Yep. The way forward is for an government space agency to master cis-lunar space ops w/GP hardware and associated spacecraft, refine methods and procedures through the experience of establishing long duration habitation on Luna, servicing same by contracting private firms then modify/adapt that knowledge base for a human expedition to Mars- if the robots report it is even worth the trip. It may not be in this era if the planet is peppered with inexpensive and reliaboe probes. That’s your space program for the next 80 years. It’s a better bet you’ll see a permanent base on the moon before you’ll see any human expeditions out to Mars. If a SRM or two make the run and return Martian soil and rocks for analysis– what’s the hurry to send crews and all the necessary support materials out. Besides, we should really wait for Elon to get there and build those condos for retirement.

And without out a government financed, faux destination to give it life-support, it would be dead, or still born. Paging Conestoga One.

Stop “believing” get to actually know. You will open your world to a totally different, fascinating and very refreshing perspective. Believing is not enough with facts. You have to know the facts.

“If either McCain or Romney had been able to win the Presidency, neither man would’ve destroyed Project Constellation, the way BO had.”

It must be wonderful to live in Chris Castro World, and to not have to face up to reality.

The Constellation program was doomed the moment Michael Griffin decided to circumvent all the spiral development work that had been done, and instead use a “Apollo on steroids” architecture. From there on the program became financially unsustainable and affordable.

Oh, and McCain questioned the program at the beginning, so yes, McCain would have quickly killed it too – he knows a bloated program when he sees it.

For a manned trip to the moon SEP or any form of electric propulsion is not a favorable method and carring enough chemical propellant fora round trip without aerocapture impossible. EP is much too slow for the trip vs. Chemical. It could be used for cargo but not people. Also you can return from the moon or cis-lunar space in about 3-4 days and there is the free return trajectory enabling you to return to earth with little to no use of propellant. Here having a capsule makes a lot of sense.

On trips out to Mars or NEO, SEP is a very favorable form of propulsion that could enable you to return to earth orbit at the end of the mission. There are questions about the survivability of direct reentry from these velocities(higher g forces, more heat generated from reentry). Your spacecraft is very soon out of range where you could return in a capsule; whereas for the moon, you are never out of range of return. Free return trajectories are much harder to nonexistent. Here dragging the mass of a capsule become more questionable. It could enable you to return faster (leaving the ship to return via SEPor be disposed of(eweh!)) but that is about it.

Also remember most of the mass of an chemically powered spacecraft is propellant so you will need to haul up just about as much mass to send something back out to EML-1 and there is less ability to do inspection and repair in space…not to mention that a bad aerocapture could put you in to an orbit with no ability to reach the station. The mass of the heat shield is rather small.

Also a direct landing on earth that did not land where it intended could have some degree of surviablity(depending on system..i.e. Orion has lots of ocean to land in, and Soyuz/Dragon/CST-100 just need somewhere flat or fail that a body of water), a lifting body like Dream chaser may be able to steer to an alternate route or bail out. A craft in the wrong orbit and unable to reenter would force a requirement that the craft needs to support a crew long enough for rescue or the crew will die. There was a NASA proposal that did return to the ISS and it requires the craft support the crew for a month to allow the shuttle to launch a rescue mission!

There are also issues with launch windows on return(every ten or so day to or from EML-1/2) to the ISS vs. anytime return from EML-1 . Anyway the most likely place for something like Nautilus-X to park would be EML-1 or EML-2 . Departure from EMl -1 or eml2 is like .14km/s in terms of Delta V vs. 3.22ish from LEO. So it is smart not to bring a reusable in-space spacecraft down to LEO unless you have to. It easier to give a small mass a big push(i.e. the capsule) than to have to push a large mass(Natilus X) out.
If you had lots of chemical propellant available at EML-1 cheaply, then it might make sense to return to a LEO station but direct reentry for the most part would be a very strong contender for all the above reasons. Also needing a truck to restock the vehicle after a mission and using workers on the ground is going to be cheaper than needing a Cygnus and astronauts to do so. It may be a long time before the economics favor in-space LEO to EML-1.

A LEO station however can make a good starting off point because it allows you to preposition things. i.e. If you left from the from, you wouldn’t need to launch 2 rockets in extremely short order(48 hours) like CXP or forced to cram everything into one like Apollo. You wouldn’t need to develop boil off technology to the same degree since the EDS stage could be sent after the crew or the station could provide active cooling and a sun shield to extend on orbit time.

“The Commercial Space companies require vast amounts of subsidizing money!”

Tell us how much money NASA is paying SpaceX to build the Falcon Heavy, which is the largest rocket since the Saturn 5?

Hmm?

“Unmanned cargo capsules able to dock to NDS ports using remote control are probably needed.”

I haven’t seen the design details of the Alpha Station that covers liquids replenishment, so we don’t know if they need a vehicle like Progress or ATV that has liquids transfer capability in it’s docking port. However all Commercial Crew vehicles can be operated autonomously, so they can all haul cargo without crew.

We need to hear more from Bigelow on how the logistics of his stations will work, amongst other things. Still too little public information, but no doubt Bigelow has this already figured out.

“I suspect that the cycle will be launch the spacecraft on a launch vehicle to LEO. In LEO either refuel or add an expendable inspace stage and fly to an EML spacestation. Change vehicles, after performing the Mars or Moon trip return to the EML spacestation. Use the original spacecraft to perform a direct re-entry to Earth. After a few repairs the spacecraft may be reusable.”

Today NASA seems to be of two minds regarding this. When they talk about Orion/MPCV, they talk about dragging it around with them no matter where they go. Let’s call this the Apollo model of space transportation.

But when the people in NASA that aren’t beholden to the Orion/MPCV talk about space travel, and they talk about Nautilus-X being the next step for them, then what you propose would likely be the next evolutionary step in space transportation.

After that, then a reusable Earth-EML vehicles can be inserted into the mix when it is determined whether using the atmosphere to slow down or fuel (or both) works best depending on the infrastructure available (i.e. is fuel assumed to be plentiful, or scarce).

“If it has a heat shield the spacecraft may as well go all the way, but will need a stronger heatshield.”

It’s a speed vs cost equation here. For speed, yes, you would just haul your heatshield around with you so you can return to Earth whenever you want. But if you are basing your transportation system on cost, and it costs a lot of money to lift that spacecraft out of Earth’s gravity well, then carrying around a smaller heatshield for stopping in LEO would be a better choice.