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This web site offers an overview of the Artemis missions. It includes diagrams of the actual or planned flight paths.
https://www.rmg.co.uk/stories/topics/na … aunch-date
rmg stands for Royal Museums Greenwich
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Those trajectories are exactly what I previously understood about SLS/Orion Block 1, and amazingly close to what I analyzed for modeling propellant return via Gateway to LEO. My 60,000 km apoapsis halo is gravitationally stable, but required a slightly-higher dV burn to enter it at periapsis.
Apparently that slight dV increase is too much for SLS/Orion Block 1, so they went to the gravitationally-unstable 70,000 km apoapsis halo, which requires frequent course corrections by Gateway just to stay in that orbit. Without them, it leaves the moon, going into a far orbit about the Earth.
GW
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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Gemini is an extension of Google Search...
I asked Gemini for information about Artemis. I was looking for specifications of the docking port.
Hi Gemini! By any chance can you find specifications for the docking port on the Orion capsule? It is thought to be similar to the one on the Apollo capsule, but with decades of progress in space systems design, there may be some differences.
The Orion capsule's docking port is based on the Apollo capsule's design but has been significantly improved with modern technology. Here are some key differences and specifications:
Key Differences:
Enhanced Docking Mechanism: The Orion uses a more advanced docking mechanism called the "NASA Docking System (NDS)." This system allows for automated docking and provides greater flexibility in docking with different spacecraft.
Improved Sealing: The Orion's docking port has a more robust sealing mechanism, ensuring a tighter and more airtight connection between spacecraft.
Data and Power Transfer: The NDS enables faster and more efficient transfer of data and power between docked spacecraft.
Future Expansion: The Orion's docking port is designed to be compatible with future spacecraft and modules, allowing for potential expansion of the spacecraft's capabilities.Specifications:
Diameter: The docking port has a diameter of 800 millimeters (31 inches).
Interface: The NDS interface can transfer power, data, and air. Future implementations will be able to transfer water, fuel, oxidizer, and pressurant as well.Crew and Cargo Transfer: The passage for crew and cargo transfer has a diameter of 800 millimeters (31 inches).
Additional Information:
The Orion's docking port is located at the forward end of the spacecraft.
The NDS is compatible with the Shuttle/Soyuz APAS-95 mechanism used on the International Space Station.The Orion's docking port is not compatible with the larger common berthing mechanism used on the US segment of the ISS, the Japanese H-II Transfer Vehicle, the original SpaceX Dragon, and Orbital Sciences' Cygnus spacecraft.
Sources:
NASA Docking System
Orion (spacecraft)
Crew Transportation With Orion Educator Guide
Orion ComponentsI hope this information is helpful!
en.wikipedia.org
en.wikipedia.org
NASA Docking System - Wikipedia
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en.wikipedia.org
profile pictureThank you! That is ** very ** helpful! (th)
You're welcome! I'm glad I could help. Let me know if you have any other questions.
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GW Johnson has been warning the public about the risks of flying Artemis II with the suspect heat shield that failed during the Artemis I test flight with three dummy astronauts on board. Members of NewMars are well aware of the problems identified by GW Johnson.
It is with some surprise that I am able to provide this quote from an Internet news feed:
Space
NASA delays Artemis missions again. What could this mean for the moon, Mars and space leadership?
Andrew Jones
Mon, December 23, 2024 at 10:00 AM EST
The latest delays stem, in part, from an issue with the Orion crew spacecraft and its heat shield which was detected after a "skip reentry" during the uncrewed Artemis 1 mission in late 2022.
"We have since determined that while the capsule was dipping in and out of the atmosphere as part of that planned skip entry, heat accumulated inside the heat shield outer layer, leading to gases forming and becoming trapped inside the heat shield," NASA Deputy Administrator Pam Melroy said during a Dec. 5 press conference. "This caused internal pressure to build up and led to cracking and uneven shedding of that outer layer."
Related: NASA delays Artemis 2 moon mission to 2026, Artemis 3 astronaut landing to mid-2027
Artemis 2 will still use Orion, but with a different reentry trajectory to better manage the resulting heat. "The safety of our astronauts is always first in our decisions," NASA Administrator Bill Nelson said.
It sure would be interesting to know the behind-the-scenes thought process that led to this decision.
A possibility is that Mr. Nelson decided to give the new incoming NASA Administrator plenty of room to maneuver. An option is to kill the over-budget program altogether. Another (less likely) option is to replace the suspect heat shield with an Apollo Era version that has already flown with success in a flight before Artemis I.
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The influence of the skip re-entry is the true part, the notion of gas pressure building up and pushing chunks of char off, does not ring true at all, because polymer char is inherently porous! How can you build up gas pressure beneath something porous? Makes no physical sense. But most people would not know about that porosity of char.
I personally think the cooling during the skip between heating pulses embrittled the unreinforced char, so that it cracked and was more vulnerable to fluid shear forces tearing out chunks erratically. I've seen that behavior up close and personal, testing experimental ablatives in ramjet combustors. It was already vulnerable because it was unreinforced, there being no hex in the tiles they made. Cooling embrittlement during the skip just makes that worse.
Doesn't matter, the fixes are the same: either (1) put the fiberglass hex back into the heat shield, or (2) do not fly skip re-entries (what they chose to do for Artemis-2, using the already-installed heat shield that proved faulty on Artemis-1). They have been assuming that EITHER they had to go back to hand-gunning the Avcoat into the hex cells bonded to Orion the way they were in Apollo and the first Orion flight test, OR that they just fly the unreinforced bonded Avcoat tiles that they wanted, and which they built for Artemis-1 and Artemis-2.
They got into trouble by building Artemis-2 that way before actually flying the Artemis-1 unmanned test, which (unexpectedly) so very clearly said that their preferred design was the wrong heat shield for doing the skip entries they wanted to do. That was a simple management mistake: do not commit your design to a process until AFTER you have tested it. But they jumped ahead to save money and time, which they lost anyway, because it was a bad bet.
I gave them a way to make their preferred Avcoat bonded tiles with the hex incorporated into those tiles. So there really are now 3 alternatives, not just two. But to install it on the Artemis-2 Orion would cause further costly delay. So I understand the decision to fly anyway, but delete the entry skip. Not that it is the right decision, but I do understand. The "right" decision would be to fly Artemis-2 unmanned with a reinforced heat shield, to prove that it works right, before risking a crew's lives on it. But they would have to renegotiate contracts with the makers of the heat shield tiles, almost from scratch. And nothing ever takes place in a timely fashion, dealing with "old space" on a government contract. So, time and money trump crew's lives yet again, when it does not have to.
What I think we are seeing here is the same upper-echelon management resistance to admitting they made a mistake, that we saw with two fatal shuttle disasters. In the case of Challenger, this even led to an attempted cover-up, but which was exposed during the Rogers commission hearings by the physicist, an astronaut, and an actively-serving air force general.
If you fail to learn from history, you end up repeating it. And they are repeating it.
GW
Last edited by GW Johnson (2025-01-02 11:52:58)
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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Given the amount of time and money spent on Artemis II to date, it's unconscionable for the contractors to green light a faulty heat shield, as well as the administrators. I would think that Jared Isaacman will tell the contractors to FIX THE HEAT SHIELD! I wouldn't want to be in the shoes of the next NASA administrator, who will be under pressure to get this damned thing flying around the moon!
They are saying that it will take a year to made a new shield, but I suspect that it could be done by someone other than Lockheed Martin in a significantly shorter time by working 24/7 in order to maintain the schedule?
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I sent them the how-to to put the hex back into the Avcoat tiles they want to bond onto the capsule substrate. Initially I thought they were casting tiles to near net shape, but it turned out they cast big blocks of Avcoat, and then "machined" the various tiles out of those blocks.
You could still put the hex back in, either way, using a plastics industry extrusion press. Cut hex to fit the mold of the big blocks (there has to be one). Extrude the Avcoat through all the cells in that chunk of hex all at once, which precludes any voids, and eliminates all the variation in hand-gunning expertise, plus all the hand-gunning labor. Then line the box mold with some Avcoat, and drop the loaded hex core into it. Anything you cut from that cured block will have hex reinforcement in it.
The problem is who has Avcoat and who does not. I suspect Lockheed-Martin and Boeing have it, but nobody in "new space" is allowed to use it. Lawyers make a lot of money making sure these things happen that way.
Avcoat is an epoxy novolac resin loaded with microballoons to lower its density in a controllable manner. You can adjust the ablation rate somewhat by varying the finished density. This also varies finished heat shield weight: lower density is lower weight but higher ablation rate (it's a tradeoff you must make for the mission). But Avcoat ablative as defined during Apollo always without exception was hand-gunned into the hex cells of a fiberglass hex honeycomb previously bonded to the capsule substrate. That produced a monolithic hex-reinforced heat shield integrally bonded to the capsule. But on Orion, there are almost 400,000 such cells to fill.
There is nothing wrong with wanting to do this as pre-made tiles bonded separately to the capsule substrate. The integrity of the bonds and the integrity of the between-tile gap fillers is not in question on Artemis. But, they cast the big blocks of Avcoat without any fiberglass hex reinforcement, and then expected it to perform the same, without any prior flight test experience to show that it would work.
It was no skin off Lockheed's nose when it did not work, they got paid anyway, as was (and still is) typical for "old space". It was the upper echelons of NASA management that made that mistake, now compounded by building both Artemis-1 and Artemis-2 in that very same way, BEFORE flying Artemis-1 to verify it would work (which it did not). This mistake was further compounded by adding the skip re-entry. The original pre-Artemis Orion flight test used the Apollo hand-gunned approach identical to Apollo, and did not fly a skip re-entry. Too many variables from test to test. That's a lesson they either forgot or never learned, over time and personnel changes.
GW
Last edited by GW Johnson (2025-01-03 10:25:58)
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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