GW Johnson Postings and @Exrocketman1 YouTube videos

GW Johnson · 2024-10-24 12:35:18

I have basically two space station articles posted on "exrocketman". One is an on-orbit propellant depot titled "A Concept for an On-Orbit Propellant Depot", dated 1 February 2022. The other is a concept for an on-orbit repair and assembly facility, titled "On-Orbit Repair and Assembly Facility", dated 11 February 2014.

There is no reason why both functions could not be fulfilled by one big facility built in orbit. I would suggest a low-inclination circular orbit in the 300-500 km altitude range, and I would include orbit modification propulsion into the design from the very outset. I would also try to combine thermal insulation with meteor shielding and with radiation protection in my designs.

To find these quickly on my "exrocketman" site, go to http://exrocketman.blogspot.com, and use the archive fast access tool on the left side of the page. Click on the year, then click on the month, then click on the title, if the article is not top-of-list for that month. I have a catalogue article of all the technical stuff I have posted there, covering a wide variety of topics. That one is titled "List of Some Articles By Topic Area", dated 21 October 2021.

I try to keep the catalogue article updated, but there are no guarantees.

To see figures enlarged, click on a figure. There is an X-out option top right of the page showing enlarged figures. It takes you right back to where you were, before you clicked on a figure to enlarge them.

GW

tahanson43206 · 2024-10-24 13:13:38

I'd like to (at least try to) encourage you to continue working on the combined depot concept.

This forum is available if you want a one-click presentation.

All that searching and finding is fine for a suitable audience.

(th)

tahanson43206 · 2024-10-24 17:25:27

This post is intended to hold links to two files prepared by GW Johnson as part of a set that covers Mars Colonization.

These two files are primarily about a lander, but the presentation included planning for an expedition, including staging of supplies using electric propulsion.

Notes on presentation:
https://www.dropbox.com/scl/fi/liabcp15 … bk83l&dl=0

Presentation:
https://www.dropbox.com/scl/fi/en1k18h6 … qghw5&dl=0

(th)

tahanson43206 · 2024-10-25 07:42:15

For GW Johnson...

In thinking about your reports of seeing different ads than I see, it occurred to me that Google is probably serving different ads to customers based upon all the information that they have collected about each of us. I see a lot of ads that tie back to inquiries I have made, or that are appropriate for my demographic.

In a spirit of scientific inquiry, I'd appreciate your creating a list of the ads you see when you click on the recovered ring video.

I'l do the same, and let's compare notes.

Please specifically record if you can skip or not. Some ads do not allow skip. These are generally political ads, I've noticed. You may get more than your fair share because of your stored data held by Google.

(th)

GW Johnson · 2024-10-25 08:22:29

In post 428, I checked both links. They both lead to the presentation notes file. I could not see the slide set.

GW

tahanson43206 · 2024-10-25 08:36:18

For GW Johnson re #430

Thanks for catching that. I corrected the link and the presentation should now load.

However, please think about where else to put the links. They will get lost pretty quickly if they are only in the one topic.

(th)

GW Johnson · 2024-10-25 09:39:20

I checked, it's OK.

These go with the other two slide sets I recently sent you: slides+notes for exploration vs experimental bases vs actual settlements, and slides+notes for unmanned direct cargo 1-way, delivering almost 40 tons. The single most important key to this approach is wanting to visit multiple sites in the 1 mission: that forces you to base out of LMO, not the surface! That is where I differ with most other mission plans. My approach is older. But it gets more done more quickly, and would actually be cheaper.

That leaves a whole lot yet to look at, such as an orbit-to-orbit transport for crews, and how to send landers and propellant ahead to LMO to support the landings and the return. But, implied by all of this (or most any other plan) is the need for a combined propellant depot and shipyard assembly facility in LEO.

As you can see, I learned the Korolev lesson of just build the bigger rocket. It worked for him.

GW

tahanson43206 · 2024-10-25 11:20:09

For GW Johnson....

Now that we have the links working, please give some thought to setting up a dedicated topic for the series you are working on.

You've already indicated (in private correspondence) that there might be a book in there somewhere, and this forum is a good place to build up a sequence of short pieces that eventually flow into a single entity.

This topic with your name on it is NOT the right place for a dedicated sequence.

We created the Course topic(s) with the flow in mind. Those could be fine tuned, because you were still creating content when we built those topics.

A Nation State is the size entity that would implement your overall vision, if the Nation State is on the large size, like China, India or perhaps the US.

It is possible that a consortium like the EU might be able to tackle something this size, but their policy of having to agree on everything suggests to me they'll never be able to agree on a project like this.

China is a likely candidate to pull this off on their own.

In any case, if you write a book, it should be written for the size entity that can pull it off, and not just for education of the public.

(th)

GW Johnson · 2024-10-25 14:57:22

I don't have enough for a book yet, for sure.

But I did do a Mars mission plan based out of LMO that visited multiple sites in the one mission. This was my Mars 2016 plan. The landers I recently sized supersede those landers. But the baton-spin crew orbit-to-orbit transport is about the same. I would use elliptic departure and capture for it at Earth. And sending landers and propellant ahead to LMO is the same issue it was in 2016.

The problem with any of this is the same as it was for Von Braun circa 1940: how do you assemble large things in Earth orbit? He did not know as much then as we do know today, about surviving long missions in space, and he knew nothing about the Van Allen radiation belts (discovered in 1958 by Explorer-1). But his basic orbit-to-orbit mission plan is still sound today. We just need to lower it from his 1000 mile altitudes, to about 200 mile altitudes, to stay out of the Van Allen belts. Especially the South Atlantic Anomaly. And, because of the Van Allen belts, we CANNOT send crew by electric propulsion (at least as we currently understand it).

Musk's Starship configured for Mars with "real" landing legs is much more appropriate to the settlement phase, when there are hard landing pads at Mars, and return propellant can be manufactured in quantity on Mars. Neither is true of the experimental base phase, and neither is true almost by definition in the exploration phase. Building hard pads and experimenting with propellant manufacture is PRECISELY what gets done in the experimental base phase, along with a lot of other life-support-related stuff.

Exploration answers the question "what all is there, and where exactly is it?". Experimental bases exist to figure out exactly how to live off the land, something NOT done during exploration. And until you answer all the issues from the experimental base phase, there is no ethical point to trying to start a settlement. PERIOD!

Why is this difficult to grasp? I've presented this before! At a Mars Society convention! To an audience who agreed with me!

GW

Last edited by GW Johnson (2024-10-25 15:08:05)

tahanson43206 · 2024-10-26 17:20:06

This post is a transfer from the Falcon 9 topic, where you had just pointed out that Falcon 9 burns kerosene and not methane.

For GW Johnson re methane leaks....

I just realized this is the Falcon 9 topic, and you've pointed out the Falcon 9 does not use methane.

I'll pick up in GW Johnson topic.

***
So here's my follow up question....

Might it be possible to set up little furnaces inside the Starship engine bay to burn any methane that might leak?

The output from the little furnaces would be co2, which would not contribute to combustion when it moves around the engine bay.

Would it make sense to set up little methane burners near any valves or joints that might leak methane?

Is this a strategy that might help to mitigate the risks due to use of methane as a propellant?

(th)

GW Johnson · 2024-10-26 17:48:07

To tell you the truth, I dunno.

I'd be very leery of deliberately setting fires where there could be a fuel gas leak, but that's just the fire protection engineering experience talking.

What we do with hydrogen welding gas is just do the plumbing "right" so that it does not leak. Standard gas bottles are typically loaded to 2200 psig. All the plumbing has to be good for more than that. And avoid risk of hydrogen embrittlement. At least methane does not have the embrittlement risk.

To the best of my knowledge, no one has ever handled methane at 4400+ psig before. I'm unsurprised that there are problems.

GW

tahanson43206 · 2024-10-28 08:38:23

for GW Johnson re Post in Starship topic ...

My take on it:
Following the link and reading the whole story, it says exactly what has already been posted on the forums. My point: this is now “official”, being published in an industry trade journal.
GW

I am reminded of the anxious moments when Neil Armstrong was tempting fate by moving the LEM landing site. My recollection is that the LEM may have been down to the last 3 seconds of fuel.

In the case of the Starship booster, the engineers had set a time limit for the booster to complete all the myriad tasks needed to position the catch pins over the chopsticks. If the timer had gone off, a completely separate set of software would have been invoked to try to move the booster away from the launch tower. ** That ** code has not yet been tested, and the only way it ** can ** be tested is with a catch failure.

(th)

GW Johnson · 2024-10-28 16:09:08

3 seconds of propellant left for Apollo 11 sounds about right. I know it was a small single handful of seconds.

The choice faced by Armstrong and Aldrin was absolutely-certain death from trying to land in a field of closely-spaced house-sized boulders (where the computer was taking them), or risking certain death if the propellant ran out before they could land (taking manual control). They were pretty much past the abort-back-to-orbit point. They chose the manual landing, and got away with it. Barely.

GW

GW Johnson · 2024-10-29 08:50:39

From AIAA’s “Daily Launch” for 29 October 2024:

NASA Finds Root Cause Of Orion Heat Shield Charring
Irene Klotz October 28, 2024

The heat shield for NASA's Artemis II Orion spacecraft was installed in June 2023 at Kennedy Space Center.
Credit: Cory Huston/NASA

NASA says it has determined why its Orion spacecraft returned from its 25-day Artemis I flight test around the Moon with unexpected charring in its heat shield.

Agency officials, however, declined to release its findings, pending ongoing internal discussions about next steps.

The finding was disclosed at two industry meetings on Oct. 28, with NASA’s Lori Glaze, acting deputy associate administrator for Explorations Systems Development Mission Directorate, speaking at NASA’s Lunar Exploration Analysis Group, and Lakiesha Hawkins, assistant deputy associate administrator for the Moon to Mars office, later addressing a question at the opening session of the American Astronautical Society’s 2024 von Braun Space Exploration Symposium.

“We have gotten to a root cause,” Hawkins said. “We are having conversations within the agency to make sure that we have a good understanding of not only what’s going on with the heat shield, but also next steps and how that actually applies to the course that we take for Artemis II.

“We’ll be in a position to be able to share where we are with that hopefully before the end of the year,” Hawkins said.

Among the issues uncovered by the Nov. 16-Dec. 11 Artemis I flight test was unanticipated charring of the Orion capsule’s ablative Avcoat heat shield material. The 16.5-ft.-dia. shield was designed to protect the spacecraft during atmospheric reentry speeds of up to about 25,000 mph and temperatures of nearly 5,000F.

Sensors in the Artemis I Orion capsule showed thermal conditions still met crew safety constraints during atmospheric reentry, but the heat shield’s performance did not match preflight thermal and mechanical computer models.

NASA in January delayed the follow-on crewed Artemis II mission to September 2025 from November 2024 in part to better understand the issue with the Orion heat shield.

Glaze said engineers have demonstrated and replicated the heat shield charring with tests at the Arc Jet Complex at NASA’s Ames Research Center. “We’re assessing what is the appropriate approach for Artemis II regarding the heat shield,” she said, noting that construction of the shield is complete.

Additional testing is underway, she added. “We expect that to be done by the end of November, and then we anticipate discussions with the administrator, who will make the final decision on how to proceed.”

Artemis II is planned to be a 10-day mission during which four astronauts—three from NASA and one from the Canadian Space Agency—fly around the Moon in an Orion capsule and return to Earth. That is to be followed about one year later by Artemis III, which features a landing on the south pole of the Moon.

My take on it:

The article indicates they went back into an arc jet tunnel and supposedly duplicated the effects they saw on Artemis-1. I suspect (opinion only) they angled the test articles to accentuate the effect of fluid shear forces across the little test article, and found the char layer shears off the virgin underneath too easily without the hex, for the flow conditions on an Orion heatshield shape.

Since they have declined to release those details, instead discussing what to do next, as the article indicates, I also suspect (again only my opinion) that this is risky enough for the Artemis-II crew to put them in a quandary. Do they change the heat shield to something better (costing a bundle of time and money), or do they go ahead and risk the crew? If they change it, what do they change it to?

I worked up what I consider to be the answers to those questions in a letter I sent to NASA Administrator Nelson some months ago. He never saw it, or they’d already know what to do. All I got as a reply was a rejection form letter for my “unsolicited proposal” to NASA. That was inappropriate on their part, because the letter explicitly said it was not a proposal to “do” anything for NASA, it was merely a sharing of knowledge and ideas.

Bureaucracy quite often shoots itself in the foot stumbling over its own Byzantine rules and procedures. The bigger they are, the worse this effect.

GW

Update 30 Oct '24: Today's AIAA "Daily Launch carries a similar Space.com story that says the same things, but includes photos of the erratic cratering damage to the Artemis-I heat shield. I tentatively conclude NASA management is desperate for their engineers to OK flying manned with the bad heat shield anyway. The engineers are trying correlate about how much cratering they get because there is no hex reinforcing the char in their Avcoat tiles. If it is not too bad in effect, and not too variable, they will OK flying manned as-is. That's what all the months of arc jet testing are all about. The problem is the variability. It will prove extreme, I predict. And NASA management will NOT like that outcome!

Last edited by GW Johnson (Yesterday 10:31:13)

tahanson43206 · Yesterday 11:14:06

For GW Johnson re discussion with RGClark about methane fire in Starship booster...

This problem ** has ** to be solved.

How would you solve it?

This vehicle is supposed to perform launches several times a day, without extensive refurbishment between launches.

At this point, replacing the Hot Staging Ring appears to be needed.

(th)

GW Johnson · Yesterday 14:26:54

I don't know anything for sure, but it certainly appeared like a fuel-air fire in the engine bay of the descending Superheavy booster on Flight Test 5. As I indicated in the other thread.

There are a lot of possibilities as to where the leaking methane might be originating. This same effect has been seen at smaller scale in Raptor ground test videos, as flames enveloping some of the plumbing about the engine power head. Whatever is leaking, and there may be more than one thing, SpaceX really needs to identify it and fix it.

An oxygen leak is a much lower probability, but not zero. If such happens, sending pure oxygen into a fuel-air fire in the engine bay, then a huge, catastrophic, and fatal-to-the-vehicle explosion is inevitable. You shouldn't man-rate things with such problems unfixed.

GW

Last edited by GW Johnson (Yesterday 14:27:24)

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