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My first thought when I heard they were going to try a landing like this years ago was that it could never be safe and reliable. I'm still thinking that.
It only needs to be moderately successful to have a significant economic impact on launch costs.
My first thought when I heard they were going to try a landing like this years ago was that it could never be safe and reliable. I'm still thinking that.
I'm not sure if humans will propulsively land on Earth from space in the next few decades, but hardware certainly is and Starship will be no different. Just bigger.
I imagine SpaceX has a backup plan for commercial Starships where they sacrifice a few passenger seats for auxiliary parachutes and beefier landing legs. It's a tough prospect, though, because until you get an engine out, you don't know how much compressed explosive rocket fuel (and worse--oxidizer!) you're going to be landing on top of...
If humans land propulsively, I think they're going to have to figure out something other than a "suicide burn" (where the engines bring velocity from terminal to zero exactly as the vehicle touches down).
The test articles might not be, but I bet a Starship commuter rocket with payload will be heavy enough that it can hover on a single engine upon landing. (Minimum throttle thrust-to-weight <1).
It's a tough prospect, though, because until you get an engine out, you don't know how much compressed explosive rocket fuel (and worse--oxidizer!) you're going to be landing on top of...
At least it's fairly benign stuff- methane and LOX, nothing too fancy.
I dont think its safe for us to say they havent yet... Probably anyone visiting here would keep quiet as not to be harrassed and examined and such.... With the vastness of space,I would assume we have had visitors already,they have gone gone un-noticed..
The main reason I'm skeptical of visitors from other planets is it assumes a civilization slightly (within a few thousand years of technological development) more advanced than ours. Less than that and they can't visit, more than that it's unlikely we'd be capable of knowing they're here unless they want us to. It isn't impossible, but it's a narrow window given the age of the milky way. Intelligent species would have to be very common, or we'd have to be very lucky.
The main reason I'm skeptical of visitors from other planets is it assumes a civilization slightly (within a few thousand years of technological development) more advanced than ours. Less than that and they can't visit, more than that it's unlikely we'd be capable of knowing they're here unless they want us to. It isn't impossible, but it's a narrow window given the age of the milky way. Intelligent species would have to be very common, or we'd have to be very lucky.
The main reason I’m sceptical about visitors from other planets is that the distance between Star systems is truly colossal. Our nearest neighbor, the Alpha Centauri triple system is over 4.2 light years away, which amounts to 24 trillion miles.
That stuff almost killed the Apollo-Soyuz crew in 1975 after landing.
And that's not even the worst one. Rocketeers have tried some crazy stuff. There's an excellent book on the 1950s development - "Ignition" - that demonstrates just how nuts they were.
At one point in time, they were delving into fluorine chemistry - nice high energy density in fluorine bonds. The challenge being not having that energy run away to breathe free when you don't want it to. The most manageable candidate was chlorine trifluoride - which had advantages in details like melting and boiling point, and didn't detonate spontaneously, unlike a good deal of other energetic fluorine compounds.
It did have drawbacks, though:
Quote:
It is, of course, extremely toxic, but that's the least of the problem. It is hypergolic with every known fuel, and so rapidly hypergolic that no ignition delay has ever been measured. It is also hypergolic with such things as cloth, wood, and test engineers, not to mention asbestos, sand, and water —with which it reacts explosively. It can be kept in some of the ordinary structural metals — steel, copper, aluminum, etc.
- because of the formation of a thin film of insoluble metal fluoride which protects the bulk of the metal, just as the invisible coat of oxide on aluminum keeps it from burning up in the atmosphere. If, however, this coat is melted or scrubbed off, and has no chance to reform, the operator is confronted with the problem of coping with a metal-fluorine fire. For dealing with this situation, I have always recommended a good pair of running shoes.
I'll take LOX every day of the week.
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