RCgothic
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Posts posted by RCgothic
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19 minutes ago, Moritz Space said:
All 33 engines, it just seemed weird that 2 seconds into the burn it's basically all dirt and no water.
My guess is the water is probably being near-instantaneously vaporised and steam is transparent. It'll still cool the pad. And I think the reddish colour is nitrogen dioxide from the exhaust impinging on air rather than dirt. There's just not that much dirt to blast off a steel pad.
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One thing to mention is that poor quality LED light driver units can generate harmonics in the cabling that can lead to interference on radio frequencies. Took a few months to track that problem down on the kitchen radio a few years back. So if you have LED lights you may find you get better reception when they're off.
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5 hours ago, kerbiloid said:
Also, it was a lack of vacuum-proof electronics, so the soviet space tech was using pressurized command pods, which limit the active existence with months or in the best case a couple of years without servicing (pressure replenishment).
And now I know why soviet probes often incorporated spherical hulls. I really should have realised they were pressure vessels before now.
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Ah, but what if they built a test stand that could accurately represent dynamic flight conditions /s
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1058 was the NASA worm marked booster. A sad loss. 19 flights was a great run.
Still, there are three more boosters already on 17 flights, and a further 5 with more than ten.
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9 hours ago, tater said:
months ago
9 hours ago, JoeSchmuckatelli said:Ok good - thanks.
Being Kraken-Banned from this Sub makes it difficult to keep up
Many months - as the video timestamp 11th July 2022. So sixteen months and change at this point. It was booster 7 which eventually flew on IFT-1 in April this year.
Booster 9 flew on IFT-2.
Booster 10 is currently in the launch prep sequence.
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1 hour ago, CatastrophicFailure said:
Sigh. I’ma say this just one, and probably regret it, and hopefully the mods just delete this whole tangent, but anyways…
X is objectively doing better now than Twitter ever was. Twitter was on a short path to bankruptcy, X is now moving strongly the other direction, and likely to break a profit next year. Certain people have been foretelling the impending dooms of Elon Musk’s various ventures for years, and they’ve been wrong every single time. Hate what X has become if you want (that’s your right, and it’s mine to say you are incorrect in thinking so), but it’s no more dying than Tesla is bankwupt or SpaceX will never fly again.
/RantOff
I must be thinking of a different X because it is not even close to cash positive, not on a trajectory to be, and is in substantially worse shape than it was before his takeover. Not only do the subscription model and staff firings not recoup even a fraction of the lost advertising revenue (lost for no good reason at all), but it has a heavy debt burden that's over a billion dollars per year and it's currently valued less than a third of what he paid for it.
The total mismanagement has completely exploded his aura of competence and poses a direct threat to his control of his other companies SpaceX included. If Shotwell retained control it could even be an improvement.
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I was a prodigious twitter user until it became X and witnessed firsthand his descent into echo-chamber and buying into his own trollish cult of personality. It has not been at all edifying, and his decisions related to the site have been almost purely destructive and he's now on the hook for billions a year in debt repayments.
Something like 73% of his Tesla stock is leveraged, so if he has to sell any significant amount to cover his twitter debt or default on that debt then that could both crash the value of Tesla and cause banks to call in his collateral and he'll lose the company.
It's a small step from there to having to sell his stake in SpaceX to cover debts. He's already previously borrowed $1B from SpaceX (albeit he paid it back quickly on that occasion).
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I'm a lot more worried about the future of SpaceX thanks to Musk's behaviour and contagion from other businesses of his than I am about technical aspects of Starship.
Technical difficulties can be solved, but there's no recent evidence Musk can keep his erratic behaviour from impacting his companies. Twitter's on a death spiral, and the debt is heavily leveraged against Tesla.
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Eloquently put.
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It's already even smarter than that. If an engine goes out it'll first gimbal the centre engines to maintain thrust through the centre of mass, and only down-throttle opposite engines if doing so is necessary to maintain sufficient margin of control authority. Actually turning opposite engines off would be a last resort.
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There isn't any evidence the engines were the source of the issues on IFT-2, and even with the previous version of engines some of the failures on SN8 to 11 were not engine related. SN8 had a sudden loss of pressure in the methane header tank and SN10 had helium ingestion.
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Uranium is really abundant in Earth's crust. More so than gold, mercury, silver and tin. There are traces basically everywhere that metals are found. Rocky inner solar system worlds in the Goldilocks zone are therefore overwhelmingly likely to have decent uranium deposits. If a previous civilization really had stripped a planet of all uranium, they'd likely have taken most of everything else of value as well.
Icy worlds and the atmospheres of gas giants would be very metal deficient generally. As well as presenting an extremely hazardous environment for visiting lifeforms, it's unclear higher life could evolve in such places. Certainly nothing needing decent quantities of iron for blood.
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Missing tomato on ISS found 8 months after disappearance, astronaut Francisco Rubio exonerated of stealing and eating the tomato.
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16 hours ago, Jacke said:
What I think limits what has been done so far is that the lifetime needed for cryogenic propellants (beyond lower amounts for fuel cells that have primarily used boil-off cooling) has just been at most a couple of days to allow for an extended parking LEO prior to the final burn. Beyond that for mission propellants it's almost completely storable hypergols or liquid noble gases for ion drives.
Which means it's whole new experience for long term cryo propellant storage. At least it's not LH2. But I expect this will take a fair amount of testing to find what measures will be worth their expense in payload mass. Adding mass on the final stage of a rocket (for cooling gear or lost propellants) is near 1-to-1 in cost of payload mass.
In this instance they could launch a 300t depot with over 200t of zero boil off gubbins and *zero* residual propellants and all it would cost is an additional refuelling mission.
Obviously there's room to refine, but as a first effort they've got a lot of mass budget to play with.
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Double layer tanks with vacuum between them and a solar powered cryo-cooler. Maybe a sunshade too. Refine as necessary.
It's not as if zero-boil-off tanks are a theoretical impossibility.
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It won t be Hydrogen. It'll be Oxygen or Methane which is what Starship has onboard already.
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2 hours ago, Nuke said:
flying is a lot different than flying and not exploding. just because someone has a fusion reactor on the drawing board or even a test reactor, doesn't mean you should demolish all your fission plants.
starship i think will make it in the long run, how long really depends on how much time the regulators and detractors waste. sls is an adequate mr. backup.
We have a perfectly operational falcon 9 and falcon heavy, and with appropriate mission architectures *those* make a nonsense of SLS.
For the same expenditure as 1 SLS mission it would be possible to purchase 40 centre-core expended falcon heavy missions for about 2000t to LEO pure payload.
Moreover that's commercial sale price, so those missions would generate enough profit for SpaceX to launch more Starlink missions and progress Starship. Whereas funds spent on SLS are not redeveloped.
The only thing keeping SLS going at this point is stubbornness.
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I don't see why the Artemis partner nations couldn't be just as bought in to a lunar surface base.
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2 hours ago, Exoscientist said:
Keep in mind Destin also doesn't like the NRHO Gateway, in addition to not liking the multiple refueling launches for the Starship HLS. He prefers an architecture that does go to low lunar orbit.
But the present SLS can’t send the Orion to LLO and be able to return Orion back to Earth again. That is why the NRHO Gateway was proposed in the first place. But a low cost modification would give the SLS the capability to send Orion to LLO and back again, and also allow a single launch architecture for the Artemis lunar lander missions:
Possibilities for a single launch architecture of the Artemis missions, Page 2: using the Boeing Exploration Upper Stage.
http://exoscientist.blogspot.com/2023/08/possibilities-for-single-launch.htmlRobert Clark
None of us like Gateway, but there isn't any cheap modification to SLS, and certainly not anything that would be as cheap or capable as simply moving Orion/ESM on top of a Starship Super Heavy stack.
NASA should stop making bad puddings just because they've spent a long time preparing bad ingredients.
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1 hour ago, Spaceception said:
IFT-3 will be a pretty big test, if they're going to attempt to complete a major milestone during the flight. Does it technically make it the first contracted flight of Starship, at least indirectly?
Propellant transfer is a milestone, true, a really important one.
But demonstrating RVac apparently was a milestone as well, got there first on IFT-2.
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Richard Branson to provide no more funding for Virgin Galactic, says it has enough, alarms investors, shares plummet.
https://www.theguardian.com/science/2023/dec/04/virgin-galactic-shares-richard-branson-funding
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And even if an engine exploded, it's not necessarily the fault of the engine. E.g. fuel starvation causing turbine overspeed, or the control system getting fragged by shrapnel from a pressurised line failing.
SpaceX are the people with the data.
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15 hours ago, darthgently said:
Small neighborhood state of the art nukes would be the best solution, imo
Traditional grids generate their power close to where it is needed, and long-distance power transmission is fractional amounts for rural purposes and load balancing.
Decentralised grids to support unpredictable power sources need to be able to send large fractions of national consumption over long distances and have many more connection points. This also adds to the price per kWh, which will soon become apparent.
Large nukes use fuel more efficiently than small nukes (it's a function of the surface area to lose neutrons from vs volume - another square cube law), but as fuel is a relatively small proportion of the lifetime costs this isn't necessarily a huge deal if you can make other savings with economies of scale on smaller plants, but this would rely on there being enough permissible nuclear sites. The current policy of reusing existing sites (in the UK at least), tends to favour large plants.
Small plants close to where the power is needed would be particularly effective for using the by-product heat for heating and industrial process heat. By using this heat it's possible to triple the fuel efficiency of nuclear plants (any thermal plant actually).
It's bizarre we don't do this already.
Edit: It's even more bizarre 6 of you liked this post before I corrected all the word substitutions autocorrect snuck in that I didn't immediately notice yesterday. I'm amazed anyone understood what I was on about.
SpaceX Discussion Thread
in Science & Spaceflight
Posted · Edited by RCgothic
The level of reddish colour is fairly constant for the steady state portion of the burn. If it were dirt you'd expect it to decreasing as the dirt was cleared.
Whereas if it were nitrogen dioxide production the colour would be fairly constant at constant throttle, which is what we see.
I'm not 100% certain, but seems like a much better fit to the evidence to me.
Another source would be iron oxide from constant erosion of the steel, but the deluge is supposed to prevent that .