The Parker-type 5 meter water shield massing over a thousand tons can only be propelled by a single off-the-shelf system; nuclear pulse propulsion.

The polar opposite of such a fully shielded nuclear propelled spaceship is the unshielded chemically propelled spacecraft. In between are many variations. NASA seems to have entertained a NTR which is low risk but also low performance.

http://www.youtube.com/watch?v=WoiVej1rccs

I strongly desire to give credit to Dr. Eugene Parker and illustrator Kent Snodgrass for this graphic which if anything should be a huge draw for STEM in our school system (the subject matter is mathematically related in very interesting ways).

This magazine article in Scientific American concerning heavy nuclei really caught my attention in 2006. Unlike the rest of the human race which seemed to be flying on left-over wheaties from the 50’s I was up to 2002, the year after 911, when “Project Orion, the true story of the atomic spaceship” was published. Making the connection between massive shielding and nuclear pulse propulsion seemed obvious (to me) but no one else has caught on and recognized the very narrow path to humans expanding into the solar system.

U.S. space policy has been infamously lost in space for several decades. The national goal to be pursued has always been, in the public mind at least, to gain Lebensraum. The only clearly defined plan for implementing such a move to the stars has been “The High Frontier” of Gerard K. O’Neill back in the 70’s. Nothing ever materialized concerning space solar power. A cislunar network using lunar resources is the only new plan for any true commercial space project.

I think you’re right. A LOX/LH2 lunar lander could be designed that could stay in orbit for months without any significant loss of fuel. I like to toy with notional designs for reusable LOX/LH2 lunar landers that take advantage of NASA’s emerging zero boil-off cryocooler technology. By simply adding solar panels to the landing vehicle, cryocoolers could be utilized to re-liquify ullage gases:

An SLS Launched Cargo and Crew Lunar Transportation System Utilizing an ETLV Architecture

http://newpapyrusmagazine.blogspot.com/2014/01/an-sls-launched-cargo-and-crew-lunar.html

But I’m absolutely obsessed with the simplicity of the Spudis/Lavoie architectural concept of storing water at orbital depots for eventual conversion into propellant. While solar powered crycoolers could store liquid oxygen and hydrogen for several years, water could be stored indefinitely!

Pre-deployed water depots should make it pretty easy, IMO, to travel to the orbits of Mars, Venus, and maybe even as far out as the asteroid belt and back to cis-lunar space with simple hydrogen/oxygen chemical rockets– if interplanetary vehicles are initially launched from the Earth-Moon Lagrange points.

Marcel

Yes the Lunar resource architecture. Actually I was thinking of privately funded donations. Yes I know $88 Billion is a LOT of money. –

If fund was just for exploration rather mining lunar water, it should cost considerably less than 88 billion
to explore the Moon in order to find if and where there was minable water.

One could of it think of it like an Google Xprize, but have prize 300 million rather than 30 million, And one could various type of exploration prizes which could total 5 to 10 billion.
As example, one could have a prize that find a location on the Moon where at the surface [less than a foot depth] there 5% water concentration. One could also have addition prize that find 10% and one for more than 15%.
One also have a prize for find 1 ton or more of pure ice. And a prize for mining a ton of lunar water.

The need to launch within hours/days of the first launch in a dual launch scenario was an artifact of the 1 ½ launch scenario adopted for Constellation Systems (CS).

The reason was the boil off of propellant (especially hydrogen) from the Earth Departure Stage (EDS) while waiting for the crew launch. The original CS requirements called for the capability to launch as much as 90 days later, but that caused an un acceptable oversizing of the EDS.

In the dual launch configuration we are discussing the lunar lander is delivered (by its own EDS) to Low Lunar Orbit (LLO) first then (when it has been checked out) the crew is launched on the second flight to LLO to rendezvous/ dock with the lander. While boil off would still be an issue for the lander its tanks would be much smaller than those for the EDS and easier to better insulate.

As you pointed out the Shuttle was launched 9 times in one year from a single pad (an average of once about every 41 days). While I agree it would not be optimal and would prefer 2 pads and faster launches, that period between launches is probably doable – at least for some initial period.

We are in complete agreement about the need for the RS-25E. I wonder if the administration will try to slow that down.

You also can’t have multiple SLS launches until the expendable RS-25E engines are finally in production, hopefully, by 2021.

Marcel

Would almost make someone think they are not serious about the Mars proposals.

Somehow I do not think that is going to fly. Packaging fissionable material and sending it outside the magnetosphere to be played with is not an impossible safety challenge but…….lighting off a nuclear torch in Low Earth Orbit? No.

I am not a fan of NTR even though these engines have been tested. A reaction one million times more powerful than chemical combustion yet an ISP only twice that of conventional propellents.

It depends on where you fuel and launch your reusable orbital transfer vehicle. Its probably a non-starter from LEO because the delta-v requirements are at least 4.3 km/s just to achieve a Mars transfer orbit. But from the Earth-Moon Lagrange points, approximately 1km/s or less would be required.

Thousands of tons of water shielding are required only if you are– permanently– stationed at a habitat in space for the rest of your life. But for interplanetary vehicles traveling for only a few years round trip, only 50 centimeters of water would be required to protect passengers from major solar events and heavy nuclei while also reducing exposure to cosmic radiation during the solar minimum (the worse conditions) to less than 25 Rem per year. So a large two habitat rotating interplanetary vehicle would require only a couple of hundred tonnes of water shielding in order to avoid reaching 50% of the lifetime exposure limit for the most vulnerable passengers (young women around 25 years of age).

Cosmic Radiation and the New Frontier

http://newpapyrusmagazine.blogspot.com/2014/03/cosmic-radiation-and-new-frontier.html