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DigiPen? I graduated from there. It is a non-accredited video game development school. What are they doing sending up cube sats?
Or you can send a smaller craft to build a landing pad.
We don’t design 787’s to land on rough terrain.
ULA is developing a new Centaur stage.
Louis,
Well, at least the sheet steel is cheap to play with. I really do think this can work, but only if they put some serious engineering behind it and stop trying to crank out another one as fast as humanly possible. I know that they're smart and capable, but this is increasingly looking like tossing darts over your shoulder at a wall and hoping something sticks. Stainless is a very old and well-proven technology, insofar as upper stages are concerned, but everything we're seeing looks like inexperience with using it and/or very poor quality control. I'd like to see a successful pressure test, successful landing, and stricter QC program, but I'll chalk up what I've seen thus far to "new technology" (for them). ULA makes stainless work with boring reliability, despite the extreme measures they've taken to reduce weight.
You are looking at it incorrectly. You are evaluating the performance of individual rockets coming off the assembly line. They are looking at it in terms of performance of the assembly line itself. There’s time to correct the engineering of the craft, but they will do so within the constraints of the assembly line.
It’s no coincidence that this strategy follows Musk’s do-or-die ramp up of Tesla’s automotive production line. You can’t just design anything and expect to be able to build it at scale, as Elon learned. You have to design for mass manufacturing. That is what SpaceX is doing right now.
Louis,
When SN4 meets the same fate, is there a SN5 under construction?
Maybe it's time to slow down just a little to analyze what's happening and also to start using proper tooling?
It's an assembly line. There's at least an SN4, SN5, and SN6 already under construction. They're re-tooling the assembly line based on the tests. But we can expect a new SNx basically one every other week (eventually every week) until it works or Musk runs out of money.
I think my earlier point wasn't conveyed adequately. NASA is currently doing research on what large, hot, plasma plumes do to regolith surfaces in lower gravity, mainly for the purpose of landing on the moon but a lot of the research carries over to Mars. It's turning out that we got very, very lucky on Apollo without knowing it. One of the people doing this is Dr. Phil Metzger of UCF, and he's been great about answering questions on Twitter. Here's one specifically about landing Starship on a fine-grained regolith environment:
https://twitter.com/DrPhiltill/status/1 … 3942992898
In short summary, it seems that larger landers than Apollo risk creating a deep crater during landing, which in turn causes the rocks and dust to start getting blown out closer to vertical than we saw with Apollo, and risk damaging the other engines and landing gear. It also means that the hot plasma exhaust starts going deep into the ground, where it could get trapped in cavities, causing an explosive blowback event. Finally, regolith (on the moon or Mars) consists of extremely fine powders whose physics isn't really well characterized, and for which there isn't really any terrestrial analogue (even the course simulants we use), and we have a hard time predicting its behavior when subjected to the extremes of a rocket landing.
The current plan for the moon is to land a small, solar powered rover before any very large lander. The rover would be able to clear and level an area large enough to serve as a landing pad, and use microwaves (or perhaps lasers) to heat the regolith material. The resulting sintered material would work as a makeshift landing pad for the first couple of landings.
Where would you possibly find an existing, level, flat slab of granite with no regolith covering and near where you wanted to land anyway?
Louis, a rocket of that size is more likely to blast a crater in the ground and destroy its own landing gear if landing on random terrain. Among people who are seriously looking at this (like Dr Phil at UCF), it seems more likely that a precursor mission would be required to prepare a landing site for Starship arrival. This would involve sintering a rough but level landing pad.
Louis-
I seriously doubt that SX is working on habitats. They would be getting spread way to thin financially to do so. Out of Elon's own mouth: "we are a transportation company." Bigelow seems to be a viable option to pursue, however.
SpaceX isn't working on habitats, as far as I know, but they should be. Sending full Starships to Mars and back is ludicrous. If you're going to send that much mass, keep it there. Makes far more sense to launch Bigelow or Mars Direct style habitats in the payload bay of a Starship, then stage those somewhere in cislunar space for a caravan journey every 2 years. Use just one starship to carry people and cargo back. Launch needs are going to be asymmetric for a very long time.
I don't think "entitlement" here carries the definition you are assuming. It's a legal word used to describe benefits which the government must pay out based on qualification, regardless of whether Congress allocated funds. It's just another word for "non-discretionary" benefits, and nothing more is meant than that. Normally Congress is allowed to decide year-by-year what gets spent (i.e. "nope, we're not going to pay $13bn for that new aircraft carrier"). But really they can only do that for so-called discretionary spending. Non-discretionary spending, like social security or medicare, is paid out regardless, unless and until Congress amends the governing rules.
They didn't even apply for the ISS expansion contract. Bigelow brought this on themselves. Real echos of Bell aerospace here.
Guys, does it matter? The virus is out.
Musk tweeted that the tiles are hexagonal-shaped because that provides "no straight path for hot gas to accelerate through the gaps." The tiles will be installed on the windward side, towards the direction of re-entry, "with no shielded need on the leeward side." The hottest sections will have a "transpiration cooling" system, with microscope pores on the exterior that allow water or methane to ooze out and cool the exterior. That would minimize damage on the heat shields and allow the Starship to return to service shortly after a flight merely by refilling the heatshield reservoir. "Transpiration cooling will be added wherever we see erosion of the shield,".
Which means he does not know whether he needs it or not.....
I don't know how you got that idea from the quote. He knows that transpiration cooling will be required--the physics demands that. What's not clear is which parts of the exterior will need it the most. Which is reasonable since reentry dynamics are not something which simulations are 100% correct on. So put extra tiles on the first test model, and add the active cooling where the outer tiles burn through.
This is just old-school iterative engineering design.
I think that the active cooling has been discarted from the first version of the Rocket.
By first version do you mean the SNx orbital test vehicles, or the first commercial versions? The test vehicles are treated as expendable and I doubt they're targeting same-day reuse for them.
You are only considering passively cooled designs. Starship will be using plain stainless steel with active cooling. If it works, it would require very little servicing, not much more than an aircraft (they claim).
My point is this: (1) there are no known materials capable of 100 LEO entries and no hints on the horizon of any such thing existing, and (2) the only things we have capable of surviving 12-17 km/s entries off of interplanetary trajectories are ablatives (with very limited life).
I’m sorry I’m not following what you said. Are you saying you have copies of the database and files that were lost in the crash, but they need to be integrated? Or are there pieces that are irretrievably lost?
Is that sarcasm? ISS doesn’t use in-orbit refueling for station keeping.
No Void, I don’t want you to go away. I just found some humor in the situation. Keep being weird!
Done.
You keep using that word. I do not think it means what you think it means.
Actually stepping down from the board of Tesla is a pretty big deal. For better or worse musk has banked a lot of the mars project on success at Tesla, in the form of his incentive-based rewards that would let him keep SpaceX private while still pursuing big projects like the BFR. Now that he’s no longer chairman of the board he doesn’t Have near singular control over the direction of Tesla, and may not be able to make those bonuses. That could have a huge implications for SpaceX
I’m very surprised this hasn’t been mentioned yet in the thread, the definitive resource on self-replicating machinery:
http://www.molecularassembler.com/KSRM.htm
And the NASA study:
That's why you sign up for Alcor. But anyway, back to awesome cave art of plutoid objects.
Void, well that line of thinking can bifurcate in two directions.
The first is trans/posthumanist: assume people will upload themselves to machine/computer bodies and ask what the best computational substrates are at that temperature, pressure, and available resources. Carbon (for diamond) and silicon are probably still two very desirable elements for computation itself, but you also have to think about heat transfer and energy distribution. Energy will probably distributed via hydrocarbons.. a nitrogen atmosphere would be useful for heat dissipation, but liquid cooling is probably more efficient.
That's really as far as I've thought this through -- I'm too busy working on transhumanist tech at standard temperature and pressures to consider optimal low temperature, low pressure designs, but I would read with earnest speculation anyone else wants to put together.
The second is exemplified by Robert Forward's book Camelot 30K. It's a terrible book -- very little plot and character development, long-winded chemical explanations that drag on for pages -- but the speculative biology is absolutely incredible in its worked out detail and reasonableness (except the isotopic separation, but you got to allow at least one hand-wavey exception in a work of fiction). Without spoilers, the book deals with first contact between humans and a hive-like pre-technology species living on a plutoid object. The speculative biology (both chemical and evolutionary) is really interesting and relevant to this conversation -- pressurized liquid blood & internal chemistry, an energy cycle feeding on cosmic ray spallation, and a reproductive cycle enabling ecosystem spores to spread from object to object in the Kuiper belt.
Except for maybe the destructive reproductive cycle, it illustrates a wonderful basis for what life might look like in low pressure, low temperature environments. For those that are more in the wilderness camp than gardeners (I count myself in that group), it would be interesting to work out a minimally viable low-P, low-K single-celled organism would be -- probably engineered based on entirely different speculative chemistry than Earth biology -- and then guide the rapid evolution of ecosystems using targeted genetic engineering to introduce complexity and then let the results play out naturally. Every plutoid object in the Kuiper belt could have a differently evolving ecosystem overseen by its post-human occupants themselves in low-P, low-K compatible bodies.
It may seem more science fiction to someone not previously exposed to transhumanist ideas. But it is a more realistic idea of how this might actually play out.
Void, you're assuming Earth-like biology. There us no reason the creatures that colonize the plutoids need to be carbon-based life forms.
If you want to talk of glaciers:
http://www.lpi.usra.edu/meetings/lpsc2008/pdf/2441.pdf
Evidence for a 0.28km thick glacier just east of Helles basin.