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The goal is not to go to moon in this decade or even the next decade.

Everybody is over their skis. 

Imagine Congress cutting costs while astronauts are on a moon base.

Pragmatism v Idealism v Socialism v Fantasy Island

Game over
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Having some non-zero amount of "self-focusing" effect isn't enough. The mere fact that you saw the words "self-focusing" somewhere doesn't save you, therefore.

For a nuclear implosion you need nothing less than perfect sphericality and uniformity, otherwise the core will just "blorp" out the side. :-\  Yes that is the technical term.  :D
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As this is in the news again I figured I'd go look for pictures, video or *anything* that gives us an impression of what it is.. can someone save me the effort?

I noticed an uptick in aerogel research also, that I attribute to the more ready availability of materials for experimentation, which is great! Love for something from the zap-it-till-it-flies community to go the same way. Make a drone or something. Oh, all your kajillion volts are too dangerous? Oh well, it's not like you can test it in space...

How 'bout them superconductors?  :-X
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Rotating detonation engines are over-rated. None of them have demonstrated even mediocre performance, yet.

The detonation is just another way of trying to get a higher effective combustion pressure. A good pump system is at least as viable.

The detonation velocity of methalox is about half the exhaust velocity of a Raptor.
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3.5% failure on recovery suggests to a casual reader that those failures are somehow part of a statistical distribution and have something to do with the reliability of recovery.

You know that it doesn't, and yet you keep making those statements.  The failures occurred during the development phase, and are clustered at the beginning.

Data is only as impartial as the person collating it.

We were only talking about post-2016, so I did not include the first half-dozen or so landing failures that occurred during that early development phase. 

 - Ed Kyle
I'd be happy to stand corrected, but how many of the 3.5% occurred, say, during the first 20% of the operational history?

Because the data you choose should be usable to reflect the reliability of the system we're discussing, which was the whole point, right?

Well it's been a couple of weeks, I'm back from my trip, so I decided to look it up myself.

2017 started with flight #29
We're now at flight #325
There have been some 8-odd landing failures during the intervening years (out of about 300 flights), which is about 2.5%
The last F9 landing failure occurred in early 2021 (flight 108) so the last 200 flights were failure-free.

So - first of all, how did you even get 3.5%?

But much more importantly - characterizing this vehicle as having a 3.5% (or 2.5%) failure rate is absolutely misleading. There's zero correlation between the calculation you made and the reliability of F9 today. It's a dishonest use of data.  You're taking your opinion, and painting the numbers around it to create the picture you want.

You did the same with the payload comparison you made elsewhere this week between the Starship prototype that just flew, and the New Glenn specification that is entirely on paper - neglecting everything that is important about the comparison, again just painting the numbers into the picture you want to see.

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Rotating detonation engines are over-rated. None of them have demonstrated even mediocre performance, yet.

The detonation is just another way of trying to get a higher effective combustion pressure. A good pump system is at least as viable.

Detonation destroys metals - the combination of extreme pressure fluctuations and ultra high temperatures penetrates normal boundary layers exposing surface of metals to destructive thermal spikes and pressure forces that are normally buffered by protective boundary layers.  This breaks down metal surfaces, stripping oxide protections and wrecks cavitating water pumps, water turbines, items left too long in sound nodes of ultrasonic baths, engine pistons + rings and other combustion chamber elements etc.  I strongly doubt that RDE's will ever be more than lab curiosities - much as they have been (in the form of variant pressure gain combustors) for 60 years.
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Chinese Launchers / 7 Sats - ? - ? - 2024
« Last post by mikezang on Today at 04:03 am »
合肥逐梦星辰 加速驰骋“新质”赛道
Quote
Hefei Chasing Dream Stars accelerates on the “new quality” track

The group is planning to build a remote sensing satellite constellation based on SAR satellites - the AIRSAT constellation. It plans to achieve the first phase of 21 satellites in orbit in 2026. Seven satellites will be launched this year
The 7 payloads of AIRSAT constellation will be launched this year.
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Perhaps it's just me, but I saw Ingenuity as game-changing for de-risking Martian flight in general and the fetch copter concept in particular. If a safe, Cat II landing site at Isidis Planitia is 100km away, then I'm not sure why this would be especially more risky than if the landing site was <10km away. Run a campaign of landing ~3 such starships, landing 1-2 weeks apart during the same transit window so lessons from EDL can be iterated/tested rapidly. Each has some number of robust fetch copters capable of making the traverse and picking up a tube each, perhaps multiple times, plus the MAV as shown. Derisk the mission through numbers.  Bonus is that we probably get to see external footage of at least one of the starships landing on Mars.

You're assuming that the loss of certain samples is acceptable.  I'm not sure that's a valid assumption.  It seems as if the science team is willing to pick and choose between which samples they want, but that doesn't necessarily mean that point-losses amongst what they choose won't be fairly devastating.

Long-distance flight on Mars is a very low-TRL proposition.  Even with multiple helicopters, there's some time/distance/repetition threshold where the chance of failure grows very rapidly.  Maybe you can get a few tens of km to be fairly reliable.  But 180km (which seems like the round trip that would be required for a landing in the flatter parts of Isidis Planitia) would be well outside the capability of an Ingenuity-like platform, which only went 17km.

Remember, they're trying do de-risk the mission, not push the envelope.

I didn’t mean to make any assumptions about losing samples - actually intended the opposite. It seems to me that - given we’re already pushing the envelope on size of landing craft by quite a lot, we’re now into a size regime where EDL failure is very possible no matter who does it.

It’s in SpaceX’s interest to gain data from multiple landing attempts - indeed that’s how they have lowered costs so far - so I was predicting that multiple redundant landers/retrieval craft would make it more likely that we end up with a (single) MAV loaded full of retrieved samples ready to fly.

Necessarily, any landing campaign done the SpaceX way should happen far away from any sites deemed of value. Ergo, pushing the envelope on the retrieval flights traverse distance helps to lower risk/cost from every other part of the mission.

I think it’s fairly well accepted that horizontal flight is the least risky part of flight. Ingenuity’s high number of flights has derisked the liftoff/landing portion of each flight. So I have trouble reconciling why a somewhat bigger craft of the same basic design as Ingenuity, traversing distances 1-2+ orders of magnitude longer, is such a big jump in TRL. To me this seems like low hanging fruit that makes everything else easier.
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Bob departed PC on Apr 21 @ 7:21pm ET

https://twitter.com/SpaceOffshore/status/1781826068329934937

Quote
Gav Cornwell
@SpaceOffshore
Departure! SpaceX's Bob is outbound to support Starlink 6-53. 📸 http://nsf.live/spacecoast
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Doug + ASOG + B1080 returned to PC on Apr 21 @ 1:58pm ET
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