A landing on an airless Earth, launched from the moon? It would be a bit more efficient than the moon landing, because the spacecraft would be at its heaviest (with a full stack of stages fully loaded with propellant) in low lunar gravity and would be doing its final braking in Earth's heavy gravity after burning most of its propellant and discarding most of its stages, but gravity losses are fairly small in comparison to the overall acceleration/deceleration requirements. You'd need something of similar size, just with fewer first stage engines to get it off the moon.

> they would presumably cheaply adjust their incoming trajectory to be as close to the ISS orbit as possible

That's a pretty major presumption. It can be hard enough just intercepting Earth, requiring that interception to also occur with the probe trajectory aligned with the orbital plane of the ISS would greatly restrict the set of targets we could retrieve samples from.

Numerous military commanders throughout history have landed a force with ships, and then destroyed the ships to eliminate any option of retreat. You might not prevent people centuries down the line from rebuilding communications equipment or spacecraft to go back to Earth, but you could make it so there's nothing there to go back to...

Enceladus is fairly deep in Saturn's gravity well, hence the tidal heating that drives its activity. There's numerous icy moons that would be easier to get ice from, even moons of Saturn.

> On the other hand, would it be easier to collect millions of tiny bodies in the asteroid belt of even mine ice from Ceres due to vicinity to Mars when aligned?

The Belt asteroids would be a relatively expensive place to get ice, in part because they're closer. It takes a substantial delta-v to reshape their orbits to hit Mars.

Kuiper belt objects could be sent in towards Mars for less than a km/s of delta-v, if you're willing to wait a few decades for them to arrive. Note that getting out there to send them back is also going to take a long time.

That part kind of works: the light from further sources was emitted at longer wavelengths. But you have to not only shrink everything material, but shrink the interactions with light while not shrinking the light in transit, increase the rate at which physical processes happen while objects shrink (since otherwise the speed of light would appear to increase as distances shrink), etc. There's a whole mess of things you have to adjust that mean other things need to be adjusted in compensation, all while covering up any physical sign that any of this is happening. It doesn't lead to any new understanding and certainly doesn't simplify things, so it's little more than an academic curiosity.

Even if we had a way to mathematically model his path through a black hole, something that the current state of theory considers outright impossible, we wouldn't have any of the numbers needed to plug into it.

It seems like the third stage separated and ignited normally, and that's attached to the front. Maybe it broke away before that though, the CGI was obviously not an accurate depiction of what was going on.

They keep doing this to themselves, putting themselves into a position where they can't take advantage of an opportunity they didn't plan for. They ridiculed the idea of using reusable boosters because they wouldn't be able to keep the production lines busy at the 12 launches a year they planned to do.

It happened about a minute into the second stage burn, and lasted for the remainder of the burn. https://youtu.be/CokbWoYm9w4?t=1103

It looked like it lit, burned a while, then something happened that caused the plume to become much wider and more diffuse, and the stage was either gyrating or tumbling. Maybe a major failure of the nozzle?

CO2 and water for full combustion. Since rockets run fuel-rich, also some CO, H2, and a little elemental carbon...the methane itself decomposes at high temperatures. There's also a little bit of nitrogen oxides produced when the hot exhaust mixes with the air.

Hydrolox rockets technically don't produce CO2, but producing the hydrogen does. And while you could technically produce carbon-neutral hydrogen, you could also use that hydrogen with captured CO2 to make carbon neutral methane, and the latter's much less energy intensive to store and will have far lower losses due to leakage. Plus, hydrogen-burning rockets usually need solid boosters to get off the ground, and those put out all sorts of noxious stuff, including lots of carbon and lots of hydrogen chloride.

You have to keep the scale in mind though. Even a Starship launch only uses about a thousand tons of methane (most of its propellant by mass is liquid oxygen). Global consumption in 2021 was about 8 billion tons per day, just losses to leakage were several hundred thousand tons per day. All rocket launches together are in the rounding error of total emissions. In short, any effort spent on them is wasted, no matter how effective it is...you could eliminate rocket emissions entirely and make no difference globally.

The biggest problem with Spinlaunch isn't the physics, it's the economics. The big complicated launcher, the acceleration hardened hardware and requirements for the payload to be similarly hardened, the mass penalties that result and mean the payload will be less functional for its mass, even ignoring the things it's just not feasible to harden for those launch stresses, the limited target orbits...all of this adds to costs and limits flexibility, with the explicit goal of reducing propellant requirements in exchange.

The problem: the total propellant cost for a Falcon 9 launch is around $200-300k. One Falcon 9 launch is equivalent to around 80 Spinlaunch launches in a direct mass comparison, likely double or triple that when you account for the mass penalties on the Spinlaunch side, so that's around $1-2k for a Spinlaunch-equivalent payload. The booster is bigger and more expensive, but hey, SpaceX reuses that part, and in fact burns extra propellant to do so. Spinlaunch is a fundamentally misguided attempt at optimizing something that's almost totally irrelevant. Yaney doesn't understand why launch is expensive, he hasn't bothered to learn anything about the subject, he's just convinced that his "vision" is enough. In space launch, it isn't.

Additionally, Spinlaunch requires a huge flight rate, they've spoken of launching over a dozen times a day. There simply aren't enough individual satellite launches to provide that kind of business, so it needs a Starlink-scale megaconstellation to keep it busy. However, such a customer won't see any benefit from Spinlaunch, they don't need individual launches to customized orbits on a short schedule, they need bulk deliveries of satellites to common orbits. They can get that more cheaply and faster with other launchers, and without having to harden thousands of satellites against the Spinlaunch launch accelerations.

They may not be about to conquer space and then the world, or even grab any unusually valuable territory, but:

1. they are genuinely growing in capability at a rapid rate.
2. it would be better to overestimate them than underestimate them.
3. there's a sizable group of people who are more motivated by national competition than by anything else. It's not my reason to support space, but it gets support for space. And frankly, peaceful cooperation and "common heritage of mankind" blather isn't getting us anywhere.

..."now"? They've pretty consistently been coming second only to SpaceX in launch rate and mass to orbit, and have been regularly flying astronauts to their own space stations.

And that sample of one actually shows that intelligent life can exist for evolutionarily long periods without advancing much technologically. We spent over 3.3 million years using stone tools. The Neolithic only ended about 6.5 thousand years ago. The period we spent slowly refining stone tools was over 500 times as long as the entire period from discovering how to use copper to landing on the moon. Whole new species of humanity evolved and died out in that timeframe.

And animal life had been around for about 500-600 million years before the first humans popped up. It took until a couple hundred million years ago for the first mammal-like species to show up. And there's evidence that single-celled life first showed up about 3 billion years before the first animals, about as soon as Earth could support it.

From that single example, it looks like a planet could potentially spend a very long time without animal life, with only non-tool-using animal life, or with intelligent life but very primitive technology, and that none of these steps are particularly inevitable. Or it could have gone much faster than it did here. Other examples, if we ever find them, are likely to have quite different histories.

And that's the sidereal rotation period, with respect to the stars. Since Venus rotates in the opposite direction to its revolution around the sun, an actual solar day, the time taken to rotate with respect to the sun, is 116.75 Earth days, a bit over half the orbital period.

Another number that gives some perspective: over six times that mass of meteoric material hits Earth each day.

Even that's understating it a bit. You could put 5 other objects in Earth's orbit around the sun, as far from their neighbors (including Earth) as they are from the sun.

And asteroid sizes roughly follow a power law, with many, many more small asteroids than large ones. The sixth most massive asteroid has only 2% of the mass of the 5 most massive asteroids, which together hold over 60% of the mass of the entire belt. You could put 60% of the belt's mass in Earth's orbit without any of it getting closer to Earth than to any of the other objects or the sun itself.