Obama's capsule conundrum, what you hadn't noticed?

Broaden your thinking, Rob! It doesn't have to look just like Apollo!

You make the mistake of assuming that the same vehicle used for ascent and reentry will be used for leaving earth orbit. The new policy intends to encourage the development of robust, efficient commercial transport to and from LEO over the next few years. With that system in place, it is not at all obvious that the best exploration architecture is a single dedicated vehicle for going all the way from the launch pad to the Moon or beyond. This is precisely the point of the proposed new emphasis on R&D to develop propellant depots, more efficient in-space engines, etc., which can enable dedicated exoatmospheric (and possibly reusable) vehicles. In the long run, this is how humanity will expand into the solar system, not with "Apollo on steroids."

Wow. only one commenter before me and he (Bill H.)echoes my sentiments exactly. Why must the beyond LEO vehicle be the earth re-entry vehicle. It seems to me to be an inefficient, dangerous and expensive assumption.

Naturally there are trade-offs. My point is to not prejudge the architecture. If possible you want to leverage the infrastructure since it will already be paid for. Commercial capsules will all doubtless be designed to stay on station at ISS for at least six months. ISS is not the best departure point because of its orbit, but perhaps a Bigelow station in an equatorial orbit would be available. You will need more fuel to reenter LEO if you don't do aerobraking, but you won't have to haul your TPS to the moon. There are lots of trades to consider. Let's look at all the options and not just assume an Apollo-style architecture.

Didn't think there was still any intention of leaving Earth orbit. NASA was now just another National Science Foundation. Space taxis between lunar & Earth orbit have been fantasized for years. Suspect the structural wear of repeated aerobraking, the need for variable payloads, & the need for ground based maintenance made them uneconomical.

VASIMR, Rob. Gets you to your destination and then back into LEO to rendezvous with your re-entry vehicle. Then refuel the VASIMR module and wait for the next crew.

orion is irrelevant, that is why it was cancelled

what does a space ship need with a heat shield and almost zero radiation shielding? this isn't the 60s

The spacecraft delivering crew from Earth to orbit and vice versa should do just that, and nothing else. Fly to a depot in geosync or L1 or whatever, leave it there, and hop onto your interplanetary s/c which doesn't carry all that massive TPS and such.

The interplanetary craft (Bigelow module with a vasimr; if a B-module can be boosted from Earth at a few g's, it most certainly can be boosted in space at a fraction of a g) flies from Earth L1 to Phobos or some other high-orbit depot, where, again, dedicated entry vehicles are stored for use locally. Just the way a big harbor works today.

It seems actually cruel to me, to put four dudes in a can the size of Orion and keep them in there for half a year! (And that's just the outbound leg.)

I'm not an engineer, so I'll defer to what Bill said as it sounds correct. My point is that there are options rather than having an Apollo style mission. The larger point should be that the only meaningful exploration in human history happened when there was a commercial driver. At over a half century of spacefaring we can and should push the commercial option along. That will open up other options around natural extensions of commercial LEO both technically and financially. We flat out don't have the money for the big government architecture that Ares embodies. I do think that we should continue/retain the goal of going to the moon and Mars, but set the bar for commercial entities to do it. That's the American way.

Bill, Jake, Moose: spot-on! We need a smarter way to do all this. Too bad we already blew 12 billion bucks to figure it out. B-2, F-22, F-35, Marine One, KC-X: What do we not understand about government 'procurement'?

Regarding heat shields, only one commercial capsule has even entered the preliminary design phase (manned Dragon), and it uses a PICA heat shield, which has already been proven to handle speeds of up to 28,000 mph (PICA was used on the Stardust mission). Since Elon Musk has a longing for interplanetary travel, he was probably thinking ahead when he over-speced the heat shield. Capsules from other commercial providers haven't been through the requirements phase yet, so there's no reason NASA couldn't ask for capsules capable of lunar or interplanetary re-entry.

If the plan is to build orbital fuel depots I would imagine it is for a reusable in-space ship. What is the point of building a gas station in space if you are going to spend billions on hardware and jettison everything after returning from the moon, mars or an asteroid but a capsule?

If we are going to stay with the apollo model and jettison billions in hardware after every flight it will never be sustainable. Reusable space based vehicles that can be refueled and launch again is the only way to proceed.

I was rather surprise by the apparent demise of Orion too, but we are still early in the game. Orion may rise again ;-). Upgrading space station taxis for service beyond LEO isn't that difficult. Why do we need to develop a super capsule now? Isn't over-specification also a problem? The Shuttle is a great example of this.

Hensley: "Commercial capsules will all doubtless be designed to stay on station at ISS for at least six months."

Why? Don't prejudice the design, a wise poster said a few hours back (wasn't it you?). With critical-speed evacuation covered by last-chance inflatable descent vehicles and liesurely-evacuation covered by a robust surge capacity from Earth, why require all taxis be certified for 6-12 months? Why not 3-4 days, and see what that does to your design and cost?

"ISS is not the best departure point because of its orbit, but perhaps a Bigelow station in an equatorial orbit would be available."

I used to think that, too, until a wise old celestial mechanician beat me mercilessly about the head and shoulders with his, uh, I think he called it a slice-rule' or something, it looked really ancient... But I digress...

With very cheap plane changes at very distant apogee, and escape burns at next perigee, interplanetary departures into any desired heliocentric plane, from any original geocentric orbital plane, have been available already -- look at some of the Japanese probes in recent years.

The critical payload penalty of accessing ISS from KSC can be 20-30% or more for the shuttle because you're carrying wings up and back. With more-efficient payload fractions, the actual energy penalty is much, much less -- on the order of 3-4 % or less.

This may amaze and astound, but that's what the numbers tell us.

So -- escape the old paradigms. Once the new infrastructure architecture is laid down, it may endure for the rest of the century, so let's get it as right -- well, as non-REALLY-wrong -- as possible.

JimO // jameseoberg at comcast dot net

Do not forget: Politicians will lie to your face.

There will be little chance of us ever seeing a U.S. Manned Space Program in our lifetimes if they kill this program. Why? Because there is always other priorities to these people... like bailing out Auto Manufactures who are to big for their market or banks that don't know how to manage money.

I am all about passing the hat for donations to keep this alive and would consider it money worth spending.

The closest near earth asteroid mission I've heard of so far would involve a round trip time of at least 6 months. I'd hate to do that in a capsule alone.

At the least a fairly capable Centaur-type propulsion module is needed. Why not also add one of Bigelow's inflatable habitat modules. The capsule does not need to do everything. A Dragon-type capsule might do just fine with beefed up TPS and heatshield. Other components might need to be beefed up for a longer service life as well.

Rob is right about the lack of a beyond LEO return vehicle in the Obama/Bolden budget. But Orion had problems of it's own, which in theory, can now be bypassed.

The Orion's Apollo-moldline is really only suitable for reentry speeds of lunar return class mission, and not for the higher speeds of a Mars mission. Sure sure, one could modify a Mars architecture to barely permit Orion to suffice, but to do so makes an ugly and very expensive hash of the Mars architecture. Griffin's moon fixation was reflected in forcing Orion into the Apollo shape and would have in every practical sense limited manned operations to the cis-lunar region.

The last released document I had seen using Orion for a Mars mission showed a horrifically massive architecture that dwarfed the previous Design Reference Missions for Mars. Orion (in current form) is an albatross that a potential Mars mission is well rid of.

The thickness of a generic LEO capsule heat shield may be just fine for high velocity entry (2x orbital energy), IF you increase the total heat shield area by a factor of two, giving lower area loading and thus lower erosion rate.

This might be accomplished via an add-on kit installed at the orbital depot, with an multiple segment skirt surrounding the base of the capsule. This could also allow an asymmetric planform to enable higher L/D entry, and would keep the plasma farther from the capsule walls in the wake.

Bottom line, your LEO delivery vehicle can be scarred for add-on kits, but not carry their mass penalty during the manned ascent to orbit. On-orbit depots can supply more than just fuel...

If your capsule had a transpiration cooled shield, you might be able to upgrade it for high velocity entry by just adding coolant and increasing the flow rate.