Friday, January 09, 2009

A Cheap Solution for Getting to Mars?

Knight's proposal, which he calls "Mars on a Shoestring," outlines two shuttles going into Earth orbit, hooking them together with a truss and strapping on a powerful enough propulsion system. And that's pretty much it. A pressurized inflatable conduit would connect the two orbiters so the astronauts could go back and forth between the two shuttles.

Then comes the really cool part; a way to provide artificial gravity during the trip to Mars.

More on this inspiring idea here.


Anonymous said...

A one way ticket to mars? Any volunteers?

nergal said...

Yeah, that's a bunch of flight tested hardware and all, but *man* that's a lot of excess mass to push to mars. Plus the shuttles were designed for LEO and have no protection from solar storms and the like. The more I look at it, the more this only seems a good idea if we have to launch for mars at the next closest approach and worry about how to get home later. Only development time would be saved; even dev money would still have to be spent to get them home, or even just to send more people. Wow, though - talk about thinking outside the box.

Intense said...

Although Eric Knight, a former advertising copywriter and the author of this brief, non-technical paper characterizes it as a "thought experiment," this concept qualifies as an incredibly bad, totally impractical idea from both a fiscal and engineering perspective at the very least. The devil is in the most basic details.

There are so many misconceived and ill-considered things wrong with this idea, it's difficult to know where to even begin.

The Space Shuttles were designed for low earth orbit (LEO), and for use in LEO for a maximum of a couple weeks in orbit at any one time. Any trip to Mars using conventional rocket propulsion would take a minimum of 9 to 10 months. But let's look at just a few of the primary obstacles that makes this idea extraordinarily awful, as a different kind of "thought experiment," shall we?

First, Knight suggests the two shuttles rendevous in orbit, where, somehow, a large truss structure will then be, in orbit, assembled and connected underneath each shuttle, and a large propulsion stage, or orbital launch rocket (which itself would have to fueled in orbit, which would be more than tricky, since it's never been done--would we then need to use a third shuttle as some kind of flying rocket fuel tanker? Or a fourth shuttle to heft the truss structure into LEO?) is then attached.

Think about how long the ISS has been under construction, and the difficulty of working in LEO conditions. Even if the fuel, propulsion system, and truss assembly are brought up to LEO piece by piece, like with the ISS, this requires many shuttle missions at an average cost of $1.5 billion each, and would, over the time required, take months or years to get these "shoestring" components of such a launch from orbit interplanetary mission to LEO and then assembled safely and properly. Consider also the diversionary costs of the multiple billions of dollars just to even begin to retrofit two shuttles in the manner he suggests for "interplanetary flight."

The details noted in this paper would make Rube Goldberg blush with envy--Knight thinks, for example, the two shuttles could be tethered together, after in some unknown manner ejecting the truss and huge fueled rocket structure into space after travel velocity has been achieved, nose to nose, "a few hundred feet apart" and spin around each other, or a Knight puts it, "set the pair into an elegant pirouette" on their way to Mars to provide "a comfortable level of artificial gravity for the crew's voyage," while simultaneously installing a "crew-transfer conduit" -- a "pressurized, accordion-style inflatable system that connects the airlock hatches of the two orbiters so that the crew could freely move between the two spacecrafts."

Yeah, right, Mr. Knight. Two shuttles, going tens of thousands of miles per hour, weighing over 90 tons each, attached nose to nose with a "tether" while spinning around each other and with a plastic accordion tube stretched over "a few hundred feet" between them. Remember the last time the shuttle experimented with a tethered, relatively small object? The tether broke. I also suspect there may be a few problems with such small issues as mass, inertia, and thrust/stress forces involved. Not to mention energy supplies on the way to Mars. The current shuttle fuel cells on-board only last a few weeks. Do we then need to jerry-rig large solar panels to these spinning shuttles for power? Or add plutonium-based reactors for electrical energy? What about meteorite protection?

The shuttles also have completely inadequate radiation shielding for interplanetary travel, and would require a massive research, design and heavy shielding retrofit, plus there is insufficient space for the nearly one-year one-way voyage that would be required for sufficient oxygen, food, crew living space, etc., and, the best part, Knight's idea also posits dropping from Mars orbit two 180,000 pound Space Shuttles, if they could even get there without the crews dying, on very large parachutes (even though the atmosphere of Mars is extremely thin compared to Earth, the shuttle would be travelling into Mars atmosphere at over Mach 2, and launching a parachute, which would have to over 300 ft wide, in a supersonic descent low to Mars surface would result in an abrupt and unavoidable crash), to land with no means of leaving--a one way trip, which ridiculously presumes the crews, if they survived the trip (unlikely) and the descent to Mars (even less likely) would then be required to be "settlers" on Mars, with no adequate provisions for habitat or means to generate oxygen, food, or energy for sustainable use on Mars.

So, if you didn't die getting out of Earth orbit, or go insane cooped up in the extremely limited space onboard the shuttles with your fellow astronauts for nearly a year, or crash onto Mars as your football-field sized parachute was shredded by supersonic drag effects, and you actually survived landing, you could look forward to a delayed death on Mars. Who would be both qualified, and insane enough, to sign up for such a fate?

Any crew that would actually be able to get to Mars would be dead within days or weeks of landing. Frankly, they'd more probably be dead before they ever got near Mars, if they even got out of Earth orbit, considering all the real-world variables. Consider also the time it would take to lift to orbit and assemble a truss structure and rocket assembly, while in LEO, to propel the twin shuttles. Weeks or probably months. Considering the history of shuttle launch scheduling, perhaps a few years.

What great PR for NASA that would accomplish, eh? Think how all this would affect NASA's budget and current technical difficulties and already existant delays in the ARES and Constellation projects already under budgetary review and stress.

Knight's plan would also likely require refueling pit stops in interplanetary space by cryogenic means, which has also never been done, and which suggests pre-flight launches of "fuel depots" of some unknown kind between Earth and Mars be setup beforehand. More tens of billions of dollars in ludicrous, wasted preparatory launch and R&D expenses. Oh, and btw, in the midst of a deep recession that may become a devastating depression. The idiocy of Knight's fantasy is breathtaking in its naivete and obtuseness.

This is a remarkably terrible idea. Knight adds a few final notes to his paper, where he says, "This thought paper is certainly not meant to be the technical be all, end all on the topic -- but merely a springboard to new thought.

"The science and topics touched on herein are superficial; the concepts are simply provided to fuel the imagination and promote discussion."

Superficial indeed and in fact.

I'd say what this horrendously misconceived and terribly poor quality idea of Knight's (and how absolutely stupid it is on any practical level) will spur most is a discussion of just how absurd this bizarre concept actually is. This isn't creative or lateral "thinking outside the box"--it's just fabulously dumb, and better characterized as a fantastic way to waste tens of billions of NASA/taxpayer dollars, kill a bunch of astronauts, impugn and negatively impact the future of manned spaceflight, and could be best noted as "Knight's folly." Mars on a shoestring, my ass: this would be the most expensive, least productive "shoestring" in the history of spaceflight, and doomed to inevitable failure.

See: and
for further reservations about this "thought experiment" and Knight's curious background. As Scotty would say to Kirk, "It cannot work, Captain!"

Hate to be a downer, but on so many levels, this idea is completely and uttterly D.O.A., even as a "thought experiment."