If "it is not a lie" you **prove your claim** that Neither alternative is **possible**. **A spacecraft orbiting Earth cannot ever change orbit to orbit Mars and land.**

If you can't do that I stand by what I said!

OK. I assume we all agree that any spacecraft/rocket sent from Earth orbits Earth and that Earth gravity controls shape of the orbit.

Sorry, we disagree almost straight away. Once the spacecraft is no more than one *Hill radius* from Earth, about 1.5 million km, it is essentially in orbit around the Sun and the Earth's gravitation has very little control.

The *Hill radius* can be calculated from where *r*_{H} is the *Hill radius*, *a* is the average Earth-Sun distance, *M* is the mass of the Sun and *m* is the mass of the Earth.

From here until it gets inside the *Hill radius* of Mars the spacecraft can follow a *Hohmann transfer orbit* about the Sun.

So going to Mars starting from Earth you are always orbiting Earth until you one way or other arrive at Mars,

No, you are not!

Once outside the *Hill radius* of the Earth the Earth's gravitation has very little control.

For almost all the distance the spacecraft is in a Solar orbit - what's so difficult to understand about that?

Then the spacecraft can enter an orbit about Mars or head directly to a landing. Both require rocket retro-thrusts to slow it down.

*<< I'll ignore that rest of this crap! >>*

Try again!

Well, any human built spacecraft/rocket leaving Earth always orbits Earth. It cannot possibly orbit the Sun! Only the planets orbit the Sun. A spacecraft leaving Earth cannot start orbiting the Sun.

If said spacecraft is well within the

*Hill radius* of Earth it will continue orbiting Earth but if it's placed in an orbit outside the

*Hill radius* it would

*eventually* end up in a Solar orbit.

A spacecraft in a LEO at 200 km above the surface can be put into a

*Hohmann transfer orbit* to 2 million km orbit with a DeltaV of just over 3200 m/s - no problem!

The Hill radius? What is it? Listen!

An astronomical body's Hill radius is the radius of the sphere (Hill sphere) within which smaller bodies would tend to orbit the body. Outside the radius, the body would be drawn to orbit around the next larger body which the initial hosting body is orbiting. For example, the Moon is within Earth's Hill radius, and if it weren't, it would not retain a stable orbit around Earth but would eventually orbit around the Sun. If outside the Hill radius, it can still take multiple orbits before the smaller body breaks away.

Sure, if left to itself "If outside the Hill radius, it can still take multiple orbits before the smaller body breaks away".

But once at that radius you have to apply the extra DeltaV to put that spacecraft into its

*Hohmann transfer orbit* to Mars.

Why is that any problem?

OK, believing this rubbish any spacecraft/rocket leaving Earth orbit suddenly starts orbiting the Sun instead, because it is bigger than Earth.

Nobody, except YOU, ever said that it "suddenly starts orbiting the Sun instead"!

OK. But how does my spacecraft then flies on to planet Mars? How to get out of Sun orbit?

Do I have to explain every little obvious step to YOU?

Once at that radius you have to apply the extra DeltaV to put that spacecraft into its

*Hohmann transfer orbit* to Mars.

But, of course, there's also no big reason why enough DeltaV could not be applied direct from LEO though sometimes these extra steps are used to correct for small errors in velocity.

*<< Insults ignored >>*