I hope this is an ok place for the thing that is bugging me about the just-flown Starship test 9. Sanity-check me. I am not an engineer, so perhaps molehill -> mountain. The attitude control system based on ullage gas strikes me as the opposite of robust, with its complete dependence on propellant container integrity. Ship seemed to lose attitude control almost immediately SECO. 1) Was the perhaps limited supply of thruster gas used up rapidly fighting off-axis forces caused by leaks, some of which were likely off-camera? (I noticed a persistent jet midbody in the view down the side of the spacecraft — with the apparent torque on Ship opposed to that jet. Leak, or thruster trying to compensate?)2) can someone ballpark the Isp of an ullage-gas thruster fed by a pressure of 6 bar? What does this do to available impulse? Does the large volume of the reservoir redeem the apparent inefficiency?3) (especially when longer-duration missions are in the cards) will the designers have to bite the bullet and build in an RCS more along known designs — higher Isp for higher total impulse budget, and reliably storable until needed?
Quote from: aporigine on 05/28/2025 10:47 amI hope this is an ok place for the thing that is bugging me about the just-flown Starship test 9. Sanity-check me. I am not an engineer, so perhaps molehill -> mountain. The attitude control system based on ullage gas strikes me as the opposite of robust, with its complete dependence on propellant container integrity. Ship seemed to lose attitude control almost immediately SECO. 1) Was the perhaps limited supply of thruster gas used up rapidly fighting off-axis forces caused by leaks, some of which were likely off-camera? (I noticed a persistent jet midbody in the view down the side of the spacecraft — with the apparent torque on Ship opposed to that jet. Leak, or thruster trying to compensate?)2) can someone ballpark the Isp of an ullage-gas thruster fed by a pressure of 6 bar? What does this do to available impulse? Does the large volume of the reservoir redeem the apparent inefficiency?3) (especially when longer-duration missions are in the cards) will the designers have to bite the bullet and build in an RCS more along known designs — higher Isp for higher total impulse budget, and reliably storable until needed?The loss of pressure in the main tanks (and maybe headers) was caused by the "harmonic response vibrations" which damaged the already "retorqued" connections and caused loss of propellant. Luckily they made it to orbit with whatever "fixes" they have been doing.
I think the isp of cold gas thrusters is <100 and google AI says" Cold gas thrusters generally have an Isp ranging from 30 to 75 seconds, although this can vary depending on the propellant used."
Quoting AI is a waste of time, it is notoriously ignorant about science. LLM's can't even do simple math.
SpaceX Launch Successful (Friday, October 3rd, 2008) Direct audio link, MirrorLast weekend, private space transportation company SpaceX successfully launched a payload into orbit, becoming the first privately-developed rocket to orbit the planet. The launch last weekend was the fourth try by the company to make orbit with its new launch system, named the Falcon 1. The company plans to offer commercial space launch services at rates significantly below existing methods."The data shows we achieved a super precise orbit insertion — middle of the bullseye — and then went on to coast and restart the second stage, which was icing on the cake," Elon Musk, founder of the company, said in a statement. In this segment we'll talk with Musk about the launch of the Falcon 1 and what's next for the company.Restructuring Space Flight (Friday, April 16th, 2010) Direct audio link, MirrorIn February, President Obama unveiled his proposed budget for 2011. This week, President Obama rolled out some details of how those changing budgets and changing priorities will affect NASA -- including different roles for various NASA centers, the termination of the 'Constellation' launch vehicle moon program, and plans for a larger role for private business in space flight. We'll talk about the government's new space strategy, and what lies ahead for NASA. Is an eventual trip to Mars on the distant horizon? With Elon Musk the CEO and CTO of SpaceX, Bill Adkins of Adkins Strategies and Former Staff Director House Space and Aeronautics Sub-Committee, and Howard McCurdy a Professor at the School of Public Affairs at American University.SpaceX Craft To Head To Space Station (Friday, August 19th, 2011) Direct audio link, Mirror The SpaceX company has gotten approval to launch its Dragon spacecraft this fall. If all goes well, the ‘craft will dock at the International Space Station nine days later, making it the first private spacecraft to do so. SpaceX CEO Elon Musk discusses plans for the launch. On Eve of Launch, SpaceX Head Talks about Mission (Friday, May 18th, 2012) Direct audio link, MirrorSpaceX is set to launch its Dragon spacecraft to rendezvous with the International Space Station this weekend. If successful, it will be the first commercially developed, launched and operated craft to meet the ISS. SpaceX head Elon Musk talks about the launch, and his other project, Tesla Motors.
Quote from: meekGee on 05/19/2025 10:52 pmQuote from: Twark_Main on 05/19/2025 08:40 pmQuote from: BN on 05/18/2025 01:12 pmwe know for sure that 0g is not viable for embryogenesis.development in 0.34g seems quite likely to result in deformities. [citation needed] for the bold claim...We all seen it with our own eyes! The mutants! And they have powers!All that, while absolutely acknowledging it's a risk. How about the first crew brings some mammals with them, and maybe refrain from starting pregnancies until they have some baby whatevers? As an aside, animals are real good at converting low grade agricultural product into stuff we can eat.I often joke "Who will eat the grass?" in reference to non row crop suitable land here on earth. There are huge areas of ag land where row crops can't be grown, but will support cattle, sheep, and goats. Cows, goats, and sheep can turn many of the non human edible parts of plants into human edible food. Catfish also can. One would need to convert the plant refuse into pellets for them to eat. Actually many types of fish can do the conversion. An interesting one is tadpoles. Many species are grazers on algae and plants. One would have to harvest them before they turn into frogs and change diets.What is the life expectancy of a mouse in a chicken yard? Peck, peck, gulp. Chickens can eat seeds and grains, but they prefer insects, and other much higher protein foods like mice. They aren't cellulose eaters like geese are. I don't know of any bird that would be good to bring.Of course, all this plant matter has an important use, compost. Compost for making more soil for growing more food in. Especially types of plants that don't like hydroponics.
Quote from: Twark_Main on 05/19/2025 08:40 pmQuote from: BN on 05/18/2025 01:12 pmwe know for sure that 0g is not viable for embryogenesis.development in 0.34g seems quite likely to result in deformities. [citation needed] for the bold claim...We all seen it with our own eyes! The mutants! And they have powers!All that, while absolutely acknowledging it's a risk. How about the first crew brings some mammals with them, and maybe refrain from starting pregnancies until they have some baby whatevers? As an aside, animals are real good at converting low grade agricultural product into stuff we can eat.
Quote from: BN on 05/18/2025 01:12 pmwe know for sure that 0g is not viable for embryogenesis.development in 0.34g seems quite likely to result in deformities. [citation needed] for the bold claim...
we know for sure that 0g is not viable for embryogenesis.development in 0.34g seems quite likely to result in deformities.
Quote from: meekGee on 05/19/2025 10:52 pmQuote from: Twark_Main on 05/19/2025 08:40 pmQuote from: BN on 05/18/2025 01:12 pmwe know for sure that 0g is not viable for embryogenesis.development in 0.34g seems quite likely to result in deformities. [citation needed] for the bold claim...We all seen it with our own eyes! The mutants! And they have powers!All that, while absolutely acknowledging it's a risk. How about the first crew brings some mammals with them, and maybe refrain from starting pregnancies until they have some baby whatevers? As an aside, animals are real good at converting low grade agricultural product into stuff we can eat.Haven't they done mice pregnancy and birth on the space station?It seems like a no-brainer to have been done already?
https://babylonbee.com/news/elon-musk-leaves-job-of-making-government-more-efficient-for-much-easier-job-of-sending-humans-to-mars"Elon Musk Leaves Job Of Making Government More Efficient For Much Easier Job Of Sending Humans To Mars"
"Working in government is a far more complicated and challenging job than inventing rockets capable of taking humans to other planets," Musk said of his decision to leave DOGE. "Coming up with ways to make interplanetary travel a reality is one thing, but dealing with senators and congressmen is truly difficult. I look forward to having a more relaxing job of figuring out how to safely transport people to Mars, colonize it, and terraform the planet's surface."
Thanks @rookisaacman for stopping by Starbase and handing out pizzas. Very cool to meet you in person.
It was nice meeting everyone. As I think what comes next--I know I can always fall back on slinging pizzas.
Jared Isaacman just visited Starbase:https://x.com/MFederschm7630/status/1936150536119803948QuoteThanks @rookisaacman for stopping by Starbase and handing out pizzas. Very cool to meet you in person.https://x.com/rookisaacman/status/1936162089132847508QuoteIt was nice meeting everyone. As I think what comes next--I know I can always fall back on slinging pizzas.As the saying goes, It's times like these when you realize who your true friends are...
But clearly it would make much more sense to just skip all the failures and go straight to the successes?...(Just kidding)
Seeing as we'll be waiting a bit longer for any visible progress, I spent a bit of time this afternoon toying with alternative starship propellant tank layouts. Not that I think the current layout isn't pretty firmly locked in already, it just seems to be lacking in some respects, and a bit of brainstorming can never hurt.Main idea here being to move the SL raptors (or their derivatives) to the waist, using them as gimballed, elevated thrusters for lunar/Mars landing. (Surely we don't need both SL raptors at the base *and* waist thrusters?). In any case, I've moved the associated prop tankage to the nose of starship, and the crew/payload space into the middle (cargo starship gets a cylindrical payload door). This also leaves room for some unpressurised payload in the space between the RVacs. The lower LOX tank is intended to be just enough O2 to supply the RVacs for launch (and/or TLI, TMI) so that the engines would face the sun during cruise phase. Methane for RVacs is routed through downcomers either side of the crew/payload space.Where necessary, starships would dock tail to tail in this config. More practically, this could mean a pressurised chine running down the dorsal side of starship to a docking port planar with the base of starship. But a fun alternative could be having airlocks on top and bottom of the lower O2 tank during cruise phase, and actually use it as open space during the cruise portion of trips. Anyway, I didn't think it was worth a thread on it's own, but maybe it will trigger something for someone.
Quote from: mikelepage on 06/26/2025 01:27 pmSeeing as we'll be waiting a bit longer for any visible progress, I spent a bit of time this afternoon toying with alternative starship propellant tank layouts. Not that I think the current layout isn't pretty firmly locked in already, it just seems to be lacking in some respects, and a bit of brainstorming can never hurt.Main idea here being to move the SL raptors (or their derivatives) to the waist, using them as gimballed, elevated thrusters for lunar/Mars landing. (Surely we don't need both SL raptors at the base *and* waist thrusters?). In any case, I've moved the associated prop tankage to the nose of starship, and the crew/payload space into the middle (cargo starship gets a cylindrical payload door). This also leaves room for some unpressurised payload in the space between the RVacs. The lower LOX tank is intended to be just enough O2 to supply the RVacs for launch (and/or TLI, TMI) so that the engines would face the sun during cruise phase. Methane for RVacs is routed through downcomers either side of the crew/payload space.Where necessary, starships would dock tail to tail in this config. More practically, this could mean a pressurised chine running down the dorsal side of starship to a docking port planar with the base of starship. But a fun alternative could be having airlocks on top and bottom of the lower O2 tank during cruise phase, and actually use it as open space during the cruise portion of trips. Anyway, I didn't think it was worth a thread on it's own, but maybe it will trigger something for someone.Crazier things have come to pass.Not many and not by much, but still...I like the trade offs.
One advantage is that fuel doesn't care that's in in a "weird shape" of the nose cone, whereas any monolithic payload or piecemeal loading needs to be fit around the curve of the nose. In this case all payloads just fit in a cylinder, like Shuttle.
Another advantage is that the maximum thrust configuration goes from 6 RVacs + 3 SL engines up to 7 RVacs + 6 (or more?) SL engines.
I guess, sure, but I wasn't really thinking of this as a way to increase total thrust. The plumbing/structural reinforcement around the waist thrusters is complicated enough, (no idea if it's better to go canted, or have thruster pods). And for lunar/Mars landers it will be very useful to have unpressurised payload space in the trunk/engine compartment.
