 and the spacecraft is approaching the apogee of this orbit.  The is another point on the orbital track that is labelled Distant Retrograde Departure, but it is later than the apogee.  What is the benefit of this burn occurring after the apogee has past?

Ask, and Lord Scott Manley shall answer

https://www.youtube.com/watch?v=XFIvKSVRtZ0

Square orbit? I would have laughed if that had come from most other people...

Yeah! I think that would make most Flat Earthers' heads explode!!
► What you can assert without evidence, I can dismiss without evidence
► When you argue with idiots you risk being dragged down to their level and beaten with experience.
► Conspiracism is a shortcut to the illusion of erudition

Peter B

• Saturn
• Posts: 1261
Re: The Artemis Program
« Reply #40 on: December 04, 2023, 09:14:04 AM »
https://www.youtube.com/watch?v=OoJsPvmFixU (about an hour)

Smarter Every Day video of a talk by Destin at the American Astronautical Society.

He seemed to be challenging NASA with awkward questions about Artemis, but I would be curious to know what the Brains Trust here thinks of his questions.

Cheers

Peter

jfb

• Mars
• Posts: 395
Re: The Artemis Program
« Reply #41 on: December 06, 2023, 11:29:00 AM »
Definitely not part of the brain trust, but ...

I kinda wish he'd twisted the knife a little harder with respect to why Orion can't get to LLO; that is the reason for this whole Rube Goldberg-esque architecture with the Gateway in NRHO and a dozen Starship launches and and and...

I mean, we all know why; under the Constellation conops Orion would launch on Ares I, the Altair lander and EDS would launch on Ares V, they'd dock in Earth orbit and the whole stack would do a TLI burn directly to LLO.  Orion was always part of a distributed lift program, but the parts that would make it useful were cancelled.  SLS can't do distributed lift; we can't build the boosters quickly enough or cheaply enough.  We can build one unit every 2 years at > \$4 bn a pop.  That's not sustainable or useful.

Fortunately Starship is almost flying, which will add significant lift capability for not that much money.  We could likely design a much simpler mission architecture around Starship.

But we spent all this time and money on Orion, so we're going to use it, even though it drives this complicated architecture.  We're designing the mission around the equipment, not the other way around, and we're doing it because of the sunk cost fallacy.  That's something that everyone really needs to understand.

But Destin rightly points out that's all spilt milk under the bridge; this is the architecture going forward, so we have to make it work.  But to make it work we have to be honest and clear-eyed about the effort it's going to take and communicate that information clearly and completely to all stakeholders, and so far we haven't done either of those things.
« Last Edit: December 06, 2023, 12:42:53 PM by jfb »