OT: Earth landing.

[Tim+]

Okay, I know the film is an advert and bits of it are cgi, but what they have achieved is still very cool.

Tim

[Albert Zweistein]

That is really amazing, I thought they'd lost it about 30 ft before touchdown but it executed a pretty amazing recovery. Powerful computers and thrust vectoring I assume.

[Tim Streater]

Why no parachutes to slow the descent?

[Albert Zweistein]

I suppose that if you want to land at a specific spot parachutes don't cut it. Once something is dangling from a chute the wind blows it all over the place. Plus it's another layer of complexity/source of failure. These are just guesses, my rocket science is a bit rusty these days. :)

[charles]

Special Forces a manage it.

[Albert Zweistein]

Sometimes and usually on non-windy days I suspect.

[Tim+]

Hard to see but it looked like all the vectoring was being done by a single rocket motor rather than the more usual multiple motors.

I guess "simplicity" makes for reliability but vectoring a main engine that quickly must need some pretty clever engineering.

Tim

[Albert Zweistein]

Yes it looks like a single nozzle device. It does seem to be astoundingly agile. It looked like Space-x were gonna make it here but it toppled at the last moment.

[newshound]

Impressive though this is, it actually does not compare technically to what Elon Musk's team have done.

Dreadful coverage in the Guardian, see the comments section for more details

[Tim+]

Um, can't speak for others but I wasn't trying to compare it to any other team's operations.

As a "stand alone" feat of engineering, it's impressive.

Tim

[Dave Liquorice]

Presumably because you have a surfit of thrust? There is enough thrust to lift the thing reasonably quickly off the lauch pad fully laden so coming back in without most of the fuel load and the capsule you could "bounce" the thing on the thrust without too much bother.

Assuming the voice over is vaugely in sync with reality from 1'45" the thing goes from > 2,000'/second (1,300 mph) to 100'/second (70 mph) in about 4 seconds when the engine fires. It also appears to actually stop at about 50' then decend to the ground.

The landing of the passenger capsule looks a bit hard to me but then so do the Soyuz landings...

[Albert Zweistein]

Especially as regardless of other companies near misses it's the first time it's been done.

[newshound]

Not true, Musk's smaller prototype did it ages ago. The dramatic spacex failures which you have seen are for something with orbital capability, and this is very far short of that.

[Albert Zweistein]

I see you are quoting Musk on that. Of course I'm sure he's completely unbiased...lol.

[newshound]

No, there are other detailed comments in both Guardian CIF and in The Average.

I am also slightly influenced by the fact that the Bezos video is obviously a slick PR effort, while Musk released untouched video of the failures.

It is all part of a PR game, and Musk plays it as much as anyone. But, in this case the evidence is that Bezos played the media and a lot of people have bought it.

And let's not forget that Musk, presumably for safety reasons, is landing his MUCH LARGER rocket on a platform at sea with a few metres of swell. Altogether a more challenging exercise.

[Dave Liquorice]

capability,

But it is far easier to balance a short stubby marker pen on your finger than a new pencil. B-)

[Albert Zweistein]

Tim+ pointed that out in the OP but anyway the actual technical achievement is as shown in the video.

How so? In any case Musk's successful attempts were only prototypes.

They land it where they launch and an equator launch gives you a head start energy wise, nothing to do with safety. That's why ESA launches from obscure equatorial countries. Musk probably didn't wanna get tied down in some jungle or other.:)

I know I posted the link in this thread. I haven't got a downer on Musk though, I'm a big fan of what he's done/is attempting to do. He's probably a better human being than Bezos too although I haven't met either of them. :)

[Albert Zweistein]

Too true blue, so for spaceflight short and stubby aces long and thin if you want to land the silly thing afterwards. I know there are ballistic arguments for long and thin but I'm sure they aren't necessarily binding.

[Tim+]

Not sure that analogy works. Try balancing a pencil on one finger, then a broomstick. I know which one I find a *lot* easier.

Tim