Quote from: Artemis3 on January 17, 2019, 09:03:06 PM

Quote from: Spendulus on January 16, 2019, 03:56:53 AM

Note that I referenced THINGS THAT EXIST. The Orion exists and is a deep space capable vehicle.

If you want to extend the subject to conceptual plans, would you like to see a hundred? Of which you have shown one, right?

There is a lot wrong with this particular scheme that you linked to. It may interest you that for the US Apollo program, a similar "single big rocket lander and return vehicle" concept was considered, and abandoned, in favor of the Saturn stages, command module and lunar excursion module.

Mathematics and physics dictated that decision. The original research paper comparing and contrasting the two approaches is available from the NASA archives; but one may also calculate directly.

Spacecraft are optimized to transit in space. They can use propulsion systems that won't work to land on planets or take off, but which are very practical for missions like 8 months to mars. (VASIMR, ion propulsion).

Landers, re entry vehicles and launch vehicles are all optimized for specific mission profiles.

Don't get me wrong, I'm all for going into space and staying there. But there's either a practical business model or there's not, and more of the same-old-same-old grubbing for government dollars is not going to make this all happen. Nay-sayers shut down the Apollo program early, in the Clinton years NASA was given a choice: The space station or the shuttle.

In that case there is nothing to do but wait until they deliver. Do you think SpaceX doesn't know about the advantages / disadvantages of staging? I see them using stages in their current rockets, up to the falcon heavy...

On the other hand, how many years have passed since the Apollo program? You'd think some advances have been made in all these years. They want to reuse parts, yet they can't recover the second stage in their current rockets. Perhaps keeping it all together allows them to achieve that goal?

In my opinion, they are going to waste more fuel by not using stages, but don't forget they don't plan to go straight away, they plan to refuel in orbit so the fuel they need is only to reach orbit, not Mars. The more efficient engines for vacuum/light atmosphere are already attached to the spacecraft.

Once (if) these concepts become reality, we can see if they were wrong or not. At the very least, they have been delivering results so far.

FYI, the debate over "keeping it all together" started WITH the Apollo program, and physics/math defeated it.

But the concepts continued, and found advocates during the 1980s. In the 1990s BMDO created the Delta Clipper test vehicle.

https://www.youtube.com/watch?v=o2sHf-udJI8

That used four RL10 h2/o2 engines as a proof of concept. That's where these ideas come from, they do not originate with SpaceX.

With Mars mission profiles though, I can guarantee you that the concept drawing you showed me is not feasible and the opposite of optimum. Let's just say it's ridiculous. Elon Musk is not going to open up Mars to humanity with bad ideas. But who knows, maybe someone will talk some sense into him.

I am curious, though. Why would you not see the merit in a true spacecraft, something that could loop continually between Mars and Earth? It could have artificial gravity, use ion propulsion, be extremely lightweight as it would never be stressed by gravitational fields, and in every way be optimized for deep space extended travel. As an example of this, consider that you could attach a suitable propulsion unit, and send the ISS to mars and back.

Then you would have ferry style transports at each planet.