In article ,
says...

On 2018-03-16 16:15, Jeff Findley wrote:

Block 1 will almost certainly not be Mars landing capable.

If it is able to propulsively land on Earth, doesn't that more or less
imply ability to land on Mars?

Block 1 might not be able to be refueled, so it couldn't get to Mars in
the first place. The first block will almost certainly be less capable
than later Blocks. Even SpaceX might not know all its limitations until
it's tested. There is no real substitute for test flights.

I write engineering software for a living. It's "garbage in, garbage
out". If the engineers don't input exactly the right constraints,
loads, material properties, and etc. the best simulation in the world is
still going to give you a wrong result. That's why you test, to verify
that your design actually works the way you intended.

Look at how many tries it took SpaceX to land a Falcon 9 first stage.
Many things had to be tweaked until they got it right.

The first Block of BFR/BFS will not be perfect.

How much bigger would the paddles have to be to have same aerodynamic
control in Mars atmosphere vs Earth?

From pictures and drawings, there are no grid fins on the Big Falcon
Spaceship (2nd stage).

The Big Falcon Rocket (1st stage) has them, but it's entirely
suborbital. It's never going to orbit let alone Mars.

Jeff
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