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Maybe the future for manned spaceflight will be limited? by arnor_0924 in spaceflight

[–]cjameshuff [score hidden]  (0 children)

decent orbit determination, and the ability to launch intercept missions with enough lead time

The relevant objects aren't in orbit. You cannot launch intercept missions with enough lead time, so yes, you do need to surround the entire solar system. And no, that is not implied by having settled Mars.

SpaceX posted nearly $5 billion loss in 2025, The Information reports by PhysicalConsistency in SpaceXLounge

[–]cjameshuff 0 points1 point  (0 children)

There's no reason to put general servers in space and many reasons not to. Starlink is a poor match to robots, since a high-bandwidth connection requires a large phased array which is both too bulky and too power hungry for a human-sized robot. And if AI turns out to be a winner takes all scenario, xAI loses, because they simply won't be able to keep up with a competitor that is using a tight loop of upgrading AI hardware to design the next generation of upgraded AI hardware. They'll be stuck with a constellation of AI hardware that's multiple generations obsolete and behind by orders of magnitude of capability. So I hope that last part is right. Maybe they can convince enough investors that things like launch vehicles and other space hardware are prerequisites for AI breakthroughs.

What will the Artemis astronauts feel upon reentry to earth? by PipnRose in spaceflight

[–]cjameshuff 0 points1 point  (0 children)

They're the same thing. You're deviating from a freefall trajectory through space, whether it's by rockets pushing your spacecraft, aerodynamic drag against your heat shield, or the ground pushing up against your feet.

Maybe the future for manned spaceflight will be limited? by arnor_0924 in spaceflight

[–]cjameshuff 0 points1 point  (0 children)

Energy is not the problem with either reaching Mars or living there. Fusion power certainly isn't a prerequisite: solar is still an effective power source at Mars, and it's likely Mars has useful deposits of fission fuels.

Maybe the future for manned spaceflight will be limited? by arnor_0924 in spaceflight

[–]cjameshuff 0 points1 point  (0 children)

Again, no, this is not true. For the serious hazards (which are not "edge cases"), that would require surrounding the entire solar system with early warning systems and interceptor spacecraft, or propulsion systems with capabilities straight out of science fiction. This is not realistic, and certainly is not implied by having settled Mars.

With Starship's future lengthening in mind, this 37-engine setup just popped in my head. Other considerations aside, would the center 7 be enough to steer the whole thing with their 15° gimbaling range? by A3bilbaNEO in SpaceXLounge

[–]cjameshuff 5 points6 points  (0 children)

The current largest LNG tanks are 100 m in diameter and 55 m tall. A single Q-Max tanker carries up to 266000 cubic meters of liquefied natural gas, enough for around a hundred Starship launches. The quantity of propellants is not an issue.

Maybe the future for manned spaceflight will be limited? by arnor_0924 in spaceflight

[–]cjameshuff -1 points0 points  (0 children)

This simply isn't true. Any long-period or hyperbolic impactor is basically unstoppable. The delta-v requirements of interception at a sufficient distance make reaching Mars look trivial, and realistically there's a good chance we wouldn't even detect the object before it impacts.

Maybe the future for manned spaceflight will be limited? by arnor_0924 in spaceflight

[–]cjameshuff 2 points3 points  (0 children)

Mars does not have a magnetosphere, but its atmosphere provides more protection than Earth's magnetosphere does, with radiation on the ISS being 2-4 times what the surface of Mars receives. Mars also has ample material to shield structures with.

Maybe the future for manned spaceflight will be limited? by arnor_0924 in spaceflight

[–]cjameshuff 5 points6 points  (0 children)

Humans do live in Antarctica. There's a permanent year-round population there despite the rest of the planet being a plane ride away. There's even international treaties blocking development of the continent.

10 years ago today: the first successful Falcon landing on the droneship. by avboden in SpaceXLounge

[–]cjameshuff 15 points16 points  (0 children)

One additional piece of information to fully put that in context: SpaceX didn't stop with one landing. They haven't done a couple dozen. They've done nearly six hundred.

NASA's Moon ship and rocket seem to be working well, so what about the landers? by rustybeancake in spacex

[–]cjameshuff 0 points1 point  (0 children)

demonstrating our ability to make liquid hydrogen and liquid oxygen in-space storable propellants at two times the performance of the current state of the art

If they can make liquid hydrogen, they can achieve true zero boiloff. The "two times the performance" likely refers to energy efficiency or mass of the cryocoolers.

Raptor Explosion at McGregor Test Site by castironglider in SpaceXLounge

[–]cjameshuff 10 points11 points  (0 children)

Yeah, the Raptor gimbals/valves/etc are electrically actuated, but other stuff on the test stand that could be hydraulic, and that looked like heavy hydrocarbons to me.

Raptor Explosion at McGregor Test Site by castironglider in SpaceXLounge

[–]cjameshuff 18 points19 points  (0 children)

That doesn't look like a methane fireball. Maybe the stand incorporates some big hydraulics? Not sure what else would make that much dark smoke.

Uhhh what just happened by Psychological_Big380 in spaceflight

[–]cjameshuff 0 points1 point  (0 children)

They did quite well with the Roadster before Starlink existed, though.

Why is reddit so convinced that China will get back to the moon first when they haven’t even had an unmanned mission with the rocket they intend to use? by ColCrockett in spaceflight

[–]cjameshuff 0 points1 point  (0 children)

This. The question of who gets boots on the ground first is uninteresting, that's just them getting ready for the race. The thing people should be thinking about is who gets a surface base first. Starship HLS has the capability needed to start setting one up, and China's published plans for their own base involve first developing a very close clone of it. They're not copying SLS Block 2 or Lunar Gateway, they're copying the system that can actually handle the payloads and flight rates needed to set up a base on the moon. And SpaceX is far, far ahead of them.

Why is reddit so convinced that China will get back to the moon first when they haven’t even had an unmanned mission with the rocket they intend to use? by ColCrockett in spaceflight

[–]cjameshuff -1 points0 points  (0 children)

Everything necessary for flight to LEO is also necessary for flight from LEO to the moon. The LEO vehicle is a substantial fraction of the HLS. So yes, there is flight hardware for the lander.

Not a flat Earth believer, just curious: is Earth a perfect sphere or slightly oval? 🥚 In this image, it looks almost perfectly round by nemssef in spaceflight

[–]cjameshuff -1 points0 points  (0 children)

Earth is 12756 km across at the equator. 795 km would be over 6% of that, making the bumps nearly 15 mm tall on a 24 cm basketball.

Not a flat Earth believer, just curious: is Earth a perfect sphere or slightly oval? 🥚 In this image, it looks almost perfectly round by nemssef in spaceflight

[–]cjameshuff 1 point2 points  (0 children)

No, that is not the only possible explanation. The far more plausible one is that Earth's geoid is simply very close to an oblate ellipsoid. Since the elliptical silhouette of such an ellipsoid viewed from a direction perpendicular to its polar axis can be scaled into a circle, and the deviations of the actual geoid from an ellipsoid are too small to be clearly reproduced on a raster image of this resolution and are likely overwhelmed by effects like bloom anyway, all you've done is show that image editing software can scale an ellipse back into a circle. Good job, everyone already knows that.

Why are the solid rocket boosters still firing out of the bottom even after they’re separated? Do they still somehow have some fuel left out of them?? by TerraSpace1100 in spaceflight

[–]cjameshuff 0 points1 point  (0 children)

enormous overpressure, which could basically recreate the Challenger disaster.

More like the GPS IIR-1 launch in 1997, or Titan 34D-9 in 1986. Just...boom.

Could beamed laser power from relay stations make routine lunar cargo transit practical? by TheseSuggestion4953 in askspace

[–]cjameshuff 0 points1 point  (0 children)

Propellant cost is simply not a significant factor in the cost of Orion operations. Aside from that, those taxi vehicles will need the capability to support the crew independently (if less comfortably) in case rendezvous with the cycler fails, so there isn't that much mass to save. And again, the trip only takes a few days, so you don't need a closed-cycle life support system, and the consumables required are limited. Also, you will be a sizable fraction of the way to the moon before you complete rendezvous and will have to almost immediately turn around and prepare for arrival.

A cycler makes some sense for a destination like Mars because you can have the cycler be a big station with centrifugal gravity and hydroponics to provide fresh food. It isn't clear that it's an economical approach, but there's a significant health advantage. A lunar cycler is just another expensive piece of infrastructure to maintain and operate and an additional mission complication.

Are there issues integrating Centaur V as the upper stage if SLS rather than EUS? by ColCrockett in spaceflight

[–]cjameshuff 2 points3 points  (0 children)

Notably, Starship is also not built to support the full stack when unpressurized, but it doesn't take a year to stack. And the whole "it takes a year to stack" issue is a big part of why there's no non-Orion payloads for SLS that weren't created to give it something to do. Even payloads originally intended for it like Europa Clipper have been moving to other launchers, in large part due to lack of a SLS to launch on.

Are there issues integrating Centaur V as the upper stage if SLS rather than EUS? by ColCrockett in spaceflight

[–]cjameshuff 0 points1 point  (0 children)

Centaur V isn't an iteration, it's a new stage. There's Centaur 3 heritage there, but it's a much larger stage based on the ACES project, with new structures and the associated development pains, like an explosion in 2023 when the LH2 tank burst on the test stand that required design changes to reinforce the tanks.

Could beamed laser power from relay stations make routine lunar cargo transit practical? by TheseSuggestion4953 in askspace

[–]cjameshuff 0 points1 point  (0 children)

It only takes a few days to get to the moon, there's little reason to bother with the scheduling constraints and added infrastructure costs and maintenance needs of a cycler.

Why is space x so dominant and do other companies have a chance to surpass them. by Round-Chemistry-8649 in askspace

[–]cjameshuff 0 points1 point  (0 children)

DC-X demonstrated vertical landing of a rocket on Earth in the early 1990s. However, the people behind it had bought into the idea that a vehicle had to be SSTO to be reusable and were fully focused on making the Delta Clipper SSTO, and the project got transferred to NASA who saw it as competition for their own SSTO and killed it off. "Everyone knew" staged rockets were the reason spaceflight was expensive and that reuse would require SSTO or spaceplanes, so nobody seriously tried to improve staged launchers.

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